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2,500 | Prolonged ventricular asystole, sinus arrest, and paroxysmal atrial flutter-fibrillation: an uncommon presentation of vasovagal syncope. | We described a 55-year-old woman with recurrent syncope, complete atrioventricular (AV) block, sparsely scattered idioventricular beats lasting for 56 seconds, and long sinus arrest recorded during the syncopal episode. Paroxysmal atrial flutter-fibrillation was also presented during Holter electrocardiograph (ECG) monitoring without clinical symptom. During tilt test, atrial flutter with variable AV block was induced and the patient suddenly passed out. The vasovagal syncope was successfully treated with a DDD permanent pacemaker with a rate drop response algorithm. Vasovagal syncope with concomitant ventricular asystole and sinus arrest is rare. Aggressive management with permanent pacemaker is strongly advocated in malignant vasovagal syncope. |
2,501 | Sympathetic nerve sprouting, electrical remodeling, and increased vulnerability to ventricular fibrillation in hypercholesterolemic rabbits. | Whether hypercholesterolemia (HC) can induce proarrhythmic neural and electrophysiological remodeling is unclear. We fed rabbits with either high cholesterol (HC, n=10) or standard (S, n=10) chows for 12 weeks (protocol 1), and with HC (n=12) or S (n=10) chows for 8 weeks (protocol 2). In protocol 3, 10 rabbits were fed with various protocols to observe the effects of different serum cholesterol levels. Results showed that the serum cholesterol levels were 2097+/-288 mg/dL in HC group and 59+/-9 mg/dL in S group for protocol 1 and were 1889+/-577 mg/dL in HC group and 50+/-21 mg/dL in S group for protocol 2. Density of growth-associated protein 43- (GAP43) and tyrosine hydroxylase- (TH) positive nerves in the heart was significantly higher in HC than S in protocol 1. Compared with S, HC rabbits had longer QTc intervals, more QTc dispersion, longer action potential duration, increased heterogeneity of repolarization and higher peak calcium current (ICa) density (14.0+/-3.1 versus 9.1+/-3.4 pA/pF; P<0.01) in protocol 1 and 2. Ventricular fibrillation was either induced or occurred spontaneously in 9/12 of hearts of HC group and 2/10 of hearts in S group in protocol 2. Protocol 3 showed a strong correlation between serum cholesterol level and nerve density for GAP43 (R2=0.94; P<0.001) and TH (R2=0.91; P<0.001). We conclude that HC resulted in nerve sprouting, sympathetic hyperinnervation, and increased ICa. The neural and electrophysiological remodeling was associated with prolonged action potential duration, longer QTc intervals, increased repolarization dispersion, and increased ventricular vulnerability to fibrillation. |
2,502 | Serum C-reactive protein elevation in left ventricular remodeling after acute myocardial infarction--role of neurohormones and cytokines. | We previously reported that increased peak serum C-reactive protein (CRP) level after acute myocardial infarction (AMI) was a major predictor of cardiac rupture and long-term outcome. The aim of this study was to clarify the role of serum CRP elevation as a possible marker of left ventricular (LV) remodeling after AMI.</AbstractText>We prospectively studied 31 patients who underwent primary angioplasty for a first anterior Q-wave AMI. Peak serum CRP level was determined by serial measurements after admission. LV volume and the plasma levels of various neurohormones and cytokines were measured on admission, and 2 weeks and 6 months after AMI.</AbstractText>Patients with higher peak CRP levels (above the median) had a greater increase in LV end-diastolic volume during 2 weeks after AMI (+21+/-14 vs. +5+/-6 ml/m(2), P=0.001) and a lower ejection fraction (45+/-11 vs. 53+/-7%, P=0.02) than those with lower CRP levels, associated with a higher incidence of pump failure, atrial fibrillation, and LV aneurysm. Plasma levels of norepinephrine, brain natriuretic peptide, and interleukin-6 2 weeks after AMI were higher in the high CRP group than in the low CRP group.</AbstractText>Increased peak serum CRP level was associated with a greater increase in LV volume after anterior AMI. Plasma norepinephrine and interleukin-6 levels were increased in patients with higher CRP levels, suggesting a possible role of sympathetic activation and enhanced immune response in the development of LV remodeling after AMI.</AbstractText> |
2,503 | Effect of diurnal variability of heart rate on development of arrhythmia in patients with chronic obstructive pulmonary disease. | We examined the possible effect of diurnal variability of heart rate on the development of arrhythmias in patients with chronic obstructive pulmonary disease (COPD). Forty-one COPD patients (M/F: 39/2, mean age: 59+/-8.5 years) and 32 (M/F: 27/5, mean age: 57+/-11 years) healthy controls were included. Twenty-four hour ECG recordings were analyzed for atrial fibrillation (AF) or ventricular premature beats (VPB), and circadian changes in heart rate variability (HRV) were assessed by dividing the 24-h period into day-time (08:00-24:00 h) and night-time (24:00-08:00 h) periods. Night-time total (TP), low frequency (LF) and high frequency (HF) powers were similarly lower from day-time parameters in AF(-) COPD patients (HF 3.91+/-1 vs. 4.43+/-1.04 ms(2), P=0.001) and controls (HF 3.95+/-0.72 vs. 4.82+/-0.66 ms(2), P<0.001). The LF/HF ratios were also significantly reduced in the same patient groups (AF(-) COPD 1.35+/-0.21 vs. 1.27+/-0.19, P=0.04, controls 1.43+/-0.14 vs. 1.24+/-0.09, P<0.001). Night-time TP and LF were increased, HF unchanged and LF/HF significantly increased (1.11+/-0.25 vs. 1.19+/-0.27, P<0.05) in AF(+) COPD patients. Frequency of VPB was correlated with corrected QT dispersion (QTc(d)) (r=0.52, P=0.001) and the day-time/night-time HF ratio (r=0.43, P=0.02). Patients with QTc(d)>or=60 ms did not have the expected increase in night-time HF and had a statistically insignificant increase in LF/HF ratio. In COPD patients with QTc(d)<60 ms, circadian changes in HRV parameters were parallel with the controls. We concluded that COPD patients with arrhythmia had circadian HRV disturbances such as unchanged night-time parasympathetic tone and disturbed sympatho-vagal balance in favor of the sympathetic system all day long, which may explain the increased frequency of arrhythmia. |
2,504 | Cardiac arrhythmias in pregnancy: clinical and therapeutic considerations. | Pregnancy can precipitate cardiac arrhythmias not previously present in seemingly well individuals. Risk of arrhythmias is relatively higher during labor and delivery. Potential factors that can promote arrhythmias in pregnancy and during labor and delivery include the direct cardiac electrophysiological effects of hormones, changes in autonomic tone, hemodynamic perturbations, hypokalemia of pregnancy, and underlying heart disease. Paroxysmal supraventricular and ventricular tachycardia may cause hemodynamic compromise with consequences to the fetus. Management of arrhythmias in pregnant women is similar to that in non-pregnant but a special consideration must be given to avoid adverse fetal effects. No drug therapy is usually needed for the management of supraventricular or ventricular premature beats, but potential stimulants, such as smoking, caffeine, and alcohol should be eliminated. In paroxysmal supraventricular tachycardia, vagal stimulation maneuvers should be tried first. Adenosine or a cardioselective beta-blocker could be used if vagal maneuvers are ineffective. Alternatively, verapamil or diltiazem may be given. In pregnant women with atrial fibrillation, the goal of treatment is conversion to sinus rhythm or to control ventricular rate by a cardioselective beta-adrenergic blocker drug or digoxin. Ventricular arrhythmias may occur in the pregnant women with cardiomyopathy, congenital heart disease, valvular heart disease, or mitral valve prolapse. Termination of ventricular arrhythmias can usually be achieved by intravenous lidocaine or procainamide or by electrical cardioversion. Amiodarone is not safe for the fetus. Beta-blocker therapy must be continued during pregnancy and postpartum period in women with long QT syndrome and torsade de pointes. |
2,505 | Long-term improvements in quality of life by biventricular pacing in patients with chronic heart failure: results from the Multisite Stimulation in Cardiomyopathy study (MUSTIC). | To assess the impact of biventricular pacing on quality of life over 12 months of follow-up, 76 patients in the MUSTIC trial were evaluated by 2 instruments: The Minnesota Living with Heart Failure Questionnaire and the Karolinska Quality of Life Questionnaire. MUSTIC is a randomized, controlled study to evaluate the effects of biventricular pacing in patients in New York Heart Association class III heart failure with intraventricular conduction delay. Following a single, blind, crossover comparison of 3 months of biventricular pacing to inactive pacing (sinus rhythm group) or ventricular-inhibited pacing (atrial fibrillation group), 85% of patients preferred and were programmed to biventricular pacing and were followed for 12 months. In parallel with clinical improvements, substantial benefits in quality of life for most broad domains of quality of life and cardiovascular symptoms were found during biventricular pacing already within the crossover phase with a maintained benefit over the 12-month follow-up. Biventricular pacing improved quality of life in patients with heart failure and intraventricular conduction delays. The benefits were sustained over 12 months of follow-up. |
2,506 | Acute and long-term results of radiofrequency ablation of common atrial flutter and the influence of the right atrial isthmus ablation on the occurrence of atrial fibrillation. | The purpose of this study was to evaluate the acute success rate and long-term efficacy of radiofrequency ablation of common type atrial flutter (AFL) by using a standardised anatomical approach in a large series of patients and to assess the influence of right atrial isthmus ablation on the occurrence of atrial fibrillation. There are no large scale prospective or retrospective multicentre studies for radiofrequency ablation of AFL.</AbstractText>The study population consisted of 363 consecutive patients with AFL (mean age 58+/-16 years, 265 men) who underwent radiofrequency ablation at the inferior vena cava-tricuspid annulus (IVC-TA) isthmus using a standardised anatomic approach. Bidirectional isthmus block at the IVC-TA was achieved in 328 patients (90%). Following radiofrequency ablation, 343 patients (95%) were followed for a mean of 496+/-335 days. During the follow-up period, 310 patients (90%) remained free of AFL recurrences. Multivariate analysis identified five independent predictors of AFL recurrence: fluoroscopy time (p<0.001), atrial fibrillation after AFL ablation (p=0.01), lack of bidirectional block (p=0.02), reduced left ventricular function (p=0.035) and right atrial dimensions (p=0.046). Atrial fibrillation occurrence was significantly reduced after AFL ablation (112 in 343 patients, 33%) as compared to occurrence of atrial fibrillation before radiofrequency ablation (198 in 363 patients, 55%, p<0.001).</AbstractText>The current anatomical ablation approach for AFL and criteria for evaluation of the IVC-TA isthmus block is associated with an acute success rate of 90% and a long-term recurrence rate of 10%. Radiofrequency ablation of common AFL results in a significant reduction in the occurrence of atrial fibrillation.</AbstractText> |
2,507 | Nicotine gum-induced atrial fibrillation. | A 39-year-old man with no prior history of atrial fibrillation was hospitalized with atrial fibrillation and a rapid ventricular rate. For the 7 months before presentation, he had been chewing nicotine polacrilex gum on his own. The week he first developed palpitations, he was chewing more than 1 piece of nicotine Polacrilex gum per hour during work. His diagnostic work-up during hospitalization found no cause for atrial fibrillation. He was cardioverted to sinus rhythm. At 6-month follow-up, he had not renewed chewing nicotine polacrilex gum, was in sinus rhythm, and had no history of palpitations. The temporal relation between more frequent gum usage and the excessive consumption of nicotine polacrilex chewing gum with a probable high serum nicotine level at the time the patient developed his first episode of atrial fibrillation suggests a causal relationship. |
2,508 | A case of complete situs inversus. | Complete situs inversus is a rare syndrome, with overall frequency estimated at 1/10,000 births, resulting from abnormal rotation of the cardiac tube during embryogenesis, of unknown mechanism. Recent studies suggest that left-right asymmetry defects are likely to be due to genetic abnormalities in the lefty, nodal, i.v., HAND, ZIC3, Shh, ACVR2B and/or Pitxz genes. In dextrocardia with situs inversus the heart is structurally normal in 90-95% of cases, in contrast to dextroversion (dextrocardia with situs solitus), which has a high incidence of structural cardiac defects. Atrial septal defect is one of the most common congenital cardiac anomalies in adults. Diagnosis is based on clinical manifestations and simple complementary diagnostic exams like abdominal and thoracic radiography and electrocardiogram. Prognosis in isolated dextrocardia depends on the congenital cardiac defects present. By contrast, in dextrocardia with situs inversus life expectancy is similar to that of the general population. The authors present the case of a 64-year-old German man admitted to the emergency care unit with a diagnosis of embolic stroke due to atrial fibrillation with fast ventricular rate. As clinical history could not be assessed due to language limitations, routine admission tests were performed. They revealed complete situs inversus with corrected ostium secundum atrial septal defect. Finally, the anatomic, pathologic, embryologic and etiologic features of complete situs inversus and related abnormalities of the cardiac structures are presented. Special emphasis is given to genetic abnormalities, the study of which has seen great advances since the 1990s thanks to new techniques of DNA analysis. |
2,509 | [Cardioversion for atrial fibrillations: not better than ventricular rate control].<Pagination><StartPage>636</StartPage><EndPage>638</EndPage><MedlinePgn>636-8</MedlinePgn></Pagination><Abstract><AbstractText>Atrial fibrillation is a frequent cardiac arrhythmia in the elderly, which can be treated either by rate control, or by rhythm control through chemical or electrical cardioversion. Rate control is easily achieved, but leaves the arrhythmia with its inherent risk of heart failure and stroke intact. Although rhythm control is logistically more complex to obtain, it does restore normal sinus rhythm. However, dangerous antiarrhythmics are then needed to maintain this. Recently, two randomised trials showed that rate control is not inferior to rhythm control. Restoration and maintenance of sinus rhythm was accompanied by a higher incidence of death, ventricular arrhythmias, heart failure, stroke and the need for permanent pacemaker implantation. Recurrent atrial fibrillation can be treated optimally by rate control through digitalis, beta-blockers or calcium antagonists, accompanied by oral anticoagulation. Once the sinus rhythm has been restored, oral anticoagulation should be continued.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Verheugt</LastName><ForeName>F W A</ForeName><Initials>FW</Initials><AffiliationInfo><Affiliation>Universitair Medisch Centrum St Radboud, afd. Cardiologie, Postbus 9101, 6500 HB Nijmegen. [email protected]</Affiliation></AffiliationInfo></Author></AuthorList><Language>dut</Language><PublicationTypeList><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList><VernacularTitle>Cardioversie voor atriumfibrilleren: niet beter dan ventrikelfrequentieverlaging.</VernacularTitle></Article><MedlineJournalInfo><Country>Netherlands</Country><MedlineTA>Ned Tijdschr Geneeskd</MedlineTA><NlmUniqueID>0400770</NlmUniqueID><ISSNLinking>0028-2162</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000319">Adrenergic beta-Antagonists</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000889">Anti-Arrhythmia Agents</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000925">Anticoagulants</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D002121">Calcium Channel Blockers</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D004071">Digitalis Glycosides</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000319" MajorTopicYN="N">Adrenergic beta-Antagonists</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D000889" MajorTopicYN="N">Anti-Arrhythmia Agents</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D000925" MajorTopicYN="N">Anticoagulants</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000188" MajorTopicYN="Y">drug therapy</QualifierName><QualifierName UI="Q000628" MajorTopicYN="N">therapy</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002121" MajorTopicYN="N">Calcium Channel Blockers</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002561" MajorTopicYN="N">Cerebrovascular Disorders</DescriptorName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004071" MajorTopicYN="N">Digitalis Glycosides</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D010138" MajorTopicYN="N">Pacemaker, Artificial</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D016896" MajorTopicYN="N">Treatment Outcome</DescriptorName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2003</Year><Month>4</Month><Day>26</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2003</Year><Month>6</Month><Day>11</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2003</Year><Month>4</Month><Day>26</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">12712644</ArticleId></ArticleIdList></PubmedData></PubmedArticle>
<PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">12712609</PMID><DateCompleted><Year>2003</Year><Month>06</Month><Day>20</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>18</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">1019-5297</ISSN><JournalIssue CitedMedium="Print"><Issue>1</Issue><PubDate><Year>2003</Year><Season>Jan-Feb</Season></PubDate></JournalIssue><Title>Likars'ka sprava</Title><ISOAbbreviation>Lik Sprava</ISOAbbreviation></Journal>[Structural manifestations of changes in lipid metabolism at the blood-gas barrier developed following prior ventricular fibrillation in patients in the acute period of myocardial infarction]. | Atrial fibrillation is a frequent cardiac arrhythmia in the elderly, which can be treated either by rate control, or by rhythm control through chemical or electrical cardioversion. Rate control is easily achieved, but leaves the arrhythmia with its inherent risk of heart failure and stroke intact. Although rhythm control is logistically more complex to obtain, it does restore normal sinus rhythm. However, dangerous antiarrhythmics are then needed to maintain this. Recently, two randomised trials showed that rate control is not inferior to rhythm control. Restoration and maintenance of sinus rhythm was accompanied by a higher incidence of death, ventricular arrhythmias, heart failure, stroke and the need for permanent pacemaker implantation. Recurrent atrial fibrillation can be treated optimally by rate control through digitalis, beta-blockers or calcium antagonists, accompanied by oral anticoagulation. Once the sinus rhythm has been restored, oral anticoagulation should be continued.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Verheugt</LastName><ForeName>F W A</ForeName><Initials>FW</Initials><AffiliationInfo><Affiliation>Universitair Medisch Centrum St Radboud, afd. Cardiologie, Postbus 9101, 6500 HB Nijmegen. [email protected]</Affiliation></AffiliationInfo></Author></AuthorList><Language>dut</Language><PublicationTypeList><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList><VernacularTitle>Cardioversie voor atriumfibrilleren: niet beter dan ventrikelfrequentieverlaging.</VernacularTitle></Article><MedlineJournalInfo><Country>Netherlands</Country><MedlineTA>Ned Tijdschr Geneeskd</MedlineTA><NlmUniqueID>0400770</NlmUniqueID><ISSNLinking>0028-2162</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000319">Adrenergic beta-Antagonists</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000889">Anti-Arrhythmia Agents</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000925">Anticoagulants</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D002121">Calcium Channel Blockers</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D004071">Digitalis Glycosides</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000319" MajorTopicYN="N">Adrenergic beta-Antagonists</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D000889" MajorTopicYN="N">Anti-Arrhythmia Agents</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D000925" MajorTopicYN="N">Anticoagulants</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000188" MajorTopicYN="Y">drug therapy</QualifierName><QualifierName UI="Q000628" MajorTopicYN="N">therapy</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002121" MajorTopicYN="N">Calcium Channel Blockers</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002561" MajorTopicYN="N">Cerebrovascular Disorders</DescriptorName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004071" MajorTopicYN="N">Digitalis Glycosides</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D010138" MajorTopicYN="N">Pacemaker, Artificial</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D016896" MajorTopicYN="N">Treatment Outcome</DescriptorName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2003</Year><Month>4</Month><Day>26</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2003</Year><Month>6</Month><Day>11</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2003</Year><Month>4</Month><Day>26</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">12712644</ArticleId></ArticleIdList></PubmedData></PubmedArticle>
<PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">12712609</PMID><DateCompleted><Year>2003</Year><Month>06</Month><Day>20</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>18</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">1019-5297</ISSN><JournalIssue CitedMedium="Print"><Issue>1</Issue><PubDate><Year>2003</Year><Season>Jan-Feb</Season></PubDate></JournalIssue><Title>Likars'ka sprava</Title><ISOAbbreviation>Lik Sprava</ISOAbbreviation></Journal><ArticleTitle>[Structural manifestations of changes in lipid metabolism at the blood-gas barrier developed following prior ventricular fibrillation in patients in the acute period of myocardial infarction].</ArticleTitle><Pagination><StartPage>46</StartPage><EndPage>49</EndPage><MedlinePgn>46-9</MedlinePgn></Pagination><Abstract>On the material of necropsies, structural changes were studied in the blood-air barrier in patients in the acute period of myocardial infarction developed in the wake of prior ventricular fibrillation. It has been ascertained that in the lungs, there develop significant alterative changes that are characterized by adipose degeneration and destruction of components of the surfactant system. |
2,510 | Reperfusion-induced arrhythmias are suppressed by inhibition of the angiotensin II type 1 receptor. | We examined antiarrhythmic effects of drugs, including renin-angiotensin system (RAS) inhibitors, on reperfusion arrhythmias in rats in vivo. Anesthetized rats were subjected to 5 min of coronary occlusion and 30 min of reperfusion. Arrhythmia scores, calculated as the product of the type of arrhythmia (1 for ventricular tachycardia, 2 for ventricular fibrillation) and its duration (in seconds), were adopted to evaluate the severity of arrhythmias. Reperfusion arrhythmias were suppressed by Na(+)/H(+) exchange inhibitor, Na(+)/Ca(2+) exchange inhibitor and L-type Ca channel antagonist by more than 90%. Angiotensin-converting enzyme inhibitor and angiotensin II (Ang II) type 1 receptor (AT(1)) antagonist also modestly (by 60-70%) but significantly decreased reperfusion arrhythmias. These effects were not reversed by co-administration of bradykinin B(2) receptor antagonist or AT(2) antagonist, respectively. Effects of superoxide dismutase (SOD) were also examined, but SOD proved ineffective. Effects of Na(+)/H(+) exchange inhibitor, Na(+)/Ca(2+) exchange inhibitor and L-type Ca channel antagonist suggest a causative relationship of Ca overload in reperfusion arrhythmias. These transport systems are known to be activated by Ang II. Thus, the antiarrhythmic action of RAS inhibitors might be attributable to the inhibition of the action of Ang II via AT(1). |
2,511 | Reversible myoglobinuric renal failure following rhabdomyolysis as a rare complication of cardioversion. | Reversible myoglobinuric renal failure following rhabdomyolysis that was related to repeated countershocks delivered for the treatment of refractory recurrent VT and VF attacks during acute myocardial infarction is presented in this case report, in which scan with technetium-99m pyrophosphate has been used for in the diagnosis of extensive skeletal muscle damage. |
2,512 | Biventricular pacing for severe mitral regurgitation following atrioventricular nodal ablation. | A 69-year-old woman developed acute pulmonary edema and severe mitral regurgitation (MR) 2 days following an uncomplicated AV nodal (AVN) ablation and insertion of VVI pacemaker for chronic atrial fibrillation. There was no history of significant mitral valve disease. Left ventricular function was normal and there was no evidence of an acute cardiac ischemic event. Transthoracic echo and right heart catheterization studies showed reduction in the severity of MR with biventricular pacing as opposed to RV pacing alone. A permanent pacemaker configured for biventricular pacing was implanted with complete resolution of symptoms and significant reduction in degree of MR. |
2,513 | A case of a short-coupled variant of torsades de Pointes with electrical storm. | This case report describes a short-coupled variant of Torsades de Pointes with a characteristic ECG pattern consisting of a prominent J wave in leads V3-V6, in which an electrical storm was evoked with autonomic receptor stimulation and a blockade test. The patient's frequent VF attacks were triggered by short-coupled premature ventricular contractions with a right bundle branch block morphology and left-axis deviation, and were suppressed by deep sedation followed by a combination therapy using verapamil and mexiletine. Interestingly, with the use of those drugs, the prominent J wave diminished. The mechanism underlying this syndrome is discussed. |
2,514 | Postoperative ventricular arrhythmias after cardiac surgery: immediate- and long-term significance. | AF is frequent after cardiac surgery. However, ventricular arrhythmias are less known. The purpose of the study was to evaluate the causes and the prognostic significance of severe ventricular arrhythmias occurring after cardiac surgery. For 10 years, among 2,100 cardiac surgeries, 16 (0.8%) patients (13 men, 3 women; age 49-71 years, mean 62 +/- 9 years) without previous ventricular arrhythmias, with preserved left ventricular ejection fraction, and without acute cause of ventricular arrhythmias, developed VF (n = 4) or a sustained VT between 3 days and 3 weeks after cardiac surgery (coronary artery bypass grafting [n = 6], valve replacement [n = 10]). Rapid AF (n = 5) or slow AF (n = 1) were present at the time of VT/VF. Programmed ventricular stimulation occurred after up to three extrastimuli in the basal state and after infusion of 20-30 micrograms of isoproterenol. An echocardiogram, coronary angiography, Holter monitoring with heart rate variability (HRV) study were performed. Ventricular stimulation was negative in six patients (with AF); sustained and clinical VT was induced in 10 patients with a left ventricular ejection fraction > 0.40, except in one patient. Valvular prothesis and coronary bypass graftings were normal. In all patients, HRV was normal before surgery and decreased after cardiac surgery; before versus after surgery, respectively, HR 69 +/- 9 and 89 +/- 30 beats/min (P < 0.01), SDNN 117 +/- 31 and 50 +/- 11 ms (P < 0.001), low frequency (LF) 474 +/- 658 and 51 +/- 40 ms2 (P < 0.05), high frequency (HF) 115 +/- 23 and 33 +/- 32 ms2 (P < 0.05), LF:HF 4 +/- 3 and 1 +/- 0.6 (P < 0.01). Follow-up lasted from 6 months to 10 years (mean 3 +/- 2 years). In patients without induced VT, 1 patient died from asystole, 1 had an ICD but no subsequent events, and the other 4 untreated patients are free of events. Patients with induced VT were treated with amiodarone and beta-blockers except in one patient who died from extracardiac complications. Six of nine patients had no inducible VT with this treatment and are alive; 3 patients had inducible VT, 1 died suddenly before implantation of ICD, and 2 patients are alive with an ICD; recurrent VTs were noted in one patient and received an ICD. In conclusion, recent heart surgery may increase the risk of ventricular arrhythmias. The reduction of indexes reflecting sympathetic and parasympathetic tone could facilitate the occurrence of atrial arrhythmias (and then VT) in patients without ventricular arrhythmogenic substrate or the development of VT/VF in patients with a latent previous ventricular arrhythmogenic substrate. In patients without inducible VT, the prognosis is excellent and an ICD is not recommended in these patients. In those with inducible VT, there is a high incidence of responders to antiarrhythmic drugs with a favorable prognosis. |
2,515 | Prospective randomized comparison of two defibrillation safety margins in unipolar, active pectoral defibrillator therapy. | Various techniques are used to establish defibrillation efficacy and to evaluate defibrillation safety margins in patients with an ICD. In daily practice a safety margin of 10 J is generally accepted. However, this is based on old clinical data and there are no data on safety margins using current ICD technology with unipolar, active pectoral defibrillators. Therefore, a randomized study was performed to test if the likelihood of successful defibrillation at defibrillation energy requirement (DER) + 5 J and + 10 J is equivalent. Ninety-six patients (86 men; age 61.0 +/- 10.3 years; ejection fraction 0.341 +/- 0.132; coronary artery disease [n = 65], dilated cardiomyopathy [n = 18], other [n = 13]) underwent implantation of an active pectoral ICD system with unidirectional current pathway and a truncated, fixed tilt biphasic shock waveform. The defibrillation energy requirement (DER) was determined with the use of a step-down protocol (delivered energy 15, 10, 8, 6, 4, 3, 2 J). The patients were then randomized to three inductions of ventricular fibrillation at implantation and three at predischarge testing with shock strengths programmed to DER + 5 J at implantation and + 10 J at predischarge testing or vice versa. The mean DER in the total study population was 7.88 +/- 2.96 J. The number of defibrillation attempts was 288 for + 5 J and 288 for + 10 J. The rate of successful defibrillation was 94.1% (DER + 5 J) and 98.9% (DER + 10 J; P < 0.01 for equivalence). Charge times for DER + 5 J were significantly shorter than for DER + 10 J (3.65 +/- 1.14 vs 5.45 +/- 1.47 s; P < 0.001). A defibrillation safety margin of DER + 5 J is associated with a defibrillation probability equal to the standard DER + 10 J. In patients in whom short charge times are critical for avoidance of syncope, a safety margin of DER + 5 J seems clinically safe for programming of the first shock energy. |
2,516 | Safety of a controlled-release flecainide acetate formulation in the prevention of paroxysmal atrial fibrillation in outpatients. | The cardiac safety of a once-a-day 200 mg controlled-release formulation of flecainide acetate in the prevention of paroxysmal atrial fibrillation (PAF) was assessed in outpatients.</AbstractText>The drug was administered for 24 weeks to 227 patients diagnosed with recurrent Paf episodes. Cardiac safety was assessed primarily by the maximum change from baseline in QRS duration. Changes in left ventricular function at echocardiography, incidence of proarrhythmic effects determined from ECG and Holter recordings and cardiovascular adverse events were also taken into account to assess cardiac safety. Efficacy was documented by actuarial methods.</AbstractText>Mean maximum QRS increase from baseline was 11.4% (n = 181); QRS increase was < 15% in 71.8% of the patients and > or = 25% in 18.8%. Only 4 patients had maximum QRS value > 100 ms under treatment. Left ventricular ejection fraction remained within +/- 20% of baseline for 90% of the patients, increased above 20% for 8.6% and decrease below 30% for 1.4% (n = 139). Bradycardia (13.2%; n = 129) and ventricular extrasystoles (10.6%; n = 104) were the most frequently identified proarrhythmic effects. Atrio-ventricular block (4.0%), supra-ventricular tachycardia (2.2%), bundle branch block (1.8%) and atrial fibrillation (1.3%) were the most frequent drug-related cardiac adverse events. Estimated treatment success rate was 74% (95% CI: [68%; 80%]) and the incidence of Paf episodes decreased from baseline 28.6% to 11.0% (P < 0.0001).</AbstractText>We provided evidence for a good cardiac safety profile of the controlled-release formulation of flecainide acetate and confirmed the effectiveness of the drug in the prevention of PAF recurrences.</AbstractText> |
2,517 | Blunt chest trauma: an experimental model for heart and lung contusion. | Blunt chest trauma is an important clinical problem leading to injury of the heart and lungs that may be fatal. Experimental models in large animals have been developed previously. This study was aimed at developing a small-animal (rat) model for the purpose of evaluating blunt chest trauma.</AbstractText>Blunt trauma was delivered to the left side of the chest in rats by a captive bolt handgun. The gun was modified so that the amount of energy delivered to the chest wall could be adjusted. The injury energy varied from 1.7 to 6.8 J. Thirty-eight experiments in adult rats were performed. Electrocardiographic monitoring was performed continuously to determine cardiac rhythm. Gross and histologic examination of lungs and heart was performed at the time of death resulting from injury or euthanasia up to 13 days after injury.</AbstractText>Some form of cardiac arrhythmia accompanied blunt chest trauma in every case. Serious ventricular arrhythmia (tachycardia or fibrillation) was nearly always fatal (15 of 16 cases), but gross or histologic evidence of cardiac injury was present in only 31% of fatal cases. Lung injury (often bilateral) as shown by atelectasis and hemorrhage into the parenchyma or airway was found in 93% of the experiments when medium range energy force was applied.</AbstractText>This study has established a useful model for the study of blunt chest trauma in a small animal (rat). Blunt chest trauma is associated with cardiac arrhythmia, which may be fatal. Injury to the heart may not correlate with serious cardiac arrhythmia resulting in death, lending credence to the concept of cardiac concussion or commotio cordis. Lung contusion is always more obvious than morphologic injury to the heart.</AbstractText> |
2,518 | Pulmonary venous flow by doppler echocardiography: revisited 12 years later. | In 2003, pulmonary venous flow (PVF) evaluation by Doppler echocardiography is being used daily in clinical practice. Twelve years ago, we reviewed the potential uses of PVF in various conditions. Some of its important uses in cardiology have materialized, while others have not and have been supplanted by newer approaches. Current applications of measuring PVF have included: differentiating constrictive pericarditis from restriction, estimation of left ventricular (LV) filling pressures, evaluation of LV diastolic dysfunction and left atrial (LA) function, and grading the severity of mitral regurgitation (MR). However, there have been a number of controversies raised in the use of PVF profiles. Using transthoracic echocardiography, there may be technical issues in measuring the atrial reversal flow velocity. The use of PVF in the evaluation of the severity of MR is not always specific and can be affected by atrial fibrillation (AF) and elevated mean LA pressure. Mitral valvuloplasty and radiofrequency ablation for AF, which are the newer applications of PVF in monitoring invasive procedures, are mentioned. This article reviews the important clinical role of Doppler evaluation of PVF, discusses its limitations and pitfalls, and highlights its newer applications. |
2,519 | Cardiopulmonary bypass strategy during concomitant surgical treatment of mitral valve disease and atrial fibrillation. | In recent years, the popularity of simplified intraoperative ablation approaches to treat atrial fibrillation (AF) has been progressively increasing. Our group has described a left atrial procedure based on epicardial radio frequency ablation on cardiopulmonary bypass (CPB). We report our CPB and myocardial protection strategy in 157 patients who underwent AF ablation combined with open-heart surgery from February 1998 to February 2002. Since epicardial ablations are performed on CPB on the beating heart, the CPB strategy is crucial. Total normothermic CPB allows a safe dissection around the pulmonary veins on the decompressed heart; after the ablating catheter has been positioned, an adequate filling of the left atrium favours a uniform contact with the atrial wall. After crossclamping, low-flow retrograde cardioplegia delivery is administered while ablating endocardially to protect the main coronary arteries in the atrio-ventricular groove from radio frequency-related trauma. All patients were successfully weaned from CPB. Sinus rhythm was restored in 152 of 157 (96.8%) patients immediately after surgery. No procedure-related complications were recorded. Epicardial ablations allowed us to reduce significantly the aortic crossclamping time required for ablations. The conduct of CPB and myocardial protection play a central role in the surgical strategy by improving intraoperative feasibility and effectiveness of radio frequency ablation and preventing some of the potential postoperative complications related to the procedure. |
2,520 | A new tool for estimating left ventricular ejection fraction derived from wall motion score index. | Radionuclide angiography (RNA) and echocardiography (biplane Simpson method) are the most accepted techniques for left ventricular ejection fraction (LVEF) assessment. A new method to evaluate LVEF based on the regional wall motion assessment of the LV was attempted.</AbstractText>To develop a simple method for LVEF estimation using wall motion score index (WMSI) with transthoracic echocardiography (TTE).</AbstractText>Two hundred and forty-three patients with abnormal LV contractility had TTE and RNA performed less than three days apart. The WMSI was calculated in all patients using the 16-segment model as proposed by the American Society of Echocardiography. For the first 150 patients, a correlation between LV WMSI and RNA EF was established to create a regression equation. This regression equation (RNA LVEF=92.8-25.8xWMSI) was used on 93 consecutive patients to compare this equation with RNA EF. From the total cohort (243 patients), three subgroups were studied specifically: atrial fibrillation (AF) (n=50 patients), dyskinesia (DK) (n=40 patients) and aneurysm (AN) (n=42 patients).</AbstractText>Correlation between RNA EF and WMSI in the first 150 patients was r=0.82. In the second group of 93 consecutive patients, WMSI EF derived from the estimated regression equation correlated well with RNA EF (r=0.86). Correlation remained high in the three subgroups: AF (r=0.87), DK (r=0.87) and AN (r=0.80). In the 111 patients without DK, AN or AF correlation between RNA and the studied method was even higher (r=0.91). In a random subgroup of 54 patients, RNA was compared with the biplane Simpson method (49 of 54 patients, r=0.82). In the same subgroup of 54 patients, the score was modified to allow for mild hypokinesia (score=1.5) and severe hypokinesia (score=2.5) (54 of 54 patients, r=0.83).</AbstractText>LVEF assessment by this new simple mathematical model using the WMSI is feasible and easy to use during routine TTE. It has excellent correlation with other methods such as biplane Simpson and RNA.</AbstractText> |
2,521 | Physician specialty and quality of care for CHF: different patients or different patterns of practice? | Previous reports have suggested that internists employ evidence-based care for congestive heart failure (CHF) less frequently than cardiologists. Reasons for this possible difference are unclear.</AbstractText>A retrospective review of 185 consecutive patients admitted to a Canadian tertiary care facility between April 1998 and March 1999 with a primary diagnosis of CHF and who were treated by internists (IM group) or cardiologists (CARD group) was conducted.</AbstractText>The CARD group (n=65) was younger (70 versus 76 years, P<0.001) and had larger left ventricular end-diastolic diameter by echocardiography (57 versus 51 mm, P=0.006) than the IM group (n=120). The CARD group documented ejection fraction in 90% of cases versus 54% in the IM group (P<0.05). There was no difference in angiotensin-converting enzyme (ACE) inhibitor usage (68% versus 63%, P=0.48) or optimal ACE dosage (CARD 50% versus IM 42%, P=0.44). Multivariate predictors of ACE inhibitor usage were serum creatinine, male sex, peripheral edema and increasing serum glucose. The CARD group had higher usage of beta-blockers (69% versus 49%, P<0.009), lipid lowering medication (35% versus 17%, P<0.004) and warfarin therapy for atrial fibrillation (74% versus 28%, P<0.005).</AbstractText>The data suggest that Canadian cardiologists and internists use ACE inhibitors equally and care for a relatively similar group of CHF patients. However, beta-blockade, warfarin, lipid lowering therapy and documentation of critical data occurred more frequently under cardiologist care. The possibility that there may be a gradation of adoption of newer guidelines for CHF care according to physician specialty is raised.</AbstractText> |
2,522 | CCORT/CCS quality indicators for congestive heart failure care. | Quality indicators are measurement tools for assessing the structure, processes and outcomes of care. Although quality indicators have been developed in other countries, Canadian cardiovascular disease indicators do not exist.</AbstractText>To develop quality indicators for measuring and improving congestive heart failure (CHF) care in Canada.</AbstractText>An 11-member multidisciplinary national expert panel was selected from nominees from national medical organizations. Potential quality indicators were identified by a detailed search of published guidelines, randomized trials and outcomes studies. A two-step modified Delphi process was employed with an initial screening round of indicator ratings, followed by a national quality indicator panel meeting, where definitions of the indicators were developed using consensus methods. Indicators were designed to be measurable, using retrospective chart review and linking existing administrative databases.</AbstractText>The case definition criterion was developed based on a discharge diagnosis of CHF (International Classification of Diseases, 9th revision [ICD-9] code 428.x), with diagnostic confirmation using clinical criteria. In total, 29 indicators and five test indicators were recommended. Process indicators included prescription for angiotensin-converting enzyme inhibitors, beta-blockers or warfarin (for atrial fibrillation) at hospital discharge. Nonpharmacological in hospital process indicators included evaluation of left ventricular function, weight measurement and selected patient education counselling instructions. Process indicators in the ambulatory setting included prescription and adherence to drug therapies and physician follow-up. Outcome indicators included mortality, readmissions and emergency visits.</AbstractText>A set of Canadian quality indicators for CHF care encompassing organizational attributes, pharmacotherapy, investigations, counselling, continuity of care and disease outcomes has been developed. These quality indicators will serve as a foundation for future studies evaluating the quality of CHF care in Canada.</AbstractText> |
2,523 | Effects of burst stimulation during ventricular fibrillation on cardiac function after defibrillation. | The purpose of defibrillation is to rapidly restore blood flow and tissue perfusion following ventricular fibrillation (VF) and shock delivery. We tested the hypotheses that 1) a series of 1-ms pulses of various amplitudes delivered before the defibrillation shock can improve hemodynamics following the shock, and 2) this hemodynamic improvement is due to stimulation of cardiac or thoracic sympathetic nerves. Ten anesthetized pigs received a burst of either 15 or 30 1-ms pulses (0.1-10 A in strength) during VF, after which defibrillation was performed. ECG, arterial blood pressure, and left ventricular (LV) pressure were recorded. Defibrillation shocks and burst pulses were delivered from a right ventricular coil electrode to superior vena cava coil and left chest wall electrodes. Sympathetic blockade was induced with 1 mg/kg timolol and trials were repeated. The first half of this protocol was repeated in two animals that were pretreated with reserpine. Heart rate (HR) after 1-, 2-, 5-, and 10-A pulses was significantly higher than after control shocks without preceding pulse therapy. Mean and peak LV pressure measurements increased 38 and 72%, respectively, following shocks preceded by 5- and 10-A pulses compared with shocks preceded by no burst pulses. Mean and peak arterial pressures increased 36 and 43%, respectively, following shocks preceded by 5- and 10-A pulses compared with shocks preceded by no burst pulses. After beta-blockade, HR, mean and peak arterial pressures, and mean LV pressure were not significantly different after pulses of any strength compared with control shocks. LV peak pressure following the 10-A pulses was significantly higher than with no burst pulses but was significantly lower than the response to the 10-A pulses delivered without beta-blockade. HR, mean and peak arterial pressures, and mean and peak LV pressure responses after 15 or 30 5- or 10-A pulses were similar to the responses to the same pulses after beta-blockade. We conclude that a burst of 15-30 1-ms pulses delivered during VF can increase HR, arterial pressure, and LV pressure following defibrillation. beta-Blockade or reserpine pretreatment prevents most of this postshock increase in HR, arterial pressure, and LV pressure. |
2,524 | KCNQ1 mutations in patients with a family history of lethal cardiac arrhythmias and sudden death. | Long QT syndrome (LQTS) is the prototype of the cardiac ion channelopathies which cause syncope and sudden death. LQT1, due to mutations of KCNQ1 (KVLQT1), is the most common form. This study describes the genotype-phenotype characteristics in 10 families with mutations of KCNQ1, including 5 novel mutations. One hundred and two families with a history of lethal cardiac events, 55 LQTS, 9 Brugada syndrome, 18 idiopathic ventricular fibrillation (IVF), and 20 acquired LQTS, were studied by single-strand conformational polymorphism (SSCP) and DNA sequence analyzes. Families found to have KCNQ1 mutations were phenotyped using ECG parameters and cardiac event history, and genotype-phenotype correlation was performed. No mutations were found in Brugada syndrome, IVF, or acquired LQTS families. Ten out of 55 LQTS families had KCNQ1 mutations and 62 carriers were identified. Mutations included G269S in domain S5; W305X, G314C, Y315C, and D317N in the pore region; A341E and Q357R in domain S6; and 1338insC, G568A and T587M mutations in the C-terminus. W305X, G314C, Q357R, 1338insC, and G568A, appeared to be novel mutations. Gene carriers were 26 +/- 19 years (32 females). Baseline QTc was 0.47 +/- 0.03 s (range 0.40-0.57 s) and 40% had normal to borderline QTc (< or = 0.46 s). Typical LQT1 T wave patterns were present in at least one affected member of each family, and in 73% of all affected members. A history of cardiac events was present in 19/62 (31%), 18 with syncope, 2 with aborted cardiac arrest (ACA) and six with sudden death (SD). Two out of 6 SDs (33%) occurred as the first symptom. No difference in phenotype was evident in pore vs. non-pore mutations. KCNQ1 mutations were limited to LQTS families. All five novel mutations produced a typical LQT1 phenotype. Findings emphasize (1) reduced penetrance of QTc and symptoms, resulting in diagnostic challenges, (2) the problem of sudden death as the first symptom (33% of those who died), and (3) genetic testing is important for identification of gene carriers with reduced penetrance, in order to provide treatment and to prevent lethal cardiac arrhythmias and sudden death. |
2,525 | Echocardiographic markers of severe tricuspid regurgitation associated with right-sided congestive heart failure. | Severe tricuspid regurgitation (TR), diagnosed with echocardiography, is not necessarily symptomatic. The study aim was to identify echocardiographic markers associated with right-sided congestive heart failure (RCHF) in patients with severe TR.</AbstractText>Ninety-six patients (30 males, 66 females; mean age 67 +/- 11 years) with echocardiographic findings of severe TR were followed clinically and with transthoracic echocardiography (TTE). Clinical data were collected on heavy diuretic consumption and signs of volume overload (neck vein congestion, lower-limb edema, ascites). TTE included evaluation of the right heart chamber dimensions, systolic function, pulmonary pressure and change in inferior vena cava (IVC) diameter during respiration. Patients were subdivided according to the presence (group A, n = 52) or absence (group B, n = 44) of signs of RCHF that included volume overload and heavy diuretic consumption (i.e. > or = 80 mg furosemide/day or combined furosemide/spironolactone at any dosage).</AbstractText>Among the patients, 52 (54.2%) had RCHF and 44 (45.8%) did not. Atrial fibrillation was present in 88% of group A and 76% of group B (p = NS). Group A patients had a significantly larger right ventricular area, right atrial area and IVC diameter than group B patients, but a significantly smaller variation in IVC diameter during respiration (11.2 +/- 8.5% versus 24.3 +/- 14.1%, p = 0.001). Right ventricular systolic function and systolic pulmonary pressure were similar in the two groups. On multivariate analysis, respiratory-related variation in IVC diameter (p <0.001) and systolic pulmonary artery pressure (p = 0.04) were the only independent echocardiographic markers of RCHE CONCLUSION: Diminished respiratory variation in IVC diameter and systolic pulmonary artery pressure are independent markers of volume overload in patients with severe TR. These findings may reflect exhaustion of IVC capacitance due to markedly increased right heart filling pressures, though intrinsic changes in IVC tonus may also be involved.</AbstractText> |
2,526 | Quality of life after mitral valve surgery: differences between reconstruction and replacement. | Quality of life (QoL) is of increasing interest in major surgical procedures. Mitral valve reconstruction (MRr) is assumed to be better tolerated than mitral valve replacement (MVR). The study aim was to assess mid-term QoL in patients undergoing isolated mitral valve surgery.</AbstractText>QoL was monitored in 115 consecutive patients who had isolated mitral valve surgery (62 with MVR, 53 with MRr). Mid-term survival was assessed after a mean of 37 +/- 18 months using the SF-36 health survey questionnaire.</AbstractText>Patients undergoing MVR were younger (61.9 +/- 12.7 versus 64.9 +/- 12.5 years; p <0.01) and had significantly more frequently a history of left heart failure (43.5% versus 13.2%; p <0.01) than patients with MRr. No significant difference was found between the two groups when considering preoperative NYHA functional class and left ventricular function. In-hospital mortality was significant higher in MVR than in MRr patients (6.4% versus 0%; p <0.01). QoL was significantly impaired in patients with MVR in physical function (PF), role function (RF) and general health (GH) compared with patients undergoing MRr. Nevertheless, only slight impairments in two of eight aspects in MVR, and in one of eight aspects in MRr, were found compared with an age- and sex-matched standard population. Mid-term survival was similar in both groups.</AbstractText>Outcome after MVR was excellent, though these patients had a more advanced stage of the disease preoperatively than MRr patients. Mid-term outcome and QoL was, however, similar in the two groups.</AbstractText> |
2,527 | Prediction of paroxysmal atrial fibrillation after aortic valve replacement in patients with aortic stenosis: identification of potential risk factors. | Paroxysmal atrial fibrillation (AF) is a frequent complication after cardiac surgery. The study aim was to identify preoperative predictors of risk for this condition in patients with aortic stenosis after aortic valve replacement.</AbstractText>The influence of clinical, echocardiographic and 24 h electrocardiogram (ECG) parameters on episodes of paroxysmal AF after aortic valve replacement (AVR) in 423 patients (156 women, 267 men; mean age 58 +/- 10 years) with aortic stenosis was analyzed. Episodes of postoperative paroxysmal AF were noted in 120 patients (28%).</AbstractText>Univariate analyses identified the following variables as risk factors for arrhythmia: age, NYHA functional class, history of preoperative paroxysmal AF, left ventricular mass index, >300 supraventricular beats on 24h ECG before surgery, presence of supraventricular tachycardia (SVT), SVT of >5 beats or with a rate >120 beats/min. Concomitant coronary artery bypass (CABG) grafting and presence of enlarged left atrium had no impact. By multivariate analysis, four variables were identified as independent predictors: age (odds ratio 1.7; 95% CI 1.2-2.1); history of paroxysmal AF (OR 3.2; CI 1.4-7.3); presence of >300 supraventricular beats/24 h (OR 1.9; CI 1.1-3.4); and presence of SVT (OR 2.1; CI 1.3-3.4). Discriminatory analysis revealed that a model comprising these four parameters enabled risk prediction in 68% of patients.</AbstractText>In patients with isolated aortic stenosis, age, past history of paroxysmal AF episodes, >300 supraventricular beats/24 h and presence of SVT during 24 h before AVR were predictors of postoperative paroxysmal AF episodes. Left atrial diameter and simultaneous CABG during AVR did not influence the likelihood of postoperative paroxysmal AF.</AbstractText> |
2,528 | Effect of atrial fibrillation and an irregular ventricular response on sympathetic nerve activity in human subjects. | Although the hemodynamic changes associated with atrial fibrillation (AF) have been extensively studied, the neural changes remain unclear. We hypothesized that AF is associated with an increase in sympathetic nerve activity (SNA) and that the irregular ventricular response contributes to this state of sympathoexcitation.</AbstractText>In 8 patients referred for an electrophysiological study, SNA, blood pressure (BP), central venous pressure (CVP), and heart rate were recorded during 3 minutes of normal sinus rhythm (NSR) and 3 minutes of induced AF. In 5 of 8 patients who converted to NSR, right atrial (RA) pacing was performed for 3 minutes in atrial pacing triggered by ventricular sensing mode triggered by playback of an FM tape previously recorded from the right ventricle during AF (RA-irregular) and atrial pacing inhibited by atrial sensing mode at a rate equal to the mean heart rate obtained during AF (RA-regular). SNA data were expressed as percentage of baseline during NSR. SNA increased in all 8 patients during induced AF compared with NSR (171+/-40% versus 100%, respectively; P<0.01). This was associated with a trend for a decrease in BP and an increase in CVP (P=0.02). Similarly, SNA was significantly higher during RA-irregular pacing compared with RA-regular pacing (124+/-24% versus 91+/-20%, respectively; P=0.03). BP and CVP were not significantly different between the 2 pacing modes.</AbstractText>Induced AF results in a significant increase in SNA, which is in part attributable to the irregular ventricular response. Our findings suggest that restoring NSR or regularity might be beneficial, particularly in patients with heart failure.</AbstractText> |
2,529 | Arterial hypertension, left ventricular geometry and QT dispersion in a middle-aged Estonian female population. | The aim of the present study was to determine the prevalence of Left ventricular hypertrophy (LVH) and different left ventricular (LV) geometric patterns in the middle-aged women population of Tallinn, to assess the relationship between LV geometry, age, blood pressure and LV repolarization duration and inhomogeneity. A random sample of the population, 482 women aged 35-59, was examined in the framework of a cardiovascular risk factors survey for the WHO/CINDI programme years 1999-2000. Patients with valvular pathology, primary cardiomyopathy, atrial fibrillation, bundle branch blocks and flat T wave on electrocardiography (ECG) were excluded; 398 (82.2%) of the participants underwent echocardiography (Echo) and standard 12-lead ECG at rest and were included in the study. LVH was defined if left ventricular mass (LVM), LVM/height and LVM/BSA were >198 g, >121 g/m and > 120 g/m2, respectively. Arterial hypertension was determined in 23.1% of the women. The prevalence of arterial hypertension was three times higher in those aged 50-59 than in those aged 40-49 (37.4% vs 13.2%; p < 0.05). Different geometric patterns were found as follows: concentric hypertrophy in 9.1%; eccentric hypertrophy 33.9%; concentric remodelling 9.5% and normal geometry 47.5% of the participants. Concentric hypertrophy was found exclusively in hypertensive women and increased with age. No age-related eccentric hypertrophy and concentric remodelling differences were found, either in the normotensive or in the hypertensive group. Prolonged QT dispersion--a marker of increased myocardial electrical instability, was associated with LVH and arterial hypertension and was related mostly to concentric hypertrophy in hypertensives. |
2,530 | Microdislodgment of ventricular pacing lead undetectable during rapid pacing one year after implantation. | A 71-year-old woman had undergone valvular heart surgery in 1981, and implantation of a permanent ventricular pacemaker for ventricular pauses during atrial fibrillation in 2001. One year after pacemaker implantation, she complained of faintness. When pacing at 100 beats/min the pacemaker functioned properly. However, pacing and sensing failure was detected at a pacing rate of 60 beats/min. At rapid pacing rates, the lead tip was in closer contact with the endocardium, and its microdislodgment was undetectable. The symptoms have resolved since the lead was repositioned. |
2,531 | Open-chest epicardial "surgical" defibrillation: biphasic versus monophasic waveform shocks. | The aim of the study was to compare biphasic versus monophasic shocks for open-chest epicardial defibrillation. Transthoracic biphasic waveform shocks require less energy to terminate ventricular fibrillation compared to monophasic waveform shocks. However, if biphasic shocks are effective for open-chest epicardial ("surgical") defibrillation has not been established. Twenty-eight anesthetized adult swine (15-25 kg) underwent a midline sternotomy. Ventricular fibrillation was electrically induced. After 15 seconds of ventricular fibrillation, each pig in group 1 (n = 16) randomly received damped sinusoidal monophasic epicardial shocks and truncated exponential biphasic epicardial shocks from large (44.2 cm2) paddle electrodes at eight energy levels (2-50 J). Pigs in group 2 (n = 12) received monophasic and truncated exponential biphasic shocks from small (15.9 cm2) paddle electrodes. In group 1 (large paddle electrodes), the overall percent shock success rose from 15 +/- 9% at 2 J to 97 +/- 3% at 50 J. In this group there was no significant difference in percent of shock success between damped sinusoidal monophasic and biphasic waveform shocks. In group 2 (small paddle electrodes), biphasic shocks yielded a significantly higher percent of shock success than monophasic shocks at mid-energy levels from 7 to 20 J (all P < 0.01). With small surgical paddle electrodes, biphasic waveform shocks demonstrated a significantly higher percent of shock success rate compared to monophasic waveform shocks. With large paddle electrodes, the two waveforms were equally effective. |
2,532 | Paced QT dispersion and QT morphology after radiofrequency atrioventricular junction ablation: impact of left ventricular function. | Catheter ablation of the atrioventricular junction (AVJ) is a widely accepted treatment for drug refractory atrial fibrillation. Unfortunately, there have been some reports of pause dependent ventricular arrhythmias associated with QT interval prolongation, mainly in patients with reduced LV function. The present investigation evaluates the association of LV function with QT dispersion in response to a sudden rate drop. ECGs were' recorded on 20 patients (13 with normal LV function) on the day following AVJ ablation while paced at a range of ventricular rates (40-120 beats/min), and during a sudden drop from 80 to 40 beats/min. The maximum QT interval (QTmax), minimum QT interval (QTmin), and QT interval dispersion (QTdisp) were compared. In both groups, the QTmax and QTmin increased at slower paced heart rates while the QTdisp did not change. In response to a sudden rate drop from 80 to 40 beats/min, the QTmax increased in both groups of LV function (trend), while the QTmin increased in those with normal LV function (24 +/- 22 ms), but not in those with reduced LV function (0 +/- 14 ms; P = 0.01). Consequently, the QTdisp increased significantly in those with reduced LV function (31 +/- 23 ms) but not in normal LV function (-5 +/- 29 ms; P = 0.01). Morphological QTU changes developed following the sudden rate drop in 67% of the reduced LV versus 8% of the normal LV (P = 0.02) function groups. Following AVJ ablation, QTdisp increased during a sudden rate drop in patients with reduced LV function, but not in patients with normal LV function. |
2,533 | Circadian variation in ventricular tachycardia and atrial fibrillation in a medical-cardiological ICU. | To assess the diurnal distribution of ventricular tachycardia (VT) and atrial fibrillation (AF) in critically ill patients.</AbstractText>Prospective observational study (episode-based design) in an eight-bed medical/cardiological ICU at a university hospital that also admits postoperative patients.</AbstractText>98 consecutive patients with AF ( n=55) or ventricular tachycardia ( n=43).</AbstractText>There were a total of 218 arrhythmia episodes (83 AF, 136 VT). The time of arrhythmia onset was not evenly distributed. Circadian variation in VT but not AF onset was well represented by a sine wave function. Both VT and AF fibrillation showed a trough during the night. The distribution of VT and AF episodes did not differ significantly with or without analgosedation.</AbstractText>In critically ill patients the onset of VT and AF over 24-h is nonuniformly distributed. In VT this circadian pattern of occurrence is well modeled by a sine wave function peaking between noon and 2 p.m. The circadian pattern is less clear for AF. The circadian variation is seen irrespective of the presence of absence of analgosedation for both arrhythmias.</AbstractText> |
2,534 | Prospective study of sudden cardiac death among women in the United States. | There are few data regarding the determinants of sudden cardiac death (SCD) in women, primarily because of their markedly lower rate of SCD compared with men. Nonetheless, existing data, although sparse, suggest possible gender differences in risk factors for SCD.</AbstractText>In this prospective cohort of 121 701 women aged 30 to 55 years at baseline, SCD was defined as death within 1 hour of symptom onset. From 1976 to 1998, 244 SCDs were identified. Although the risk of SCD increased markedly with age, the percentage of cardiac deaths that were sudden decreased. Most (69%) women who suffered a SCD had no history of cardiac disease before their death. However, almost all of the women who died suddenly (94%) had reported at least 1 coronary heart disease risk factor. Smoking, hypertension, and diabetes conferred markedly elevated (2.5- to 4.0-fold) risk of SCD, similar to that conferred by a history of nonfatal myocardial infarction (relative risk, 4.1; 95% confidence interval, 2.9 to 6.7). Family history of myocardial infarction before age 60 years and obesity were associated with moderate (1.6-fold) elevations in risk. With regard to mechanism, 88% of SCDs were classified as arrhythmic. In 76% of these, the first rhythm documented was ventricular tachycardia or ventricular fibrillation.</AbstractText>These prospective data suggest that, as in men, coronary heart disease risk factors predict risk of SCD in women and that SCD is usually an arrhythmic death. Therefore, prevention of atherosclerosis or ventricular arrhythmias may reduce the incidence of SCD in women.</AbstractText> |
2,535 | Defibrillator Versus beta-Blockers for Unexplained Death in Thailand (DEBUT): a randomized clinical trial. | Sudden Unexplained Death Syndrome (SUDS) is the leading cause of death in young, healthy, Southeast Asian men. The role of an implantable cardioverter defibrillator (ICD) for mortality reduction in these patients remains unclear.</AbstractText>The Defibrillator Versus beta-Blockers for Unexplained Death in Thailand (DEBUT) study is a randomized, clinical trial conducted in 2 phases (pilot study followed by the main trial) to compare the annual all-cause mortality rates among SUDS patients treated with beta-blockers versus that among those treated with an ICD. A total of 86 patients who were SUDS survivors and probable SUDS survivors were randomized to receive an ICD or propranolol (20 patients were in the pilot study and 66 were in the main trial). The primary end point was death from all causes. The secondary end point was recurrent ventricular tachycardia/ventricular fibrillation (VF) or cardiac arrest. During the 3-year follow-up period of the main trial, there were 4 deaths; all occurred in the beta-blocker group (P=0.02). Seven subjects in the ICD arm had recurrent VF, and all were effectively treated by the ICD. On the basis of the main trial results, the Data Safety Monitoring Board stopped the study. In total (both from the Pilot study and the main trial), there were 7 deaths (18%) in the beta-blocker group and no deaths in the ICD group, but there were a total of 12 ICD patients receiving ICD discharges due to recurrent VF.</AbstractText>ICD treatment provides full protection from death related to primary VF in a SUDS population and is superior to beta-blockade treatment.</AbstractText> |
2,536 | Digoxin remains useful in the management of chronic heart failure. | Despite the introduction of a variety of new classes of drugs for the management of heart failure, digoxin continues to have an important role in long-term outpatient management. A wide variety of placebo-controlled clinical trials have unequivocally shown that treatment with digoxin can improve symptoms, quality of life, and exercise tolerance in patients with mild, moderate, or severe heart failure. These benefits are evident regardless of the underlying rhythm (normal sinus rhythm or atrial fibrillation), etiology of the heart failure, or concomitant therapy (eg. ACE inhibitors). Unlike other agents with positive inotropic properties, digoxin does not increase all-cause mortality and has a substantial benefit in reducing heart failure hospitalizations. Consensus guidelines have recently been published by the Heart Failure Society of America and the American College of Cardiology/American Heart Association, and they contain the following recommendations for digoxin treatment: 1. Digoxin should be considered for the outpatient treatment of all patients who have persistent symptoms of heart failure (NYHA class II-IV) despite conventional pharmacologic therapy with diuretics, ACE inhibitors, and a beta-blocker when the heart failure is caused by systolic dysfunction (the strength of evidence = A for NYHA class II and III; strength of evidence = C for NYHA class IV). 2. Digoxin is not indicated as primary treatment for the stabilization of patients with acutely decompensated heart failure. (Strength of evidence = B). Digoxin may be initiated after emergent treatment of heart failure has been completed in an effort to establish a long-term treatment strategy. 3. Digoxin should not be administered to patients who have significant sinus or atrioventricular block, unless the block has been treated with a permanent pacemaker (strength of evidence = B). The drug should be used cautiously in patients who receive other agents known to depress sinus or atrioventricular nodal function (such as amiodarone or a beta-blocker) (strength of evidence = B). 4. The dosage of digoxin should be 0.125-0.25 mg daily in the majority of patients (strength of evidence = C). The lower dose should be used in patients over 70 years of age, those with impaired renal function, or those with a low lean body mass. Higher doses (eg, digoxin 0.375-0.50 mg daily) are rarely needed. Loading doses of digoxin are not necessary during initiation of therapy for patients with chronic heart failure. 5. Serial assessment of serum digoxin levels is unnecessary in most patients. The radioimmunoassay was developed to assist in the evaluation of toxicity, not the efficacy of the drug. There appears to be little relationship between serum digoxin concentration and the drug's therapeutic effects. 6. Digoxin toxicity is commonly associated with serum levels >2 ng/mL but may occur with lower digoxin levels if hypokalemia, hypomagnesemia, or hypothyroidism coexist. Likewise, the concomitant use of agents such as quinidine, verapamil, spironolactone, flecainide, and amiodarone can increase serum digoxin levels and increase the likelihood of digoxin toxicity. 7. For patients with heart failure and atrial fibrillation with a rapid ventricular response, the administration of high doses of digoxin (>0.25 mg daily) for the purpose of rate control is not recommended. When necessary, additional rate control should be achieved by the addition of beta-blocker therapy or amiodarone (strength of evidence = C). If amiodarone is added, the dose of digoxin should be reduced. Digitalis preparations are now entering their fourth century of clinical use for the treatment of chronic heart failure symptoms. Its clinical efficacy can no longer be doubted and its safety has been verified by the multicenter DIG trial. Future advances in pharmacogenetics should facilitate identification of those patients most likely to benefit from its pharmacologic effects. |
2,537 | Novel brugada SCN5A mutation leading to ST segment elevation in the inferior or the right precordial leads. | Mutations in the SCN5A gene can lead to the Brugada syndrome, a genetically inherited form of idiopathic ventricular fibrillation that has a characteristic ECG phenotype usually restricted to precordial leads V1-V3. We identified a novel G752R SCN5A missense mutation leading to various degrees of the Brugada ECG phenotype in members of a French family. In the proband, the G752R mutation produced ST segment elevation and prominent J wave in leads II, III, and aVF. In four other relatives, ST segment elevation in the right precordial but not in the inferior leads was observed either spontaneously or under flecainide challenge. Recombinant G752R mutant exhibited a markedly reduced Na+ current amplitude and a voltage shift in both activation and inactivation curves. The mutant was found in all affected but not in nonaffected family members. One additional gene-carrier had an almost normal ECG (silent gene-carrier). We provide genetic demonstration that Brugada ECG anomalies related to a unique SCN5A mutation can be observed either in the inferior or the right precordial leads. |
2,538 | Clinical investigation of a new dual-chamber implantable cardioverter defibrillator with improved rhythm discrimination capabilities. | Despite continuing advances, inappropriate implantable cardioverter defibrillator (ICD) therapies in response to nonventricular tachyarrhythmias continue to cause patient discomfort and increased follow-up demands.</AbstractText>We investigated the performance of a new dual-chamber ICD (Photon DR, St. Jude Medical), with specific attention to its arrhythmia discrimination and detection capabilities. The system uses a hierarchical approach to tachyarrhythmia classification utilizing a new AV Rate Branch feature and subsequently utilizing morphology analysis, onset, and stability criteria. The arrhythmia discrimination results from this study group were compared to historical control group data from a recent clinical investigation of single-chamber Contour MD (Morphology Discrimination) and Angstrom MD ICDs without the Rate Branch feature. Rhythm discrimination was evaluated by comparing ventricular tachycardia diagnosis sensitivity and specificity between the two groups. To determine whether the new discrimination scheme affected detection speed, median ventricular fibrillation (VF) detection and redetection times also were compared. The study group consisted of 107 patients, and the control group consisted of 161 patients. Use of the AV Rate Branch feature was associated with significant improvements in both sensitivity (100% vs 97.9%, P < 0.0001) and specificity (84% vs 55.7%, P = 0.0002) of ventricular tachycardia diagnosis. Use of the new scheme slightly but significantly accelerated VF detection times (2.8 vs 3.0 sec, P < 0.0001) and redetection times (1.3 vs 1.4 sec, P < 0.0001). Adverse events were typical for this patient population.</AbstractText>Compared with earlier St. Jude Medical ICDs, the Photon DR ICD offers improved rhythm discrimination without compromising VF detection time.</AbstractText> |
2,539 | Comparative effects of aspirin with ACE inhibitor or angiotensin receptor blocker on myocardial infarction and vascular function. | We previously showed that an angiotensin-converting enzyme inhibitor (captopril) or an angiotensin receptor blocker (losartan) reduced infarct size and improved endothelial function in a rat model of ischaemia-reperfusion. The present study was undertaken to see if aspirin (ASA) antagonised the beneficial effects of captopril or losartan.</AbstractText>One hundred and fourteen Sprague-Dawley rats were randomised into six groups; Control, ASA, captopril, losartan, ASA+captopril, and ASA+losartan. ASA, captopril or losartan were given at a concentration of 40 mg/kg/day in drinking water. After six weeks of pre-treatment, the rats were subjected to 17 minutes of left anterior descending coronary artery occlusion and 120 minutes of reperfusion, with haemodynamic and ECG monitoring. During the reperfusion period, the effective refractory period (ERP), ventricular fibrillation threshold (VFT) and bleeding time (BT) were measured. In fresh aortic rings precontracted with phenylephrine, endothelium-dependent and -independent relaxations were assessed using acetylcholine and nitroglycerin.</AbstractText>Haemodynamic changes were not different between the groups. Serum ASA concentrations were 0.5, 1.1 and 0.6 mg/dl in the ASA, ASA+captopril and ASA+losartan groups, respectively, and BT was prolonged (p<0.01). ASA alone reduced endothelium-dependent relaxation (-29+8 vs. -69+11%, p<0.01), but did not change endothelium-independent relaxation. ASA did not affect endothelial relaxation induced by acetylcholine in the presence of either captopril or losartan. Angiotensin I and ERP were elevated by captopril and losartan. Angiotensin II and VFT were elevated by losartan. ASA with captopril, captopril and losartan equally reduced infarct size, compared with control (39+3, 39+4, and 39+5 vs. 53+3%, all p<0.05).</AbstractText>Captopril and losartan had similar cardiovascular protective effects in a rat model of ischaemia-reperfusion. Aspirin did not attenuate the cardiovascular protective effects of captopril or losartan.</AbstractText> |
2,540 | Linguistic analysis of the human heartbeat using frequency and rank order statistics. | Complex physiologic signals may carry unique dynamical signatures that are related to their underlying mechanisms. We present a method based on rank order statistics of symbolic sequences to investigate the profile of different types of physiologic dynamics. We apply this method to heart rate fluctuations, the output of a central physiologic control system. The method robustly discriminates patterns generated from healthy and pathologic states, as well as aging. Furthermore, we observe increased randomness in the heartbeat time series with physiologic aging and pathologic states and also uncover nonrandom patterns in the ventricular response to atrial fibrillation. |
2,541 | Evidence for time-dependent maximum increase of free radical damage and eicosanoid formation in the brain as related to duration of cardiac arrest and cardio-pulmonary resuscitation. | Recovery of neurological function in patients following cardiac arrest and cardiopulmonary resuscitation (CPR) is a complex event. Free radical induced oxidative stress is supposed to be involved in this process. We studied levels of 8-iso-PGF2alpha (indicating oxidative injury) and 15-keto-dihydro-PGF2alpha (indicating inflammatory response) in venous plasma obtained from the jugular bulb in a porcine model of experimental cardiopulmonary resuscitation (CPR) where 2, 5, 8, 10 or 12 min of ventricular fibrillation (VF) was followed by 5 or 8 min of closed-chest CPR. A significant increase of 8-iso-PGF2alpha was observed immediately following restoration of spontaneous circulation in all experiments of various duration of VF and CPR. No such increase was seen in a control group. When compared between the groups there was a duration-dependent maximum increase of 8-iso-PGF2alpha which was greatest in animals subjected to the longest period (VF12 min + CPR8 min) of no or low blood flow. In contrast, the greatest increase of 15-keto-dihydro-PGF2alpha was observed in the 13 min group (VF8 min + CPR5 min). Thus, a time-dependent cerebral oxidative injury occurs in conjunction which cardiac arrest and CPR. |
2,542 | Broad applicability of ultrarapid train stimulation as an efficient alternative to conventional programmed electrical stimulation. | Conventional programmed electrical stimulation (PES) is useful for establishing inducibility or noninducibility of clinical ventricular arrhythmias (VA), but is complex and time-consuming. This study compared a standard PES protocol with ultrarapid train stimulation (UTS) in a broad range of patients with and without a history of ventricular arrhythmias or structural heart disease.</AbstractText>Patients prospectively underwent electrophysiologic testing with both UTS and conventional PES protocols in a randomized, crossover design.</AbstractText>The results were concordant in 79% of 150 matched pairs of comparisons in 104 patients (NS). There were no differences related to underlying heart disease or arrhythmia, or antiarrhythmic treatment. Induction of nonclinical arrhythmias with the two methods was similar (P = 0.524). Inhibition phenomena were minor except in some patients receiving amiodarone. Fewer drive-extrastimuli sequences and less time were needed to complete the trains protocol (P < 0.0001).</AbstractText>In cases where the main intent is to induce ventricular arrhythmias, UTS yields results that are similar to those of conventional PES protocols in a shorter length of time.</AbstractText> |
2,543 | End tidal CO2 is a quantitative measure of cardiac arrest. | Predictors of severity of cardiac arrest or efficacy of cardiopulmonary resuscitation are few. Respiratory end tidal CO2 (ETCO) is a marker of pulmonary blood flow and, possibly, cardiac arrest. The purpose of this study was to evaluate ETCO as a quantitative marker of cardiac arrest in a human model of ventricular fibrillation (VF).</AbstractText>Thirty-one cardiac arrest/VF episodes (mean BP < 40 mmHg) in 8 men and 3 women mean age = 42 +/- 24 years, mean left ventricular ejection fraction = 39%) undergoing defibrillator (ICD) implant for ventricular tachycardia or previous cardiac arrest were evaluated with continuous ETCO monitoring during defibrillation threshold testing. All patients but one were intubated.</AbstractText>Significant differences (P < 0.001) were noted between ETCO values prior (mean 37.2 +/- 6.8 mmHg) versus during VF (mean 27.1 +/- 5.9 mmHg), and during VF versus return of spontaneous circulation (mean 36.6 +/- 6.6 mmHg). ETCO decreased by 23% +/- 8% from pre-VF to during VF. It increased by 37% +/- 16% during VF to return of spontaneous circulation. These changes were significantly different (P < 0.001).</AbstractText>Significant changes in ETCO were measured during VF arrest. ETCO can predict acute cardiac arrest in a quantitative manner.</AbstractText> |
2,544 | Safety of a single successful conversion of ventricular fibrillation before the implantation of cardioverter defibrillators. | Multiple successful conversions of ventricular fibrillation (VF) at 10 J below the maximum output of implantable cardioverter defibrillator (ICD) have been recommended as a minimum device implantation criterion. This recommendation is based on the probabilistic properties of defibrillation that necessitates multiple shocks to establish an adequate safety margin for the conversion of subsequent spontaneous arrhythmias. We hypothesized that a single successful shock at a 14 J may suffice.</AbstractText>The Low Energy Safety Study (LESS) enrolled 720 patients undergoing initial ICD implantation with a dual-coil transvenous lead and active pulse generator. At implant, an enhanced defibrillation threshold (DFT++) was determined by a rigorous protocol beginning at 14 J, and requiring at least 4 shocks. Fifty percent of all patients were then randomized to full output shock energy and the conversion rates for spontaneous ventricular tachyarrhythmias at rates > 200 beats/min were measured. There were 318 patients randomized to 31 J, of whom 254 were successfully defibrillated by an initial 14 J shock. During a mean follow-up of 24 +/- 12 months, 112 spontaneous VF episodes occurred in 31 patients. The combined conversion success of the first and second shock (when needed) did not differ between the subgroup of patients who were successfully defibrillated by an initial 14 J shock, regardless of the results of additional testing, and the whole cohort who underwent more systematic testing (97% vs 97%). All spontaneous episodes of VF were successfully treated during long-term follow-up.</AbstractText>A first successful shock of 14 J may be a sufficient endpoint to allow the implantation of ICDs with the Triad lead configuration, when programming all shocks to 31 J.</AbstractText> |
2,545 | Rhythm discrimination by rate branch and QRS morphology in dual chamber implantable cardioverter defibrillators. | Morphology Discrimination is a discriminator based on QRS morphology analysis that has been recently implemented in dual chamber implantable cardioverter defibrillators (ICDs). Detected events are initially classified according to median atrial and ventricular rates (Rate Branch). Then, a series of discriminators (Morphology Discrimination, Stability, Sudden Onset) analyze the rhythm according to specific criteria and the number of discriminators required for VT diagnosis (i.e., requiring "any" or "all" of the specific discriminators to indicate VT). The discriminating accuracy of the algorithm was evaluated in 645 detections recorded during the follow-up of 25 patients. The overall specificity for 397 supraventricular arrhythmias was 73.5% (292/397) with the tachycardia diagnosis criteria set to "any" and 90.9% (361/397) with the tachycardia diagnosis criteria set to "all." Sensitivity for VT was 100% and 98.7% (231/234) with the tachycardia diagnosis criteria set to "any" and "all," respectively. With the tachycardia diagnosis criteria set to "any," specificity for atrial fibrillation was 88.6%, for atrial flutter 40.3%, for atrial tachycardia 0%, and for sinus tachycardia 97.0%. With the tachycardia diagnosis criteria set to "all," specificity for atrial fibrillation was 92.40%, for atrial flutter 93.5%, for atrial tachycardia 54.7%, and for sinus tachycardia 99.0%. The contribution of Morphology Discrimination was crucial to improve the specificity of the Rate Branch algorithm. The implementation of Morphology Discrimination in a dual chamber ICD with Rate Branch rhythm classification allows the attainment of high specificity and high sensitivity for ventricular tachyarrhythmias. |
2,546 | Evaluation of a dual chamber implantable cardioverter defibrillator for the treatment of atrial and ventricular arrhythmias. | Eighty-nine patients with a documented history of atrial tachyarrhythmias or fibrillation (AF) received a cardioverter defibrillator designed to selectively differentiate and treat atrial and ventricular arrhythmias. Twenty-two patients received a coronary sinus lead and, therefore, could use a separate shock vector for selective treatment of atrial tachyarrhythmias/AF. The device is designed to treat tachyarrhythmias with antitachycardia pacing (ATP) and/or shock therapy using an atrial and/or a ventricular shock vector. Patients underwent induction and shock termination of atrial or dual tachyarrhythmias (AF/VF) to verify proper device function and to measure the arrhythmia detection time with enhancements and preventive algorithms programmed On and Off, respectively. Detection time for 329 VF inductions was 2.41 +/- 0.64 seconds with enhancements On and 2.29 +/- 0.47 with enhancements Off (NS). At implant or predischarge, 283 AF and/or AF/VF (121 atrial and 162 atrial/ventricular fibrillation) were induced. Shock conversion efficacy was 89.8% with AF conversion energies ranging from 0.9 to 27 J. Thirteen of the 23 patients had atrial shock conversions using the separate shock vector with an average conversion energy of 1.9 +/- 1.4 J. (range 0.5-5 J). During follow-up the efficacy of ATP on atrial tachyarrhythmias was 59% and the efficacy of delivered shocks on AF was 85%. This new dual chamber cardioverter defibrillator appropriately detected and classified atrial arrhythmias, and shock therapy for AF was highly effective. The detection algorithm differentiated atrial tachyarrhythmia/AF and did not delay VF detection. The separate shock vector converted induced AF with energies ranging from 0.6 to 5 J. |
2,547 | Value of heart rate variability to predict ventricular arrhythmias in recipients of prophylactic defibrillators with idiopathic dilated cardiomyopathy. | This study investigated the relation between heart rate variability (HRV) measured as standard deviation of normal to normal RR intervals (SDNN) on baseline 24-hour ambulatory electrocardiogram (ECG) and subsequent appropriate implantable cardioverter defibrillator (ICD) interventions in 70 patients with idiopathic dilated cardiomyopathy (IDC) in whom ICDs were implanted prophylactically in the presence of a low left ventricular ejection fraction (LVEF). During 43 +/- 26 months of follow-up, 26 of 70 (37%) study patients with IDC received one or more appropriate ICD interventions for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) documented by electrograms stored in the ICD. Mean SDNN at ICD implant was 94 +/- 33 ms. No difference was found between patients with (90 +/- 25 ms) versus without (96 +/- 37 ms) appropriate ICD interventions for VT or VF during follow-up. Multivariate Cox regression analysis of baseline clinical characteristics including age, gender, LVEF, NYHA functional class, nonsustained VT on Holter, history of syncope, left bundle branch block, baseline medication and HRV revealed LVEF as the only significant predictor of arrhythmia. These findings do not support the use of HRV measured as SDNN on 24-hour ambulatory ECG to select patients with IDC for prophylactic ICD therapy. |
2,548 | Abnormal cardiac innervation in patients with idiopathic ventricular fibrillation. | Idiopathic ventricular fibrillation (VF) is diagnosed in up to nearly 10% of survivors of out-of-hospital cardiac arrest. The arrhythmogenic substrate is unknown. This study examined the role of cardiac innervation as a possible contributor to this arrhythmia. Eight patients with idiopathic VF were compared with eight normal subjects (controls) by [123] I metaiodobenzylguanidine SPECT (MIBG), measuring peak uptake, late uptake, and clearance of the nuclear tracer. The left ventricle was divided in 13 segments in the bull's-eye target plot. Peak and late MIBG uptake was increased in the anterolateral segments (2,3,7,8) compared to the inferoposterior and septal segments, in controls and in patients. No difference was observed between controls and patients in the inferoposterior and septal segments. In contrast, a significantly higher MIBG uptake was observed in patients compared to controls in the anterolateral segments (94 +/- 4% vs 81 +/- 11%, P < 0.03 for peak uptake; 94 +/- 5% vs 79 +/- 12%, P < 0.01 for late uptake). No difference was observed in MIBG clearance in any segment in either study group. Cardiac sympathetic innervation is highly heterogeneous, though predominant in anterolateral segments in normal subjects. Patients with idiopathic VF exhibit the same distribution, though have a significantly greater density of sympathetic terminals in the anterolateral segments than controls, which may promote ventricular arrhythmias. |
2,549 | Ventricular dyssynchrony and risk markers of ventricular arrhythmias in nonischemic dilated cardiomyopathy: a study with phase analysis of angioscintigraphy. | Biventricular pacing is a new form of treatment for patients with dilated cardiomyopathy and ventricular dyssynchrony. Limited information is available regarding the relationship between ventricular dyssynchrony and risk markers of ventricular arrhythmias in idiopathic dilated cardiomyopathy (IDC). In 103 patients with IDC, Fourier phase analysis of both ventricles was performed from equilibrium radionuclide angiography (ERNA). The difference between the mean phase of the LV and RV was a measure of interventricular dyssynchrony, and the standard deviations of the mean phases in each ventricle measured intraventricular dyssynchrony. There were no significant differences in inter- and intraventricular dyssynchrony between patients with versus without histories of sustained VT or VF, nonsustained VT, abnormal signal-averaged ECG, or induced sustained monomorphic VT. Dyssynchrony was not related to decreased heart rate variability (HRV). LV and interventricular dyssynchrony were weakly related to QT duration and QT dispersion. During a follow-up of 27 +/- 23 months, 21 patients had major adverse cardiac events (MACE), including 7 cardiac deaths, 11 progression of heart failure leading to cardiac transplantation, and 3 sustained VT/VF. The only independent predictors of MACE were an increased standard deviation of LV mean phase (P = 0.003), a decreased HRV (standard deviation of normal-to-normal intervals, P = 0.004), and histories of previous VT/VF (P = 0.03) or nonsustained VT (P = 0.04). In conclusion, left intraventricular dyssynchrony evaluated with ERNA was an independent predictor of MACE in IDC and was not related to usual risk markers of ventricular arrhythmias. This may have implications for resynchronization therapy and/or the use of implantable cardioverter defibrillators in IDC. |
2,550 | Flecainide test in Brugada syndrome: a reproducible but risky tool. | The flecainide test is widely used in Brugada syndrome. However, its reproducibility and safety remain ill-defined. This study included 22 patients (18 men, mean age 34 years). Mutations in the SCN5A gene were found in eight patients. Two patients had aborted sudden cardiac death, 8 had syncope/presyncope, and 12 were asymptomatic. The ECG was diagnostic in 19 patients and suggestive in 3. At baseline, 21 of 22 patients underwent a flecainide test (2 mg/kg IV bolus over 10 minutes). In 21 of 21 patients the test was diagnostic or amplified the typical ECG pattern. At the end of drug infusion, sustained VT lasting 7-10 minutes developed in two patients. A second flecainide test was performed within 2 months in 20 patients. The test was not repeated in the two patients with prior development of VT. The flecainide test was diagnostic in 20 of 20 patients. Sustained VT occurred in one patient and recurrent VF in another. The reproducibility of the flecainide test was 100%. In 4 (18%) of 22 patients major VAs were documented after the end of flecainide infusion. VA occurred in 3 (43%) of 7 patients with, versus 1 (7%) 15 without SCN5A gene mutation (P < 0.05). No diagnostic ECG changes or arrhythmias developed in 25 control patients without structural heart disease who underwent the same study protocol. This study shows a high flecainide reproducibility, supporting its diagnostic value in Brugada syndrome. However, the occurrence of major VA, significantly higher in patients with documented SCN5A gene mutation, including in asymptomatic patients, mandates the performance under appropriate medical supervision. Whether a slower rate of drug infusion can lower the risk of VA induction, while maintaining the sensitivity of the test should be explored. |
2,551 | Enhancement of J-ST-segment elevation by the glucose and insulin test in Brugada syndrome. | The effects of glucose and insulin on J-ST-segment elevation were evaluated in seven men (mean age 45 +/- 10 years) with Brugada syndrome. Six patients had been reanimated from VF and one patient had experienced syncope. The effects of intavenous (1) pilsicainide 50 mg, (2) glucose 50 g, and (3) glucose 50 g plus regular insulin 10 IU on the precordial ECG leads were examined. Pilsicainide significantly enhanced J-ST elevation in all patients and induced VF in 1 patient. A significant accentuation of the abnormal J-ST configuration was observed in all patients at a mean of 51 +/- 40 minutes after glucose and insulin infusion. Changes in blood glucose and serum potassium concentration were 111 +/- 158 mg/dL and -0.30 +/- 0.48 mEq/L, respectively. These changes were not directly related to the ECG changes. Glucose infusion without insulin caused a subtle increase in J-ST elevation. In conclusion, the administration of glucose and insulin safely unmasked or accentuation the J-ST-segment elevation in Brugada syndrome. Blood glucose and insulin concentrations may be factors modulating the circadian or day-to-day ECG variations in this syndrome. |
2,552 | Thromboembolic risk of patients referred for radiofrequency catheter ablation of typical atrial flutter without prior appropriate anticoagulation therapy. | Radiofrequency catheter ablation of isthmus dependent atrial flutter is considered the therapy of choice. There is, however, controversy with regard to the thrombogenicity of atrial flutter in comparison with atrial fibrillation.</AbstractText>Consecutive patients scheduled for catheter ablation of documented typical atrial flutter receiving insufficient (INR < 2.0) or no anticoagulation during the three weeks preceding the procedure underwent multiplane transesophageal echocardiography (TEE). Patients with exclusive documentation of atrial flutter were classified as group I, whereas patients with additional documentation of atrial fibrillation were classified as group II.</AbstractText>The study included 201 patients, 62 of whom were not on therapeutic anticoagulation (mean age 64 +/- 9 years, 87% men). In 10 of these 62 patients (16%), TEE detected a left atrial (LA) appendage thrombus in 4, or dense spontaneous echo contrast (SEC) in 6 patients. Comparison of patients with versus without SEC or thrombus, revealed a higher incidence of valvular heart disease (60% vs 26%, P = 0.05), but no differences with respect to age, gender, LA diameter, left ventricular end-diastolic diameter, or left ventricular ejection fraction. The incidence of positive TEE findings in group I was 1 in of 36 versus 9 of 26 in group II (3% vs 35%, P < 0.001), and the relative risk for thromboembolism in group II versus group I was 12.5 (95% CI: 3-55, P < 0.001).</AbstractText>There is a significant risk for thromboembolism in patients referred for ablation of typical atrial flutter who have not been appropriately anticoagulated.</AbstractText> |
2,553 | Angiotensin-converting enzyme and endothelial nitric oxide synthase polymorphisms in patients with atrial fibrillation. | Experimental studies have shown a significant increase in angiotensin-converting enzyme (ACE) expression in atrial tissue of AF patients. ACE regulates the synthesis of endothelial nitric oxide (NO), which modulates autonomic nervous activity involved in the development of AF. The aim of the study was to evaluate the prevalence of ACE insertion/deletion and endothelial NO synthase (eNOS) T-786C, G894T, and 4a/4b polymorphisms in 148 patients with persistent AF, compared with 210 control subjects. ACE insertion/deletion polymorphism genotype distribution and allele frequency were significantly different between patients and controls (P < 0.0001 and P < 0.0001, respectively). ACE DD genotype was significantly associated with the risk of AF (OR DD/ID + II = 3.24, P < 0.0001). Analysis of eNOS polymorphisms showed no significant difference in genotype distribution and allele frequency between patients and controls. The results suggest a possible role of ACE DD genotype as a predisposing factor to AF and a pathophysiological mechanism of ACE inhibition in reducing the incidence of AF in patients with left ventricular dysfunction. |
2,554 | Hemodynamic effects of alternative atrial pacing sites in patients with paroxysmal atrial fibrillation. | Recently, multisite atrial pacing has been suggested as an alternative therapy to prevent recurrences of paroxysmal atrial fibrillation (PAF). A study was conducted to compare the acute effects of biatrial (BiA), left atrial (LA), and right atrial appendage (RAA) pacing on cardiac hemodynamics. In 14 patients with PAF and a BiA pacemaker (with leads in the RAA and coronary sinus), cardiac output (CO), right (RV) and left ventricular (LV) filling, RA-LA contraction delay [PA(m-t)] and the difference in A wave duration [Adif(m-p)] at the level of the mitral valve (Adurm) and pulmonary veins (Adurp) during RAA, BiA, and LA pacing were examined by echo-Doppler measurements. The atrial pacing site did not affect the CO. LA, but not BiA, pacing resulted in delayed RA contraction in comparison with RAA pacing with significant diminution of the RA contribution to RV filling. With LA pacing, the usual right-to-left atrial contraction sequence was reversed (PA(m-t): 8 +/- 7 ms control; 5 +/- 30 ms RAA; -10 +/- 21 ms BiA; -72 +/- 36 ms LA; LA versus control versus RAA and versus BiA, P < 0.001. LA and BiA pacing prolonged Adurp (LA 186 +/- 52 ms, BiA 180 +/- 45 ms, RAA 153 +/- 49 ms; LA and BiA vs RAA, P < 0.01). Thus Adurp exceeded Adurm [Adif (m-p): control 38 +/- 40 ms, RAA 7 +/- 42 ms, BiA -12 +/- 43 ms, LA -20 +/- 44 ms; control vs RAA, BiA, and LA; and RAA vs LA, P < 0.05]. The study showed that (1) the atrial pacing site has no influence on global cardiac performance; (2) the hemodynamic effect of BiA pacing is not superior to that of RAA pacing, and LA pacing can even be deleterious; (3) LA pacing reverses the usual right-to-left atrial contraction sequence and reduces the RA contribution to RV filling; (4) BiA and LA pacing prolong Adurp due to an altered activation pattern, decreased pulmonary venous return, or increased LA pressure. |
2,555 | Contributions of high resolution electrograms memorized by DDDR pacemakers in the interpretation of arrhythmic events. | The accuracy of information retrievable from the memories of DDDR pacing systems has been limited by the absence of actual electrograms confirming the proper sensing of spontaneous cardiac activity versus that of extraneous signals. This study examined the diagnostic power of a new arrhythmia interpretation scheme, which includes the recording and storage of high resolution endocavitary atrial and ventricular electrograms (HREGM). HREGM stored in the memories of new generation pacemakers (PM) in response to nonsustained ventricular tachycardia (NSVT), sustained VT, and atrial arrhythmias were analyzed in a follow-up registry of 520 patients at 1 month, and 3 to 6 months after implantation of a PM for standard indications. For each sequence of stored HREGM, the accuracy of the PM response was examined, classified as accurate (true positive), versus inaccurate (false positive), versus undetermined, and the relative contribution of the HREGM in verifying the PM diagnosis was measured. During a follow-up of 4.9 +/- 2 months, 256 (49%) of the 520 patients had an event recorded, which was confirmed to be arrhythmic on the basis of HREGM. Overall, approximately 34% of atrialtachy response (ATR) episodes were confirmed to be appropriate. Similar percentages of episodes were prompted by oversensing of signals unrelated to cardiac arrhythmias, while nearly 12% of the episodes could not be clarified because of such brief duration as to preclude recording of their onset. Approximately one-third of NSVT, and one-half of VT detections were false positive. Ventricular oversensing, most often due to myopotential interference in presence of unipolar sensing, and atrial undersensing were both identified as sources of false-positive detections of ventricular events. The proportion of true-positive detections was significantly higher in the bipolar (83%) than unipolar configuration. Among 520 PM recipients, miscellaneous episodes of atrial arrhythmias were confirmed by HREGM in 37% of patients within 3 to 6 months of follow-up. Atrial fibrillation was confirmed in only 6% of patients, of whom over 50% already had histories of atrial fibrillation. The prevalence of unsuspected atrial arrhythmia in this unselected population was lower than previously reported. |
2,556 | Optical mapping technique applied to biventricular pacing: potential mechanisms of ventricular arrhythmias occurrence. | Although it has been suggested that multisite ventricular pacing alleviates heart failure by restoring ventricular electrical synchronization, the respective roles of voltage output, interventricular delay, and pacing sites in the development of ventricular arrhythmias occurrence have not been studied during biventricular pacing or LV pacing. Voltage-sensitive dye was used in eight ischemic Langerdorff-perfused guinea pig hearts to measure ventricular activation times and examine conduction patterns during multisite pacing from three RV and four LV sites. The hearts were stained with di-4-ANEPPS and mapped with a 16 x 16 photodiode array at a resolution of 625 microns per diode. Isochronal maps of RV and LV activation were plotted. Ischemia was produced by gradually halving the perfusion output over 5 minutes. Pacing the RV apex and the base of the LV anterior wall was associated with the most homogeneous and rapid activation pattern (28 +/- 9 vs 41 +/- 12 ms with the other configurations, P < 0.01), and no inducible arrhythmia. In six hearts, ventricular tachycardia could be induced when pacing from the right and left free walls with 20 ms of interventricular delay, at six times the pacing threshold output. In four hearts, simultaneous RV and LV pacing at high voltage output induced ventricular fibrillation with complex three-dimensional propagation patterns, independently of the pacing sites. During biventricular pacing with ischemia, pacing at high voltage output with a long interventricular delay is likely to induce ventricular arrhythmias, particularly when left and right pacing results in a conduction pattern orthogonal to the ventricular myocardial fibers orientation. |
2,557 | Long-term experience with a preshaped left ventricular pacing lead. | This study describes a long-term experience with a new LV pacing lead. The study population consisted of 62 patients (85% men, 71 +/- 10 years old) with advanced dilated cardiomyopathy, in NYHA Class III or IV despite optimal drug therapy, and a QRS duration > 150 ms. Patients in sinus rhythm were implanted with a triple chamber pacemaker to maintain atrioventricular synchrony. A dual chamber pacemaker was implanted in patients in atrial fibrillation for biventricular pacing only. A clinical evaluation and interrogation of the resynchronization pacemaker were performed at implant, at 1 week (W1), one (M1), four (M4), and seven (M7) months after implantation. A longer follow-up (2 years) is available for patients implanted at the authors institution. LV measurements were pacing threshold at 0.5-ms pulse duration and pacing impedance. R wave amplitude (mV) was measured at the time of implantation only. The system was successfully implanted in 86% of patients with the latest design of the lead. Mean R wave amplitude at implant was 15 +/- 7 mV and mean pacing impedance was 1054 +/- 254 omega. Between implant (n = 38) and M7 (n = 15), pacing threshold rose from 0.73 +/- 0.54 to 1.57 +/- 0.60 V (P < 0.001). In conclusion, the situs lead was successfully implanted in a high percentage of patients. In addition, low pacing threshold and high impedance measured during follow-up are consistent with a low pacing current drain, ensuring a durable pulse generator longevity. |
2,558 | Ibutilide versus amiodarone in atrial fibrillation: a double-blinded, randomized study. | Ibutilide, a class III antiarrhythmic drug, has been shown to convert atrial fibrillation to sinus rhythm more rapidly than procainamide or sotalol. Our objective was to compare the efficacy and safety of ibutilide and amiodarone in patients after cardiac surgery.</AbstractText>Prospective, randomized, double-blinded study.</AbstractText>Intensive care unit of a university hospital.</AbstractText>Forty adults with an onset of atrial fibrillation within 3 hrs after admission.</AbstractText>Before the administration of antiarrhythmic drugs, a 24-hr Holter electrocardiograph was attached. Patients in the ibutilide group received ibutilide 0.008 mg/kg body weight over 10 mins; treatment was repeated if atrial fibrillation or flutter persisted. If sinus rhythm was not achieved within 4 hrs, amiodarone 5 mg/kg was administered over 30 mins, followed by amiodarone 15 mg/kg over 24 hrs. Patients in the amiodarone group received amiodarone 5 mg/kg over 30 mins, followed by amiodarone 15 mg/kg over 24 hrs if atrial fibrillation or flutter continued.</AbstractText>Within the first 4 hrs, atrial fibrillation was converted in nine of 20 patients (45%) in group ibutilide and in ten of 20 patients (50%) in group amiodarone (not significant). Mean time for conversion overall was 385 mins in group ibutilide and 495 mins in group amiodarone (not significant). In group amiodarone, the protocol was discontinued in two patients because of severe arterial hypotension. Atrial fibrillation recurred in 11 of 20 patients (55%) in group ibutilide and in seven of 20 patients (35%) in group amiodarone (not significant). Ventricular arrhythmia did not occur during the first 24 hrs of the protocol.</AbstractText>Ibutilide has no significant advantage over amiodarone for the conversion of atrial fibrillation to sinus rhythm in either time to conversion or conversion overall, but severe hypotension was not seen with ibutilide.</AbstractText> |
2,559 | [Training in cardiopulmonary reanimation with early defibrillation to nurses from the 7th area of Madrid]. | Ventricular fibrillation and ventricular tachicardia without pulse are the most frequent causes of suddenly death, therefore, it was considered that training hospitals and healthcentre nurses in identifying arritms and using properly the defibrilators was necessary. It was made by practical-theoric courses. The main aim of this study has been to know does the nurses value these type of courses and its repercussion on their level of knowledge. This is a descriptive study. The course consisted of 2 parts, one theoric and other practical. The valuation was made with a practical exam (A, B o C, being C a fail) and the other was written. To obtain the certificate of the course, you need to get at least 70% in the written part, and an A or a B in the practical exam. An exam was set at the beginning of the course and other at the end of it, in order to see the improvement. To value the course, we passed one anonimous poll, for this, it was used one scale from 1-5. we have gone 8 courses with 226 pupils, and the 74.3% of them, have passed. The level of knowledges has considerably increased p < 0.0001 the level of satisfaction was 4.7 0.5, of the teachers was of 4.6 0.5 and theirs enthusiasm on the course was 4.7 0.6. For them, theirs level of theorical and practical knowledges were 2.7 0.7 and 2.5 0.7 respectively.</AbstractText>1) Nurses have had a great interest in this course. 2) After the course, the level of knowledge was increased. 3) The califications of the pupils on the teachers and the course has been high. 4) The training of nursery in RCP and early defibrillation is absolutely essential as it is shawn in their low level of theorical and practical knowledge.</AbstractText> |
2,560 | Understanding implantable cardioverter defibrillator shocks and storms: medical and psychosocial considerations for research and clinical care. | The experience of shock is the distinguishing feature for patients with implantable cardioverter defibrillators (ICDs) and is associated with diminished psychological functioning and quality of life. Multiple shocks and ICD storm are a relatively common event among patients with ICDs (10-20%) and may present specific challenging medical and psychological management for the attending health care providers. This paper examines the medical and psychological aspects of ICD shocks and storms and describes a model of biopsychosocial management for patients following the experience of ICD storm. Successful management of patients post shock includes the use of antiarrhythmic medications and careful attention to the causality of the shocks via stored electrograms. The psychological management includes specific attention to debriefing post-shock feelings and attributions, preventing avoidance behavior, and facilitating positive "return to life" actions. Preliminary research examining formal psychosocial treatment supports a cognitive behavioral strategy to reduce psychological distress and facilitate quality of life. Collectively, these data suggest that interdisciplinary management of patients with multiple ICD shocks or the experience of ICD storm is advised, and routine psychological consultation may be indicated for the patient post ICD storm to reduce the possibility of symptoms of post-traumatic stress. |
2,561 | High defibrillation thresholds in transvenous biphasic implantable defibrillators: clinical predictors and prognostic implications. | The aim of this study was to identify clinical characteristics that distinguish patients with high DFTs and assess the prognostic implication. DFTs testing is a lengthy, potentially painful, and a hazardous process. Little information is available concerning the identification of patients with high DFT who undergo ICD surgery with transvenous leads and biphasic energy. This study analyzed 968 patients from two separate clinical studies who received a Medtronic cardioverter defibrillator from January 1995 through November 1999 and who had DFT testing measured by a binary search protocol. Compared to 865 patients with low defibrillation thresholds (< 18 J), the 103 patients with high thresholds (> or = 18 J) had a lower LVEF (34 +/- 16.7 vs 38.3 +/- 16.2%, P = 0.01), a worse NYHA functional class (23% Class I, 43% Class II, 29% Class III, 5% Class IV vs. 27% Class I, 55% Class II, 17% Class III, 1% Class IV, P < 0.0001), had bypass surgery less often (10.7 vs 27.5%, P < 0.0001), used amiodarone within the past 6 weeks (42.7 vs 27.2%, P = 0.002), and had a history of ventricular fibrillation more often (44.7 vs 33.1%, P = 0.02). Information concerning the number of shocks delivered was available in 345 (35%) patients; 23 were in the high DFT group and 322 were in the low DFT group. Twelve (52%) of the 23 patients in the high DFT arm received 3.6 +/- 2.7 shocks (median 2.5) and 106 (33%) of the 322 patients with low DFT received 4.9 +/- 9.5 shocks (median 2). After 6 months the mortality rate of patients with high thresholds was 11.7 vs 7.8% in patients with low thresholds (P = 0.118). Using a multivariate logistic regression model the significant predictors of death were older age, higher NYHA class, lower LVEF, amiodarone use, had a presenting arrhythmia of ventricular fibrillation and CHF but not initial high defibrillation thresholds. The study found that (1) 11% of patients have high DFTs, (2) clinical characteristics that identify high defibrillation thresholds are NYHA Class III, IV, low ejection fraction, no previous history of bypass surgery, prior amiodarone use preoperatively, and presenting with ventricular fibrillation, and (3) while high DFTs were associated with a more ill patient population, there was no difference in survival in a 6-month follow-up. Patients with a predicted low DFTs may be eligible for abbreviated ICD testing while high risk patients require formal testing. |
2,562 | Atrial septal versus atrial appendage pacing: feasibility and effects on atrial conduction, interatrial synchronization, and atrioventricular sequence. | Atrial septal (Se-P) and atrial appendage pacing (Ap-P) were compared in a randomized, controlled study to assess the feasibility, the reliability, and the effects of Se-P on atrial conduction, interatrial synchronization, and the AV sequence. The main baseline characteristics of the patients were comparable in both groups. There was no difference in feasibility or reliability between the two techniques. Compared to Ap-P (n = 28), Se-P (n = 28) decreased the P wave duration, left atrial electromechanical delay (LAEMD), and interatrial interval (-1.6% vs +28%, P < 0.001; -3% vs +30%, P < 0.001; -130% vs +78%, P < 0.001); it induced a smaller increase of the right AEMD, a slight reversal of the timing of the atrial systoles and a shortening of the PR interval (-13% vs +25%, P < 0.001) and of the interval separating atrial systoles from ventricular activation. Finally, the shortening of the PR interval was smaller during high Se-P versus low Se-P. Se-P avoids the undesirable prolongation of the atrial, interatrial, and AV conductions observed during Ap-P. In addition, Se-P creates a slight reversal of the timing of the atrial systoles and induces a shortening of PR interval, the extent of which could depend on the height of the pacing site on the septum. |
2,563 | Oral nicorandil recaptures the waned protection from preconditioning in vivo. | 1. Protection from preconditioning (PC) wanes and is eventually lost when multiple bouts of short ischemia or a prolonged reperfusion interval precedes the following sustained ischemia. The activation of mitochondrial K(ATP) channels plays a pivotal role in the intracellular signaling of PC. We tested whether the K(ATP) channel opener nicorandil (nic) preserves the given protection from PC in conditions where this benefit decays and is lost. 2. Eight groups of rabbits were divided into two equal series of experiments, one without nic (placebo) and one with nic treatment. Nic was given orally for 5 consecutive days in a dose of 5 mg kg(-1) d(-1). In a second step, four additional groups were treated with nic plus the K(ATP) channel blocker 5HD and 1 additional control group with nitroglycerin only. All the animals were anesthetized and then subjected to 30 min of myocardial ischemia and 2 h of reperfusion with one of the following interventions before the sustained ischemia: Control groups to no intervention; 3PC groups to three cycles of 5-min ischemia-10-min reperfusion; 8PC groups to eight cycles of 5-min ischemia - 10-min reperfusion; and 3PC90 groups to the same interventions as the 3PC groups but with a prolonged (90 min) intervening reperfusion interval before the sustained ischemia. The infarcted and the risk areas were expressed in percent. 3. There was no significant change in infarct size between the placebo, the nic and the 5HD-nic in the control groups (41.5+/-4.7, 43.9+/-7.1 and 48.7+/-6.4%) and 3PC groups (10.3+/-3.4, 12.2+/-3.9 and 12.6+/-4.5%). However, there was a significant decrease after nic treatment in groups 8PC (47.7+/-8.8% vs 13.0+/-2.6%, P<0.01) and 3PC90 (37.3+/-6.0% vs 14.2+/-2.4%, P<0.01), which was abrogated (38.2+/-4.7 and 42.7+/-4.4%, respectively, for 8PC and 3PC90 groups). Nitroglycerin had no effect on infarct size (39.1+/-3.1%, P=NS vs other controls). 4. Oral treatment with nic recaptures the waned protection of PC, both after repetitive bouts of short ischemia or after a prolonged reperfusion interval, preserving the initially obtained benefit. Nic by itself is insufficient to initiate PC in vivo. |
2,564 | Outcomes of cardiac surgery in nonagenarians: a 10-year experience. | With an increasing awareness of health issues and greater emphasis on preventive medicine, the general population is living longer and healthier lives than ever before. Physicians are taking care of older patients, many of whom may require cardiac surgical procedures. Improving cardiopulmonary bypass technology allows for safer procedures with reduced morbidity and mortality even in older patients.</AbstractText>We have performed a retrospective analysis of 42 consecutive nonagenarian patients who underwent open-heart procedures over a 10-year period (1993 to 2002) at our institution. Their demographic profiles, operative data, perioperative results, and long-term outcomes were recorded and analyzed.</AbstractText>Twenty-two women and 20 men with an age range of 90 to 97 years (mean, 91.4 years) had open-heart surgery over the study period. The complication rate was 67% overall, consisting of 7% respiratory (pneumonia, respiratory failure, reintubation), 7% hemorrhagic or embolic (postoperative bleeding, cerebral vascular accident), 12% infectious (wound infection, sepsis), and 31% new arrhythmia (atrial fibrillation, atrial flutter, ventricular tachycardia, ventricular fibrillation). Despite these complication rates, average hospital stay was 17.5 days (median, 11 days), with an intensive care unit stay of 12.0 days (median, 5 days). Thirty-day survival was 95% and survival to discharge was 93% (three deaths total; one cardiac arrest at hospital day 134 and two perioperative deaths; one ventricular arrhythmia, one cerebral vascular accident). The only statistically significant risk factor of mortality was emergency surgery. Currently, 81% are still alive an average of 2.53 years since surgery (range, 0.16 to 7.1 years).</AbstractText>With improving techniques and greater attention to detail, the select nonagenarian can safely undergo cardiac surgery.</AbstractText> |
2,565 | Early and late arrhythmias in patients in preoperative sinus rhythm submitted to mitral valve surgery through the superior septal approach. | It has been hypothesized that the use of the superior septal approach to the mitral valve can lead to postoperative loss of sinus rhythm. This study was undertaken to evaluate the early and mid-term alterations of the cardiac rhythm in patients with preoperative sinus rhythm (SR) submitted to mitral valve surgery through the superior septal approach.</AbstractText>Seventy-five cases in preoperative SR submitted to primary isolated mitral valve surgery through the superior septal approach constitute the study population. All patients underwent 12-lead electrocardiography on admission, every day after surgery until discharge and every year during the follow-up period.</AbstractText>On admission in the intensive care unit, 46 cases maintained their preoperative rhythm, whereas 18 developed a junctional rhythm (JR) and 7 had a first- or second-degree atrio-ventricular block (AVB). Four cases arrived in the unit in atrial fibrillation (AF). On the first postoperative day, these proportions were substantially unchanged, with the only exception being a slight increase in the number of patients in AF. The day before discharge, only 35 of the 74 surviving cases maintained the preoperative SR, whereas 13 developed AF, 10 were in JR, and 16 were in AVB. During the follow-up period (mean, 26 +/- 14 months), the majority of cases (47/74) regained SR; 11 patients had AVB, 3 were in JR, and the remaining 13 were in AF.</AbstractText>The use of the superior septal approach for mitral valve procedures in patients in preoperative SR is associated with minor, transient cardiac rhythm disturbances.</AbstractText> |
2,566 | What characterizes episodes of atrial fibrillation requiring cardioversion? Experience from patients with an implantable atrial cardioverter. | Episodes of paroxysmal atrial fibrillation may cause disabling symptoms. Asymptomatic episodes of paroxysmal atrial fibrillation are, however, more common than symptomatic episodes. The aim of the study was to investigate whether episodes of atrial fibrillation for which the patient requires cardioversion differ from those in which the patient does not seek this therapy.</AbstractText>We studied 21 patients with atrial fibrillation treated with an implanted atrial cardioverter. The device displayed intracardiac electrograms from episodes of atrial fibrillation in which the patient received cardioversion and from episodes that did not lead to a hospital visit or cardioversion. The heart rate (mean, highest, and lowest) and the degree of ventricular interval irregularity were analyzed with these electrograms.</AbstractText>There were 132 episodes of atrial fibrillation available for analysis, of which 73 led to cardioversion and 58 did not. Episodes leading to hospital/clinic visits and therapy had a higher maximum ventricular rate (130 vs 115/min, P =.0004) than episodes that did not cause the patients to seek therapy. This difference in heart rate was most prominent at the beginning of the episode, but tended to become more similar during the episode. There were no differences in ventricular cycle length irregularity between the 2 types of episodes. Moreover, treated episodes also had a significantly longer duration (mean duration 33 vs 9 hours, P =.002).</AbstractText>Episodes of atrial fibrillation that cause the patient to seek cardioversion are characterized by a high initial ventricular rate and a longer duration than those that go untreated.</AbstractText> |
2,567 | Effects of heart isolation, voltage-sensitive dye, and electromechanical uncoupling agents on ventricular fibrillation. | We tested whether the interventions typically required for optical mapping affect activation patterns during ventricular fibrillation (VF). A 21 x 24 unipolar electrode array (1.5 mm spacing) was sutured to the left ventricular epicardium of 16 anesthetized pigs, and four episodes of electrically induced VF (30-s duration) were recorded. The hearts were then rapidly excised and connected to a Langendorff perfusion apparatus. Four of the hearts were controls, in which 24 additional VF episodes were then mapped. In the remaining 12 hearts, four VF episodes were mapped after isolation, four more episodes were mapped after exposure to the voltage-sensitive dye di-4-ANEPPS, and six more episodes were mapped after exposure to the electromechanical uncoupling agents diacetyl monoxime (DAM; 20 mmol/l, n = 6) or cytochalasin D (CytoD; 10 micromol/l, n = 6). VF episodes were separated by 4 min. VF activation patterns were quantified using custom pattern analysis algorithms. From comparisons with time-corrected control data, all interventions significantly changed VF patterns. Most changes were broadly consistent with slowing and regularization due to loss of excitability. Heart isolation had the largest effect on VF patterns, followed by CytoD, DAM, and dye. |
2,568 | [Guideline 'Resuscitation', revision 2002]. | In 2002, the Netherlands Resuscitation Council published a translation of guidelines on Basic Life Support, use of the Automated External Defibrillator, and Advanced Life Support for adults and children, as laid down in 2000 by the International Liaison Committee on Resuscitation. The Dutch situation has altered in that there has been a change from the Netherlands-specific 'CAB' scheme to the internationally accepted 'ABC' scheme. This means that upon encountering a patient, the airways should be checked first (A), then artificial ventilation should be administered twice (B), after which the circulation should be checked in the third place (C) and chest compression should be initiated if necessary. In the Dutch guideline 'assessment of signs of circulation' for the identification of circulatory arrest by lay people was not accepted, but the pulse check at the carotid artery has been maintained. Medical professionals should also assess possible circulatory arrest in this way. Regardless of the number of people attending the patient, the ratio of chest compressions to artificial ventilation in adults is now 15:2 rather than the previously-advocated ratio of 5:1. This ratio is more effective in building up the blood pressure during the chest compressions. In terms of medication, the most important modification is the addition of amiodarone for persistent ventricular fibrillation. |
2,569 | [Efficacy of Nifekalant hydrochloride for life-threatening ventricular tachyarrhythmias in patients with resistance to lidocaine: a study of patients with out-of-hospital cardiac arrest]. | Class I antiarrhythmic agents are not always effective in the treatment of life-threatening ventricular tachycardia/ventricular fibrillation (VT/VF) especially in patients with cardiopulmonary arrest. Nifekalant hydrochloride(NIF) is a novel class III antiarrhythmic agent for malignant VT/VF. This study prospectively evaluated NIF efficacy for life-threatening VT/VF observed after cardiopulmonary arrest.</AbstractText>Thirty-two of 145 patients who were transferred to the emergency room in Tokai University Hospital showed VT/VF after resuscitation from cardiopulmonary arrest from June 2000 to March 2001. These 32 patients were treated with 12 mg (mean) epinephrine and 1.0-2.0 mg/kg lidocaine following direct current application(200 to 360J), and then classified into two groups. Eleven patients received intravenous 0.15 to 0.3 mg/kg NIF followed by intravenous infusion of 0.3 to 0.4 mg/kg/hr NIF(NIF group). The other 21 patients received 1.0 to 2.0 mg/kg of lidocaine(non-NIF group).</AbstractText>Sinus rhythm was restored in the nine patients(82%) in the NIF group but only four patients (19%) in the non-NIF group. QTc was not prolonged(0.45 +/- 0.04 sec, n = 9) and no torsades de pointes was observed in the NIF group. Two patients survived but the remaining nine patients died in the NIF group. Five patients died of cardiac standstill following sinus bradycardia and repeated sinus arrest within 2 to 27 hr after admission, two patients died of sudden cardiac arrest from sinus rhythm, and two patients died of persistent VT/VF. In contrast, all 21 patients in the non-NIF group died. Seventeen patients died of persistent VT/VF before hospitalization, one patient died of recurrent VT/VF, and three patients died of cardiac standstill following sinus bradycardia.</AbstractText>NIF effectively suppresses VT/VF which is refractory to direct current shock in patients with cardiopulmonary arrest. However, NIF may rather worsen electrophysiological function in the sinus node after administration of high doses of epinephrine, and may induce sinus bradycardia and/or sinus arrest. Careful observation, such as monitoring of electrocardiography and blood pressure and temporary cardiac pacemaker use, is needed to prevent death in patients surviving after cardiopulmonary arrest if NIF is administered following high dose epinephrine infusion.</AbstractText> |
2,570 | I-123 MIBG imaging and heart rate variability analysis to predict the need for an implantable cardioverter defibrillator. | Iodine 123 metaiodobenzylguanidine (MIBG) imaging and heart rate variability (HRV) analysis were compared in patients with an implantable cardioverter defibrillator (ICD) who did and did not receive defibrillator discharges. Although the ICD has been shown to abort potentially fatal ventricular arrhythmias, identification of patients who most benefit from this device remains difficult. As the autonomic nervous system has been implicated in the genesis of these arrhythmias, we undertook a pilot study to evaluate local myocardial sympathetic innervation with the use of I-123 MIBG myocardial imaging, as well as central autonomic tone with the use of HRV, in patients with implantable defibrillators. Test results were correlated with the occurrence of ICD discharges.</AbstractText>Seventeen patients with previously implanted defibrillators were studied. Of these, 10 had at least 1 appropriate device discharge for ventricular tachyarrhythmias, whereas 7 had no discharge. Patients with a discharge had a significantly lower I-123 MIBG heart-mediastinal tracer uptake ratio, higher I-123 MIBG defect scores, more extensive sympathetic denervation, and significantly reduced values for several HRV parameters, particularly those in the frequency domain. When combined, the I-123 MIBG heart-mediastinal ratio and HRV 5-minute low-frequency variables were highly predictive of defibrillator discharges. All patients with a heart-mediastinal ratio lower than 1.54 and 5-minute low frequency lower than 443 ms(2) had an ICD discharge (4/4), whereas no patient with an uptake ratio greater than 1.54 and 5-minute low frequency greater than 443 ms(2) did (0/3, P =.03).</AbstractText>Cardiac autonomic assessment using a combination of myocardial scintigraphic and neurophysiologic techniques may help select patients who would most benefit from an implantable defibrillator by identifying those at increased risk for potentially fatal arrhythmias.</AbstractText> |
2,571 | Management of arrhythmias in heart failure. | Arrhythmias continue to contribute significantly to morbidity and mortality in heart failure. Implantable defibrillators have assumed an increasingly important role in preventing sudden death and are recommended for patients who have been resuscitated from cardiac arrest, have unexplained syncope, or exhibit inducible ventricular tachycardia in the setting of prior myocardial infarction. The extension of survival conferred by implantable defibrillators is likely to be limited in patients with advanced heart failure. Ongoing trials will help define the use of these devices in heart failure populations, in whom atrial fibrillation is common and rate control and anticoagulation are of major importance. Among pharmaceutical options, amiodarone and dofetilide are the major agents for maintenance of sinus rhythm. The complexity of coexistent heart failure and arrhythmia management warrants close collaboration between heart failure and arrhythmia specialists. |
2,572 | Pharmacologic and nonpharmacologic options to maintain sinus rhythm: guideline-based and new approaches. | Atrial fibrillation is a common arrhythmia in patients with heart failure and is responsible for substantial morbidity and mortality. Restoration and preservation of sinus rhythm, therefore, has a premium. Of the numerous treatment options available, many must be avoided because of their potential for adverse effects or because of limited proof of efficacy in defined populations. Published guidelines provide help by synthesizing clinical trial data into a recommended approach. This article summarizes current information regarding the best methods applicable to patients with left ventricular dysfunction for rate control, sinus rhythm restoration and maintenance, and stroke prevention. New and evolving therapies and how they might fit into the evolving treatment paradigm are also briefly reviewed. |
2,573 | Risks and benefits of rate control versus maintenance of sinus rhythm. | There are 2 fundamental approaches to managing patients with recurrent atrial fibrillation (AF): to restore and maintain sinus rhythm with cardioversion and/or antiarrhythmic drugs, or to control the ventricular rate only. Over the past few years, there have been several important prospective clinical trials comparing rate control with rhythm control in patients with recurrent AF. The Pharmacological Intervention in Atrial Fibrillation (PIAF) trial was the first prospective randomized study to test the hypothesis of equivalency between the 2 management strategies for AF. The trial demonstrated that rate control was not inferior to rhythm control with respect to symptoms, quality of life, or number of hospitalizations in patients with persistent AF. The Strategies of Treatment in Atrial Fibrillation (STAF) trial was a pilot study that enrolled approximately 200 patients with AF who were randomized to either ventricular rate control or cardioversion and maintenance of sinus rhythm. The results showed that over a 1-year period there was little difference in outcome in terms of morbidity or symptoms. In the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial, patients with AF and risk factors for stroke were randomized to either rhythm control or rate control, with both groups receiving anticoagulation with warfarin. There was no difference in the composite end point of death, disabling stroke or anoxic encephalopathy, major bleeding, or cardiac arrest between the 2 arms. In addition, no major differences were noted in functional status or quality of life. The Rate Control Versus Electrical Cardioversion (RACE) trial also reached a similar conclusion. Thus, rate control is an acceptable primary strategy for management of patients with recurrent AF. |
2,574 | Old and new antiarrhythmic drugs for converting and maintaining sinus rhythm in atrial fibrillation: comparative efficacy and results of trials. | In managing atrial fibrillation (AF), the main therapeutic strategies include rate control, termination of the arrhythmia, and the prevention of recurrences and thromboembolic events. Safety and efficacy considerations are important in optimizing the choice of an antiarrhythmic drug for the treatment of AF. Recently approved antiarrhythmics, such as dofetilide, and promising investigational drugs, such as azimilide and dronedarone, may change the treatment landscape for AF. For medical conversion of recent-onset AF, class IC antiarrhythmic drugs, administered as an oral bolus, have been demonstrated to be the most efficacious pharmacologic conversion agents. Intravenous ibutilide and oral dofetilide both have efficacies superior to placebo in controlled trials for converting persistent AF. Comparative trials in paroxysmal AF have demonstrated that flecainide, propafenone, quinidine, and sotalol are equally effective in preventing recurrences of AF. Amiodarone has been demonstrated to be more efficacious than propafenone or sotalol in the Canadian Trial of Atrial Fibrillation. In persistent AF, twice-daily dofetilide has been shown to be as or more effective than low-dose sotalol given twice daily for the maintenance of sinus rhythm in patients with AF. Trials have demonstrated that subjective adverse effects are less frequent with class IC drugs, sotalol, and dofetilide compared with such drugs as quinidine. In patients without structural heart disease, flecainide, propafenone, and D,L-sotalol are the initial drugs of choice, given their reasonable efficacy, low incidence of subjective side effects, and lack of significant end-organ toxicity. Treating AF in patients with left ventricular dysfunction can be difficult because of associated electrophysiologic derangements, potential proarrhythmic concerns, and negative inotropic effects of antiarrhythmics. Some data exist suggesting that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can prevent AF either by preventing atrial dilation and stretch-induced arrhythmias or by blocking the renin-angiotensin system. In post-myocardial infarction patients, D,L-sotalol, dofetilide, and amiodarone-and in congestive heart failure patients, amiodarone and dofetilide-have demonstrated neutral effects on survival in controlled trials. In the Congestive Heart Failure Survival Trial of Antiarrhythmic Therapy (CHF-STAT), amiodarone lowered the frequency of AF development and improved left ventricular ejection fraction over time. In CHF-STAT, there was lower mortality in patients who converted from AF to sinus rhythm. Dofetilide decreased rehospitalization for congestive heart failure in the Danish Investigations of Arrhythmia and Mortality on Dofetilide (DIAMOND) trials. Neutral effects on survival and favorable hemodynamics have positioned amiodarone and dofetilide as the antiarrhythmics of choice in patients with left ventricular dysfunction. In post-myocardial infarction patients, sotalol is an additional agent to consider for treatment of AF in this setting. |
2,575 | Sudden cardiac death: implantable cardioverter defibrillators and pharmacological treatments. | Sudden cardiac death (SCD) is the leading cause of death in advanced heart failure and cardiomyopathy patients, regardless of the underlying causes of cardiomyopathy. Ventricular tachycardia and ventricular fibrillation are the causes of SCD. This article examines pharmacological interventions and mostly, the role of implantable cardioverter defibrllators in preventing SCD in heart failure patients. The indications for various methods of treatment of SCD are discussed in this article. |
2,576 | Therapeutic hypothermia after prolonged cardiac arrest due to non-coronary causes. | Mild resuscitative hypothermia has been shown to improve neurological outcome after cardiac arrest presenting with ventricular fibrillation (VF) due to cardiac causes. We describe the experience of inducing mild hypothermia in three patients with non-cardiac causes of arrest and long delays before a return of spontaneous circulation (ROSC). In one patient, extreme metabolic acidosis due to inadvertent oesophageal intubation complicated therapy, and the role of point-of-care diagnostics in the prehospital setting is briefly discussed. All patients survived to discharge from hospital, and neuropsychological examinations revealed good recovery. It is concluded that mild resuscitative hypothermia may be beneficial also in patients with obvious non-coronary causes for cardiac arrest. |
2,577 | A comparison of alpha-methylnorepinephrine, vasopressin and epinephrine for cardiac resuscitation. | The objective of this research was to compare the effects of an alpha- and beta-adrenergic agonist, epinephrine, a selective alpha(2)-adrenergic agonist, alpha-methylnorepinephrine (alpha-MNE), and a non-adrenergic vasopressin on post-resuscitation myocardial function and duration of survival. Epinephrine continues to be the primary adrenergic agent for advanced cardiac life support. However, its major inotropic actions and especially its beta-adrenergic and, to a lesser extent, its alpha(1)-actions increase the severity of global ischemia during cardiac arrest and adversely affect post-resuscitation myocardial function and survival. We had previously observed significantly better outcomes with a selective alpha(2)-adrenergic agonist when compared with epinephrine. Non-adrenergic vasopressin also has promise of more favorable actions. The present study was, therefore, undertaken to compare a selective alpha(2)-adrenergic vasopressor drug with vasopressin, epinephrine, and saline placebo. Ventricular fibrillation (VF) was induced in 20 Sprague-Dawley rats. Mechanical ventilation and precordial compression were initiated after 8 min of untreated VF. About 2 min later, alpha-MNE in a dose of 100 microgram/kg, vasopressin in a dose of 0.4 U/kg, epinephrine in a dose of 30 microgram/kg, or saline control was administered. Defibrillation was attempted after 6 min of CPR. Left ventricular pressure, dP/dt(40), -dP/dt, and cardiac index were measured for an interval of 240 min after resuscitation. Except for saline controls, comparable increases in coronary perfusion pressure (CPP) were observed after each drug intervention. All animals were successfully resuscitated. Post-resuscitation myocardial function and survival were significantly better in animals treated with alpha-MNE. Both post-resuscitation myocardial function and survival were most improved after administration of the selective alpha(2)-adrenergic agonist, intermediate after vasopressin and least after epinephrine and saline placebo. |
2,578 | Comparison of six clinically used external defibrillators in swine. | External defibrillation has long been practiced with two types of monophasic waveforms, and now four biphasic waveforms are also widely available. Although waveforms and clinical dosing protocols differ among defibrillators, no studies have adequately compared performance of the monophasic or the biphasic waveforms. This is the first study to compare defibrillation efficacy among biphasic external defibrillators, and does so as part of a study comparing all commonly available waveforms using their respective manufacturer-provided and clinically used doses.</AbstractText>Efficacy of six waveforms was tested in 852 short-duration ventricular fibrillation episodes in 14 swine. Protocol 1: 200-J monophasic damped sine (MDS) and monophasic truncated exponential (MTE) shocks were compared to 150-J biphasic shocks in six swine at the low-impedance of these animals. Protocol 2: Four commercially available biphasic defibrillators were compared using their respective manufacturer-recommended dose protocols in eight swine at low and simulated high-impedance. At low-impedance, all biphasic shocks achieved near-perfect success, while efficacy was significantly lower for MDS (67%) and MTE (30%) shocks. In protocol 2, first-shock success rates of the four biphasic defibrillators were uniformly high (97, 100, 100, and 94%) for low-impedance shocks, and decreased for high-impedance shocks (62, 92, 82, and 64%). There were statistically significant differences in efficacy among devices.</AbstractText>Commonly used MDS and MTE waveforms provide markedly dissimilar efficacies. Despite impedance-compensation schemes in biphasic defibrillators, impedance has an impact on their efficacy. At high-impedance, modest efficacy differences exist among clinically available biphasic defibrillators, reflecting differences in both waveforms and manufacturer-provided doses.</AbstractText> |
2,579 | Efficacy of CPR in a general, adult ICU. | To investigate the initial cardiopulmonary resuscitation (CPR) success rate and long term survival in an Intensive care unit (ICU) population.</AbstractText>All patients with cardiac arrest over a 2-year-period (1999-2000) in a general, adult ICU of a general hospital of Athens.</AbstractText>Retrospective collection of clinical data concerning patients, CPR characteristics and survival rates.</AbstractText>We examined 111 ICU patients, aged 56.4+/-1.9 years (72 males). SAPS II score was 43.9+/-3.8. CPR was performed in 98.2% of the patients within 30 s. Initial restoration of cardiac function (RCF) and successful CPR rate was 100% while 24 h survival was 9.2%. Survivors at 24 h were younger, mainly males, with lower SAPS II score, mainly with pulmonary disease, ventricular fibrillation or ventricular tachycardia (8/10) and initial pupil reactivity (5/10). Four patients required more than one cycle of CPR. Survival to discharge was zero.</AbstractText>Although the initial successful CPR rate in ICU patients may be high, long term survival and hospital discharge is disappointing. Although ICU patients are better monitored and treated in a timely fashion, they are disadvantaged by chronic underlying diseases, severe current medical illnesses and multi organ dysfunction syndrome (MODS) leads to worst outcome after CPR compared with in-ward patients.</AbstractText> |
2,580 | Characteristics and outcome among patients suffering from out of hospital cardiac arrest of non-cardiac aetiology. | To describe the epidemiology for out of hospital cardiac arrest of a non-cardiac aetiology.</AbstractText>All patients suffering from out of hospital cardiac arrest in whom resuscitation efforts were attempted in the community of Göteborg between 1981 and 2000.</AbstractText>Between October 1, 1980 and October 1, 2000, all consecutive cases of cardiac arrest in which the emergency medical service (EMS) system responded and attempted resuscitation were reported and followed up to discharge from hospital.</AbstractText>In all, 5415 patients participated in the evaluation. Among them 1360 arrests (25%) were judged to be of a non-cardiac aetiology. Among these 24% were caused by a surgical cause or accident, 20% by obstructive pulmonary disease, 13% by drug abuse and the remaining 43% by 'another cause'. Of the patients with out of hospital cardiac arrest of a non-cardiac aetiology 4.0% survived to discharge from hospital as compared with 10.1% of the patients with a cardiac aetiology (P<0.0001). In the various subgroups survival was highest in those with drug abuse (6.8%) and lowest in those with 'another cause' (4.2%). Cerebral performance categories (CPC) score at hospital discharge tended to be worse among survivors from an arrest of non-cardiac than cardiac aetiology. Patients with a cardiac arrest of a non-cardiac aetiology differed from the remaining patients by being younger, including more women, less frequently having a witnessed arrest and less frequently being found in ventricular fibrillation/tachycardia. When simultaneously considering age, sex, witnessed status, presence of bystander cardiopulmonary resuscitation (CPR) and initial arrhythmia, the aetiology (non-cardiac vs. cardiac aetiology) was not an independent predictor of survival.</AbstractText>Among patients with out of hospital cardiac arrest in whom resuscitation was attempted 25% were judged to be of a non-cardiac aetiology. These patients had a lower survival than patients with a cardiac arrest of cardiac aetiology. However, this was mainly explained by a lower occurrence of ventricular fibrillation and witnessed cardiac arrest.</AbstractText> |
2,581 | Analysing the ventricular fibrillation waveform. | The surface electrocardiogram associated with ventricular fibrillation has been of interest to researchers for some time. Over the last few decades, techniques have been developed to analyse this signal in an attempt to obtain more information about the state of the myocardium and the chances of successful defibrillation. This review looks at the implications of analysing the VF waveform and discusses the various techniques that have been used, including fast Fourier transform analysis, wavelet transform analysis and mathematical techniques such as chaos theory. |
2,582 | Comparison of arrhythmia recurrence in patients presenting with ventricular fibrillation versus ventricular tachycardia in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial. | Because many episodes of ventricular fibrillation (VF) are believed to be triggered by ventricular tachycardia (VT), patients who present with VT or VF are usually grouped together in discussions of natural history and treatment. However, there are significant differences in the clinical profiles of these 2 patient groups, and some studies have suggested differences in their response to therapy. We examined arrhythmias occurring spontaneously in 449 patients assigned to implantable cardioverter-defibrillator (ICD) therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial to determine whether patients who receive an ICD after VT have arrhythmias during follow-up that are different from patients who present with VF. ICD printouts were analyzed both by a committee blinded to the patients' original presenting arrhythmia and by the local investigator. During 31 +/- 14 months of follow-up, 2,673 therapies were reported. Patients who were enrolled in the AVID trial after an episode of VT were more likely to have an episode of VT (73.5% vs 30.1%, p <0.001), and were less likely to have an episode of VF (18.3% vs 28.0%, p = 0.013) than patients enrolled after an episode of VF. Adjustment for differences in ejection fraction, previous infarction, and beta-blocker and antiarrhythmic therapy did not appreciably change the results. Ventricular arrhythmia recurrence during follow-up is different in patients who originally present with VT than in those who originally present with VF. These findings suggest there are important differences in the electrophysiologic characteristics of these 2 patient populations. |
2,583 | Effects of long-term exercise training on cardiac autonomic nervous activities and baroreflex sensitivity. | Reductions in tonic vagal controls of the heart and depressed baroreflex sensitivity (BRS) have been associated with a postural fall in blood pressure (BP) and the incidence of cardiac events among older people. We examined the hypothesis that BP regulation during orthostatic challenge as well as heart rate variability (HRV) at rest can be better maintained in long-term exercise-trained, healthy, older men (aged 60-70 years). Subjects were classified into two groups; long-term exercise-trained (LTET, n=14) and sedentary (SED, n=10) according to their history of physical activity. Prior to the dynamic BRS assessment, supine resting autonomic cardiac modulation was assessed by means of time domain HRV [standard deviation of ECG R-R interval (RRISD) and the coefficient of variation (CV)]. The BRS was assessed during 60 degrees head-up tilting by simultaneously measuring beat-by-beat systolic blood pressure (SBP) and ECG R-R interval changes. The BRS gain was determined by the regression slope coefficient based on the extent of the SBP fall and the corresponding ECG R-R shortening during the orthostatic challenge. The results indicated that the LTET group manifested greater ECG R-R interval fluctuations with significantly higher resting RRISD and CV, compared with the SED group [59.5 (10.4) versus 27.7 (7.8) ms, p<0.05; 5.5 (0.8) versus 2.8 (0.7)%, p<0.05], respectively. Using dynamic BRS testing during the acute orthostatic challenge, the LTET group showed a significantly higher BRS gain than the SED [6.4 (0.8) versus 3.8 (0.6) ms x mmHg(-1), p<0.017] group. These results indicate that CV and BRS are well maintained in healthy, LTET older individuals when compared with their sedentary peers. Our data suggest that this augmented autonomic cardiac modulation reflects better parasympathetic responsiveness in LTET individuals. Data provide further support for long-term exercise training as another possible cardioprotective factor that might decrease susceptibility to ventricular fibrillation as well as assist arterial BP at the onset of an orthostatic challenge in older men. |
2,584 | Sodium-hydrogen exchange inhibition during ventricular fibrillation: Beneficial effects on ischemic contracture, action potential duration, reperfusion arrhythmias, myocardial function, and resuscitability. | Inhibition of the sarcolemmal sodium-hydrogen exchanger isoform-1 (NHE-1) is emerging as a promising novel strategy for ameliorating myocardial injury associated with ischemia and reperfusion. We investigated whether NHE-1 inhibition (with cariporide) could minimize mechanical and electrical myocardial abnormalities that develop during ventricular fibrillation (VF) and improve outcome using a porcine model of closed-chest resuscitation.</AbstractText>Two groups of 8 pigs each were subjected to 8 minutes of untreated VF and randomized to receive either a 3-mg/kg bolus of cariporide or 0.9% NaCl immediately before an 8-minute interval of conventional closed-chest resuscitation. Cariporide prevented progressive increases in left ventricular free-wall thickness (from 1.0+/-0.2 to 1.5+/-0.3 cm with NaCl, P<0.001 versus 0.9+/-0.1 to 1.1+/-0.3 cm with cariporide, P=NS), maintained the coronary perfusion pressure above resuscitability thresholds (10+/-8 versus 19+/-3 mm Hg before attempting defibrillation, P<0.05), and increased resuscitability (2 of 8 versus 8 of 8, P<0.005). In 2 additional groups of 4 pigs each subjected to a briefer interval of untreated VF, cariporide ameliorated postresuscitation shortening of the action potential duration (APD) at 30%, 60%, and 90% repolarization (ie, APD60 at 2 minutes after resuscitation; 75+/-29 versus 226+/-16 ms, P<0.05), minimized postresuscitation ventricular ectopic activity preventing recurrent VF, and lessened postresuscitation myocardial dysfunction.</AbstractText>NHE-1 inhibition may represent a highly potent novel strategy for resuscitation from VF that can ameliorate myocardial manifestations of ischemic injury and improve the effectiveness and outcome of closed-chest resuscitation.</AbstractText> |
2,585 | Pre-operative balloon counterpulsation and off-pump coronary surgery for high-risk patients. | Coronary artery bypass surgery (CABG) can be performed less invasively without cardiopulmonary bypass (CPB). Multivessel off-pump CABG (OPCAB) is challenging in patients with critical left main stenosis (> 70%) and/or severe ventricular dysfunction (ejection fraction < 0.35) Our objective was the evaluation of efficiency of intra aortic balloon pump (IABP) preoperatively in this high-risk group in order to perform OPCABG safely.</AbstractText>In a consecutive 10-month period (out of 88 OPCABG patients) 23 high-risk patients were treated and were compared with 15 on-pump patients (out of 69) with the same criteria.</AbstractText>Preoperative implantation of IABP was significantly higher in the OPCABG group (70% vs 46%, p < 0.05). No conversion to CPB was required in the OPCABG group. Post-operative angiography was systematically performed and demonstrated 97.5% patency of anastomosis. No device-related complications occurred. No difference was found concerning age, risk factors, emergency surgery, ejection fraction, mean number of grafts per patient (2.64 versus 2.75) and average operating time. In contrast, OPCABG demonstrated a trend toward reduced morbidity in terms of atrial fibrillation, reexploration for bleeding and prolonged ventilator requirement > 12 h. Mortality was less in the OPCABG group (p < 0.05).</AbstractText>More randomized controlled trials are needed to evaluate the true efficacy of elective IABP in OPCABG high-risk patients. Until such studies are evaluated, and therefore because older and sicker patients now constitute a greater percentage of candidates for OPCABG, the timing of application of the IABP is warranted. These results may further justify preoperative use of the IABP in a large proportion of this group of patients.</AbstractText> |
2,586 | Open access echocardiography: a prospective audit of referral patterns from primary care. | Following recently published recommendations and guidelines, a prospective audit of 222 consecutive patients referred for open access echocardiography was conducted over a period of three months in a large district general hospital in the UK. Our study demonstrated the waiting time for an open access echocardiogram to be shorter than the waiting time for the outpatient clinic, which allowed identification of clinically significant cardiac disease sooner, leading to early advice on patient management. Specialist referral was avoided by the inclusion of management comments by a cardiologist in the technical echocardiogram report. We showed that open access echocardiography for detection of left ventricular systolic function, should be performed only if the ECG is abnormal, confirming previous reports. ECG interpretation in primary care is unreliable. In view of limited resources, hospitals should vigorously screen referrals for open access echocardiography. |
2,587 | Sustained ventricular arrhythmias and mortality among patients with acute myocardial infarction: results from the GUSTO-III trial. | In many patients, ventricular arrhythmias will develop early after acute myocardial infarction. We studied the incidence, timing, and outcomes of such arrhythmias in the international Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries (GUSTO)-III trial.</AbstractText>We identified independent predictors of inhospital ventricular fibrillation (VF) and ventricular tachycardia (VT) and compared 30-day and 1-year mortality rates of patients who did (n = 1121) and did not (n = 13,921) have these arrhythmias during the index hospitalization.</AbstractText>Significant independent predictors of inhospital VF were higher Killip class, lower baseline systolic pressure, intravenous preenrollment lidocaine use, shorter time to thrombolysis, and beta-blocker use <2 weeks before enrollment; independent predictors of inhospital VT were lower baseline systolic pressure, intravenous lidocaine use before enrollment, higher Killip class, faster baseline heart rate, and advanced age. The 30-day mortality rate was 31% in patients with VF, 24% in those with VT, 44% in those with both, and 6% in those with neither (P =.001). The corresponding 1-year mortality rates were 34%, 29%, 49%, and 9% (P =.001). The 30-day and 1-year mortality rates were higher for patients with late (>48 hours after enrollment) versus early arrhythmias (< or =48 hours after enrollment).</AbstractText>Despite thrombolysis, inhospital ventricular arrhythmias are associated with higher 30-day and 1-year mortality rates after acute myocardial infarction, particularly when occurring later during the initial hospitalization. Better therapies are needed to improve outcomes of these arrhythmias.</AbstractText> |
2,588 | Long-term amiodarone therapy and the risk of complications after cardiac surgery: results from the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial (CAMIAT). | This study was undertaken to determine the association between amiodarone therapy and risk of complications of cardiac surgery in patients in the randomized placebo-controlled, double-blind Canadian Amiodarone Myocardial Infarction Arrhythmia Trial.</AbstractText>Prospectively collected data regarding postoperative complications in 82 patients who underwent cardiac surgery during Canadian Amiodarone Myocardial Infarction Arrhythmia Trial participation were analyzed; 36 patients were randomly assigned to receive amiodarone and 46 were assigned to receive placebo. Of the patients randomly assigned to receive amiodarone, 24 patients continued amiodarone treatment to within 7 days of the operation (active amiodarone group) and 12 patients had the amiodarone discontinued at least 7 days before the operation (discontinued amiodarone group).</AbstractText>The baseline characteristics of the three groups were similar. The risks of ventricular fibrillation, atrial fibrillation, and respiratory complications were similar. The risk of requiring an intra-aortic balloon pump was significantly increased by amiodarone (34.8% vs 16.7% vs 8.7% for active amiodarone, discontinued amiodarone, and placebo groups, respectively, P =.024). There was no significant difference in the use of temporary pacing. Neither the mean duration of stay in the intensive care unit nor the 7- and 30-days mortalities were affected by amiodarone.</AbstractText>Patients receiving long-term amiodarone treatment after myocardial infarction had a higher rate of intra-aortic balloon use after cardiac surgery. There was no increased risk of pulmonary complications, need for pacing, or death.</AbstractText> |
2,589 | Effect of sotalol and acute ventricular dilatation on action potential duration and dispersion of repolarization after defibrillation shocks. | Ventricular dilatation shortens action potential duration and increases the defibrillation threshold, whereas sotalol prolongs action potential duration and may decrease the defibrillation threshold. Whether these action potential changes remain after defibrillation shocks, and how they relate to defibrillation success, is not known. In this study, eight monophasic action potentials were recorded simultaneously during electrical defibrillation (shock strength: 20%-200% of the defibrillation threshold) in 16 normal and acutely dilated isolated rabbit hearts at baseline and after addition of sotalol (2 x 10-5 M). Post-shock action potential duration (PS-APD) and dispersion of PS-APD [Disp(PS-APD)] of monophasic action potentials were analyzed after 322 defibrillation shocks at different repolarization levels and related to defibrillation success. Acute ventricular dilatation shortened PS-APD, whereas sotalol prolonged PS-APD. Successful defibrillation was associated with lower Disp(PS-APD) at all repolarization levels in the normal and dilated heart at baseline and with sotalol (mean difference: 33%-46%, all P < 0.005). Minimal PS-APD was longer (mean difference: 5%-11%), while maximal PS-APD was shorter (mean difference: 2%-16%) after successful defibrillation shocks than after failing defibrillation shocks. Therefore, sotalol prolongs action potential duration after defibrillation shocks. Synchronization of repolarization, caused by both prolongation of short PS-APD and shortening of long PS-APD, is associated with successful defibrillation in the normal, acutely dilated, and sotalol-treated heart. |
2,590 | Effect of pilsicainide on atrial electrophysiologic properties in the canine rapid atrial stimulation model. | The heterogeneous process of atrial electrical remodeling (AER) in the canine rapid atrial stimulation model has been previously reported although it has been reported that a sodium channel blocker might suppress the shortening of the atrial effective refractory period (AERP), its effect on long-term electrical remodeling is unknown. In the present study, the effect of pilsicainide on AER was evaluated. The right atrial appendage (RAA) was paced at 400 beats/min for 2 weeks. In the RAA, Bachmann's bundle (BB), the right atrium near the inferior vena cava (IVC) and in the left atrium (LA), AERP, AERP dispersion (AERPd) and the inducibility of atrial fibrillation (AF) were evaluated at several time points of the pacing phase and the recovery phase (1 week). The same protocol was performed during the administration of pilsicainide (4.5 mg/kg per day) and the parameters were compared with the controls. In the control dogs, the AERP was significantly shortened by rapid pacing at all atrial sites studied and the AERP shortening (DeltaAERP) was larger at the RAA and LA sites (p<0.03). However, pilsicainide decreased these DeltaAERPs at all 4 atrial sites. AERPd was increased during the pacing phase whereas it was decreased during the recovery phase in the control dogs. In contrast, this pacing-induced AERPd was attenuated by the administration of pilsicainide. The AF inducibility was highest at the LA site in both groups, and the inducibility was lower in the pilsicainide group than the control group at all atrial sites. During the rapid pacing phase, the ventricular heart rate was significantly lower in the pilsicainide group than the control because of intra-atrial conduction block. In a canine rapid right atrial stimulation model, pilsicainide suppressed the shortening of the AERP at all atrial sites, possibly through the improvement of the hemodynamics as well as the action of the Na - Ca exchanger. |
2,591 | Protective effect of basic fibroblast growth factor against myocyte death and arrhythmias in acute myocardial infarction in rats. | The present study in rats investigated whether basic fibroblast growth factor (bFGF) plays an important role in cardioprotection against myocardial cell death and arrhythmias in acute myocardial infarction (AMI). After ligating the left coronary artery in 62 Wistar rats, 20 Eg of human recombinant bFGF was injected into the infarcted myocardium in 33 rats (group F), while saline was used for 29 control rats (group C). The development of ventricular tachyarrhythmias was assessed during the first 30 min of ischemia. After 24 h occlusion, the hearts of the surviving rats (group F: n=13, group C: n=10) were excised to assess minimum infarct wall thickness and infarct size, determine the number of TUNEL-positive cardiomyocytes and to analyze Bcl-2 and Bax expression by immunohistochemical staining and Western blotting. The incidence of ventricular tachycardia was higher in group C than in group F (p<0.05). The thinning ratio was higher in group F than in group C (p<0.05). There were fewer TUNEL-positive cardiomyocytes in the infarct border area in group F than in group C (p<.0001). Western blot analysis showed greater expression of Bcl-2 in group F than in group C (p<0.05), but similar expression of Bax in the 2 groups. In conclusion, intramyocardial administration of bFGF prevented ischemia-induced myocardial cell death and arrhythmias. |
2,592 | Risk stratification for asymptomatic patients with Brugada syndrome. | Ventricular fibrillation (VF) is induced in some asymptomatic patients with Brugada syndrome (BS), but the prognostic value of programmed electrical stimulation (PES) in such patients is controversial. The clinical characteristics of 41 asymptomatic BS patients, divided into 2 groups according to whether VF was induced by PES (inducible VF group: n=13, non-inducible VF group: n=28) were evaluated. ST levels in the right precordial leads were measured before and after administration of pilsicainide and the abnormal late potential (LP) was evaluated on the signal-averaged electrogram. The ST level at V(2) at baseline in the inducible VF group was significantly higher than that in the non-inducible VF group (p<0.05). Pilsicainide induced significant ST segment elevation in both groups and the ST level after pilsicainide in the inducible VF group was higher than that in the non-inducible VF group (p<0.01). LP was more frequent in the inducible VF group than in the non-inducible VF group. The criterion of ST level >0.15 mV at baseline with pilsicainide-induced additional ST elevation >0.10 mV and positive LP showed high sensitivity (92%) and specificity (89%) for detection of PES-induced VF in asymptomatic BS patients. |
2,593 | Left ventricular performance during acute rate control in atrial fibrillation: the importance of heart rate and agent used. | The relation between heart rate and left ventricular function during rate control in atrial fibrillation is incompletely understood.</AbstractText>Twenty-four patients (age 67 +/- 11 years) with symptomatic recent onset rapid atrial fibrillation and rapid ventricular rate (> 110 bpm) were randomly assigned to receive either intravenous digoxin (13 mcg/kg) or intravenous diltiazem (0.25 mg/kg bolus plus a maintenance infusion). A portable radionuclide detector was used to collect validated measures of relative left ventricular volumes, along with heart rate data, every 15 seconds for 6 hours.</AbstractText>Heart rate decreased significantly at 15 minutes and 180 minutes in the diltiazem group (from 133 +/- 18 bpm to 111 +/- 26 bpm [P <.01] to 94 +/- 24 bpm [P <.001]) but not in the digoxin group (from 129 +/- 18 bpm to 126 +/- 17 bpm [P = NS] to 118 +/- 15 bpm [P = NS]). Left ventricular ejection fraction improved in both groups to a similar extent (from 39 +/- 10% to 50 +/- 8%, [P <.05] after diltiazem, and from 38 +/- 8% to 52 +/- 11% [P <.05] after digoxin at baseline vs 180 minutes, respectively). The ejection fraction vs heart rate slope was steeper in the digoxin group than in the diltiazem group (-0.34 +/- 0.18 vs -0.16 +/- 0.17, P =.048) indicating a more pronounced improvement in ejection fraction per unit decrease in heart rate.</AbstractText>In patients with acute atrial fibrillation, digoxin led to similar improvements in ejection fraction compared to diltiazem despite a slower and less potent heart rate slowing.</AbstractText> |
2,594 | Ventricular fibrillation resulting from acute right ventricular infarction from isolated occlusion of a right ventricular branch artery. | Malignant ventricular arrhythmias can result from isolated right ventricular infarction, and reports of this phenomenon in the literature are rare. We present a case of a 46-year-old man with acute onset of chest pain angiographically confirmed to be a result of isolated occlusion of a right ventricular branch artery. He developed ventricular fibrillation within 5 hours of symptom onset. This case highlights the point that despite its benign clinical appearance and preserved left ventricular function, necrosis of right ventricular tissue can have life-threatening consequences. |
2,595 | The dual pathway electrophysiology of the atrioventricular conduction. A new look at an old phenomenon. | Although we soon will be marking the 100th anniversary of the discovery of the atrioventricular (AV) node, the mysteries of this most complex of all parts of the conduction system of the heart remain. We are still battling controversies related to the precise morphology of the AV node and its atrial approaches. We are still debating the exact reentrant pathways of the AV nodal reentrant tachycardia. We are still uncertain if the so-called dual AV nodal electrophysiology encompasses two or more pathways, and what exactly makes these pathways in the absence of distinct insulated cables between the atrium and the AV node. It may be just surprising, in view of the above limitations, that current level of knowledge has nevertheless made possible some of the most spectacular successes in the modern cardiac electrophysiology. Thus, the cases of typical AVNRT are cured with a very high rate of success by radiofrequency ablations, increasing the quality of life of thousands of patients. AV nodal modifications are being performed to slow the ventricular rate during atrial fibrillation, although more progress is needed in this endeavor. The goal of the present review is to outline the major anatomic and electrophysiologic efforts in understanding the mechanisms underlying the dual pathway AV nodal propagation and to trace some novel approaches that promise to widen the horizon of the experimental and clinical fields. |
2,596 | Successful implantation of cardiac defibrillators without induction of ventricular fibrillation using upper limit of vulnerability testing. | Conventionally, the implantable cardioverter-defibrillator (ICD) is tested at implantation by measurement of defibrillation threshold (DFT), which involves repeated induction of ventricular fibrillation (VF). We report our data on successful ICD implantation without VF induction using a modified upper limit of vulnerability (ULV) testing method, compared to standard DFT testing.</AbstractText>Fourteen patients underwent ICD implantation using a modified ULV testing method by delivering a 15 J shock during the vulnerable period on the peak of the T wave, and if VF was not induced 15 J shocks were repeated at -20 and -40 msec before the peak of T wave. Failure to induce VF, indicating a ULV <15 joules (J), suggested a DFT < or =20 J based on previous studies demonstrating a close correlation (+/-5 J) between ULV and DFT. If VF was induced, a 20 J rescue shock was delivered. ICD therapy was then programmed on the basis of ULV testing. All patients underwent pre-discharge DFT testing to confirm adequate DFT.</AbstractText>Using a modified ULV testing method, ICD implantation was completed without induction of VF in 8 patients and only a single episode of VF in 6 patients. The mean number of VF episodes (0.42 +/- 0.5) induced with ULV testing was significantly lower (p <.001) than the number induced during DFT testing (3.9 +/- 0.8). Pre-discharge DFT testing did not alter ICD programming in any patient. During follow-up of 14.85 +/- 12.31 months, three patients had seven episodes of VT/VF, six of whom were converted with the programmed first-shock strength, while one required a second high-energy shock to convert. This patient had a pre-discharge DFT of 10 joules.</AbstractText>Successful ICD implantation can be safely performed with no or fewer episodes of VF induction using a modified ULV testing method.</AbstractText> |
2,597 | Comparison of coronary venous defibrillation with conventional transvenous internal defibrillation in man. | Animal studies have shown that defibrillation in coronary veins is more effective than in the right ventricle. We aimed to assess the feasibility of placing defibrillation electrodes in the middle cardiac vein (MCV) in man and its impact on defibrillation requirements.</AbstractText>A prospective randomised study conducted in a tertiary referral centre. 10 patients (9 male) undergoing ICD implantation (65 (12) yrs) for NASPE/BPEG indications were studied. Defibrillation thresholds (DFT) were measured, using a binary search and an external defibrillator after 10 seconds of ventricular fibrillation, for the following configurations in each patient (order of testing randomised): RV + MCV --> Can and RV --> SVC + Can.</AbstractText>A dual coil defibrillation electrode was placed transvenously in the right ventricle (RV) in the conventional manner. Using a guiding catheter a 3.2 Fr (67.5 mm length) electrode was placed transvenously in MCV. A test-can was placed subcutaneously in the left pectoral region.</AbstractText>Lead placement was possible in 8/10 pts. Time to perform a middle cardiac venogram and place the electrode was 21 (23) mins. No adverse events were observed. Defibrillation current was less (6.7 (2.7) A) with RV + MCV --> Can compared to the conventional RV --> SVC + Can configuration (8.9 (3.4) A, p = 0.03). There was no significant difference in defibrillation voltage or energy. However, shock impedance was higher in the former configuration (57 (10) v. 43 (6) Omega, p = 0.001).</AbstractText>In the majority of cases placement of a defibrillation lead in MCV is feasible. Defibrillation current requirements are 25% less when the shock is delivered using a MCV electrode.</AbstractText> |
2,598 | Atrial fibrillation ablation leads to long-term improvement of quality of life and reduced utilization of healthcare resources. | In some patients, rapid activation from one or several foci can lead to atrial fibrillation. This study evaluated long-term changes in quality of life and healthcare resource utilization in patients with atrial fibrillation treated by ablation of focal triggers. Thirty-three patients underwent ablation for paroxysmal atrial fibrillation. Health surveys (SF-36) were obtained at baseline, and after 1 year and 3 years of follow-up. Health care costs were measured for the 3 years before and after ablation. Ablation was successful in 82%, partially successful in 12% (no sustained episodes but on antiarrhythmic drug therapy), and unsuccessful in 6% of patients. The average number of ablation procedures was 1.6 +/- 0.6 per patient. After ablation, patients reported significantly improved quality of life in all SF-36 categories except bodily pain. Healthcare resource utilization was significantly reduced after ablation (Clinic visits: 7.4 +/- 2.5 per year vs. 1.1 +/- 0.6 per year, p < 0.05; Emergency room visits: 1.7 +/- 0.90 per year vs. 0.03 +/- 0.17 per year, p < 0.05; Hospitalization: 1.6 +/- 0.81 vs. 0, p < 0.05). Cost of healthcare (not including procedural costs) was significantly reduced after ablation (Pre-ablation: 1,920 +/- 889 dollars/year vs. post-ablation: 87 +/- 68 dollars/year; p < 0.01). Procedural cost of ablation was 17,173 +/- 2,466 dollars/patient. Ablation of focal triggers of atrial fibrillation is associated with a sustained improvement in quality of life. Although the initial cost of ablation is high, after ablation, utilization of healthcare resources is significantly reduced. |
2,599 | Selective atrionodal input ablation for induction of proximal complete heart block with stable junctional escape rhythm in patients with uncontrolled atrial fibrillation. | The study tests the hypothesis that ablating all inputs to the atrioventricular (AV) node can result in complete heart block with stable junctional escape rhythm.</AbstractText>We attempted atrionodal input ablation in 76 consecutive patients with uncontrolled atrial fibrillation. Fast and slow pathways were first ablated. If there was no AV block, additional energy applications were done between fast and slow pathway locations. The patients were followed for 42 +/- 11 months. Group I (n = 57) comprised patients with complete heart block and junctional escape rhythm (53 +/- 4 beats/min) at the end of the procedure. The escape rhythm remained stable throughout follow-up. Group II (n = 15) were patients who failed the stepwise atrionodal input ablation and required AV junctional ablation guided by His bundle potential to achieve complete heart block. Four patients showed a slow escape rhythm after ablation (33 +/- 4 beats/min). Others had no escape rhythm. All 15 pts remained pacemaker dependent. The total death rate of groups I and II was 18/57 (31.6%) vs 10/15 (66.7%), respectively (p < 0.02). These differences could not be explained by a difference of left ventricular ejection fraction (0.42 +/- 0.07 vs 0.41 +/- 0.04, respectively, p = NS).</AbstractText>(1) In most patients, ablation of both fast and slow pathways did not result in complete heart block, indicating the presence of multiple atrionodal inputs. (2) Ablation of all atrionodal inputs may result in complete heart block with stable junctional escape rhythm. (3) As compared with AV junctional ablation, atrionodal input ablation was associated with a lower mortality rate on long-term follow up.</AbstractText> |
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