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5,400 | [A case of asymptomatic Brugada syndrome with type 1 ECG pattern and cardiac arrest: an evaluation of the prognostic value of electrophysiologic study]. | Brugada syndrome is characterized by ST-segment elevation in the leads V1-3 of electrocardiography (ECG) in the absence of a structural heart disease. A 26-year old male patient was admitted with sudden cardiac arrest. Cardiopulmonary resuscitation was successful and he was referred to the reanimation unit due to unconsciousness. A year before, he was diagnosed as having Brugada syndrome with type 1 ECG pattern at another center, at which time electrophysiologic study (EPS) was not performed due to lack of symptoms and a family history of sudden cardiac death. In addition, family screening revealed two asymptomatic brothers having Brugada syndrome with type 1 ECG pattern. Medical follow-up was recommended to one of them. The other sibling underwent EPS at a different center where ventricular fibrillation was induced. An implantable cardioverter defibrillator (ICD) was recommended, but the patient refused. A further analysis of the family made at our center showed type 2 ECG changes in the father and in one of the cousins. Due to the development of persistent brain injury and an expected survival of less than a year, an ICD was not considered in the patient. The prognostic value of EPS is still controversial in asymptomatic patients with type 1 Brugada syndrome, without a family history of sudden cardiac death. |
5,401 | Mesenchymal stem cell injection ameliorates the inducibility of ventricular arrhythmias after myocardial infarction in rats. | Mesenchymal stem cell transplantation is a promising new therapy to improve cardiac function after myocardial infarction (MI). The electrophysiological consequences of MSC implantation has not been systematically studied.</AbstractText>We investigated the electrophysiological and arrhythmogenic effects of mesenchymal stem cells (MSCs) therapy in experimental infarction model. Rats were subjected to MI operation by LAD ligation and randomly allocated to receive intramyocardially injection PBS (MI-PBS) or 5 × 10(5) EGFP labeled MSCs (MI-MSCs). Electrophysiological study, histological examination, and western blotting were performed 2 weeks after cell transplantation.</AbstractText>Programmed electrical stimulation (PES) showed a significant reduced inducible ventricular tachycardias (VTs), raised ventricular fibrillation threshold (VFT) and prolonged ventricular effective refractory period (VERP) in MSC-treated rats compared to PBS-treated animals. MSC implantation led to markedly longer action potential duration (APD) and shorter activation time (AT) in infarcted border zone (IBZ) of left ventricular epicardium compared with PBS-treated hearts. Histological study revealed that fibrotic area and collagen deposition in infarcted region were significantly lower in MI-MSC group than in MI-PBS group. Abnormal alterations of Connexin 43 including reduction and lateralization were significantly attenuated by MSC treatment.</AbstractText>This study provide strong evidence that MSC implantation ameliorates interstitial fibrosis and the remodeling of gap junction, attenuates focal heterogeneity of reporlarization and conduction and reduces vulnerability to VTs. The results suggest that MSC transplantation might emerge as a new preventive strategy against VAs besides improving cardiac performance in ischemic heart disease.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,402 | Asymptomatic sustained ventricular fibrillation in a patient with left ventricular assist device. | Optimal medical treatment, cardiac resynchronization, and the use of an implantable cardioverter defibrillator are established therapies of severe congestive heart failure. In refractory cases, left ventricular assist devices are more and more used not only as bridging to cardiac transplantation but also as destination therapy. Ventricular arrhythmias may represent a life-threatening condition and often result in clinical deterioration in patients with congestive heart failure. We report a case of asymptomatic sustained ventricular fibrillation with preserved hemodynamics caused by a nonpulsatile left ventricular assist device. Consecutive adequate but unsuccessful discharges of the implantable cardioverter defibrillator were the only sign of the usually fatal arrhythmia, prompting the patient to consult emergency services. Electrolyte supplementation and initiation of therapy with amiodarone followed by external defibrillation resulted in successful restoration of a stable cardiac rhythm after 3.5 hours. |
5,403 | Causes and management of drug-induced long QT syndrome. | Long QT syndrome (LQTS) is characterized by inherited or acquired prolonged QT interval on the surface electrocardiogram. This can lead to torsade de pointes ventricular tachycardia (TdP VT) and ventricular fibrillation. In the acquired form of the disease, medications from several classes can cause TdP VT or potentiate the electrocardiographic findings. These include class IA and III antiarrhythmics, antibiotics (macrolides and quinolones), antidepressants (tricyclics and selective serotonin reuptake inhibitors), antipsychotics (haloperidol and phenothiazines), and antiemetics (ondansetron and prochlorperazine). We present four cases of drug-induced LQTS resulting in life-threatening cardiac arrhythmias. Antiarrhythmic medications were the cause in two cases, and the other two cases involved noncardiac medications. All four patients had at least one risk factor for LQTS in addition to the offending drug, including female gender, hypokalemia, hypomagnesemia, and bradycardia. In one patient, amiodarone was administered for treatment of VT, although the correct diagnosis was actually TdP VT. In patients with polymorphic VT or ventricular fibrillation without a significant history of cardiovascular disease, drug-induced LQTS should be high in the differential diagnosis. Prompt diagnosis is key, as amiodarone, while often used to suppress VT, is potentially harmful in the setting of LQTS and TdP VT. |
5,404 | Focused nurse-defibrillation training: a simple and cost-effective strategy to improve survival from in-hospital cardiac arrest. | Time to first defibrillation is widely accepted to correlate closely with survival and recovery of neurological function after cardiac arrest due to ventricular fibrillation or ventricular tachycardia. Focused training of a cadre of nurses to defibrillate on their own initiative may significantly decrease time to first defibrillation in cases of in-hospital cardiac arrest outside of critical care units. Such a program may be the best single strategy to improve in-hospital survival, simply and at reasonable cost. |
5,405 | Ventricular fibrillation in an ex-premature neonate following reperfusion of ischemic gut incarcerated within an inguinal hernia. | We describe the case of a neonate who underwent surgery for bowel obstruction. The child was born at 25 weeks postconception, and at the time of surgery, he had a postconceptual age of 44 weeks. He had undergone two previous laparotomy procedures for necrotizing enterocolitis. At laparotomy, there was unexpected extensive compromise to gut perfusion. The child developed ventricular fibrillation following the reperfusion of a segment of ischemic gut found incarcerated in an inguinal hernial orifice. We discuss the pathophysiology of intestinal ischemia-reperfusion (I-R) injury. We have reviewed the interventions that may be employed to minimize the systemic impact of I-R. |
5,406 | Association of early repolarization pattern on ECG with risk of cardiac and all-cause mortality: a population-based prospective cohort study (MONICA/KORA). | Early repolarization pattern (ERP) on electrocardiogram was associated with idiopathic ventricular fibrillation and sudden cardiac arrest in a case-control study and with cardiovascular mortality in a Finnish community-based sample. We sought to determine ERP prevalence and its association with cardiac and all-cause mortality in a large, prospective, population-based case-cohort study (Monitoring of Cardiovascular Diseases and Conditions [MONICA]/KORA [Cooperative Health Research in the Region of Augsburg]) comprised of individuals of Central-European descent.</AbstractText>Electrocardiograms of 1,945 participants aged 35-74 y, representing a source population of 6,213 individuals, were analyzed applying a case-cohort design. Mean follow-up was 18.9 y. Cause of death was ascertained by the 9th revision of the International Classification of Disease (ICD-9) codes as documented in death certificates. ERP-attributable effects on mortality were determined by a weighted Cox proportional hazard model adjusted for covariables. Prevalence of ERP was 13.1% in our study. ERP was associated with cardiac and all-cause mortality, most pronounced in those of younger age and male sex; a clear ERP-age interaction was detected (p = 0.005). Age-stratified analyses showed hazard ratios (HRs) for cardiac mortality of 1.96 (95% confidence interval [CI] 1.05-3.68, p = 0.035) for both sexes and 2.65 (95% CI 1.21-5.83, p = 0.015) for men between 35-54 y. An inferior localization of ERP further increased ERP-attributable cardiac mortality to HRs of 3.15 (95% CI 1.58-6.28, p = 0.001) for both sexes and to 4.27 (95% CI 1.90-9.61, p<0.001) for men between 35-54 y. HRs for all-cause mortality were weaker but reached significance.</AbstractText>We found a high prevalence of ERP in our population-based cohort of middle-aged individuals. ERP was associated with about a 2- to 4-fold increased risk of cardiac mortality in individuals between 35 and 54 y. An inferior localization of ERP was associated with a particularly increased risk. Please see later in the article for the Editors' Summary.</AbstractText> |
5,407 | The impact of diastolic dysfunction on the atrial substrate properties and outcome of catheter ablation in patients with paroxysmal atrial fibrillation. | The presence of diastolic dysfunction increases the risk of atrial fibrillation (AF), and might be associated with the left atrial (LA) substrate. The aim of the present study was to investigate the relationships between the diastolic dysfunction, atrial substrate and outcome of the catheter ablation.</AbstractText>Eighty-three patients with paroxysmal AF were enrolled. Diastolic dysfunction was defined as a left ventricular ejection fraction (LVEF) of ≥ 50%, and one of the following criteria: (1) a mitral inflow early filling velocity to atrial filling velocity ratio (E/A) of ≤ 0.75; or (2) an E/A ratio of >0.75 and a ratio of the mitral inflow early filling velocity to the velocity of the early medial mitral annular ascent of >10. Patients with diastolic dysfunction were older than those with normal cardiac function. There were no differences in the other baseline characteristics, LA diameter, or LVEF. A decreased LA voltage, and higher recurrence rate were noted in patients with diastolic dysfunction. In the univariate analysis, the patients with recurrence had a lower LA voltage and greater diastolic dysfunction. The multivariate analysis also indicated diastolic dysfunction and LA voltage as independent predictors of recurrence.</AbstractText>The patients with diastolic dysfunction developed a different atrial substrate and had a worse outcome of catheter ablation for atrial fibrillation.</AbstractText> |
5,408 | How the knowledge of genetic "makeup" and cellular data can affect the analysis of repolarization in surface electrocardiogram. | This review article sought to describe patterns of repolarization on the surface electrocardiogram in inherited cardiac arrhythmias and to discuss how the knowledge of genetic makeup and cellular data can affect the analysis based on the data derived from the experimental studies using arterially perfused canine ventricular wedge preparations. Molecular genetic studies have established a link between a number of inherited cardiac arrhythmia syndromes and mutations in genes encoding cardiac ion channels or membrane components during the past 2 decades. Twelve forms of congenital long QT syndrome have been so far identified, and genotype-phenotype correlations have been investigated especially in the 3 major genotypes-LQT1, LQT2, and LQT3. Abnormal T waves are reported in the LQT1, LQT2, and LQT3, and the differences in the time course of repolarization of the epicardial, midmyocardial, and endocardial cells give rise to voltage gradients responsible for the manifestation of phenotypic appearance of abnormal T waves. Brugada syndrome is characterized by ST-segment elevation in leads V1 to V3 and an episode of ventricular fibrillation, in which 7 genotypes have been reported. An intrinsically prominent transient outward current (I(to))-mediated action potential notch and a subsequent loss of action potential dome in the epicardium, but not in the endocardium of the right ventricular outflow tract, give rise to a transmural voltage gradient, resulting in ST-segment elevation, and a subsequent phase 2 reentry-induced ventricular fibrillation. In conclusion, transmural electrical heterogeneity of repolarization across the ventricular wall profoundly affects the phenotypic manifestation of repolarization patterns on the surface electrocardiogram in inherited cardiac arrhythmias. |
5,409 | Transition of the ST segment from a J wave to a coved-type elevation before ventricular fibrillation induced by coronary vasospasm in the precordial leads. | We describe the case of a 63-year-old man whose electrocardiogram showed transition of the ST segment from a J wave to a coved-type elevation in precordial leads before ventricular fibrillation induced by right coronary artery vasospasm. Simultaneously, the ST segment in inferior leads was gradually depressed with a J wave. Considering the sudden death of his son, induced ventricular fibrillation by programmed electrical stimulation, and modulations of the ST segment in the precordial and inferior leads by pilsicainide, some abnormalities in repolarization associated with Brugada syndrome or early repolarization syndrome might have caused these atypical ST-segment manifestations. |
5,410 | Subcutaneous electrocardiogram monitors and their field of view. | Continuous electrocardiogram (ECG) monitoring of cardiac patients on a long-term, even permanent, basis has become possible. Postsurgical cases, those with significant risk factors, or patients with chronic conditions are candidates for these procedures to assess evolving risk factors and detect life-threatening events. A small sensing device can be implanted subcutaneously to assess the ECG, transmitting status and alerts to local caregivers or a remote monitoring service. We and others have shown that a differential electrode pair with only 2- to 3-cm spacing can produce QRS amplitudes greater than 1 mV, sufficient to accurately identify asystole, tachyarrhythmias, and ST-segment changes. Medtronic's REVEAL and St Jude Medical's CONFIRM are implantable look recorders (ILRs) with a single pair of subcutaneous electrodes mounted on the surface of the case (6 × 2 × 0.7 cm). They store representative rhythm strips when the heart rate exceeds preset limits or when the patient presses a button on the accompanying actuator. These records may be transferred for physician review during a subsequent office visit. Transoma's SLEUTH is a similar ILR, except that one of the electrodes is at the end of a 6-cm lead tunneled under the skin and the wider separation may result in a larger ECG amplitude. Instead of storing the records, SLEUTH transmits them through the skin to a home base unit, which sends them via telephone to a monitoring service. Angel Medical's ALERT system also has a tunneled lead, but one that is introduced pervenously into the right ventricle hoping to detect ST changes in addition to rhythm abnormalities. Advanced multivector ILR devices with integrated event alerting are rapidly approaching commercialization. AJ Medical Devices' CARDIOALARM (4 × 4 × 0.6 cm) has 4 electrodes at the corners of the square package, arranged as 2 orthogonal recording pairs that can produce a robust signal that is relatively immune to signal fluctuations caused by changes in the direction of cardiac activation and patient's body position. This permits accurate identification of dramatic changes in the ECG pattern, such as those occurring in ventricular fibrillation and polymorphic tachycardia. Because of this feature, CARDIOALARM can detect cardiac arrest, and its external receiver can alert bystanders to begin cardiopulmonary resuscitation and can automatically summon Emergency Medical Services. In the future, addition of other sensors, integration of data streams via body surface wireless networks, and real-time interpretive algorithms will allow enhanced monitoring systems to more generally assess evolving risks, the impacts of therapeutic interventions, and patient compliance with rehabilitative programs. When coupled to remote medical monitoring services, these devices have the potential to dramatically impact patient outcomes by lessening the diagnostic dependence on symptom recognition and decreasing event response times. Significant cost savings may also be realized through more efficient use of specialist resources, reduction in the number of office visits to physicians, and long-term improvements in patient health. Structural and behavior barriers to adoption need to be addressed for these methods to reach their full potential, addressing patient privacy concerns, adequate reimbursement, and integration into standard care protocols. |
5,411 | Short QT interval in clinical practice. | The last ten years have seen a growing interest in clinical scenarios, where a short QT interval may play a role, especially because of an increased risk of sudden cardiac death in some situations. One such entity is Short QT Syndrome, which has emerged as a rare, but very malignant disease, in particular when the QT interval is very short. A short QT interval has also been noticed in some patients with other arrhythmic syndromes such as Idiopathic Ventricular Fibrillation, Brugade Syndrome and Early Repolarization Syndrome, but the role of a short QT interval in these settings is so far not known. Hypercalcemia often leads to shortening of the QT interval, but there are no data in humans to suggest an increased risk of sudden cardiac death in this setting. In addition, a shorter-than-usual QT interval has been reported in patients with Chronic Fatigue Syndrome and in response to atropine, catecholamine and Hyperthermia. When a short QT interval is encountered in daily clinical practice, these various scenarios needs to be considered, but it is still not possible to come up with clear guidelines for how to work up and risk stratify such individuals. Genetic testing is only useful in very few and the value of an electrophysiologic study, Holter monitoring or stress testing to assess QT adaptation to heart rate and T wave morphology analysis may all be helpful, but not well-established, tests in this setting. |
5,412 | A transthoracic, left ventricular vent facilitates challenging sternal reentry. | In this brief report, we describe a technique to facilitate hypothermic arrest before a redo sternotomy that is likely to require extensive dissection. This approach may be well-suited for patients with significant aortic insufficiency, as it allows control of left ventricular distention once hypothermic ventricular fibrillation ensues. The procedure entails inserting a second venous cannula through the left ventricular apex through a 7-cm left mini-thoracotomy. We used the technique successfully in a patient with a ruptured, infected ascending aortic pseudoaneurysm and severe aortic insufficiency who had undergone a previous sternotomy. |
5,413 | Should patients with severe degenerative mitral regurgitation delay surgery until symptoms develop? | The American College of Cardiology/American Heart Association practice guidelines recommending surgery for asymptomatic patients with severe mitral regurgitation caused by degenerative disease remain controversial. This study examined whether delaying surgery until symptoms occur causes adverse cardiac changes and jeopardizes outcome.</AbstractText>From January 1985 to January 2008, 4,586 patients had primary isolated mitral valve surgery for degenerative mitral regurgitation; 4,253 (93%) underwent repair. Preoperatively, 30% were in New York Heart Association (NYHA) class I (asymptomatic), 56% in class II, 13% in class III, and 2% in class IV. Multivariable analysis and propensity matching were used to assess association of symptoms (NYHA class) with cardiac structure and function and postoperative outcomes.</AbstractText>Increasing NYHA class was associated with progressive reduction in left ventricular function, left atrial enlargement, and development of atrial fibrillation and tricuspid regurgitation. These findings were evident even in class II patients (mild symptoms). Repair was accomplished in 96% of asymptomatic patients, and in progressively fewer as NYHA class increased (93%, 86%, and 85% in classes II to IV, respectively; p < 0.0001). Hospital mortality was 0.37%, but was particularly high in class IV (0.29%, 0.20%, 0.67%, and 5.1% for classes I to IV, respectively; p = 0.004). Although long-term survival progressively diminished with increasing NHYA class, these differences were largely related to differences in left ventricular function and increased comorbidity.</AbstractText>In patients with severe degenerative mitral regurgitation, the development of even mild symptoms by the time of surgical referral is associated with deleterious changes in cardiac structure and function. Therefore, particularly because successful repair is highly likely, early surgery is justified in asymptomatic patients with degenerative disease and severe mitral regurgitation.</AbstractText>Copyright 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,414 | Efficacy of amiodarone on refractory ventricular fibrillation resistant to lidocaine and cardioversion during weaning from cardiopulmonary bypass in aortic valve replacement for severe aortic stenosis with left ventricular hypertrophy. | Intravenous injection of amiodarone, a class III anti-arrhythmic is widely used for persistent refractory arrhythmias. We present a case report suggesting the efficacy of amiodarone in refractory ventricular fibrillation (Vf) during weaning from cardiopulmonary bypass (CPB). A 66-year-old woman with hypertension had a medical examination as a result of an episode of palpitations and syncope. Echocardiography and an invasive hemodynamic study revealed severe aortic stenosis (AS) with left ventricular (LV) hypertrophy because of calcified degeneration in a congenital bicuspid aortic valve (AV). Aortic valve replacement (AVR) was scheduled under general anesthesia and CPB. Intraoperative diagnosis was AS with calcified AV, LV hypertrophy, and aneurysm of ascending aorta (Ao). AVR with a biological valve, artificial vessel replacement of ascending Ao, and excision of the outflow myocardial septum were performed under CPB with intermittent antegrade blood cardioplegia at a body temperature (BT) of 24°C. The patient suffered from Vf at a BT of 35.3°C. Vf was not responsive to lidocaine 100 mg and 10 direct current (DC) shocks. After continuous intravenous infusion of amiodarone 225 mg/h for 10 min and a single intravenous injection of amiodarone 150 mg followed by a single DC shock, she returned to normal sinus rhythm. Sinus rhythm was maintained by continuous intravenous infusion of amiodarone 60 mg/h. Total CPB time was 5 h 43 min. Aortic cross-clamping time was 3 h 50 min. Administration of amiodarone is effective for refractory Vf resistant to lidocaine and cardioversion during weaning from CPB in cardiac surgery for heart diseases with LV hypertrophy. |
5,415 | The signal-averaged electrocardiogram before and after electrical cardioversion of persistent atrial fibrillation-implications of the sudden change in rhythm. | Atrial fibrillation (AF), electrical cardioversion (direct current, or DC) shock energy, and a sudden change to sinus rhythm (SR) might all influence the interpretation of the signal-averaged electrocardiogram (SAECG) as risk markers of ventricular tachyarrhythmia.</AbstractText>The SAECG was recorded in 82 patients with persistent AF before and 2 hours after DC and analyzed for ventricular late potentials (LPs) and spectral turbulence.</AbstractText>Sixty-nine patients (84%) obtained SR. Their mean (SD) heart rate decreased by 22 (20) beats/min, and the QTcF interval was significantly prolonged, 17 (38) milliseconds, as was the filtered QRS duration, 1.1 (4.7) milliseconds (40 Hz). The proportion of LP positivity (20%) did not change with the change in rhythm. Eight of 60 spectral turbulence-negative patients before DC became positive after DC (P = .01). The change in SAECG variables did not correlate significantly with the amount of energy delivered at DC.</AbstractText>The LP analysis provided similar results in AF and SR, whereas the spectral turbulence analysis was more abnormal in SR. The electrical shock itself did not seem to explain this phenomenon.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,416 | Altered circadian rhythm of cardiac β3-adrenoceptor activity following myocardial infarction in the rat. | Circadian rhythms influence the incidence of adverse cardiac events but the underlying mechanisms are not well defined. We sought to investigate the role of the β3-adrenoceptor (β3-AR) in cardiac circadian disorders and arrhythmia severity after myocardial infarction (MI). MI was created by ligating the left anterior descending coronary artery of the rat heart in situ. Circadian variations of the myocardial expressions of β3-AR and clock genes Bmal1 and Npas2 were examined by real time reverse transcription polymerase chain reaction, Western blot and immunohistochemistry. Electrocardiograms and myocardial contraction were recorded in vivo and/or ex vivo. Ventricular tachyarrhythmias were induced by isoprenaline. Normal rats showed circadian oscillations in both the myocardial transcriptional expression of β3-AR and the β3-AR-induced positive chronotropic and negative inotropic cardiac effects. However, these circadian rhythms were significantly blunted or even abolished in rats with either acute MI (within 24 h) or healed MI (14 days after coronary ligation). The nocturnal level of β3-AR protein was higher in MI rats than in normal rats. In contrast, the circadian oscillations of the transcripts of Bmal1 and Npas2 in the myocardium were significantly augmented in rats with either acute MI or healed MI. BRL37344, a preferential β3-AR selective agonist, reduced the occurrence of ventricular tachycardia (VT) and ventricular fibrillation (VF) in rats with either acute MI or healed MI. We conclude that circadian rhythms of myocardial β3-AR activities are disturbed after MI and β3-AR activation offers anti-arrhythmic protection. |
5,417 | Systolic anterior motion causing hemodynamic instability and pulmonary edema during bleeding. | Systolic anterior motion (SAM) of mitral valve is the prolapse of a mitral leaflet into the left ventricle outflow tract (LVOT) during systole, causing LVOT obstruction and mitral valve regurgitation. We report the case of a patient who developed SAM-induced hemodynamic instability during bleeding with a clinical picture resembling pulmonary edema. A 77-year-old woman was admitted to our emergency room for abdominal bleeding in polycystic renal disease. Upon arrival, she was normotensive, despite being anuric and acidotic. After infusion of fluids and packed red blood cells (total 3 680 mL in 6 hours) she developed atrial fibrillation and clinical and radiological signs of pulmonary edema. Sedation and non-invasive ventilation brought to immediate severe hypotension. A transesophageal echocardiogram showed an "empty" hypertrophic hypercontractile left ventricle, SAM with LVOT obstruction (intraventricular gradient 154 mmHg) and moderate-to-severe mitral regurgitation. With further fluid infusion hemodynamic stability and sinus rhythm were recovered. SAM, LVOT obstruction and mitral regurgitation disappeared. SAM is a rare but dangerous cause of hemodynamic instability. It has been described in patients with and without left ventricular hypertrophy, in presence of hypovolemia and sympathetic stimulation. In our case it presented with a misleading clinical picture of pulmonary edema simulating fluid overload in an actually hypovolemic patient. In fact, SAM-associated mitral regurgitation together with diastolic dysfunction and tachycardia induced a pulmonary edema whose treatment worsened hypovolemia and precipitated LVOT obstruction and hypotension. Further fluid infusion was resolutive. Echocardiography was fundamental for diagnosis and treatment. |
5,418 | In situ simulation comparing in-hospital first responder sudden cardiac arrest resuscitation using semiautomated defibrillators and automated external defibrillators. | Multifaceted approaches using simulation and human factors methods may optimize in-hospital sudden cardiac arrest (SCA) response. The Arrhythmia Simulation/Cardiac Event Nursing Training-Automated External Defibrillator phase (ASCENT-AED) study used in situ medical simulation to compare traditional and AED-supplemented SCA first-responder models.</AbstractText>The study was conducted at an academic 719-bed hospital with institutional review board approval. Two simulation scenarios were developed and featured either respiratory arrest with perfusing bradycardia or ventricular fibrillation (VF) arrest. Study floors were equipped with either a semiautomated defibrillator (SD) only (control) or with both SD and AED (experimental); subjects functioned as solitary first responders and did not receive resuscitation training.</AbstractText>Fifty nurses were enrolled on control (n=25) and experimental (n=25) floors. The groups' nonblinded performances exhibited the following differences during VF scenario: slower calls for help by the control group [mean time to completion of 25+/-17 seconds versus 18+/-11 seconds for the experimental group (P<0.05)] and fewer subjects in the control group performing chest compressions [44.0% versus experimental group's 95.8% (P<0.001)]. Eighty-eight percent of the control group defibrillated the manikin at an average of 155+/-59 seconds, with 32.0% of those subjects using semiautomated rhythm analysis; 100% (not significant [NS]) of experimental group defibrillated at 154+/-72 seconds (NS) with 100% AED analysis (P<0.001). Fewer control group subjects (28.0%) were observed during the bradycardia scenarios to perform inappropriate chest compressions than the AED-supplemented subjects [69.6% (P=0.01)]; nonindicated defibrillation was delivered during these scenarios by a single subject in the control group. Twenty-eight percent and 72% of VF scenarios were managed appropriately by control and experimental groups, respectively; bradycardia scenarios were managed without severe adverse event by 64% of control group and 28% of experimental group.</AbstractText>In situ simulation can provide useful information, both anticipated and unexpected, to guide decisions about proposed defibrillation technologies and SCA response models for in-hospital resuscitation system design and education before implementation.</AbstractText> |
5,419 | Ligating LAD with its whole length rather than diagonal branches as coordinates is more advisable in establishing stable myocardial infarction model of swine. | A reproducible and reliable myocardial infarction (MI) model with less inter-individual variation in ischemic size and ventricular function is essential in cardiovascular research. Little is known about whether the different ligation coordinates [whole length of left anterior descending artery (LAD) or diagonal branches] affect the inter-individual variation of ventricular function in the MI model. The present study compared the characteristics of the experimental swine MI model induced by surgical occlusion of LAD in two groups: group A (n=24), where ligation was performed below the second ventricular branch (D(2) branch), and group B (n=23), where ligation was performed at a distance one-third distal to the apex. Variation of ischemic size and left ventricular ejection fraction (LVEF) at 4 weeks after MI was compared between the two groups using the homoscedasticity F test and coefficient of variance (CV). Difficulty in identifying ventricular branches and the great variation of branching patterns encumbered the precise ligation of LAD in group A. The ischemic size and LVEF in group B were less variable than those of group A. There were significant correlations between the percentile of LAD ligation and infarct size or ventricular function. In conclusion, ligating LAD using its whole length rather than ventricular branches as coordinates may be more practical and advisable for establishing reproducible MI models, and this procedure may prove to help standardize the location of occlusion and infarct size. |
5,420 | Differences between out-of-hospital cardiac arrest in residential and public locations and implications for public-access defibrillation. | The majority of out-of-hospital cardiac arrests (OHCAs) occur in residential locations, but knowledge about strategic placement of automated external defibrillators in residential areas is lacking. We examined whether residential OHCA areas suitable for placement of automated external defibrillators could be identified on the basis of demographic characteristics and characterized individuals with OHCA in residential locations.</AbstractText>We studied 4828 OHCAs in Copenhagen between 1994 and 2005. The incidence and characteristics of OHCA were examined in every 100 x 100-m (109.4 x 109.4-yd) residential area according to its underlying demographic characteristics. By combining > or =2 demographic characteristics, it was possible to identify 100 x 100-m (109.4 x 109.4-yd) areas with at least 1 arrest every 5.6 years (characterized by >300 persons per area and lowest income) to 1 arrest every 4.3 years (characterized by >300 persons per area, lowest income, low education, and highest age). These areas covered 9.0% and 0.8% of all residential OHCAs, respectively. Individuals with OHCA in residential locations differed from public ones in that the patients were older (70.6 versus 60.6 years; P<0.0001), the ambulance response interval was longer (6.0 versus 5.0 minutes; P<0.0001), arrests occurred more often at night (21.2% versus 11.2%; P<0.0001), the patients had ventricular fibrillation less often (12.8% versus 38.1%; P<0.0001), and the patients had a worse 30-day survival rate (3.2% versus 13.9%; P<0.0001).</AbstractText>On the basis of simple demographic characteristics of a city center, we could identify residential areas suitable for automated external defibrillator placement. Individuals with OHCA in residential locations were more likely to have characteristics associated with poor outcome compared with public arrests.</AbstractText> |
5,421 | Improving evidence-based care for heart failure in outpatient cardiology practices: primary results of the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF). | A treatment gap exists between heart failure (HF) guidelines and the clinical care of patients. The Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF) prospectively tested a multidimensional practice-specific performance improvement intervention on the use of guideline-recommended therapies for HF in outpatient cardiology practices.</AbstractText>Performance data were collected in a random sample of HF patients from 167 US outpatient cardiology practices at baseline, longitudinally after intervention at 12 and 24 months, and in single-point-in-time patient cohorts at 6 and 18 months. Participants included 34 810 patients with reduced left ventricular ejection fraction (< or =35%) and chronic HF or previous myocardial infarction. To quantify guideline adherence, 7 quality measures were assessed. Interventions included clinical decision support tools, structured improvement strategies, and chart audits with feedback. The performance improvement intervention resulted in significant improvements in 5 of 7 quality measures at the 24-month assessment compared with baseline: beta-blocker (92.2% versus 86.0%, +6.2%), aldosterone antagonist (60.3% versus 34.5%, +25.1%), cardiac resynchronization therapy (66.3% versus 37.2%, +29.9%), implantable cardioverter-defibrillator (77.5% versus 50.1%, +27.4%), and HF education (72.1% versus 59.5%, +12.6%) (each P<0.001). There were no statistically significant improvements in angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use or anticoagulation for atrial fibrillation. Sensitivity analyses at the patient level and limited to patients with both baseline and 24-month quality measure data yielded similar results. Improvements in the single-point-in-time cohorts were smaller, and there were no concurrent control practices.</AbstractText>The Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting, a defined and scalable practice-specific performance improvement intervention, was associated with substantial improvements in the use of guideline-recommended therapies in eligible patients with HF in outpatient cardiology practices.</AbstractText>URL: http://www.clinicaltrials.gov. Unique identifier: NCT00303979.</AbstractText> |
5,422 | [Atrial fibrillation in patients with type 2 diabetes mellitus: specific features of development and antirecurrence therapy]. | We examined 212 patients aged 52-70 years with persistent symptomatic atrial fibrillation (AF). Comparison of AF substrates in patients with (n=26) and without (n=27) type 2 diabetes mellitus (DM2) revealed slowing of intraatrial conduction, increased vulnerability of atria, and more pronounced worsening of left ventricular diastolic function among DM2 patients. Comparison of groups of patients with (n=32) and without (n=33) diabetic cardiac autonomic neuropathy (CAN) revealed augmentation of adrenergic influences on the heart and comparatively higher antirecurrence efficacy of sotalol among patients with CAN. In 94 patients with type 2 DM complicated with CAN after randomization we administered antiarrhythmic therapy with sotalol in combination with perindopril (n=33), lipoic acid (n=31), perindopril and lipoic acid (n=30), and compared results with sotalol monotherapy. In 6 months percentage of patients in sinus rhythm was significantly higher in the group of combination therapy (sotalol plus perindopril plus lipoic acid). This was probably a result of simultaneous correction of disturbances caused by both "diabetic cardiomyopathy" and CAN. |
5,423 | Atrial contractile protein content and function are preserved in patients with coronary artery disease and atrial fibrillation. | Atrial fibrillation (AF) causes atrial contractile dysfunction. The focus of this study was to determine whether the contractile deficit of human AF is the result of altered contractile protein abundance and/or function.</AbstractText>Atrial tissue from patients with chronic AF undergoing open-heart surgery was compared with the tissue from patients in normal sinus rhythm (NSR). Myosin isoform composition and content were determined. Intact native thin filament and cardiac myosin contractile protein performance were independently assessed in an in-vitro motility assay.</AbstractText>Myosin isoform expression and total myosin content were not different between AF and NSR. Calcium-activated native thin filament function was similar between AF and NSR as measured by calcium sensitivity and maximal activation. Myosin isolated from the atria of AF and NSR groups showed similar unloaded shortening speeds and isometric force generation.</AbstractText>Unlike human ventricular dysfunction where contractile protein function is directly affected, the contractile deficit of AF is not the result of alterations in myosin content or contractile protein function.</AbstractText> |
5,424 | Early repolarization associated with ventricular arrhythmias in patients with chronic coronary artery disease. | Early repolarization, indicated on the standard 12-lead ECG, has recently been associated with idiopathic ventricular fibrillation in patients without structural heart disease. It is unknown whether there is an association between early repolarization and ventricular arrhythmias in the coronary artery disease (CAD) population.</AbstractText>Patients with CAD with implantable cardioverter-defibrillators in the healed phase of myocardial infarction were analyzed. In a case-control design, 60 patients who had ventricular arrhythmic events were matched for age and sex with 60 control subjects. ECGs were analyzed for early repolarization, defined as notching or slurring morphology of the terminal QRS complex or J-point elevation ≥0.1 mV above baseline in at least 2 lateral or inferior leads. Results were adjusted for left ventricular ejection fraction. Overall, early repolarization in 2 or more leads was more common in cases than control subjects (32% versus 8%, P=0.005). Early repolarization was noted more commonly in inferior leads (23% versus 8%, P=0.03), and a trend was noted in leads V(4) through V(6) (12% versus 3%, P=0.11). Early repolarization was uncommon in leads I and aVL in cases and control subjects (3% versus 0%). Notching was more common in cases than control subjects (28% versus 7%, P=0.008). Slurring and J-point elevation were not associated with ventricular arrhythmias.</AbstractText>Early repolarization and, in particular, notching in the inferior leads is associated with increased risk of life-threatening ventricular arrhythmias in patients with CAD, even after adjustment for left ventricular ejection fraction. Our findings suggest early repolarization, and a notching morphology should be considered in a risk prediction model for arrhythmias in patients with CAD.</AbstractText> |
5,425 | High-resolution coronary imaging by optical coherence tomography: Feasibility, pitfalls and artefact analysis. | Optical coherence tomography is an imaging method that enables cardiologists to study atheromatous plaques, and to check the implantation and evolution of coronary stents. It is an invasive technique, providing high-resolution (10 microm) in vivo images, but with limitations and artefacts that need to be understood before the field of application can be extended.</AbstractText>To determine the feasibility and limitations of optical coherence tomography coronary imaging from a single-centre experience.</AbstractText>We analysed the first 301 optical coherence tomography (version M2, LightLab Imaging) sequences obtained in our department from examination of 73 patients.</AbstractText>Results showed that 92% of sequences for selected lesions were usable, with a mean examination time of 17 min. Only one complication occurred (ventricular fibrillation, reduced by external electroshock). In our registry, sequence quality depended on operator experience (improving after 20 examinations), and was impaired by artefacts, especially in right coronary analysis and in arteries of greater than 3.5 mm calibre.</AbstractText>Proximal coronary occlusion and the distal flush quality currently required for quality imaging should no longer be indispensable with the new generation of optical coherence tomography systems.</AbstractText>Copyright 2010 Elsevier Masson SAS. All rights reserved.</CopyrightInformation> |
5,426 | Sotalol-induced torsades de pointes precipitated during treatment with oseltamivir for H1N1 influenza. | Striking prolongation of the QT interval and the morphologically distinctive polymorphic ventricular tachycardia torsades de pointes can occur in patients treated with antiarrhythmic drugs and certain non-cardiovascular medications. However, there have been no reported cases of QT prolongation and torsades de pointes associated with the antiviral agent oseltamivir.</AbstractText>To determine whether exposure to oseltamivir is associated with increased risk of QT prolongation and torsades de pointes in patients treated for H1N1 influenza.</AbstractText>Two unusual case histories of patients exposed to oseltamivir who developed marked QT prolongation and torsades de pointes were examined.</AbstractText>Two patients on stable doses of sotalol for atrial fibrillation developed marked QT prolongation and torsades de pointes following administration of the antiviral agent.</AbstractText>The recent H1N1 pandemic has necessitated treatment of suspected or confirmed cases of H1N1 influenza with oseltamivir. Although the precise mechanism for this drug-drug interaction is not clear, given the large number of people expected to receive oseltamivir this winter, it is important to highlight this potentially adverse event.</AbstractText> |
5,427 | Proteomic and metabolomic analysis of atrial profibrillatory remodelling in congestive heart failure. | Congestive heart failure (CHF) leads to atrial structural remodelling and increased susceptibility to atrial fibrillation. The underlying molecular mechanisms are poorly understood. We applied high-throughput proteomic and metabolomic analysis to left-atrial cardiomyocytes and tissues obtained from sham and ventricular-tachypaced (VTP, 240 bpm × 24 h and × 2 weeks) CHF dogs. Protein-extracts were subjected to two-dimensional gel electrophoresis using differential in-gel electrophoresis technology. Differentially expressed (P<0.05) proteins were identified by tandem mass-spectrometry. Cardiac metabolites were assayed with high-resolution NMR spectroscopy. Extensive changes occurred in structural proteins, particularly at 2-week VTP, with desmin and filamin fragmentation suggesting structural damage, which was confirmed by electron-microscopy. Oxidant stress was evidenced by decreased antioxidant proteins (superoxide dismutase and peroxiredoxin) at 2-week VTP. Extensive changes in cardioprotective heat shock proteins (HSPs) occurred, with several proteins increasing rapidly (HSP27, HSP60 and HSP70) and others showing a delayed rise (GRP78, α-B-crystallin, and HSP90). An evolving adaptive response to metabolic stress was suggested by early upregulation of malate dehydrogenase (DH), α-/β-enolase and pyruvate dehydrogenase (α-subunit of E1 component) and delayed downregulation of a host of enzymes, along with extensive metabolomic changes. Early changes in metabolite expression that persisted as CHF developed included increased concentrations of glucose and alanine. ADP/ATP accumulation and alpha-ketoisovalerate depletion at 2-week VTP suggested a combination of metabolic stress and less effective energy utilization, as well as a shift from glycolysis to alpha-ketoacid metabolism. We conclude that VTP-induced CHF causes time-dependent changes in the atrial proteome and metabolome, providing insights into molecular mechanisms contributing to arrhythmogenic atrial remodelling. |
5,428 | Lability of R- and T-wave peaks in three-dimensional electrocardiograms in implantable cardioverter defibrillator patients with ventricular tachyarrhythmia during follow-up. | From experiments, we know that the heterogeneity of action potential duration and morphology is an important mechanism of ventricular tachyarrhythmia. Electrocardiogram (ECG) markers of repolarization lability are known; however, lability of depolarization has not been systematically studied. We propose a novel method for the assessment of variability of both depolarization and repolarization phases of the cardiac cycle.</AbstractText>Baseline orthogonal ECGs of 81 patients (mean ± SD age, 56 ± 13 years; 61 male [75%]) with structural heart disease and implanted single-chamber implantable cardioverter defibrillator (ICD) were analyzed. Clean 30-beat intervals with absence of premature beats were then selected. Baseline wandering was corrected before analysis. Peaks of R wave and peaks of T wave were detected for each beat, and the axis magnitude was calculated. The peaks were plotted to show clouds of peaks and then used to construct a convex hull, and the volumes of the R peaks cloud and T peaks cloud and ratio of volumes were calculated.</AbstractText>During a mean (SD) follow-up period of 13 (10) months, 9 of the 81 patients had sustained ventricular tachycardia or ventricular fibrillation (VT/VF) and received appropriate ICD therapies. All ICD events were adjudicated by three independent electrophysiologists. There was no statistically significant difference in the volume of T-wave peaks or R-wave peaks between patients with and without VT or VF during follow-up; however, R/T peaks cloud volume ratio was significantly lower in patients with subsequent VT/VF (22.4 ± 25.4 versus 13.1 ± 7.9, P = .024).</AbstractText>Larger volume of T peaks cloud, measured during 30 beats of three-dimensional ECG, is associated with higher risk of sustained ventricular tachyarrhythmias and appropriate ICD therapies. New method to assess temporal variability of repolarization in three-dimensional ECGs by measuring volume of peak clouds shows potential for further exploration for VT/VF risk stratification.</AbstractText>Copyright © 2010 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,429 | [Prevalence and risk factors of peri-procedure electrical storm in acute myocardial infarction patients underwent emergency percutaneous coronary intervention]. | To determine the prevalence and to identify risk factors of peri-procedure electrical storm (ES) in patients with acute myocardial infarction (AMI) underwent emergency percutaneous coronary intervention (PCI).</AbstractText>The clinical data of 228 AMI patients underwent emergency PCI were retrospectively analyzed and patients were divided into ES group (n = 39) and non-ES (n = 189) group. ES was referred to spontaneous ventricular tachycardia or ventricular fibrillation occurring twice or more within 24 h and requiring emergency treatment including anti-arrhythmic medicine and/or cardioversion or defibrillation.</AbstractText>ES was diagnosed in 39 out of 228 patients (17.1%) during peri-procedure stage. The incidence of ES in patients with various infarct related arteries (IRA) was as follows: 55.6% with left main artery (LM), 23.7% with right coronary artery (RCA), 12.4% with anterior descending branch (LAD) and 0 with left circumflex artery (LCX). Older age, lager diameter of IRA, higher concentration of CK-MB and cTnT, higher incidence of reperfusion arrhythmia (RA), lower grade of TIMI after PCI and higher mortality were associated with increased risks of ES (The P value was 0.043, 0.012, 0.036, 0.018, 0.001, 0.049, respectively). Gender, systolic pressure, diastolic pressure, random blood glucose level, white blood count and concentration of hs-CRP were similar between ES and non-ES patients. Logistic analysis showed that the diameter of IRA (OR 2.381, 95%CI 1.127-5.028, P = 0.023), TIMI grade of IRA after PCI (OR 4.744, 95% CI 1.773-12.691, P = 0.002) and RA (OR 12.680, 95% CI 4.360-36.879, P = 0.000) were the independent risk factors of per-procedure ES in AMI patients underwent emergency PCI.</AbstractText>The AMI patients with LM as IRA had the highest incidence of ES during emergency PCI and the diameter of IRA, TIMI grade of IRA after PCI and RA were independent risk factors for the development of ES during peri-PCI stage.</AbstractText> |
5,430 | Incidence and outcomes of out-of-hospital cardiac arrest with shock-resistant ventricular fibrillation: Data from a large population-based cohort. | The increasing survival rates after out-of-hospital cardiac arrests (OHCA) are due mainly to improvements in the first 3 steps of the chain of survival. The aim of this study was to describe the temporal trends of OHCA incidence and outcomes with shock-resistant ventricular fibrillation (VF) requiring advanced life support procedures.</AbstractText>All our subjects were persons aged 18 years or more who had suffered OHCA of presumed cardiac etiology, were witnessed by bystanders, treated by emergency medical service (EMS), and had VF as initial rhythm. Our study was conducted in Osaka Prefecture, Japan from May 1, 1998 through December 31, 2006. Data were collected by EMS personnel using an Utstein-style database. We evaluated the temporal trends of incidence and outcomes of shock-resistant VF.</AbstractText>During the study period, there were 8782 witnessed OHCA cases of presumed cardiac etiology. Among them, 1733 had VF as an initial rhythm, 392 of whom were shock-resistant. While the age-adjusted annual incidence of witnessed VF increased from 2.0 to 3.3 per 100,000 inhabitants, that of shock-resistant VF underwent little change during the study period. The proportion of shock-resistant VF among witnessed VF decreased from 37.0% to 19.0%. Neurologically intact 1-month survival rates after shock-resistant VF remained low at 5.6% even in 2006.</AbstractText>The actual incidence of shock-resistant VF has remained unchanged, and their outcomes continue to be dismal. Further efforts are required to reduce the mortality rates of such shock-resistant VF to achieve improved survival after OHCA.</AbstractText> |
5,431 | Therapeutic hypothermia for out-of-hospital cardiac arrest. | The use of therapeutic hypothermia (TH) and its application in out-of-hospital cardiac arrest patients are reviewed.</AbstractText>Each year in the United States, an estimated 250,000-300,000 out-of-hospital cardiac arrests occur. Despite advances in prehospital care, the survival rate from TH is only 6-12%. In addition, survivors often have devastating consequences ranging from mild memory impairment to permanent brain damage. It is presumed that early induction of hypothermia produces an optimal effect, though benefits can still be achieved with late induction. Several methods have been devised to induce hypothermia, yet the optimal methods of cooling have not currently been determined. Major adverse effects of cooling include hemodynamic changes, cardiovascular complications, hyperglycemia, coagulopathy, increased rates of infection, fluid and electrolyte disorders, and shivering. The majority of these adverse effects can be prevented or minimized in the intensive care setting. In 2002, the use of TH--cooling the core body temperature to 32-34 degrees C--was supported by two landmark human studies, whose results led to the endorsement of TH by the American Heart Association and its increased use. The studies demonstrated that hypothermia results in favorable neurologic outcomes in patients suffering from out-of-hospital cardiac arrest due to ventricular fibrillation (VF), without increasing complications.</AbstractText>TH is an effective strategy for improving neurologic outcomes of patients after out-of-hospital cardiac arrest due to VF. Further studies are needed to confirm the optimal time and methods for cooling to maximize the chance of complete neurologic recovery after cardiac arrest.</AbstractText> |
5,432 | Long-term follow-up of children and young adults treated with implantable cardioverter-defibrillator: the authors' own experience with optimal implantable cardioverter-defibrillator programming. | Young implantable cardioverter-defibrillator (ICD) recipients present a high rate of inappropriate interventions. Some of them are caused by suboptimal pre-discharge programming of the device. There are conflicting data as regards antitachycardia pacing (ATP) effectiveness in children and young adults. We report our experience with ICD programming and a rate of complications during a 10 year follow-up.</AbstractText>We analysed the use and effectiveness of ATP and complications rate in 63 patients aged 6-21 years. Antitachycardia pacing (burst or ramp) was programmed ON in 14 patients (22%), 49 patients (78%) had only ventricular fibrillation (VF) therapy when discharged after implantation. The incidence of effective vs. ineffective or harmful ATP therapy: 5% of patients vs. 19% of patients differed significantly (P < 0.05). Fourteen patients (22%) received > or =1 appropriate shock(s) for ventricular tachycardia/VF and 17 patients (27%) had one or multiple inappropriate therapy (IT). Inappropriate therapy resulted from T-wave over-sensing (nine patients), sinus tachycardia (three patients), fast atrial fibrillation (five patients), and lead insulation disruption (1%). Reprogramming of the device eliminated IT in all cases. There were 13 (21%) surgical complications. Serious psychological sequelae developed in 27 (43%) patients. There was one death during the follow-up period.</AbstractText>Antitachycardia pacing therapy is rarely effective and often harmful in young ICD recipients. In most patients, programming ICD for only VF therapy is sufficient. Routine pre-discharge programming against inappropriate interventions (especially T-wave over-sensing) helps to reduce the incidence of discharges during the follow-up. The incidence of complications and inappropriate therapies is high in young ICD recipients and affects 50% of patients.</AbstractText> |
5,433 | Endocrine and psychological stress responses in a simulated emergency situation. | Several studies have assessed the effects of training using patient simulation systems on medical skills. However, endocrine and psychological stress responses in a patient simulation situation and the relationship between stress reactivity and medical performance have been studied rarely, so far.</AbstractText>Medical students (18 males and 16 females) who had completed at least two months anaesthesiology training participated in the study. In a counterbalanced cross-over design they were subjected to three conditions: rest, laboratory stress (LS; public speaking), and simulated emergency situation (SIM; myocardial ischemia and ventricular fibrillation). Salivary cortisol and psychological responses (visual analogue scales, VAS) were assessed every 15 min from 15 min prior to until 60 min after intervention. Differences between stress and rest conditions were analysed. Medical performance was assessed according to the European Resuscitation Council's Guidelines for Resuscitation.</AbstractText>As compared to rest, cortisol increased significantly in both stress conditions with different time courses in LS and SIM. Psychological responses in SIM exceeded those in LS. Cortisol increase in LS (r(s)=.486; p=.019) but not in SIM (r(s)=.106; p=.631) correlated significantly with medical performance.</AbstractText>A simulated emergency situation is a profound stressor. The positive relationship between endocrine stress responsiveness in a standard laboratory situation and medical performance in a simulated emergency situation indicates that high stress responsiveness might be a predictor of good performance. At the same time the high stress response might counteract educational efforts associated with training using high-fidelity patient simulation.</AbstractText>Copyright © 2010 Elsevier Ltd. All rights reserved.</CopyrightInformation> |
5,434 | [Short-term memory study of the ventricular mathematical model]. | Ventricular fibrillation (VF) is the main cause of sudden death in cardiovascular diseases. The effects of electrophysiological heterogeneity and dynamic factors bring a lot of difficulties in understanding and revealing the mechanisms of VF. Cardiac short-term memory is one of the factors that make invalidation of restitution curve slope as the criteria for transition from ventricular tachycardia to VF. Therefore, investigation of inherent properties of short-term memory and its role in VF has great significance. In this paper we took advantage of the perturbed down-sweep protocol to measure dynamic and local S1S2 restitution curves on three widely used mathematical models to reveal their memory property. And by making abrupt change of the stimulation cycle length, we examined the attenuation process of the memory. The results showed, the rate-dependent action potendial duration (APD) is related with S1 pacing. The APD difference under different S2 cycle length is more pronounced with short S1 cycle length. Except the Luo-Rudy 1991 model, the Luo-Rudy 1994 and Noble 1991 models can at least reflect some of the short-term memory. And the memory attenuated in exponential way. Therefore, in quantitative electrophysiological study, these two models can be used in the future for investigating the characteristics of the short-term memory and its contribution to VF. |
5,435 | [Ortodromic atrio-ventricular reentrant tachycardia with functional left bundle branch block morphology - differential diagnosis of wide complex tachycardia based on case report]. | We present a case of 18 year-old man, without structural heart disease, who suffered from regular and irregular palpitations. ECG was normal during sinus rhythm, and showed LBBB morphology during tachycardia (220/min). Programmable pacing from CS induced sustained atrial fibrillation with normal and wide QRS (LBBB-like, RBBB-like) and minimal RR interval 270 ms. We found and ablate concealed left free wall accessory pathway. During 1-year observation patient stayed asymptomatic. |
5,436 | B-type natriuretic peptide level after sinus rhythm restoration in patients with persistent atrial fibrillation - clinical significance. | Persistent atrial fibrillation (AF) leads to electrical, structural and neurohormonal remodelling of the atria, including increased plasma B-type natriuretic peptide (BNP) level.</AbstractText>To assess the clinical value of plasma BNP or NT-proBNP concentrations in patients with persistent AF measured before and after sinus rhythm restoration following direct-current cardioversion.</AbstractText>The study group consisted of 43 patients with persistent AF who underwent successful electrical cardioversion. The mean AF duration was 12.3 weeks. Patients in the study group had no symptoms of heart failure and they had preserved left ventricular systolic function. Blood samples were collected twice: 24 hours before and 24 hours after electrical cardioversion. Logistic regression analysis was used to assess the predictive value of BNP and NT-proBNP levels.</AbstractText>Baseline NT-proBNP and BNP levels were increased in patients with persistent AF (290.9 +/- 257.2 pg/mL and 148.4 +/- 111.4 pg/mL, respectively) compared to a matched control group without AF (47.8 +/- 80.6 pg/mL; p = 0.0001 and 74.9 +/- 81.7 pg/mL; p = 0.01). Plasma BNP level decreased 24 hours after cardioversion (from 148.4 +/- 111.4 to 106.4 +/- 74.7 pg/mL; p = 0.0045) whereas NT-proBNP level did not (from 290.9 +/- 257.2 to 262.7 +/- 185.6 pg/mL; NS). During an 18-month follow-up period, 21 (49%) patients remained in sinus rhythm. Neither baseline plasma BNP nor NT-proBNP level predicted sinus rhythm maintenance.</AbstractText>NT-proBNP and BNP plasma levels are increased in patients with persistent AF. Conversion to sinus rhythm is associated with a significant decrease in plasma BNP but not NT-proBNP level. Baseline BNP and NT-proBNP levels do not predict long-term sinus rhythm maintenance.</AbstractText> |
5,437 | Is rhythm-control superior to rate-control in patients with atrial fibrillation and diastolic heart failure? | Although no clinical trial data exist on the optimal management of atrial fibrillation (AF) in patients with diastolic heart failure, it has been hypothesized that rhythm-control is more advantageous than rate-control due to the dependence of these patients' left ventricular filling on atrial contraction. We aimed to determine whether patients with AF and heart failure with preserved ejection fraction (EF) survive longer with rhythm versus rate-control strategy.</AbstractText>The Duke Cardiovascular Disease Database was queried to identify patients with EF > 50%, heart failure symptoms and AF between January 1,1995 and June 30, 2005. We compared baseline characteristics and survival of patients managed with rate- versus rhythm-control strategies. Using a 60-day landmark view, Kaplan-Meier curves were generated and results were adjusted for baseline differences using Cox proportional hazards modeling.</AbstractText>Three hundred eighty-two patients met the inclusion criteria (285 treated with rate-control and 97 treated with rhythm-control). The 1-, 3-, and 5-year survival rates were 93.2%, 69.3%, and 56.8%, respectively in rate-controlled patients and 94.8%, 78.0%, and 59.9%, respectively in rhythm-controlled patients (P > 0.10). After adjustments for baseline differences, no significant difference in mortality was detected (hazard ratio for rhythm-control vs rate-control = 0.696, 95% CI 0.453-1.07, P = 0.098).</AbstractText>Based on our observational data, rhythm-control seems to offer no survival advantage over rate-control in patients with heart failure and preserved EF. Randomized clinical trials are needed to verify these findings and examine the effect of each strategy on stroke risk, heart failure decompensation, and quality of life.</AbstractText> |
5,438 | Atypical electrocardiographic features of cavotricuspid isthmus-dependent atrial flutter occurring during left atrial fibrillation ablation. | Patients who have undergone percutaneous catheter ablation for atrial fibrillation (AF) may develop cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL), which can occur either spontaneously during left atrial (LA) ablation for AF or by induction from sinus rhythm during the procedure. The electrocardiographic (ECG) characteristics of CTI-dependent AFL occurring during LA ablation have not been described. The purpose of this study was to describe the ECG features of CTI-dependent AFL occurring during percutaneous LA catheter ablation for AF.</AbstractText>Of 223 patients presenting for first AF ablation at our institution between May 2004 and February 2008, 20 patients (9%) developed CTI-dependent AFL during LA ablation for AF. CTI-dependent AFL developed spontaneously in 4 patients (20%) and was induced in 16 patients (80%). Among these 20 patients, 3 (15%) had typical ECG patterns and 17 (85%) had atypical ECG patterns. Flutter waves in the inferior leads were biphasic in 10 patients (50%), downward in 3 patients (15%), positive in 3 patients (15%), and not fitting the above classifications in 4 patients (20%). There was no statistically significant association between AFL pattern and LA size, left ventricular ejection fraction, total ablation time, duration of prior AF, or type of prior AF.</AbstractText>A majority of patients with CTI-dependent AFL occurring during LA ablation have atypical ECG patterns. Biphasic flutter waves in the inferior leads are common ECG features, occurring in one-half of patients. Right atrial CTI-dependent AFL should be suspected even if the ECG appearance is atypical.</AbstractText> |
5,439 | The effectiveness and cost effectiveness of public-access defibrillation. | Many sudden cardiac deaths are due to ventricular fibrillation (VF). The use of defibrillators in hospitals or by outpatient emergency medical services (EMS) personnel can save many cardiac-arrest victims. Automated external defibrillators (AEDs) permit defibrillation by trained first responders and laypersons. AEDs are available at most public venues, and vast sums of money are spent installing and maintaining these devices. AEDs have been evaluated in a variety of public and private settings. AEDs accurately identify malignant ventricular tachyarrhythmias and frequently result in successful defibrillation. Prompt application of an AED shows a greater number of patients in VF compared with initial rhythms documented by later-arriving EMS personnel. Survival is greatest when the AED is placed within 3 to 5 minutes of a witnessed collapse. Community-based studies show increased cardiac-arrest survival when first responders are equipped with AEDs rather than waiting for paramedics to defibrillate. Wide dissemination of AEDs throughout a community increases survival from cardiac arrest when the AED is used; however, the AEDs are utilized in a very small percentage of all out-of-hospital cardiac arrests. AEDs save very few lives in residential units such as private homes or apartment complexes. AEDs are cost effective at sites where there is a high density of both potential victims and resuscitators. Placement at golf courses, health clubs, and similar venues is not cost effective; however, the visible devices are good for public awareness of the problem of sudden cardiac death and provide reassurance to patrons. |
5,440 | Clinical features of the dilated phase of hypertrophic cardiomyopathy in comparison with those of dilated cardiomyopathy. | Although the dilated phase of hypertrophic cardiomyopathy (D-HCM) characterized by left ventricular (LV) systolic dysfunction and cavity dilatation has been reported to be a poor prognosis, this is now in contrast to the improved prognosis of dilated cardiomyopathy (DCM) in the era of advancements in heart failure management. There has been no investigation of the clinical features of D-HCM compared with those of DCM from the point of management of systolic dysfunction.</AbstractText>The aim of this study was to investigate the clinical features of D-HCM in comparison with those of DCM in a single institute.</AbstractText>We studied 20 consecutive patients with D-HCM (global ejection fraction < 50%) and 115 consecutive patients with DCM.</AbstractText>At diagnosis of D-HCM, 8 (40%) of the D-HCM patients already experienced dyspnea (New York Heart Association [NYHA] class >or= III). Left atrial diameter was larger and prevalence of atrial fibrillation was higher in the D-HCM group, although LV size was larger and LV ejection fraction was lower in the DCM group. During the follow-up period (4.0 years), 11 (55%) of the patients with D-HCM died. The 5-year survival rate from all-cause mortality including cardiac transplantation was 45.6% in patients with D-HCM vs 81.6% in patients with DCM (log-rank P = .0001).</AbstractText>Patients with D-HCM were more symptomatic at diagnosis, although LV dilatation and impaired fractional shortening seemed more severe in patients with DCM. The prognosis for D-HCM patients was worse than that for patients with DCM despite similar or even more intensive treatment for heart failure.</AbstractText>Copyright (c) 2010 Wiley Periodicals, Inc.</CopyrightInformation> |
5,441 | Right ventricular stimulation threshold at ICD implant predicts device therapy in primary prevention patients with ischaemic heart disease. | Myocardial excitability is known (amongst other reasons) to be related to the degree of ischaemia, contractile dysfunction and heart failure. It was hypothesized that the right ventricular (RV) stimulation threshold has prognostic value with respect to the occurrence of ventricular arrhythmias (VAs) and patient survival in recipients of an implantable cardioverter defibrillator (ICD).</AbstractText>Ischaemic heart disease patients receiving an ICD at Leiden University Medical Center as primary prevention for sudden cardiac death were included in this study. Right ventricular thresholds were determined at ICD implant. Data were collected on VAs triggering ICD therapy and on all-cause mortality. A total of 689 consecutive patients were included (87% male, age 63 ± 11 years, left ventricular ejection fraction (LVEF) 29 ± 11%) and followed for a median of 28 months. Post-implant RV-threshold was 0.7 ± 0.5 volt (V) at 0.5 ms pulse duration. Best dichotomous separation was reached at a cut-off of 1 V. During follow-up, 167 (24%) patients received appropriate ICD therapy, 88 (13%) had appropriate shocks and 134 (19%) died. Cumulative appropriate shock incidence for patients with RV threshold ≥ 1 V (n = 166) was 16% at 1 year, 24% at 3 years and 34% at 5 years compared with 4, 11 and 17% for patients with an RV-threshold < 1 V (n = 523). Adjusted hazard ratio of RV threshold ≥ 1 V was 2.0 (95% CI: 1.4-2.9) for appropriate therapy, 3.3 (95% CI: 2.0-5.4) for appropriate shocks and 1.6 (95% CI: 1.1-2.5) for mortality.</AbstractText>The RV stimulation threshold at ICD implant has a strong independent prognostic value for the occurrence of VAs triggering appropriate ICD therapy, appropriate shocks and mortality.</AbstractText> |
5,442 | Contemporary management of atrial fibrillation: a brief review. | Atrial fibrillation (AF) is the most common cardiac arrhythmia with a prevalence of up to 10% in patients who are 80 years and older. There has been some significant progress in the understanding and management of AF in recent years. Large-scale clinical trials have provided solid evidence in supporting the role of anti-thrombotic therapies in the prevention of stroke in moderate to high risk patients. Appropriate control of the ventricular rate or the maintenance of sinus rhythm offers long-term benefits in specific groups of patients. Catheter ablation or "Maze" surgery has proven to be curative to some patients. However, the implementation of the evidence-based therapeutic strategies in the day-to-day care of the AF patients have been found to vary greatly from one institution to another, some of which are hindering the achievement of optimal long-term outcomes. In this brief review, some of the key strategies in the evidence-based management of AF are discussed, with particular emphasis on anti-thrombotic therapy, rhythm or rate control, as well as catheter ablation. |
5,443 | Randomised comparison of percutaneous left ventricular assist device with open-chest cardiac massage and with surgical assist device during ischaemic cardiac arrest. | A percutaneous left ventricular assist device can maintain blood flow to vital organs during ventricular fibrillation and may improve outcomes in ischaemic cardiac arrest. We compared haemodynamic and clinical effects of a percutaneous left ventricular assist device with a larger device deployed via endovascular prosthesis and with open-chest cardiac massage during ischaemic cardiac arrest.</AbstractText>Eighteen swine were randomised into three groups. After thoracotomy, coronary ischaemia and ventricular fibrillation was induced. Cardiac output was measured with transit-time flowmetry. Tissue perfusion was measured with microspheres. Defibrillation was performed after 20 min.</AbstractText>Cardiac output with cardiac massage was 1129 mL min⁻¹ vs. 1169 mL min⁻¹ with the percutaneous- and 570 mL min⁻¹ with the surgical device (P < 0.05 surgical vs. others). End-tidal CO₂ was 3.3 kPa with cardiac massage vs. 3.2 kPa with the percutaneous- and 2.3 kPa with the surgical device (P < 0.05 surgical vs. others). Subepicardial perfusion was 0.33 mL min⁻¹ g⁻¹ with cardiac massage vs. 0.62 mL min⁻¹ g⁻¹ with both devices (P < 0.05 devices vs. massage), cerebral perfusion was comparable between groups (all reported values after 3 min cardiac arrest, all P<0.05 vs. baseline, all P = NS for 3 min vs. 15 min). Return of spontaneous circulation was achieved in 5/6 subjects with cardiac massage vs. 6/6 with the percutaneous- and 4/6 with the surgical device (P = NS).</AbstractText>The percutaneous device improved myocardial perfusion, maintained cerebral perfusion and systemic circulation with similar rates of successful defibrillation vs. cardiac massage. Increased delivery was not obtained with the surgical device during cardiac arrest.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,444 | Models of stretch-activated ventricular arrhythmias. | One of the most important components of mechanoelectric coupling is stretch-activated channels, sarcolemmal channels that open upon mechanical stimuli. Uncovering the mechanisms by which stretch-activated channels contribute to ventricular arrhythmogenesis under a variety of pathologic conditions is hampered by the lack of experimental methodologies that can record the 3-dimensional electromechanical activity simultaneously at high spatiotemporal resolution. Computer modeling provides such an opportunity. The goal of this review is to illustrate the utility of sophisticated, physiologically realistic, whole heart computer simulations in determining the role of mechanoelectric coupling in ventricular arrhythmogenesis. We first present the various ways by which stretch-activated channels have been modeled and demonstrate how these channels affect cardiac electrophysiologic properties. Next, we use an electrophysiologic model of the rabbit ventricles to understand how so-called commotio cordis, the mechanical impact to the precordial region of the heart, can initiate ventricular tachycardia via the recruitment of stretch-activated channels. Using the same model, we also provide mechanistic insight into the termination of arrhythmias by precordial thump under normal and globally ischemic conditions. Lastly, we use a novel anatomically realistic dynamic 3-dimensional coupled electromechanical model of the rabbit ventricles to gain insight into the role of electromechanical dysfunction in arrhythmogenesis during acute regional ischemia. |
5,445 | Acute myocardial infarction with simultaneous involvement of right coronary artery and left anterior descending artery: a case report. | Acute myocardial infarction is usually caused by rupture of unstable plaque and involves a single coronary artery. Simultaneous occlusions of multiple coronary arteries in patients with ST elevation myocardial infarction are uncommon and lead to a fatal outcome. We report a 75-year-old male presenting with persistent chest pain complicated by ventricular fibrillation. After defibrillation and cardiopulmonary resuscitation, an emergency coronary angiogram showed total occlusion of the right coronary artery, and thrombus in the proximal left anterior descending artery. Both coronary arteries underwent successful balloon inflation and stenting. The patient finally survived under ventilatory support. This rare case suggests that aggressive reperfusion therapy and even mechanical support to improve poor clinical outcome are suggested in high risk patients with multivessel occlusions. |
5,446 | Implantable cardioverter defibrillator lead endocarditis causing diffuse right atrial abscess and pulmonary artery embolism. | Implantation of electrophysiological cardiac devices such as pacemakers and implantable cardioverter defibrillators has become a widely available and routine procedure in cardiovascular medicine. One of the most feared complications of device implementation is infection. Infection rates for these devices are reported to vary between 0.7% and 7.0%. Cardiac thromboembolic event is a recognized complication of permanent cardiac rhythm devices with an incidence of 0.6%-3.5%, unrelated to lead size or number. These complications are associated with high morbidity and mortality rates. In this case report, right atrial mass, right atrial abscess, perforation of tricuspid septal leaflet, and pulmonary embolism secondary to ICD lead endocarditis is presented. |
5,447 | Inhibition of the renin-angiotensin system for prevention of atrial fibrillation. | Atrial fibrillation (AF) is a source of considerable morbidity and mortality. There has been compelling evidence supporting the role of renin-angiotensin system (RAS) in the genesis and perpetuation of AF through atrial remodeling, and experimental studies have validated the utilization of RAS inhibition for AF prevention. This article reviews clinical trials on the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) for the prevention of AF. Results have been variable, depending on the clinical background of treated patients. ACEIs and ARBs appear beneficial for primary prevention of AF in patients with heart failure, whereas they are not equally effective in hypertensive patients with normal left ventricular function. Furthermore, the use of ACEIs or ARBs for secondary prevention of AF has been found beneficial only after electrical cardioversion. Additional data are needed to establish the potential clinical role of renin-angiotensin inhibition for prevention of AF. |
5,448 | Role of the atrial rate as a factor modulating ventricular response during atrial fibrillation. | During atrial fibrillation (AF), RR interval histograms show different populations of predominant RR (pRR) intervals. These pRR intervals have been suggested to be multiples of the refractory period of the atrioventricular (AV) node or caused by the existence of a dual AV node physiology. In this study, the hypothesis that pRR intervals are related to the dominant atrial fibrillatory rate is tested.</AbstractText>In this study, Holter electrocardiogram signals from 55 patients with persistent AF were analyzed. Number and position of pRR intervals were detected and compared with mean and standard deviation of the dominant atrial cycle length (DACL). In addition, effects of an enhancement of vagal activity and rate-control treatments (β-blockers and verapamil) were evaluated.</AbstractText>In all patients with more than one pRR interval and in 47% with one pRR interval, RR interval populations were statistically related with multiples of the DACL. During night activities and during β-blockers treatment, mean ventricular rate was decreased (P < 0.01). This change was associated with a variation in the percentage of occurrences of each pRR (P < 0.01), whereas no statistical differences were present in the mean DACL or in the position of pRR intervals. A variation of the DACL due to verapamil was associated with a consistent modification in the position of the pRR intervals.</AbstractText>The relation between pRR and multiples of the DACL during AF suggests that more probable RR intervals are caused by different conduction ratios of the atrial rate.</AbstractText>©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.</CopyrightInformation> |
5,449 | Caffeine-related atrial fibrillation. | We present a case of caffeine-induced atrial fibrillation which spontaneously reverted to normal sinus rhythm. Caffeine is a methylxanthine alkaloid that can cause various supraventricular and ventricular arrhythmias. It is important to improve public awareness of the potential adverse effects of high consumption of caffeine-containing products as fatal and serious events can occur. |
5,450 | Clinical management of arrhythmogenic right ventricular cardiomyopathy: an update. | Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic heart muscle disease characterized by the peculiar right ventricular (RV) involvement. Distinctive pathologic features are myocardial atrophy and fibro-fatty replacement of the RV free wall, and clinical presentation is usually related to ventricular tachycardias with a left bundle branch block pattern or ventricular fibrillation leading to cardiac arrest, mostly in young people and athletes. Later in the disease evolution, progression and extension of RV muscle disease and left ventricular involvement may result in right or biventricular heart failure. In the 1994 an International Task Force proposed standardized diagnostic criteria designed to guarantee an adequate specificity and based on the presence of major and minor criteria encompassing electrocardiographic, arrhythmic, morphofunctional, histopathologic, and genetic factors; more recently, Task Force criteria have been modified to increase their diagnostic sensitivity. Retrospective analysis of clinical and pathologic series including fatal cases identified a series of risk factors such as malignant familial background, youthful age, previous syncope or cardiac arrest, competitive sport activity, severe RV disease with left ventricular involvement, and episodes of complex ventricular arrhythmias or VT. The therapeutic options include beta blockers, antiarrhythmic drugs, catheter ablation, and implantable cardioverter defibrillator (ICD). The ICD is the most effective safe-guard against arrhythmic sudden death. In patients in whom ARVC has progressed to severe RV or biventricular systolic dysfunction with risk of thromboembolic complications, treatment consists of current therapy for heart failure including anticoagulant therapy. In case of refractory congestive heart failure, patients may become candidates for heart transplantation. |
5,451 | Arrhythmias and left ventricular hypertrabeculation /noncompaction. | Arrhythmias in left ventricular hypertrabeculation/noncompaction (LVHT) comprise sustained or non-sustained ventricular tachycardia (VT) (n=135), atrial fibrillation (AF) (n=96) AV block (n=55) and QT prolongation (n=47). The prevalence differs between children and adults. In children most frequent are WPW-syndrome (n=24), AV block (n=24), VT (n=17) and bradycardia (n=15). In adults most frequent arrhythmias are VT (n=118), AF (n=95), QT prolongation (n=42) and AV block (n=31). Some arrhythmias are more frequently reported in children than in adults like WPW-syndrome (24 vs. 17 patients), second-degree AV block (4 vs. 0 patients), bradycardia (15 vs. 3 patients) and ventricular fibrillation (VF) (9 vs. 5 patients). There are nearly no pediatric cases with AF (1 vs. 95 patients). In 120 patients implantable cardioverters/defibrillators have been implanted for primary or secondary prevention of sudden cardiac death. The pathomechanisms of arrhythmias in LVHT are largely unknown, especially if patients with LVHT and neuromuscular disorders are more prone to arrhythmias than patients without. There is a need to clarify risk factors for VT or VF because 19% of LVHT patients with VT or VF have a normal systolic function and demonstration of systolic dysfunction is no reliable risk marker. Data about long-term follow-up of LVHT patients with implanted cardioverters/defibrillators are necessary since the indication for prophylactic implantation is still unclear. AF in LVHT increases the embolic risk, thus it would be useful to know which LVHT patients who have sinusrhythm at baseline are prone to develop AF in order to start early with anticoagulant therapy. |
5,452 | Serial changes in epicardial electrograms during and after a coronary artery occlusion. | Suddenly occurring ventricular tachyarrhythmias are a complication during off-pump coronary artery bypass (OPCAB) surgery, potentially leading to the need for conversion to on-pump surgery. We examined serial changes in the spatial dispersion of the electrical activity and refractoriness at the myocardial ischemia border zones during and after coronary occlusion.</AbstractText>Unipolar epicardial electrograms were continuously recorded from the anterior left ventricle at the border zones during and after a 10-min occlusion of the left anterior descending (LAD) coronary artery in 22 patients undergoing OPCAB. The local electrogram amplitude and local refractoriness were evaluated by the unipolar peak-to-peak amplitude (UPPA) and activation recovery interval (ARI), respectively. The spatial dispersion of the electrical activity and refractoriness were examined using the coefficient of variation of these parameters.</AbstractText>No sustained ventricular tachyarrhythmias occurred in any patients. The UPPA dispersion significantly increased up to 5 min after the LAD occlusion and then returned to a nonsignificant level and again increased after reperfusion. The ARI dispersion gradually increased after the LAD occlusion, reached a significantly increased level 3 min after the occlusion, and stayed at a significantly increased level for at least 5 min after the reperfusion.</AbstractText>There were unique serial changes in the spatial dispersion of the electrical activity and refractoriness at the myocardial ischemia border zones during and after coronary occlusions. Continuous monitoring of these parameters may be useful for predicting the critical electrophysiological conditions prone to the occurrence of ventricular tachyarrhythmias in patients undergoing OPCAB.</AbstractText> |
5,453 | Worsening heart failure in the setting of dronedarone initiation. | To describe a challenging patient case in which dronedarone was selected for a patient with atrial fibrillation and heart failure; the drug may have been associated with worsening heart failure, leading to acute renal and hepatic failure.</AbstractText>A 47-year-old male with a history of heart failure with New York Heart Association class III-IV symptoms presented to our institution with ventricular fibrillation and ventricular tachycardia storm. Torsade de pointes secondary to a combination of dofetilide and hypokalemia was determined to be the etiology. Upon stabilization, the patient was initiated on dronedarone 400 mg orally twice daily by the electrophysiology service for atrial fibrillation. The patient had a questionable history of amiodarone intolerance. By hospital day 9 (day 4 of dronedarone therapy), the patient demonstrated a clinical picture consistent with acute renal and hepatic failure possibly due to worsening heart failure. Dronedarone was discontinued on hospital day 10. He was subsequently transferred to an outside hospital where he required milrinone therapy for cardiogenic shock. Laboratory markers of renal and hepatic function improved over the remainder of his hospitalization and he was discharged on hospital day 20.</AbstractText>Dronedarone is a newly approved antiarrhythmic agent with multichannel blocking properties similar to amiodarone. Use of the Naranjo probability scale determined that this patient's worsening heart failure leading to acute renal and hepatic failure was possibly caused by dronedarone. The implication from the ANDROMEDA trial as well as our experience in this case is that dronedarone should be used cautiously in patients with heart failure and avoided in patients specifically outlined in the product labeling.</AbstractText>This case report, to our knowledge, represents the first published postmarketing report of worsening heart failure complicated by multiorgan dysfunction in the setting of dronedarone initiation. Dronedarone use must be approached with caution in patients with a history of heart failure.</AbstractText> |
5,454 | Comparison of the efficacy of nifekalant and amiodarone in a porcine model of cardiac arrest. | To compare the efficacy of nifekalant and amiodarone in the treatment of cardiac arrest in a porcine model.</AbstractText>After 4min of untreated ventricular fibrillation, animals were randomly treated with nifekalant (2mgkg(-1)), amiodarone (5mgkg(-1)) or saline placebo (n=12 pigs per group). Precordial compression and ventilation were initiated after drug administration and defibrillation was attempted 2min later. Hemodynamics were continuously measured for 6h after successful resuscitation.</AbstractText>Compared with saline, nifekalant and amiodarone equally decreased the number of electric shocks, defibrillation energy, epinephrine dose, and duration of cardiopulmonary resuscitation required for successful resuscitation (P<0.01). The incidence of restoration of spontaneous circulation (ROSC) and the 24-h survival rate were higher in both antiarrhythmic drug groups (P<0.05) vs. the saline group. Furthermore, post-resuscitation myocardial dysfunction at 4-6h after successful resuscitation was improved in animals given antiarrhythmic drugs as compared with the saline group (P<0.05). There were no differences between nifekalant and amiodarone for any of these parameters.</AbstractText>The effect of nifekalant was similar to that of amiodarone for improving defibrillation efficacy and for the treatment of cardiac arrest. Administration of either nifekalant or amiodarone before defibrillation increased the ROSC and 24-h survival rates and improved post-resuscitation cardiac function in this porcine model.</AbstractText>Copyright 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,455 | Epidemiology of paediatric out-of-hospital cardiac arrest in Melbourne, Australia. | Previous studies of paediatric cardiac arrest have reported a low survival rate but there is limited data from Australia. We sought to determine the characteristics and outcomes of paediatric out-of-hospital cardiac arrest in Melbourne, Australia.</AbstractText>Between October 1999 and June 2007, all cases of out-of-hospital cardiac arrest attended by emergency medical services in Melbourne, Australia were entered into a database (the Victorian Ambulance Cardiac Arrest Registry). Data on patients aged less than 16 years in cardiac arrest on arrival of ambulance paramedics was analysed.</AbstractText>There were 209 children in cardiac arrest on arrival of paramedics during the study period. Of these, resuscitation was not attempted in 16 children due to signs of definite death. Of the 193 children who had attempted resuscitation, 143 (74%) had an initial cardiac rhythm of asystole, 36 (18%) were in pulseless electrical activity and 14 (7%) were in ventricular fibrillation. There were 49 patients (25%) with return of spontaneous circulation at arrival to hospital of whom 14 (7%) survived to hospital discharge. Of 138 patients without return of a circulation, 120 were transported to hospital with continuing resuscitation and one survived (0.9%). Survival was higher in patients with an initial cardiac rhythm of ventricular fibrillation (5/14; 35%) compared with other rhythms (10/179; 4%), OR 9.38, 95% CI 2.64-33.2.</AbstractText>Overall, 7.7% of paediatric patients with out-of-hospital cardiac arrest survive to leave hospital. Increased survival was seen if the initial cardiac rhythm was ventricular fibrillation. Survival was very rare (<1%) unless there was return of spontaneous circulation prior to hospital arrival.</AbstractText>Copyright 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,456 | [Transcatheter cryoablation of tachycardia: principles and indications]. | Cryoablation is used for definitive treatment of arrhythmias by catheter after a 4 min application of a -70 degrees C temperature. There are three main indications of this technique: (1) the treatment for intranodal tachycardia is commonly performed using cryoablation. Success rates are high with no atrio-ventricular block (AVB) risk, (2) the ablation of atrioventricular accessory pathways (Wolf Parkinson-White syndrome), close to His-bundle has a high success rate; the use of a cryo focal catheter avoid AVB risk, (3) the ablation of pulmonary vein potentials with a cryo-balloon in the left atrium for atrial fibrillation. The success rate is high, similar to that achieved with radiofrequency ablation. The cryoballoon procedure is easier to perform because ablation is done in a single step, with a circular application and not point by point. It is well tolerated because it is less painful. There is no risk of pulmonary vein stenosis or esophagus injury. It is less thrombogenic. |
5,457 | Evaluation of cerebral metabolism by ¹H-magnetic resonance spectroscopy for 4°C saline-induced therapeutic hypothermia in pig model of cardiac arrest. | Previous studies have shown that therapeutic hypothermia could improve neurologic recovery when induced after cardiac arrest, but dynamic changes in cerebral metabolism have not been studied at low temperature. In this study, we aim to evaluate hypothermia-induced changes in pigs' cerebral metabolism by (1)H-magnetic resonance spectroscopy (¹H-MRS).</AbstractText>Ten anesthetized Landrace (25-30 kg) pigs were randomized into 2 groups and subjected to 4 minutes of ventricular fibrillation, followed by cardiopulmonary resuscitation. The hypothermic group was given an infusion of 30 mL/kg of 4°C normal saline (NS) at an infusion rate of 1.33 mL/kg per minute starting after restoration of spontaneous circulation (ROSC), then 10 mL/kg per hour for 4 hours. The control group received the same infusion of room temperature NS. Core temperature and hemodynamic variables were monitored at baseline and repeatedly for 240 minutes after ROSC. The ¹H-MRS scans were obtained at baseline, 1 hour, and 3 hours after successful ROSC to observe the dynamic changes of cerebral metabolism at different temperatures.</AbstractText>The mean reduction of temperature was 1.5°C ± 0.4°C in the hypothermic group. There was no difference in hemodynamic variables between groups. ¹H-MRS detected statistically significant (P < .01) changes in cerebral metabolism between the control and hypothermia groups (P < .01).</AbstractText>Infusion of 4°C NS can effectively reduce cerebral metabolism after successful cardiopulmonary resuscitation and have a protective effect on the recovery of neurologic function. The ¹H-MRS technology can be used as a powerful tool to evaluate interventions in the treatment of cardiopulmonary resuscitation.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,458 | The antianginal agent ranolazine is a potent antiarrhythmic agent that reduces ventricular arrhythmias: through a mechanism favoring inhibition of late sodium channel. | The antianginal agent ranolazine (R) has shown some promise as an antiarrhythmic agent but its mechanism of action is not known. Previously, we have shown that R suppresses ventricular arrhythmias at a concentration >10 μM that may affect multiple ion currents including IKr.</AbstractText>The present study was carried out to determine the effects of low dose (4 μM) of R that primarily inhibits late I(Na) on ischemia/reperfusion induced ventricular arrhythmias.</AbstractText>We subjected 20 anesthetized rats to 5 min of proximal left coronary artery occlusion followed by 5 min of reperfusion. Rats were randomized to vehicle control (C; n = 10) versus low dose R (n = 10; 3.33 mg/kg i.v. bolus plus 3.2 mg/kg/h R started 20 min prior to occlusion, which yields a concentration of 4 μM, within the known level that blocks late Na channels but well below the level that has effect on IKr or peak I(Na)). Reperfusion-induced arrhythmias were quantitated by electrocardiographic monitoring.</AbstractText>In the C group 9/10 rats developed any arrhythmias versus 3/10 in the R group (P = 0.02); 6/10 developed ventricular tachycardia (VT) in the C group versus 0/10 in the R group (P = 0.01). The median number of episodes of VT were 1.5 in the C group versus 0 in the R group (P = 0.005). Sustained VT (>10 sec) occurred in 3/10 C and 0/10 in R (P = 0.21). The median duration of VT was 1.8 seconds in C versus 0 in R (P = 0.005). Ventricular fibrillation occurred in 1/10 in C and 0 in R. Ventricular premature beats (VPBs) occurred in 9/10 C and 3/10 R rats (P = 0.02). The median number of VPBs was 5.5 in the C group versus 0 in R group (P = 0.01). The ischemic risk zones were equivalent in the C and R groups (35 ± 3% and 32 ± 3% of the left ventricle, respectively).</AbstractText>In conclusion, data show that the marked antiarrhythmic effect of R in the setting of acute ischemia/reperfusion occurs at low doses consistent with inhibition of late I(Na) .</AbstractText>© 2010 Blackwell Publishing Ltd.</CopyrightInformation> |
5,459 | Radiofrequency ablation in treatment of atrial fibrillation. | Beside heart failure and metabolic syndrome, atrial fibrillation is termed the cardiovascular epidemic of the twenty-first century. Its increased morbidity and mortality is alarming. The present, most effective therapy of atrial fibrillation is catheter ablation. Successful ablation of atrial fibrillation prevents the occurrence and progression of electrical, structural and mechanic myocardium remodelling, improves function of the left ventricle, and prevents the risk of thrombembolism. Onset of sinus rhythm activates the reversal remodelling leading to wall reconstruction and atrium reduction. The paper reviews the technique and presents own experience with catheter ablation. |
5,460 | Efficacy of low-dose bepridil for prevention of ventricular fibrillation in patients with Brugada syndrome with and without SCN5A mutation. | It has been reported that bepridil prevents ventricular fibrillation (VF) in patients with Brugada syndrome, but the comparative efficacy with and without mutation in the SCN5A gene has not been elucidated. The purpose of this study was to assess the efficacy of low-dose bepridil (100 mg/day) for VF prevention in patients with Brugada syndrome with and without SCN5A mutation. Among 130 patients with Brugada-type electrocardiogram (ECG), low-dose bepridil was administered to seven patients because of repetitive VF episodes, including three with and four without SCN5A mutation. Preventive effect for VF recurrence and changes of the ECG and the signal-averaged ECG were evaluated. Frequencies of VF episodes were reduced after treatment with low-dose bepridil in all three patients with the SCN5A mutation (before: 0.33 versus after: 0.02 episodes/month, P < 0.01), but not in all four patients without the SCN5A mutation (before: 0.43 versus after: 2.94 episodes/month, P = nonsignificant). Levels of ST-segment elevation at J points and duration of low-amplitude signals less than 40 µV in the terminal filtered QRS complex (LAS40) in signal-averaged ECG were improved exclusively in patients with the SCN5A mutation. Treatment with bepridil prevented recurrence of VF along with improvement of ST elevation and LAS40 in patients with Brugada syndrome with the SCN5A mutation. |
5,461 | Procainamide and survival in ventricular fibrillation out-of-hospital cardiac arrest. | Procainamide is an antiarrhythmic drug of unproven efficacy in cardiac arrest. The association between procainamide and survival from out-of-hospital cardiac arrest was investigated to better determine the drug's potential role in resuscitation.</AbstractText>The authors conducted a 10-year study of all witnessed, out-of-hospital, ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) cardiac arrests treated by emergency medical services (EMS) in King County, Washington. Patients were considered eligible for procainamide if they received more than three defibrillation shocks and intravenous (IV) bolus lidocaine. Four logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CI) describing the relationship between procainamide and survival.</AbstractText>Of the 665 eligible patients, 176 received procainamide, and 489 did not. On average, procainamide recipients received more shocks and pharmacologic interventions and had lengthier resuscitations. Adjusted for their clinical and resuscitation characteristics, procainamide recipients had a lower likelihood of survival to hospital discharge (OR = 0.52; 95% CI = 0.36 to 0.75). Further adjustment for receipt of other cardiac medications during resuscitation negated this apparent adverse association (OR = 1.02; 95% CI = 0.66 to 1.57).</AbstractText>In this observational study of out-of-hospital VF and pulseless VT arrest, procainamide as second-line antiarrhythmic treatment was not associated with survival in models attempting to best account for confounding. The results suggest that procainamide, as administered in this investigation, does not have a large impact on outcome, but cannot eliminate the possibility of a smaller, clinically relevant effect on survival.</AbstractText>(c) 2010 by the Society for Academic Emergency Medicine.</CopyrightInformation> |
5,462 | Dynamically-Induced Spatial Dispersion of Repolarization and the Development of VF in an Animal Model of Sudden Death. | Spatial dispersion of refractoriness and discordant action potential duration (APD) alternans, resulting in local conduction block, have been shown to cause wavebreak that can lead to ventricular fibrillation (VF). Previously, we developed a theory, based on action potential restitution functions, that predicts when the requisite conduction block can be created through a series of premature beats. The theory was applied successfully to normal beagle dogs; however, restitution functions in these animals were similar, both between right and left ventricles in a given animal and across animals. Consequently, for the present study we tested the theory on a population of German shepherds that, due to inherited cardiac abnormalities, presented with a wide variation of APD restitution functions. We found that the theory, when applied to restitution functions determined individually for each animal, reliably generated premature stimulation predictions that frequently resulted in the induction of VF in in vivo experiments. |
5,463 | Genome-wide association study identifies a susceptibility locus at 21q21 for ventricular fibrillation in acute myocardial infarction. | Sudden cardiac death from ventricular fibrillation during acute myocardial infarction is a leading cause of total and cardiovascular mortality. To our knowledge, we here report the first genome-wide association study for this trait, conducted in a set of 972 individuals with a first acute myocardial infarction, 515 of whom had ventricular fibrillation and 457 of whom did not, from the Arrhythmia Genetics in The Netherlands (AGNES) study. The most significant association to ventricular fibrillation was found at 21q21 (rs2824292, odds ratio = 1.78, 95% CI 1.47-2.13, P = 3.3 x 10(-10)). The association of rs2824292 with ventricular fibrillation was replicated in an independent case-control set consisting of 146 out-of-hospital cardiac arrest individuals with myocardial infarction complicated by ventricular fibrillation and 391 individuals who survived a myocardial infarction (controls) (odds ratio = 1.49, 95% CI 1.14-1.95, P = 0.004). The closest gene to this SNP is CXADR, which encodes a viral receptor previously implicated in myocarditis and dilated cardiomyopathy and which has recently been identified as a modulator of cardiac conduction. This locus has not previously been implicated in arrhythmia susceptibility. |
5,464 | V-shaped trough in autonomic activity is a possible precursor of life-threatening cardiac events. | No reliable precursor of sudden cardiac death is known.</AbstractText>Holter electrocardiograms of 34 patients experiencing a cardiac event (event group, 20 deaths) were compared with 191 controls (no event group). The event group included 25 patients with ventricular fibrillation or acute myocardial infarction (AMI), and 9 with cardiac arrest due to complete atrioventricular block. The logarithms were calculated of the moving average of 5 successive values for the low-frequency component (LF), the high-frequency component (HF), and the ratio LF/HF of heart rate variability: ln(LF), ln(HF) and ln(LF/HF). A V-shaped trough appeared in the curve of ln(LF/HF) [sV-trough] or ln(HF) [pV-trough] before such an event in 31 patients in the event group. The V-trough was marked by a small variation lasting 2 h, an abrupt descent lasting 30 min, and a sharp ascent for 40 min. An sV-trough was observed in 22 patients before the onset of ventricular fibrillation or AMI. A pV-trough was observed in all 9 patients before the onset of complete atrioventricular block. In the no event group, an sV-trough and a pV-trough were observed in 10 subjects (5%) and 20 subjects (10%), respectively. The positive predictive accuracy of an sV-trough for ventricular fibrillation or AMI and that of a pV-trough for complete atrioventricular block was 88% and 100%, respectively.</AbstractText>A previously unidentified V-trough of autonomic activity is a potential precursor of lethal events.</AbstractText> |
5,465 | Does off-pump coronary artery revascularization improve the long-term survival in patients with ventricular dysfunction? | Coronary artery revascularization with cardiopulmonary bypass (ONCAB) has been reported to carry several risks for patients with poor left ventricular (LV) function (ejection fraction <30%). Off-pump CABG (OPCAB) has been proposed to result in a better outcome, but mid- and long-term survival rates have never been compared. The aim of this study is to assess the effect of cardiopulmonary bypass on this group of patients.</AbstractText>In a 10-year period, a total of 934 patients with poor LV function undergoing isolated first-time coronary artery bypass graft were studied. They were divided into two groups, the ONCAB group, with 528 patients, and the OPCAB group with 406 patients. The EuroSCORE was significantly higher in the OPCAB group (P=0.049). After adjusting for the preoperative characteristics, postoperative complications, in-hospital mortality, mid-term survival rate (five years), and long-term survival rate (10 years) were compared.</AbstractText>The average number of grafts was 3.7 in the ONCAB group and 3.1 in the OPCAB group (P<0.001). Postoperative complications of ONCAB and OPCAB groups such as; atrial fibrillation (29.6% vs. 28.6%), renal failure (9.3% vs. 9.6%), stroke (2.3% vs. 0.7%), and perioperative myocardial infarction (MI) (3.8% vs. 2.0%), were comparable between groups. Length of intensive care unit stay, hospital stay and ventilation time were considerably shorter in the OPCAB group (P<0.05). The incidence of wound infection was also lower in the OPCAB patients (P<0.05). After adjusting for the preoperative characteristics the incidence of most postoperative complications remained the same between the two groups, except for MI, which was lower in the OPCABs (P<0.04). Despite a lower number of proximal anastomoses in the OPCAB patients, the rate of stroke remained the same between the OPCAB and ONCAB patients (0.09% vs. 1.6%). In-hospital mortality was higher in ONCAB compared to OPCAB (7.8% vs. 5.7%), but this difference did not reach statistical significance (P=0.21). Likewise, mid-term and long-term survival rates were similar even with matched preoperative characteristics. However, re-intervention rate was found to be higher in the OPCABs (P<0.001).</AbstractText>Despite the reported benefits of OPCAB, there was no significant influence on the in-hospital mortality, mid-term survival or long-term survival in patients with LV dysfunction. With adequate myocardial protection in ONCAB and complete revascularization in OPCAB, similar results are achievable.</AbstractText> |
5,466 | Acute atrial arrhythmogenicity and altered Ca(2+) homeostasis in murine RyR2-P2328S hearts. | The experiments explored for atrial arrhythmogenesis and its possible physiological background in recently developed hetero-(RyR2(+/S)) and homozygotic (RyR2(S/S)) RyR2-P2328S murine models for catecholaminergic polymorphic ventricular tachycardia (VT) for the first time. They complement previous clinical and experimental reports describing increased ventricular arrhythmic tendencies associated with physical activity, stress, or catecholamine infusion, potentially leading to VT and ventricular fibrillation.</AbstractText>Atrial arrhythmogenic properties were compared at the whole animal, Langendorff-perfused heart, and single, isolated atrial myocyte levels using electrophysiological and confocal fluorescence microscopy methods. This demonstrated that: (i) electrocardiographic parameters in intact anaesthetized wild-type (WT), RyR2(+/S) and RyR2(S/S) mice were statistically indistinguishable both before and after addition of isoproterenol apart from increases in heart rates. (ii) Bipolar electrogram and monophasic action potential recordings showed significantly higher incidences of arrhythmogenesis in isolated perfused RyR2(S/S), but not RyR2(+/S), relative to WT hearts during either regular pacing or programmed electrical stimulation. The addition of isoproterenol increased such incidences in all three groups. (iii) However, there were no accompanying differences in cardiac anatomy or action potential durations at 90% repolarization and refractory periods. (iv) In contrast, episodes of diastolic Ca(2+) release were observed under confocal microscopy in isolated fluo-3-loaded RyR2(S/S), but not RyR2(+/S) or WT, atrial myocytes. The introduction of isoproterenol resulted in significant diastolic Ca(2+) release in all three groups.</AbstractText>These findings establish acute atrial arrhythmogenic properties in RyR2-P2328S hearts and correlate these with altered Ca(2+) homeostasis in an absence of repolarization abnormalities for the first time.</AbstractText> |
5,467 | Impact of left atrial volume in prediction of outcome after cardiac resynchronization therapy. | Left atrial volume index (LAVI) as a predictor of mortality has not been well investigated in patients with cardiac resynchronization therapy (CRT). The purpose of this study is to evaluate the impact of LAVI in predicting mortality in CRT patients.</AbstractText>We studied 100 consecutive patients who received CRT (male 73, age 69.9 ± 9.6 years). The follow-up duration of all echocardiographic measurements was 14.4 ± 10.5 months after CRT. LAVI was measured from apical views on two-dimensional echocardiography by bi-plane rule. A decrease of left ventricular end systolic volume ≥ 15% after CRT was defined as a positive response to CRT.</AbstractText>The mean LAVI at baseline was 59.9 ± 22.7 ml/m(2). LAVI in patients who died (78.2 ± 27.5 ml/m(2)) was significantly greater than those who survived (55.9 ± 19.5 ml/m(2), p<0.0001) during follow-up of 17 ± 10.6 months. The area under ROC curve (AUC) for LAVI predicting death was 0.77 (p=0.0001). The cutoff point for LAVI predicting death was LAVI>59.4 ml/m(2). LAVI>59.4 ml/m(2) was related to mortality by Cox proportional univariate regression [hazard ratio (HR)=5.15, 95% CI=1.48-17.93, p=0.01]. After adjustment for the variables with significant difference by univariate regression, LAVI>59.4 ml/m(2) was continuously related to mortality by multivariate regression (HR=4.56, 95% CI, 1.30-15.97, p=0.02). LAVI>59.4 ml/m(2) was associated with a near 5-fold increase in mortality during follow-up of 17 ± 10.6 months.</AbstractText>Patients who have LAVI>59.4 ml/m(2) continue to have increased mortality despite CRT.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,468 | Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival. | The purpose of this study was to determine patient compliance and effectiveness of antiarrhythmic treatment by the wearable cardioverter-defibrillator (WCD).</AbstractText>Effectiveness of the WCD for prevention of sudden death is dependent on event type, patient compliance, and appropriate management of ventricular tachycardia/ventricular fibrillation (VT/VF).</AbstractText>Compliance and events were recorded in a nationwide registry of post-market release WCDs. Survival, using the Social Security Death Index, was compared with survival in implantable cardioverter-defibrillator (ICD) patients.</AbstractText>Of 3,569 patients wearing the WCD (age 59.3+/-14.7 years, duration 52.6+/-69.9 days), daily use was 19.9+/-4.7 h (>90% of the day) in 52% of patients. More days of use correlated with higher daily use (p<0.001). Eighty sustained VT/VF events occurred in 59 patients (1.7%). First-shock success was 76 of 76 (100%) for unconscious VT/VF and 79 of 80 (99%) for all VT/VF. Eight patients died after successful conversion of unconscious VT/VF (89.5% survival of VT/VF events). Asystole occurred in 23 (17 died), pulseless electrical activity in 2, and respiratory arrest in 1 (3 died), representing 24.5% of sudden cardiac arrests. During WCD use, 3,541 of 3,569 patients (99.2%) survived overall. Survival occurred in 72 of 80 (90%) VT/VF events and 78 of 106 (73.6%) for all events. Long-term mortality was not significantly different from first ICD implant patients but highest among patients with traditional ICD indications.</AbstractText>Compliance was satisfactory with 90% wear time in >50% of patients and low sudden death mortality during use. Survival was comparable to that of ICD patients. However, asystole was an important cause of mortality in sudden cardiac arrest events.</AbstractText>Copyright (c) 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,469 | Intraoperative management of liver transplantation in patients with hypertrophic cardiomyopathy: a review. | Hypertrophic cardiomyopathy (HCM) is a genetic disorder defined by the presence of a hypertrophied nondilated left ventricle in the absence of other known causes. Anatomic variants exist, and dynamic features of this disease process may include left ventricular outflow tract obstruction during systole, systolic anterior motion of the mitral valve, and mitral regurgitation. Patients with HCM are at higher risk for sudden cardiac death, stroke, atrial fibrillation, atrial reentrant tachycardia, syncope, and congestive heart failure (CHF). Few studies have evaluated the perioperative risk of noncardiac surgery in this patient population. However, there appears to be a relatively high incidence of perioperative adverse cardiac events, such as CHF, myocardial ischemia, stable and life-threatening arrhythmias, and transient hypotension. Interoperative challenges of patients with HCM are exacerbated in the setting of end-stage liver disease (ESLD) and liver transplantation. ESLD physiology includes relative hypovolemia, decreased systemic vascular resistance and arterial pressure, and hyperdynamic circulation characterized by increased cardiac output. General anesthesia, release of ascites, temporary occlusion of the inferior vena cava, and reperfusion of the donor liver can result in cardiovascular instability. Liver transplantation is associated with blood loss, hypovolemia, vasodilation, tachycardia, and hypotension. Anesthetic goals to limit the dynamic features of HCM include avoiding tachycardia and increased contractility, as well as maintaining preload and afterload. Transesophageal echocardiography (TEE) is an ideal monitoring technique for patients with HCM undergoing liver transplantation. Benefits of TEE include real-time visualization of cardiac function and structure, better indication of intravascular volume, and immediate evaluation of pharmacologic interventions. |
5,470 | Time dependence of life-threatening ventricular tachyarrhythmias after coronary revascularization in MADIT-CRT. | Coronary revascularization (CR) may confer electrical stability in patients with ischemic cardiomyopathy. However, data regarding the effect of CR on the development of ventricular tachyarrhythmias in this population are limited.</AbstractText>The purpose of this study was to evaluate the association between CR and arrhythmic risk in postmyocardial infarction (post-MI) patients with left ventricular dysfunction.</AbstractText>The risk for life-threatening ventricular tachyarrhythmias (defined as a first appropriate defibrillator therapy for ventricular tachycardia [VT]/ventricular fibrillation [VF] or death) was compared between post-MI patients with and those without prior CR (n = 612 and 147, respectively) enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT).</AbstractText>The 3-year cumulative rate of VT/VF or death was significantly higher among patients without prior CR (42%) than in patients who underwent prior CR (32%, P = .02). Multivariate analysis demonstrated that patients without prior CR had 48% increased risk (P = .01) for VT/VF or death. Risk reduction associated with CR was related to elapsed time from CR, assessed both as a categorical variable (tertiles for time from CR: ≥7 years, hazard ratio [HR] = 1.93, P = .001; 1.5-7 years, HR = 1.70, P = .01 vs <1.5 years) and as a continuous measure (4%, P = .002, increased risk for VT/VF or death per 1-year increment of elapsed time from CR). The effect of CR on arrhythmic risk was similar in patients treated with a defibrillator alone or when combined with cardiac resynchronization therapy.</AbstractText>Post-MI patients with left ventricular dysfunction who undergo CR experience a time-dependent reduction in the risk for subsequent life-threatening ventricular tachyarrhythmias.</AbstractText>Copyright © 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,471 | Classification and assessment of computerized diagnostic criteria for Brugada-type electrocardiograms. | Although a Brugada-type electrocardiogram (ECG) is occasionally detected in mass health screening examinations in apparently healthy individuals, the automatic computerized diagnostic criteria for Brugada-type ECGs have not been established.</AbstractText>This study was performed to establish the criteria for the computerized diagnosis of Brugada-type ECGs and to evaluate their diagnostic accuracy.</AbstractText>We examined the ECG parameters in leads V1 to V3 in patients with Brugada syndrome and cases with right bundle branch block. Based on the above parameters, we classified the ECGs into 3 types of Brugada-type ECGs, and the conditions for defining each type were explored as the diagnostic criteria. The diagnostic effectiveness of the proposed criteria was assessed using 548 ECGs from 49 cases with Brugada-type ECGs and the recordings from 192,673 cases (36,674 adults and 155,999 school children) obtained from their annual health examinations.</AbstractText>The Brugada-type ST-segment elevation in V1 to V3 was classified into 3 types, types 1, 2/3, and a suggestive Brugada ECG (type S). The automatic diagnostic criteria for each type were established by the J-point amplitude, ST-segment elevation with its amplitude and configuration, as well as the T-wave morphology in leads V1 to V3.</AbstractText>The proposed criteria demonstrated a reasonable accuracy (type 1: 91.9%, type 2/3: 86.2%, type S: 76.2%) for diagnosing Brugada-type ECG in comparison to the macroscopic diagnosis by experienced observers. Moreover, the automatic criteria had a comparable detection rate (0.6% in adults, 0.16% in children) of Brugada-type ECGs to the macroscopic inspection in the health screening examinations.</AbstractText>Copyright © 2010. Published by Elsevier Inc.</CopyrightInformation> |
5,472 | Isolated right ventricular infarct presenting as ventricular fibrillation arrest and confirmed by delayed-enhancement cardiac MRI. | Malignant ventricular arrhythmias resulting from isolated right ventricular myocardial infarction (RVMI) without left ventricular myocardial ischaemia or infarction occur rarely. We present a case of a 61 year-old male with acute onset of chest pain and ventricular fibrillation cardiac arrest requiring prompt defibrillation. Subsequent 15-lead EKG, showed ST-segment elevation in the anterior and right precordial leads without ST-segment elevation in the inferior leads. Angiography documented occlusion of a large RV marginal branch. Delayed enhancement cardiac magnetic resonance imaging (DE-CMR) with gadolinium performed two days post-infarct showed isolated RVMI. Patient remained symptom free and haemodynamically stable throughout his hospital stay. The clinical presentation of isolated RV infarct can be misleading and diagnosis difficult. EKG findings can resemble acute anterior wall myocardial infarction, while its course can be accompanied by life-threatening ventricular arrhythmias. This case uniquely combines this rare clinical sequence with DE-CMR images using gadolinium to confirm isolated RVMI. A brief review of RVMI presentation and associated EKG patterns is also discussed. |
5,473 | [Successful urgent thoracotomy in a patient with penetrating heart injury--case report]. | The case of a patient with a penetrating cardiac injury successfully treated by thoracotomy is reported. In a suicidal attempt, he suffered a self-inflicted thoracic stub wound penetrating the left ventricle. During transport to the hospital, he developed circulatory instability. He was admitted to the emergency department with no signs of life and bilateral non-responding mydriasis. Immediately, urgent anterolateral thoracotomy at the left 5th rib was performed. The pericardium was opened, cardiac tamponade was evacuated and the stab wound in the right ventricle was sutured. The subsequent ventricular fibrillation was treated using defibrillation with an electric discharge of 200 J. After sinus rhythm had resumed, the patient was transferred to the operating theatre for the finishing of thoracic exploration. No more injury was found. Intermittent myoclonus had persisted since admission, and a CT scan showed diffuse cerebral oedema due to post-hypoxic brain damage. During the following hospitalisation, the patient underwent the SSEP examination (evoked potentials) and no signs of decortication were found. At four weeks after injury, the patient was transported to his regional hospital he was afebrile, with stable circulation, spontaneous ventricular function and the GCS of 8 to 9. |
5,474 | Long-term follow-up of the first patients to undergo transcatheter alcohol septal ablation. | We describe the 10-year outcome of the first-in-human series of 12 patients with hypertrophic cardiomyopathy treated with alcohol septal ablation. There was no 30-day mortality. Survival free of death, internal cardiac defibrillator discharge for treatment of ventricular fibrillation or tachycardia, severe New York Heart Association (NYHA) class III/IV and/or Canadian Cardiovascular Society class III/IV symptoms and the need for surgical myectomy in this cohort was 91% at 1 year and 73% at 10 years. The reduction in outflow tract gradient was maintained over the 10 years, from a mean preoperative gradient of 70 mm Hg to a median of 3 mm Hg at 126 months of follow-up (p < 0.01). Two patients (16%) underwent a further ablation procedure. Two patients (16%) suffered sudden cardiac death, 91 and 102 months after the procedure. Long-term symptom benefit was experienced by all patients, with a reduction in mean NYHA class from 2.7 +/- 0.6 before the procedure to 1 after the procedure at the last follow-up (p < 0.01). This historic small cohort study demonstrates that septal ablation can provide long-term haemodynamic and symptomatic benefit. |
5,475 | Differential effects of four xylidine derivatives in the model of ischemia- and re-perfusion-induced arrhythmias in rats in vivo. | The aim of our study was to find the most effective xylidine derivative, which reduced mortality, reduced incidence and duration of severe arrhythmias and had a beneficial influence on hemodynamic parameters in an in vivo setting. We compared the action of lidocaine, articaine, ropivacaine and mepivacaine in a dose 2.5 or 5mg/kg/ml/h infused from 10min before left anterior descending coronary artery occlusion until the end of the experiment. In the rat ischemia- and re-perfusion-induced arrhythmia models, the following parameters were measured or calculated: mortality index, ventricular fibrillation and tachycardia incidence and duration, systolic, diastolic and mean arterial blood pressure, heart rate and pressure rate product. Lidocaine produced the most significant reduction in mortality index (P<0.05) after both doses. At the higher dose, lidocaine and articaine shortened ventricular fibrillation and tachycardia duration (P<0.05-P<0.001), while ropivacaine prolonged them. A hypertensive effect was observed after a lower dose of lidocaine during occlusion and early re-perfusion as compared to others (P<0.05). Beneficial effects were mainly observed with lidocaine, which protected against sudden cardiac death. The novelty was lidocaine's dose independent protection against blood pressure drop in early re-perfusion, which could be linked to the effects observed on the other end-points. Articaine showed beneficial effects but they weren't as pronounced as that of lidocaine. Nevertheless, in the light of our results, articaine could supposedly be used as a substitute for lidocaine in patients with hypertension. |
5,476 | Ventricular arrhythmias and sudden death in patients with chronic kidney disease. | One in four dialysis patients will die suddenly. Most do not fall into the high-risk categories that are associated with sudden death in the general population. The cause of sudden death in the dialysis population is unknown. It may be related to factors associated with chronic kidney disease (CKD) itself, for example, inflammation, vascular stiffness, left ventricular hypertrophy, coronary artery disease, electrolyte/fluid abnormalities or autonomic dysfunction. Studies of patients with implantable cardioverter defibrillators have shown that patients with CKD are more likely to use their devices for ventricular arrhythmias but in spite of this still have a high associated mortality. Until a comprehensive risk stratification strategy is understood, minimising risk by good control of basic parameters such as fluid balance, electrolytes and blood pressure, along with careful assessment of all patients for evidence of coronary artery disease and heart failure is the mainstay of management of the CKD patient. |
5,477 | Altered fibrin clot properties in patients with chronic heart failure and sinus rhythm: a novel prothrombotic mechanism. | Thromboembolic complications occur more frequently in patients with chronic heart failure (CHF) than in the general population. Formation of a compact fibrin clot resistant to lysis has been shown in arterial and venous thrombosis.</AbstractText>To investigate fibrin clot properties in patients with CHF.</AbstractText>Plasma clot permeability, compaction, turbidity and fibrinolysis were assessed in 36 consecutive patients with stable CHF (30M, 6F; aged 64+/-10 years, left ventricular ejection fraction (LVEF) 34.9+/-6.7%) and 36 controls matched for age, sex, cardiovascular risk factors and medication. Exclusion criteria were LVEF >40%, anticoagulant therapy, previous thromboembolic events, atrial fibrillation.</AbstractText>Clots obtained from plasma of patients with CHF had 23% lower clot permeability (p<0.0001), 13% less clot compaction (p<0.001), 15% faster fibrin polymerisation (p<0.0001) and tended to have prolonged fibrinolysis time (p=0.1) compared with controls. C-reactive protein and fibrinogen were associated inversely with clot permeability (R(2)=0.84, p<0.0001 and R(2)=0.79, p<0.0001, respectively) and positively with fibrinolysis time (R(2)=0.88, p<0.0001 and R(2)=0.80, p<0.0001, respectively) in patients with CHF. Plasma thrombin-antithrombin complex concentrations were inversely correlated with clot permeability (R(2)=0.88, p<0.0001) and positively with fibrinolysis time (R(2)=0.91, p<0.0001). Left atrium diameter, but not LVEF, correlated with fibrinolysis time (R(2)=0.61, p=0.027).</AbstractText>Patients with CHF with sinus rhythm are characterised by faster formation of compact plasma fibrin clots, which might predispose to thromboembolic complications.</AbstractText> |
5,478 | Effect of restoration of sinus rhythm by extensive antiarrhythmic drugs in predicting results of catheter ablation of persistent atrial fibrillation. | In patients with persistent atrial fibrillation (AF), an extensive antiarrhythmic drug (AAD) therapy using class III AADs and class I AADs might be more effective in restoring sinus rhythm than class I or III AADs alone. However, the significance and efficacy of this treatment before radiofrequency catheter ablation is unclear. The present study included 51 consecutive patients with long-lasting persistent AF (>12 months) in whom > or =2 previous AADs had failed to restore sinus rhythm (SR). Before performing extensive pulmonary vein isolation, extensive AAD therapy for >3 months was attempted. Before ablation, AF had converted to SR in 33 patients (65%; SR group) and had continued in 18 (35%; AF group). The left ventricular ejection fraction had increased (p <0.01) in association with the improved left atrial diameter (p <0.05) and brain natriuretic peptide plasma level (p <0.001) in the SR group. However, these parameters had not improved in the AF group. The AF-free rate without any AADs at 14 months after a single ablation procedure was greater in the SR group (61%) than in the AF group (22%; hazard ratio 2.62, 95% confidence interval 1.22 to 5.63; p = 0.013). No restoration of SR with extensive AAD therapy (odds ratio 4.493, 95% confidence interval 1.143 to 17.658; p <0.05) and sustained AF lasting for >3 years (odds ratio 4.574, 95% confidence interval 1.027 to 20.368; p <0.05) before ablation were associated with AF recurrence after ablation. In conclusion, restoration of SR with improved cardiac function and structural remodeling after extensive AAD therapy might predict favorable outcomes after ablation in patients with long-lasting, persistent AF. |
5,479 | Premature ventricular complexes as a trigger for ventricular fibrillation. | The mechanisms that trigger ventricular fibrillation (VF) are poorly understood. The aim of this study was to analyze the initiation of VF in electrograms stored in implantable cardioverter-defibrillators (ICDs).</AbstractText>We analyzed ICD electrograms from patients who had suffered at least one episode of VF.</AbstractText>Of 250 patients with ICDs, 13 (10 male and 3 female, age 49+/-22 years) had at least one episode of VF. The diagnoses were Brugada syndrome (n=4), ischemic heart disease (n=3), dilated cardiomyopathy (n=2), hypertrophic cardiomyopathy (n=1), short-coupled variant of torsades de pointes (n=1), endocardial fibroelastosis (n=1) and idiopathic VF (n=1). In 7 patients, VF was the reason for ICD implantation. Overall, 31 episodes of VF were recorded, including three episodes of arrhythmic storm. In the 7 patients who had more than one episode of VF (within minutes or up to 3 years apart), all episodes started with premature ventricular complexes (PVCs) that had the same morphology and similar coupling intervals. A short-long-short cycle was observed in 2 patients. In 21 episodes, PVCs that did not trigger VF were observed during sinus rhythm. There was no significant difference between them and PVCs that did trigger VF in terms of morphology, coupling interval (409+/-121 ms vs. 411+/-123 ms) or the preceding sinus rhythm RR interval (801+/-233 ms vs. 793+/-230 ms).</AbstractText>Spontaneous VF in the form of an arrhythmic storm or an isolated episode were triggered by PVCs. On occasions, PVCs preceded VF without triggering it.</AbstractText> |
5,480 | Achieving low defibrillation thresholds at implant: pharmacological influences, RV coil polarity and position, SVC coil usage and positioning, pulse width settings, and the azygous vein. | Approximately 30% of implantable cardioverter defibrillator (ICD) patients still die of sudden death. A major cause of these sudden deaths is the failure to defibrillate because of failure to achieve a low defibrillation threshold (DFT). Anti-arrhythmic drugs can have a profound positive or negative effect on the DFT. Unfortunately, present clinical practice continues to feature many procedures and tactics that have minimal to negative DFT benefit. In addition, many demonstrated helpful tactics are not understood or followed. This review covers the optimal RV (right ventricular) coil position and polarity, superior vena cava (SVC) coil positioning and usage, pulse width settings, and azygous vein coil implants. Specifically, the RV coil should be set to an anodal polarity and never 'reversed'. The optimal RV coil position appears to be along the mid-septum. The SVC coil should be kept out of the right atrium and placed in the innominate vein junction. The SVC coil should be always on for high impedance patients. For low impedance patients, the SVC coil should be set on or off depending on which setting gives the lowest DFT. Pulse widths should be set to correspond to optimally charging and discharging a cardiac membrane time constant of between 3.5 and 4.5 ms. For the highest DFT patients, a separate coil should be placed in the azygous vein and connected to the ICD 'SVC' port. Anachronistic approaches such as the use of polarity reversal, apical RV coil tip forcing, and subcutaneous arrays are also discussed. |
5,481 | Role of drugs and devices in patients at risk of sudden cardiac death. | The search for effective treatment for preventing sudden cardiac death (SCD) initially started with anti-arrhythmic agents in high-risk patients, but the use of randomized controlled trials clearly led to the conclusion that an approach based on anti-arrhythmic agents is not useful, and sometimes potentially harmful (the risk of arrhythmic death was increased up to 159% in CAST study). Today the approach to SCD prevention includes considering both the setting of patients who have already presented a cardiac arrest or a malignant ventricular tachyarrhythmias (secondary prevention of SCD) and the much broader setting of primary prevention in patients at variable degrees of identifiable risk. For secondary prevention of SCD, implantable cardioverter defibrillation is now the standard of care (the risk of overall mortality may be reduced by 20-31%), and anti-arrhythmic agents, specifically amiodarone, have only a complementary role (for reducing device activations or for preventing atrial fibrillation). For primary prevention of SCD in high-risk patients, cardioverter defibrillators have nowadays specific indications in patients with left ventricular dysfunction (often in combination with cardiac resynchronization therapy), where the risk of overall mortality may be reduced by 23-54%. For the large number of subjects who have some risk of SCD, but are not identified as at high risk of SCD, a series of drugs could exert a favorable effect (beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blocker agents, statins, omega-3 fatty acids and aldosterone antagonists), and for some of them evidence is emerging, from subgroup analysis, of possible SCD prevention capabilities. |
5,482 | Use of imaging techniques to guide catheter ablation procedures. | Paralleling the growth in ablation of complex arrhythmias such as atrial fibrillation and ventricular tachycardia, advanced imaging technologies are becoming more commonplace in the care of the electrophysiology patients. Although intracardiac ultrasound remains the most commonly used imaging technique, advances in real-time MRI may change this in the future. We discuss the current use of intracardiac ultrasound, CT, including rotational angiography, MRI, with an emphasis on delayed-enhancement MRI, and positron emission tomography-CT in advanced ablation procedures. Image integration is emphasized and new technologies such as direct endoscopic visualization are discussed. |
5,483 | Emergency catheter ablation in critical patients. | Emergency catheter ablation is justified in critical patients with drug-refractory life-threatening arrhythmias. The procedure can be used for ablation of an accessory pathway in preexcitation syndrome with high risk of ventricular fibrillation and in patients with shock due to ischemic cardiomyopathy and incessant ventricular tachycardia. Emergency catheter ablation can also be justified in patients with an electrical storm of the implanted cardioverter-defibrillator or in patients with idiopathic ventricular fibrillation. |
5,484 | Emergency therapy of maternal and fetal arrhythmias during pregnancy. | Atrial premature beats are frequently diagnosed during pregnancy (PR); supraventricular tachycardia (SVT) (atrial tachycardia, AV-nodal reentrant tachycardia, circus movement tachycardia) is less frequently diagnosed. For acute therapy, electrical cardioversion with 50-100 J is indicated in all unstable patients (pts). In stable SVT, the initial therapy includes vagal maneuvers to terminate tachycardias. For short-term management, when vagal maneuvers fail, intravenous adenosine is the first choice drug and may safely terminate the arrhythmia. Ventricular premature beats are also frequently present during PR and benign in most of the pts; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia [VT], ventricular flutter [VFlut] or ventricular fibrillation [VF]) may occur. Electrical cardioversion is necessary in all pts who are in hemodynamically unstable situation with life-threatening ventricular tachyarrhythmias. In hemodynamically stable pts, initial therapy with ajmaline, procainamide or lidocaine is indicated. In pts with syncopal VT, VF, VFlut or aborted sudden death, an implantable cardioverter-defibrillator is indicated. In pts with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of PR. The treatment of the pregnant patient with cardiac arrhythmias requires important modifications of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered. |
5,485 | Treating critical supraventricular and ventricular arrhythmias. | Atrial fibrillation (AF), atrial flutter, AV-nodal reentry tachycardia with rapid ventricular response, atrial ectopic tachycardia and preexcitation syndromes combined with AF or ventricular tachyarrhythmias (VTA) are typical arrhythmias in intensive care patients (pts). Most frequently, the diagnosis of the underlying arrhythmia is possible from the physical examination (PE), the response to maneuvers or drugs and the 12-lead surface electrocardiogram. In unstable hemodynamics, immediate DC-cardioversion is indicated. Conversion of AF to sinus rhythm (SR) is possible using antiarrhythmic drugs. Amiodarone has a conversion rate in AF of up to 80%. Ibutilide represents a class III antiarrhythmic agent that has been reported to have conversion rates of 50-70%. Acute therapy of atrial flutter (Aflut) in intensive care pts depends on the clinical presentation. Atrial flutter can most often be successfully cardioverted to SR with DC-energies <50 joules. Ibutilide trials showed efficacy rates of 38-76% for conversion of Aflut to SR compared to conversion rates of 5-13% when intravenous flecainide, propafenone or verapamil was administered. In addition, high dose (2 mg) of ibutilide was more effective than sotalol (1.5 mg/kg) in conversion of Aflut to SR (70 versus 19%). Drugs like procainamide, sotalol, amiodarone or magnesium were recommended for treatment of VTA in intensive care pts. However, only amiodarone is today the drug of choice in VTA pts and also highly effective even in pts with defibrillation-resistant out-of-hospital cardiac arrest (CA). There is a general agreement that bystander first aid, defibrillation and advanced life support is essential for neurologic outcome in pts after cardiac arrest due to VTA. Public access defibrillation in the hands of trained laypersons seems to be an ideal approach in the treatment of ventricular fibrillation (VF). The use of automatic external defibrillators (AEDs) by basic life support ambulance providers or first responder (FR) in early defibrillation programs has been associated with a significant increase in survival rates (SRs). However, use of AEDs at home cannot be recommended. |
5,486 | Tachyarrhythmias, bradyarrhythmias and acute coronary syndromes. | The incidence of bradyarrhythmias in patients with acute coronary syndrome (ACS) is 0.3% to 18%. It is caused by sinus node dysfunction (SND), high-degree atrioventricular (AV) block, or bundle branch blocks. SND presents as sinus bradycardia or sinus arrest. First-degree AV block occurs in 4% to 13% of patients with ACS and is caused by rhythm disturbances in the atrium, AV node, bundle of His, or the Tawara system. First- or second-degree AV block is seen very frequently within 24 h of the beginning of ACS; these arrhythmias are frequently transient and usually disappear after 72 h. Third-degree AV blocks are also frequently transient in patients with infero-posterior myocardial infarction (MI) and permanent in anterior MI patients. Left anterior fascicular block occurs in 5% of ACS; left posterior fascicular block is observed less frequently (incidence <0.5%). Complete bundle branch block is present in 10% to 15% of ACS patients; right bundle branch block is more common (2/3) than left bundle branch block (1/3). In patients with bradyarrhythmia, intravenous (IV) atropine (1-3 mg) is helpful in 70% to 80% of ACS patients and will lead to an increased heart rate. The need for pacemaker stimulation (PS) is different in patients with inferior MI (IMI) and anterior MI (AMI). Whereas bradyarrhythmias are frequently transient in patients with IMI and therefore do not need permanent PS, there is usually a need for permanent PS in patients with AMI. In these patients bradyarrhythmias are mainly caused by septal necrosis. In patients with ACS and ventricular arrhythmias (VTA) amiodarone is the drug of choice; this drug is highly effective even in patients with defibrillation-resistant out-of-hospital cardiac arrest. There is general agreement that defibrillation and advanced life support is essential and is the treatment of choice for patients with ventricular flutter/fibrillation. If defibrillation is not available in patients with cardiac arrest due to VTA, cardiopulmonary resuscitation is mandatory. |
5,487 | Concept of the five 'A's for treating emergency arrhythmias. | Cardiac rhythm disturbances such as bradycardia (heart rate < 50/min) and tachycardia (heart rate > 100/min) require rapid therapeutic intervention. The supraventricular tachycardias (SVTs) are sinus tachycardia, atrial tachycardia, AV-nodal reentrant tachycardia, and tachycardia due to accessory pathways. All SVTs are characterized by a ventricular heart rate > 100/min and small QRS complexes (QRS width < 0.12 ms) during the tachycardia. It is essential to evaluate the arrhythmia history, to perform a good physical examination, and to accurately analyze the 12-lead electrocardiogram. A precise diagnosis of the SVT is then possible in more than 90% of patients. In ventricular tachycardia (VT) there are broad QRS complexes (QRS width > 0.12 s). Ventricular flutter and ventricular fibrillation are associated with chaotic electrophysiologic findings. For acute therapy, we will present the new concept of the five 'A's, which refers to adenosine, adrenaline, ajmaline, amiodarone, and atropine. Additionally, there are the 'B,' 'C,' and 'D' strategies, which refer to beta-blockers, cardioversion, and defibrillation, respectively. The five 'A' concept allows a safe and effective antiarrhythmic treatment of all bradycardias, tachycardias, SVTs, VT, ventricular flutter, and ventricular fibrillation, as well as of asystole. |
5,488 | Irrelevant B-type natriuretic peptide levels in patients with mechanical prostheses in the mitral position presenting with congestive heart failure. | Plasma B-type natriuretic peptide (BNP) level is reported to be a strong marker of congestive heart failure (CHF). Heterogeneity of the BNP levels among individuals with CHF, however, can cause confusion in interpreting the results. The influence of mitral mechanical prostheses on BNP levels in patients presenting with CHF is not well known.</AbstractText>In the present study 214 consecutive patients with CHF diagnosed using the Framingham criteria were enrolled and divided into 2 groups with and without mitral mechanical prostheses (prosthesis group, n=31; native group, n=183). The plasma BNP levels were measured, and clinical examinations including echocardiography were performed at the same time to assess cardiac performance. There was no difference in the left ventricular ejection fractions between the 2 groups. Despite having a lower body mass index, larger prevalence ratio of atrial fibrillation and larger size of the left atrium, the prosthesis group had a significantly lower logBNP level than the native group (prosthesis group vs native group: 5.12+/-1.01 vs 6.21+/-0.92, P<0.001; BNP level: 167+/-324 pg/ml vs 498+/-380 pg/ml). On multivariate analysis the presence of a mitral mechanical prosthesis was extracted as an independent predictor for decreased BNP level in patients with CHF.</AbstractText>Plasma BNP level cannot correctly reflect the severity of CHF in patients with mechanical prostheses in the mitral position.</AbstractText> |
5,489 | Impact of systemic acidosis on the development of malignant ventricular arrhythmias after reperfusion therapy for ST-elevation myocardial infarction. | The aim of the present study was to examine the effect of systemic acidosis on the development of malignant ventricular arrhythmias, including sustained ventricular tachycardia and ventricular fibrillation (VT/VF), after reperfused ST-elevation myocardial infarction (STEMI).</AbstractText>A total of 157 consecutive patients with a reperfused STEMI were examined. Patients were divided into 2 groups according to the presence or absence of systemic acidosis, defined as arterial blood pH <7.40 on admission. Serum creatine kinase and C-reactive protein (CRP) levels were serially measured. Systemic acidosis was observed in 53 patients (34%). There was no significant difference in coronary risk factors and arrival time from onset between the 2 groups. Estimated glomerular filtration rate (eGFR) on admission was lower in patients with acidosis than in those without (P=0.001). Patients with acidosis had a higher incidence of VT/VF (26% vs 4%, P<0.0001), especially within 48 h after STEMI (23% vs 3%, P=0.0002), than those without. The peripheral white blood cell count on admission was higher in patients with than in those without acidosis. Multivariate analysis showed that systemic acidosis was a strong independent predictor of VT/VF (relative risk =8.79, P=0.002) among variables including prior MI and eGFR <60 ml . min(-1) . 1.73 m(-2).</AbstractText>Systemic acidosis was a significant determinant of VT/VF after reperfused STEMI and was associated with elevated serum CRP level. Systemic acidosis and subsequent inflammation after ischemia reperfusion may play an important role in the development of VT/VF.</AbstractText> |
5,490 | Cholesterol and cardiac arrhythmias. | Cardiac arrhythmias are a leading cause of morbidity and mortality in the Western world. Ventricular arrhythmias are reportedly responsible for the majority of sudden cardiac deaths and atrial fibrillation is responsible for 15% of all strokes in the USA. Recent evidence suggests a role for cholesterol in the development of these arrhythmias. In addition to its association with atherosclerotic plaques, high cholesterol has been shown to cause changes in membrane properties, including the function of hormone receptors, ion channels and pumps. These effects are mediated through direct interactions between cholesterol and the membrane proteins, through changes in membrane fluidity and/or an association with lipid rafts. Cholesterol-lowering therapy, therefore, may prove an effective method for the treatment of cardiac arrhythmias. Statins, a class of cholesterol-lowering drugs, have been frequently shown to protect against ventricular arrhythmias and atrial fibrillation. Some of this protection may stem from their cholesterol-lowering activities. |
5,491 | Therapeutic hypothermia after cardiac arrest: a retrospective comparison of surface and endovascular cooling techniques. | Therapeutic hypothermia (32-34 degrees C) is recommended for comatose survivors of cardiac arrest; however, the optimal technique for cooling is unknown. We aimed to compare therapeutic hypothermia using either surface or endovascular techniques in terms of efficacy, complications and outcome.</AbstractText>Retrospective cohort study.</AbstractText>Thirty-bed teaching hospital intensive care unit (ICU).</AbstractText>All patients (n=83) undergoing therapeutic hypothermia following cardiac arrest over a 2.5-year period. The mean age was 61+/-16 years; 88% of arrests occurred out of hospital, and 64% were ventricular fibrillation/tachycardia.</AbstractText>Therapeutic hypothermia was initiated in the ICU using iced Hartmann's solution, followed by either surface (n=41) or endovascular (n=42) cooling; choice of technique was based upon endovascular device availability. The target temperature was 32-34 degrees C for 12-24 h, followed by rewarming at a rate of 0.25 degrees Ch(-1).</AbstractText>Endovascular cooling provided a longer time within the target temperature range (p=0.02), less temperature fluctuation (p=0.003), better control during rewarming (0.04), and a lower 48-h temperature load (p=0.008). Endovascular cooling also produced less cooling-associated complications in terms of both overcooling (p=0.05) and failure to reach the target temperature (p=0.04). After adjustment for known confounders, there were no differences in outcome between the groups in terms of ICU or hospital mortality, ventilator free days and neurological outcome.</AbstractText>Endovascular cooling provides better temperature management than surface cooling, as well as a more favorable complication profile. The equivalence in outcome suggested by this small study requires confirmation in a randomized trial.</AbstractText>Copyright 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,492 | Predictive value of total atrial conduction time estimated with tissue Doppler imaging for the development of new-onset atrial fibrillation after acute myocardial infarction. | Patients who develop new-onset atrial fibrillation (AF) after acute myocardial infarction (AMI) show an increased risk for adverse events and mortality during follow-up. Recently, a novel noninvasive echocardiographic method has been validated for the estimation of total atrial activation time using tissue Doppler imaging of the atria (PA-TDI duration). PA-TDI duration has shown to be independently predictive of new-onset AF. However, whether PA-TDI duration provides predictive value for new-onset AF in patients after AMI has not been evaluated. Consecutive patients admitted with AMIs and treated with primary percutaneous coronary intervention underwent echocardiography <48 hours after admission. All patients were followed at the outpatient clinic for > or =1 year. During follow-up, 12-lead electrocardiography and Holter monitoring were performed regularly, and the development of new-onset AF was noted. Baseline echocardiography was performed to assess left ventricular and left atrial (LA) function. LA performance was quantified with LA volumes, function, and PA-TDI duration. A total of 613 patients were evaluated. LA maximal volume (hazard ratio 1.07, 95% confidence interval 1.04 to 1.11), the total LA ejection fraction (hazard ratio 0.96, 95% confidence interval 0.93 to 0.99) and PA-TDI duration (hazard ratio 1.05, 95% confidence interval 1.04 to 1.06) were univariate predictors of new-onset AF. After multivariate analysis, LA maximal volume and PA-TDI duration independently predicted new-onset AF. Furthermore, PA-TDI duration provided incremental prognostic value to traditional clinical and echocardiographic parameters for the prediction of new-onset AF. In conclusion, PA-TDI duration is a simple measurement that provides important value for the prediction of new-onset AF in patients after AMI. |
5,493 | The EVEREST II Trial: design and rationale for a randomized study of the evalve mitraclip system compared with mitral valve surgery for mitral regurgitation. | Mitral valve surgery is the standard of care for patients with symptomatic mitral regurgitation (MR) or asymptomatic MR with evidence of left ventricular dysfunction or dilation. Whether an endovascular approach to repair can offer comparable effectiveness with improved safety remains to be determined in randomized trials.</AbstractText>The EVEREST II Trial is a multicenter, randomized controlled trial to evaluate the benefits and risks of endovascular mitral valve repair using the MitraClip device compared with open mitral valve surgery (control) in patients with moderate or severe MR. Using a 2:1 randomization ratio, the trial is enrolling up to 186 MitraClip-treated subjects and 93 control subjects. Trial end points include a primary efficacy end point: the proportion of patients free from death, surgery for valve dysfunction, and with moderate-severe (3+) or severe (4+) MR at 12 months; the primary safety end point includes the proportion of patients with death, myocardial infarction, reoperation, nonelective cardiovascular surgery, stroke, renal failure, deep would infection, ventilation >48 hours, gastrointestinal complication, new permanent atrial fibrillation, septicemia, or transfusion of >or=2 U at 30 days or hospital discharge, whichever is longer.</AbstractText>This randomized controlled trial is designed to evaluate the performance of endovascular mitral repair in comparison to open mitral valve surgery in patients with significant MR.</AbstractText>Copyright (c) 2010 Mosby, Inc. All rights reserved.</CopyrightInformation> |
5,494 | Model of cardiac arrest in rats by transcutaneous electrical epicardium stimulation. | To establish a new model of cardiac arrest (CA) in rats by transcutaneous electrical epicardium stimulation.</AbstractText>Two acupuncture needles connected to the anode and cathode of a stimulator were transcutaneously inserted into the epicardium as electrodes. The stimulating current was steered to the epicardium and the stimulation was maintained for 3 min to induce CA. Cardiopulmonary resuscitation (CPR) was performed at 6 min after a period of nonintervention.</AbstractText>CA was successfully induced in a total of 20 rats. The success rate of induction was 12/20 at the current intensity of 1 mA; and reached 20/20 when the current intensity was increased to 2 mA. After the electrical stimulation, the femoral blood pressure quickly dropped below 25 mmHg and the arterial pulse waveform disappeared. The average time from the electrical stimulation to CA induction was 5.10 (+/-2.81) s. When the electrical stimulation stopped, 18/20 rats had ventricular fibrillation and 2/20 rats had pulseless electrical activity. CPR was performed for averagely 207.4 (+/-148.8) s. The restoration of spontaneous circulation (ROSC) was 20/20. The death rate within 4h after ROSC was 5/20, and the 72-h survival rate was 10/20. There were only two cases of complications, a minor muscle contraction and a minor lung lobe injury.</AbstractText>The model of CA in rats induced by transcutaneous electrical epicardium stimulation is a stable model that requires low-intensity current and has fewer complications. This model may provide another option for experimental research of CA induced by malignant arrhythmia (especially VF).</AbstractText>Copyright 2010. Published by Elsevier Ireland Ltd.</CopyrightInformation> |
5,495 | Renin-angiotensin system blockade is associated with the long-term protection against cardiac remodeling after cardioversion in hypertensive patients with atrial fibrillation. | Atrial fibrillation (AF) is the most common arrhythmia, and renin-angiotensin system blockade (RAS-B) may be favorable for AF because of its effect on cardiac remodeling. However, effects of RAS-B on AF in hypertensive patients are controversial. Thus, in this study, we investigated the long-term effects of RAS-B on cardiac remodeling and rhythm control after electrical cardioversion for hypertensive patients with persistent AF. We studied 27 consecutive hypertensive patients with persistent AF (duration > one week) who received electrical cardioversion and once recovered to sinus rhythm. Blood pressure of the patients was controlled by medication including RAS-B. The patients were divided into those who were pre-treated with RAS-B (n = 10) for at least two months before electrical cardioversion and those without RAS-B (n = 17). We performed echocardiography before electrical cardioversion and 3 years after electrical cardioversion in all patients and compared the differences in echocardiographic cardiac remodeling parameters, including left atrial dimension, left ventricular end-diastolic dimension and left ventricular ejection fraction. The AF recurrence-free ratio during the follow-up period was significantly higher in the RAS-B group than in the non-RAS-B group, judged by Kaplan-Meier analysis (60 vs. 24%, P = 0.01). All cardiac remodeling parameters in the RAS-B group showed better values than those in non-RAS-B group (each parameter, P < 0.05), supporting the beneficial effects of RAS-B on AF in hypertensive patients. In hypertensive patients with AF, pre-treatment with RAS-B before electrical cardioversion can prevent cardiac remodeling for 3 years and maintain sinus rhythm. |
5,496 | Vernakalant: A novel agent for the termination of atrial fibrillation. | The pharmacology, pharmacokinetics, safety, clinical efficacy, and role of intravenous vernakalant hydrochloride for the rapid conversion of atrial fibrillation (AF) to normal sinus rhythm are reviewed.</AbstractText>Vernakalant, currently being evaluated by the Food and Drug Administration (FDA), for the termination of atrial fibrillation, differs in pharmacology from other antiarrhythmics; it achieves action potential interference through blockade of sodium and potassium currents. Vernakalant's actions appear to be directed at relatively atrial-selective potassium currents, which result in lengthening of the atrial action potential and prolongation of the atrial action potential plateau, while not significantly affecting the Q-T interval or the ventricular effective refractory period. As a result, the proarrhythmic effects observed with all other agents approved by FDA for the treatment of AF are eliminated. In clinical trials of vernakalant versus placebo, a statistically significant number of patients converted to normal sinus rhythm after receiving vernakalant. For patients with atrial fibrillation continuing for 3-72 hours, the median time to conversion was between 8 and 14 minutes, with 79% of those who converted remaining in sinus rhythm at 24 hours.</AbstractText>Intravenous vernakalant, a novel, relatively atrial-selective antiarrhythmic agent, appears to offer an effective and safe approach to the rapid conversion of recent-onset AF to normal sinus rhythm.</AbstractText> |
5,497 | Heart rate nonlinear dynamics during sudden hypoxia at 8230 m simulated altitude. | Acute hypobaric hypoxia is associated with autonomic changes that bring a global reduction of linear heart rate variability (HRV). Although changes in nonlinear HRV can be associated with physiologic stress and are relevant predictors of fatal arrhythmias in ischemic heart disease, to what extent these components vary in sudden hypobaric hypoxia is not known.</AbstractText>Twelve military pilots were supplemented with increasing concentrations of oxygen during decompression to 8230 m in a hypobaric chamber. Linear and nonlinear HRV was evaluated at 8230 m altitude before, during, and after oxygen flow deprivation. Linear HRV was assessed through traditional time-domain and frequency-domain analysis. Nonlinear HRV was quantified through the short-term fractal correlation exponent alpha (alphas) and the Sample Entropy index (SampEn).</AbstractText>Hypoxia was related to a decrease in linear HRV indexes at all frequency levels. A non-significant decrease in alphas (basal, 1.39 +/- 0.07; hypoxia, 1.11 +/- 0.13; recovery, 1.41 +/- 0.05; P = .054) and a significant increase in SampEn (basal, 1.07 +/- 0.11; hypoxia, 1.45 +/- 0.12; recovery, 1.43 +/- 0.09; P = .018) were detected.</AbstractText>The observed pattern of diminished linear HRV and increased nonlinear HRV is similar to that seen in subjects undergoing heavy exercise or in patients with ischemic heart disease at high risk for ventricular fibrillation.</AbstractText>Copyright (c) 2010. Published by Elsevier Inc.</CopyrightInformation> |
5,498 | Mitral balloon valvuloplasty. | Percutaneous mitral balloon valvuloplasty (MBV) was introduced in 1984 by Inoue who developed the procedure as a logical extension of surgical closed commissurotomy. Since then, MBV has emerged as the treatment of choice for severe pliable rheumatic mitral stenosis (MS). With increasing experience and better selection of patient, the immediate results of the procedure have improved and the rate of complications declined. When the reported complications of MBV are viewed in aggregate, complications occur at approximately the following rates: mortality (0-0.5%), cerebral accident (1-2%), mitral regurgitation (MR) requiring surgery (1.6-3%). These complication rates compare favorably to those reported after surgical commissurotomy. Several randomized trials reported similar hemodynamic results with MBV and surgical commissurotomy. Restenosis after MBV ranges from 4% to 70% depending on the patient selection, valve morphology, and duration of follow-up. Restenosis was encountered in 31% of the author's series at mean follow-up 9 ± 5.2 years (range 1.5-19 years) and the 10, 15, and 19 years restenosis-free survival rates were (78 ± 2%) (52 ± 3%) and (26 ± 4%), respectively, and were significantly higher for patients with favorable mitral morphology (MES ⩽ 8) at 88 ± 2%, 67 ± 4% and 40 ± 6%), respectively (P < 0.0001). The 10, 15, and 19 years event-free survival rates were (88 ± 2%, 60 ± 4% and 28 ± 7%, respectively, and were significantly higher for patients with favorable mitral morphology (92 ± 2%, 70 ± 4% and 42 ± 7%, respectively (P < 0.0001). The effect of MBV on severe pulmonary hypertension, concomitant severe tricuspid regurgitation, left ventricular function, left atrial size, and atrial fibrillation are addressed in this review. In addition, the application of MBV in specific clinical situations such as in children, during pregnancy and for restenosis is discussed. |
5,499 | Relationship of left atrial enlargement to persistence or development of ECG left ventricular hypertrophy in hypertensive patients: implications for the development of new atrial fibrillation. | Persistence and development of ECG left ventricular hypertrophy (LVH) by Cornell product criteria are associated with an increased risk of atrial fibrillation compared with regression or continued absence of LVH. We postulated that this association might be in part mediated via greater left atrial enlargement (LAE) in patients with new and persistent ECG LVH.</AbstractText>Baseline and third year ECG LVH and left atrial systolic diameter were examined in 663 patients in the Losartan Intervention For Endpoint reduction in hypertension echocardiographic substudy who were in sinus rhythm at baseline and had no history of atrial fibrillation. Left atrial systolic diameter was measured and considered enlarged if more than 3.8 cm in women or more than 4.2 cm in men. Cornell product LVH above 2440 mm-ms was considered consistent with LVH. After 3 years follow-up, 238 patients (35.9%) had continued absence of Cornell product LVH, 156 (23.5%) had regression of LVH, 236 (35.6%) had persistent LVH and 33 patients (5.0%) developed new ECG LVH. Compared with third year mean left atrial systolic dimension and prevalence of LAE in patients with continued absence of LVH (3.62+/-0.52 cm, 12.6%), there were step-wise increases in patients with regression of LVH (3.71+/-0.49 cm, 20.5%), persistence of LVH (3.82+/-0.57 cm, 32.2%) and development of new ECG LVH (3.91+/-0.42 cm, 36.4%, both P<0.001). After controlling for differences in age, sex, baseline SBP, BMI and Sokolow-Lyon voltage, randomized treatment allocation, change in DBP and SBP between baseline and third year and for isovolumic relaxation time and presence of an abnormal mitral E/A ratio at baseline and third year, the odds of having LAE were significantly increased in patients with persistent LVH (odds ratio 1.8, 95% confidence interval 1.1-3.2, P=0.043) or new LVH (odds ratio 3.1, 95% confidence interval 1.3-7.7, P=0.016), but not in patients with regression of Cornell product LVH (odds ratio 1.1, 95% confidence interval 0.6-2.0, P=0.860).</AbstractText>Persistence or development of new ECG LVH during antihypertensive therapy are associated with an increased risk of LAE after 3-year follow-up, whereas regression of ECG LVH is not associated with an increased risk of LAE. These findings provide insight into a possible mechanism by which changes in ECG LVH are associated with changing risk of developing atrial fibrillation.</AbstractText> |
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