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6,500 | [Palpitations in competitive athletes. Risks from premature beats, nonsustained tachycardia and preexcitation]. | Cardiovascular screening tests to prevent sudden cardiac death in athletes are discussed controversially, but they should include diligent patient history and physical examination as well as registration of an ECG. If palpitations or tachycardias are described or if preexcitation, supraventricular or ventricular arrhythmias are documented, further risk stratification is mandatory. Specifically the origin and the complexity of the arrhythmia need to be analyzed and any form of structural cardiac pathologies has to be ruled out. Sinus tachycardia, supraventricular and ventricular premature beats, atrial fibrillation as well as supraventricular and ventricular tachycardia may serve as substrate for palpitations. Each of these arrhythmias is associated with a different amount of cardiac risk and can be evidence for certain forms of structural cardiac disease. Recommendations to limit physical activity and specific treatment options depend on the type of the arrhythmia and the presence and the nature of underlying cardiac disease. |
6,501 | Echocardiographic assessment of left atrial size in patients with end-stage renal disease. | Cardiac disease is the most common cause of death in patients with end-stage renal disease. It is assumed that the high rate of cardiovascular mortality is related to accelerated atherosclerosis. Patients with chronic renal insufficiency have an increased prevalence of coronary artery disease, silent myocardial ischaemia, complex ventricular arrhythmias, atrial fibrillation, left ventricular hypertrophy, annular mitral and aortic valve calcification, and enlargement of the left atrium, than patients with normal renal function. It is also well known that haemodialysis is associated with cardiovascular structural changes and rapid fluctuations in electrolyte levels. In this study, we sought to estimate left atrial size by means of echocardiography and to determine any correlations between different echocardiographic measurements in patients with end-stage renal disease.</AbstractText>We analysed data from 123 patients who were on regular haemodialysis, by means of traditional transthoracic echocardiographic examination. The usual statistical parameters, correlations and the Student's t-test were performed, with levels of significance of p < 0.01 and p < 0.05.</AbstractText>The most presented age group was 60 to 69 years old, with a predomination of females (56.1%). We found dilated left atrium in 26.02% of the study patients and a high statistical correlation between different methods of measurement and calculated volumes of the left atrium.</AbstractText>Evaluation of left atrial size should be determined by several different measurements, and left atrial enlargement should be seen as a risk factor for advancing disease.</AbstractText> |
6,502 | The role of chronic atrial stretch and atrial fibrillation on posterior left atrial wall conduction. | The posterior left atrium (LA) is involved in the initiation and maintenance of atrial fibrillation (AF).</AbstractText>The purpose of this study was to compare conduction patterns on the posterior LA in patients with mitral regurgitation (MR), with and without AF.</AbstractText>Epicardial mapping of the posterior LA was performed in 23 patients undergoing cardiac surgery. Patients were included in one of three groups: Group A-patients in sinus rhythm with normal left ventricular function undergoing coronary artery bypass grafting, Group B-patients in sinus rhythm with MR undergoing mitral valve surgery, or Group C-patients in persistent AF with MR undergoing mitral valve surgery. Conduction patterns, regional conduction velocity, conduction heterogeneity, conduction anisotropy, and complex fractionated atrial electrograms (CFAEs) were assessed.</AbstractText>LA diameter was greater in patients in Groups C (57 +/- 4mm) and B (54 +/- 6mm) than in Group A (39 +/- 7 mm, P <0.01). Patients in Group C had a greater number of lines of conduction delay than Groups A and B (2.0 +/- 0.8 vs 1 +/- 0 and 1 +/- 0, P <0.05). The extent of conduction delay and conduction heterogeneity was greater in Group C than in Group B, which was greater than in Group A (P <0.05). The percentage of CFAEs that remained stable during AF was 61% +/- 17%. There was a significant correlation between CFAEs during AF and regions of slow conduction during pacing (R = 0.36, P <0.001).</AbstractText>Patients with MR, LA enlargement, and AF have more extensive regions of conduction slowing in the posterior LA. Anatomically constant lines of conduction delay in this region lead to circuitous wavefront propagation. During persistent AF, fractionated electrograms in the posterior LA are distributed to regions demonstrating slow conduction, and the majority remain stable over time.</AbstractText> |
6,503 | Profound myocardial ischemia associated to occlusion of the right coronary artery. | A 75-year-old man with hypertension, hypercholesterolemia and history of coronary artery disease was admitted to the hospital because of sudden loss of consciousness. The patient suffered an acute myocardial infarction seven years before this admission, which was treated with percutaneous transluminal coronary angioplasty and stent implantation in the right coronary artery. The initial electrocardiogram showed a complete atrioventricular block, with narrow ventricular complexes at a rate of 40 bpm. The next electrocardiogram, obtained after the administration of atropine, showed a sinus rhythm at 84 bpm with first-degree atrioventricular block, obvious ST-segment elevation on leads II, III, aVF, V3 to V6, and electrical alternation of the ST-segment. Subsequently, he suffered three episodes of ventricular fibrillation which were successfully defibrillated. The ST-segment elevation improved after sublingual nitroglycerine and the patient underwent urgent coronary angiography, which showed a critical stenosis in the middle part of the right coronary artery with a lot of thrombus material in the site of the previous stent. The rest of the coronary arteries did not reveal significant lesions. Thrombus aspiration and balloon angioplasty were successfully performed without residual stenosis. The ST-elevation alternans is a rare phenomenon which was initially described in the setting of coronary artery spasm. It is believed to be associated to profound myocardial ischemia, particularly in relation with occlusions of the left anterior descending coronary artery, and to the occurrence of malignant ventricular arrhythmia and sudden cardiac death. |
6,504 | Combining antiplatelet and anticoagulant therapies. | Antiplatelet therapy is the cornerstone for both primary and secondary prevention therapies for ischemic events resulting from coronary atherosclerotic disease. Dual antiplatelet therapy (aspirin plus a thienopyridine, usually clopidogrel) has assumed a central role in the treatment of acute coronary syndromes and after coronary stent deployment. In addition to antiplatelet therapy, anticoagulant therapy might be indicated for stroke prevention in a variety of conditions that include atrial fibrillation, profound left ventricular dysfunction, and after mechanical prosthetic heart valve replacement. For this reason, the use of triple antithrombotic therapy (a dual antiplatelet regimen plus warfarin) is expected to become more prominent, given an aging patient population. But although triple therapy can prevent both thromboembolism and stent thrombosis, it is also associated with significant bleeding hazards. Furthermore, when bleeding events do occur, the challenge of balancing the risk of stent thrombosis or stroke and the need for hemostasis requires considerable expertise. It is both prudent and timely to review treatment strategies that employ combinations of antiplatelet and anticoagulant therapies as well as strategies aimed at reducing bleeding risk in patients treated with these therapies. |
6,505 | [Clinical characteristics of cardiac syncope in children]. | To explore the clinical characteristics of cardiac syncope (CS) in children, and understand their significance in predicting the cardiac syncope.</AbstractText>Twenty-three patients were referred to our department for evaluation of syncope. The diagnosis of the above cases was cardiac syncope. Each patient was interviewed using a standard questionnaire. The clinical histories and standard baseline electrocardiogram were analyzed to identify the variables contributing to the diagnosis of CS in children.</AbstractText>A cardiac cause was identified in 23 syncopal patients presenting to the Department of Pediatrics, Peking University First Hospital: sick sinus syndrome in 7, congenital long QT syndrome in 4, third degree atrioventricular block in 2, supraventricular tachycardia in 2, ventricular tachycardia in 1, atrial fibrillation in 1, pacemaker dysfunction in 1, idiopathic pulmonary hypertension in 3, hypertrophic cardiomyopathy in 1, and dilated cardiomyopathy in 1. The average age of CS patients was 9 years. In totally 23 patients, exertion related syncope spells were found in 14 cases (60.9%), syncope spells at various position 7/23 (30.4%), absence of prodromes in 12/23 (52.2%), syncope spells with incontinence in 4/23 (17.4%), history of heart disease in 4/23 (17.4%). Abnormal standard baseline electrocardiogram was found in 21 cases (91.7%).</AbstractText>The children with cardiac syncope have overt clinical features, especially abnormal findings in electrocardiogram and exertion related syncope spells are the most common clinical features.</AbstractText> |
6,506 | Alcohol-induced electrical remodeling: effects of sustained short-term ethanol infusion on ion currents in rabbit atrium. | In some patients, above-average alcohol consumption before occurrence of atrial fibrillation (AF) in terms of a "holiday heart syndrome" (HHS) can be determined. There is evidence that long before development of apparent alcohol-induced cardiomyopathy, above-average alcohol consumption generates an arrhythmogenic substrate which abets the onset of AF. Changes of atrial current densities in terms of an electrical remodeling after sustained short-term ethanol infusion in rabbits as a potential part of HHS pathophysiology were examined in this study.</AbstractText>Rabbits of the ethanol group (EG) received sustained short-term intravenous alcohol infusion for 120 hours (during infusion period, blood alcohol level did not fall below 158 mg/dl), whereas NaCl 0.9% was infused in the placebo group (PG). Using patch clamp technique in whole-cell mode, atrial current densities were measured and compared between both groups.</AbstractText>Ethanol infusion did not alter current densities of I(to) [58.7 +/- 5.0 pA/pF (PG, n = 20 cells) vs. 53.9 +/- 5.0 pA/pF (EG, n = 24)], I(sus) [11.3 +/- 1.4 pA/pF (PG, n = 20) vs. 10.2 +/- 1.0 pA/pF (EG, n = 24)], and I(K1) [-1.6 +/- 0.3 pA/pF (PG, n = 17) vs. -2.0 +/- 0.3 pA/pF (EG, n = 22)]. However, alcohol infusion resulted in a remarkable reduction of I(Ca,L) current densities [-28.4 +/- 1.8 pA/pF (PG, n = 20) vs. -15.2 +/- 1.4 pA/pF (EG, n = 22)] and I(Na) [-75.4 +/- 3.6 pA/pF (PG, n = 17) vs. -35.4 +/- 4.4 pA/pF (EG, n = 21)], respectively.</AbstractText>Sustained short-term ethanol infusion in rabbits alters atrial current densities. HHS might be favored by alcohol-induced atrial electrical remodeling.</AbstractText> |
6,507 | Monomorphic ventricular tachycardia caused by electrocautery during pacemaker generator change in a patient with normal left ventricular function. | Pacemaker generator replacement is a simple procedure that is mostly done on outpatient basis. Electrocautery is almost universally used for bleeding control and tissue dissection. Ventricular fibrillation (VF) caused by electrocautery in these procedures is a very uncommon occurrence and an underappreciated possibility with modern day devices. We report a case of monomorphic ventricular tachycardia induced by electrocautery in a patient with normal left ventricular ejection fraction during elective pacemaker generator change. |
6,508 | Left ventricular mechanical assist devices and cardiac device interactions: an observational case series. | Nonpulsatile left ventricular assist devices (LVADs) are increasingly used for treatment of refractory heart failure. A majority of such patients have implanted cardiac devices, namely implantable cardioverter-defibrillators (ICDs) or cardiac resynchronization therapy-pacemaker (CRT-P) or cardiac resynchronization therapy-defibrillator (CRT-D) devices. However, potential interactions between LVADs and cardiac devices in this category of patients remain unknown.</AbstractText>We reviewed case records and device logs of 15 patients with ICDs or CRT-P or CRT-D devices who subsequently had implantation of a VentrAssist LVAD (Ventracor Ltd., Chatswood, Australia) as destination therapy or bridge to heart transplantation. Pacemaker and ICD lead parameters before and after LVAD implant were compared. In addition, ventricular tachyarrhythmia event logs and potential electromagnetic interference reports were evaluated.</AbstractText>Right ventricular (RV) sensing decreased in the first 6 months post-LVAD. Mean R-wave amplitude preimplant was 10.9 +/- 5.25 mV compared with 7.2 +/- 3.4 mV during follow-up (P = 0.02). RV impedance also decreased from 642 +/- 240 ohms at baseline to 580 +/- 212 ohms at follow-up (P = 0.007). There was a significant increase in RV stimulation threshold following implantation of the LVAD from 0.8 +/- 0.6 V at baseline to 1.4 +/- 1.0 V in the first 6 months postimplant (P = 0.01). A marked increase in ventricular tachyarrhythmia burden was observed in three patients. One patient displayed electromagnetic interference between the LVAD and defibrillator, resulting in inappropriate defibrillation therapy.</AbstractText>LVADs have a definite impact on cardiac devices in respect with alteration of lead parameters, ventricular tachyarrhythmias, and electromagnetic interference.</AbstractText> |
6,509 | Sudden death: do cytokines and prothrombotic peptides contribute to the occurrence of ventricular fibrillation during acute myocardial infarction? | Sudden cardiac death (SCD) is frequently caused by ventricular fibrillation (VF) occurring in the course of acute myocardial infarction (AMI). It has not been investigated yet, to what extent markers of coagulation activation and inflammation differ between patients with and without VF in the acute phase of AMI. |
6,510 | A case of catecholaminergic polymorphic ventricular tachycardia. | Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a familial cardiac arrhythmia that is related to RYR2 or CASQ2 gene mutation. It occurs in patients with structurally normal heart and causes exercise-emotion-triggered syncope and sudden cardiac death. We experienced a case of CPVT in an 11 year-old female patient who was admitted for sudden cardiovascular collapse. The initial electrocardiogram (ECG) on emergency department revealed ventricular fibrillation. After multiple defibrillations, sinus rhythm was restored. However, recurrent ventricular fibrillation occurred during insertion of nasogastric tube without sedation in coronary care unit. On ECG monitoring, bidirectional ventricular tachycardia occurred with sinus tachycardia and then degenerated into ventricular fibrillation. To our knowledge, there has been no previous case report of CPVT triggered by sinus tachycardia in Korea. Therefore, we report the case as well as a review of the literature. |
6,511 | Myocardial perfusion imaging and cardiovascular outcomes in a cancer population. | Myocardial perfusion imaging can predict outcomes in cardiac patients. However, limited data exist regarding its prediction of cardiovascular outcomes in cancer patients. We sought to determine whether myocardial perfusion imaging predicts long-term cardiovascular outcomes in cancer patients.We performed a retrospective review of 787 consecutive patients at our institution who underwent myocardial perfusion imaging from January 2001 through March 2003. The Cox proportional hazard model was applied, and total cardiac events, cardiac death, and all-cause death were determined for 3 years. We considered P <0.05 to be statistically significant.Patients with abnormal myocardial perfusion imaging results were more likely to be male and older, with heart disease, more vascular risk factors, and lower left ventricular ejection fraction (0.52 +/- 0.14 vs 0.63 +/- 0.11; P <0.001) than patients with normal myocardial perfusion imaging results. Multivariate predictors of total cardiac events included age (P = 0.023), hyperlipidemia (P = 0.0021), pharmacologic myocardial perfusion imaging (P <0.01), left ventricular ejection fraction (P <0.001), and abnormal myocardial perfusion imaging (P = 0.012). Multivariate predictors of cardiac death included age (P = 0.026) and left ventricular ejection fraction (P = 0.0001). Multivariate predictors of all-cause death were age (P = 0.0001), atrial fibrillation (P = 0.0012), and smoking (P <0.001). Overall survival was improved when patients took aspirin (P = 0.0002) and upon each unit increase in left ventricular ejection fraction (P <0.001).Myocardial perfusion imaging in cancer patients can predict 3-year cardiac outcomes. Increasing age, atrial fibrillation, and smoking were associated with worse outcomes, whereas higher left ventricular ejection fraction and the taking of aspirin were protective. |
6,512 | Chronic heart failure and the substrate for atrial fibrillation. | We sought to define the underlying mechanisms for atrial fibrillation (AF) during chronic heart failure (HF).</AbstractText>Preliminary studies showed that 4 months of HF resulted in irreversible systolic dysfunction (n = 9) and a substrate for sustained inducible AF (>3 months, n = 3). We used a chronic (4-month) canine model of tachypacing-induced HF (n = 10) to assess atrial electrophysiological remodelling, relative to controls (n = 5). Left ventricular fractional shortening was reduced from 37.2 +/- 0.83 to 13.44 +/- 2.63% (P < 0.05). Left atrial (LA) contractility (fractional area change) was reduced from 34.9 +/- 7.9 to 27.9 +/- 4.23% (P < 0.05). Action potential durations (APDs) at 50 and 90% repolarization were shortened by approximately 60 and 40%, respectively, during HF (P < 0.05). HF-induced atrial remodelling included increased fibrosis, increased I(to), and decreased I(K1), I(Kur), and I(Ks) (P < 0.05). HF induced increases in LA Kv channel interacting protein 2 (P < 0.05), no change in Kv4.3, Kv1.5, or Kir2.3, and reduced Kir2.1 (P < 0.05). When I(Ca-L) was elicited by action potential (AP) clamp, HF APs reduced the integral of I(Ca) in control myocytes, with a larger reduction in HF myocytes (P < 0.05). I(CaL) measured with standard voltage clamp was unchanged by HF. Incubation of myocytes with N-acetylcysteine (a glutathione precursor) attenuated HF-induced electrophysiological alterations. LA angiotensin-1 receptor expression was increased in HF.</AbstractText>Chronic HF causes alterations in ion channel expression and ion currents, resulting in attenuation of the APD and atrial contractility and a substrate for persistent AF.</AbstractText> |
6,513 | Rosiglitazone-induced myocardial protection against ischaemia-reperfusion injury is mediated via a phosphatidylinositol 3-kinase/Akt-dependent pathway. | 1. Rosiglitazone is widely used in the treatment of Type 2 diabetes. However, in recent years it has become evident that the therapeutic effects of peroxisome proliferator-activated receptor gamma ligands reach far beyond their use as insulin sensitizers. Recently, the ability of rosiglitazone pretreatment to induce cardioprotection following ischaemia-reperfusion (I/R) has been well documented; however, the protective mechanisms have not been elucidated. In the present study, examined the role of the phosphatidylinositol 3-kinase (PI3-K)/Akt signalling pathway in rosiglitazone cardioprotection following I/R injury. 2. Mice were pretreated with 3 mg/kg per day rosiglitazone for 14 days before hearts were subjected to ischaemia (30 min) and reperfusion (2 h). Wortmannin (1.4 mg/kg, i.p.), an inhibitor of PI3-K, was administered 10 min prior to myocardial I/R. Then, activation of the PI3-K/Akt/glycogen synthase kinase (GSK)-3alpha signalling pathway was examined. The effects of PI3-K inhibition on rosiglitazone-induced cardioprotection were also evaluated. 3. Compared with control rats, the ratio of infarct size to ischaemic area (area at risk) and the occurrence of sustained ventricular fibrillation in rosiglitazone-pretreated rats was significantly reduced (P < 0.05). Rosiglitazone pretreatment attenuated cardiac apoptosis, as assessed by ELISA to determine cardiomyocyte DNA fragmentation. Rosiglitazone pretreatment significantly increased levels of phosphorylated (p-) Akt and p-GSK-3alpha in the rat myocardium. Pharmacological inhibition of PI3-K by wortmannin markedly abolished the cardioprotection induced by rosiglitazone. 4. These results indicate that rosiglitazone-induced cardioprotection in I/R injury is mediated via a PI3-K/Akt/GSK-3alpha-dependent pathway. The data also suggest that modulation of PI3-K/Akt/GSK-3alpha-dependent signalling pathways may be a viable strategy to reduce myocardial I/R injury. |
6,514 | Electrical storms and their prognostic implications. | The Agency for Healthcare Research and Quality (AHRQ) commissioned this report to review the evidence for the clinical effects and safety of radiofrequency catheter ablation (RFA) for the management of atrial fibrillation (AF). Over the past decade, RFA has rapidly evolved as a tool for managing AF in select patients. This rapid evolution has been driven by an enhanced understanding of the triggers and etiology of AF and the development of advanced catheter and imaging technologies. After extensive discussion with AHRQ and the technical expert panel (TEP), the key questions to be addressed in this report are: 1) What is the effect of RFA on short- (6 to 12 months) and long- (>12 months) term rhythm control, rates of congestive heart failure, left atrial and ventricular size changes, rates of stroke, quality of life, avoiding anticoagulation, and readmissions for persistent, paroxysmal and long-standing persistent (chronic) atrial fibrillation? 2) What are the patient-level and intervention-level characteristics associated with RFA effect on short- and long-term rhythm control? 3) How does the effect of RFA on short- and long-term rhythm control differ among the various techniques or approaches used? 4) What are the short- and long-term complications and harms associated with RFA? |
6,515 | Postoperative atrial fibrillation after cardiac surgery: who should receive chemoprophylaxis? | To evaluate arrhythmogenic risk factors associated with greater incidence of postoperative atrial fibrillation (POAF) in patients undergoing cardiac surgery (CABG and/or valvular surgery) in order to identify those more prone to the development of this arrhythmia for possible chemoprophylaxis. Sixty-six patients who underwent elective cardiac surgery were assessed. The following risk factors for the development of POAF were correlated: advanced age, valvular heart disease (VHD), left atrial (LA) enlargement, left ventricular dysfunction (LVD), electrolyte imbalance (EI), previous CABG, prior use and withdrawal of beta-blockers (BB) and/or digitalis 24 hours before surgery). The incidence of AF was high (47%) in our study, most frequently on the first postoperative day. Sixty-four percent of the study sample was male, and the mean age was 62 years. Among patients with two or less risk factors for AF, only 24% developed arrhythmia, while the presence of three or more risk factors was associated with increased incidence of postoperative AF (69%), (p = 0.04). Age > 65 years (58% of the patients) was the most prevalent risk factor, followed by LA enlargement in 45% (p = 0.001), and VHD in 38% (p = 0.02). The presence of three or more risk factors increases significantly the incidence of this arrhythmia in the postoperative period after cardiac surgery. Among the primary risk factors are advanced age, left atrial enlargement, and valvular heart disease. |
6,516 | Elevated depression symptoms predict long-term cardiovascular mortality in patients with atrial fibrillation and heart failure. | Depression predicts prognosis in many cardiac conditions, including congestive heart failure (CHF). Despite heightened cardiac risk in patients with comorbid atrial fibrillation (AF) and CHF, depression has not been studied in this group. This substudy, from the AF-CHF Trial of rate- versus rhythm-control strategies, investigated whether depression predicts long-term cardiovascular mortality in patients with left ventricular ejection fraction <or=35%, CHF symptoms, and AF history who receive optimal medical care.</AbstractText>Depression symptoms (Beck Depression Inventory-II) were assessed in 974 participants (833 men), with 32.0% showing elevated scores (Beck Depression Inventory-II >or=14). Over a mean follow-up of 39 months, there were 246 cardiovascular deaths (111 presumed arrhythmic; 302 all-cause deaths). Cox proportional hazards models adjusted for other prognostic factors (including age, marital status, cause of CHF, creatinine level, left ventricular ejection fraction, paroxysmal AF, previous AF hospitalization, previous electrical conversion, and baseline medications) showed that elevated depression scores significantly predicted cardiovascular mortality (primary outcome), arrhythmic death, and all-cause mortality. The adjusted hazard ratios were 1.57 (95% confidence interval 1.20 to 2.07, P<0.001), 1.69 (95% confidence interval 1.13 to 2.53, P=0.01), and 1.38 (95% confidence interval 1.07 to 1.77, P=0.01), respectively. The risks associated with depression and marital status were additive, with the highest risk in depressed patients who were unmarried.</AbstractText>Elevated depression symptoms are related to cardiovascular mortality even after adjustment for other prognostic indicators in patients with comorbid AF and CHF who receive optimized treatment. Unmarried patients are also at increased risk. Mechanisms and treatment options deserve additional study.</AbstractText> |
6,517 | Early and mid-term functional and survival benefits in ischaemic versus degenerative mitral valve repair using Duran flexible ring: a single surgeon series. | The late results of ischaemic mitral valve (MV) repair have been less than satisfying. We compared echocardiographically, the changes in LV function, mid-term durability and survival between MV repair caused by ischaemic cardiomyopathy (n=60) with degenerative MV disease (n=73) over a period of 15 years. The duration of mean follow-up was 3.7+/-4.1 years in the ischaemic group and 3.9+/-2.9 years in the degenerative group. Freedom from reoperation at seven years was 98.3%+/-1.5% and 98.9%+/-2.1%, respectively (P=0.889). At the last follow-up, NYHA functional class I or II was present in 78.4% of patients in the ischaemic group and 80.9% patients in the degenerative group (P=0.347). An improvement in LVEF was noted in both the groups: ischaemic--41.3+/-12.7 (pre-op LVEF: 38.8+/-14.1) and degenerative--46.5+/-11.1 (pre-op LVEF: 45.7+/-11.7) (P=0.014). At seven years, freedom from a cardiac cause of death was statistically similar in the two groups: 93.3%+/-1.3% and 92.2%+/-0.6% (P=0.967). In conclusion, the mid-term results of ischaemic MV repair are similar to those obtained for degenerative MV repair. Surgical correction of ischaemic MR results in long-term improved LVEF and comparable outcomes in terms of freedom from reoperation and survival. |
6,518 | Drug-induced QT interval shortening: potential harbinger of proarrhythmia and regulatory perspectives. | ATP-dependent potassium channel openers such as pinacidil and levcromakalim have long been known to shorten action potential duration and to be profibrillatory in non-clinical models, raising concerns on the clinical safety of drugs that shorten QT interval. Routine non-clinical evaluation of new drugs for their potential to affect cardiac repolarization has revealed that drugs may also shorten QT interval. The description of congenital short QT syndrome in 2000, together with the associated arrhythmias, suggests that drug-induced short QT interval may be proarrhythmic, and an uncanny parallel is evolving between our appreciation of the short and the long QT intervals. Epidemiological studies report an over-representation of short QT interval values in patients with idiopathic ventricular fibrillation. Therefore, as new compounds that shorten QT interval are progressed further into clinical development, questions will inevitably arise on their safety. Arising from the current risk-averse clinical and regulatory environment and concerns on proarrhythmic safety of drugs, together with our lack of a better understanding of the clinical significance of short QT interval, new drugs that substantially shorten QT interval will likely receive an unfavourable regulatory review unless these drugs fulfil an unmet clinical need. This review provides estimates of parameters of QT shortening that may be of potential clinical significance. Rufinamide, a recently approved anticonvulsant, illustrates the current regulatory approach to drugs that shorten QT interval. However, to further substantiate or confirm the safety of these drugs, their approval may well be conditional upon large-scale post-marketing studies with a focus on cardiac safety. |
6,519 | Sotalol and a broken heart. | An 82-year-old woman with persistent atrial fibrillation underwent successful electrical cardioversion and was begun on sotalol. After 3 days of in-hospital observation she had only mild lengthening of the QT interval. Two weeks later in clinic, the day after her husband's unexpected death, she was noted to have profound QT interval prolongation. Although she was asymptomatic and echocardiography did not disclose regional wall motion abnormalities consistent with takotsubo cardiomyopathy, she probably had a forme fruste of stress cardiomyopathy. Following emotional trauma, a period of heightened vigilance for ventricular proarrhythmia is probably warranted in women treated with antiarrhythmic drugs that lengthen repolarization. |
6,520 | Coronary artery disease, left ventricular hypertrophy and diastolic dysfunction are associated with stroke in patients affected by persistent non-valvular atrial fibrillation: a case-control study. | Persistent non-valvular atrial fibrillation (NVAF) is associated with an increased risk of cardiovascular events such as stroke, and its rate is expected to rise because of the ageing population. The absolute rate of stroke depends on age and comorbidity. Risk stratification for stroke in patients with NVAF derives from populations enrolled in randomized clinical trials. However, participants in clinical trials are often not representative of the general population. Many stroke risk stratification scores have been used, but they do not include transthoracic echocardiogram (TTE), pulsate wave Doppler (PWD) and tissue Doppler imaging (TDI), simple and non- invasive diagnostic tools. The role of TTE, PWD and TDI findings has not been previously determined. Our study goal was to determine the association between TTE and PWD findings and stroke prevalence in a population of NVAF prone outpatients.PATIENTS WERE DIVIDED INTO TWO GROUPS: P for stroke prone and F for stroke free. There were no statistically significant differences between the two groups concerning cardiovascular risk factors, age (p=0.2), sex (p=0.2), smoking (p=0.3), diabetes (p=0.1) and hypercholesterolemia (p=0.2); hypertension was statistically significant (p<0.001). There were statistically significant differences concerning coronary artery disease, previous acute myocardial infarction (AMI) (p<0.05) and non- AMI coronaropathy (p<0.04), a higher rate being in the P group. Concerning echo-Doppler findings, a higher statistically significant rate of left ventricular hypertrophy (LVH) (p<0.05) and left ventricular diastolic dysfunction (p<0.001) was found in the P group and dilated left atrium (p<0.04) in the F group, the difference was not significant for mitral regurgitation (p=0.7). Stroke prone NVAF patients have a higher rate of hypertension, coronary artery disease, with and without AMI, LVH and left ventricular diastolic dysfunction, but not left atrial dilatation. M-B mode echocardiography and PWD examination help to identify high-risk stroke patients among NVAF subjects; therefore, they may help in the selection of appropriate therapy for each patient. |
6,521 | Ventricular arrhythmic disturbances and autonomic modulation after beating-heart revascularization in patients with pulmonary normotension. | De-novo ventricular arrhythmias are potentially life-threatening complications after beating-heart revascularization (off-pump CABG). Whether pulmonary hypertension can influence initiation of ventricular arrhythmias through increased sympathetic activity is controversial. In order to determine the influence of pulmonary hypertension on its relative contribution to ventricular arrhythmia, we first had to define the role of cardiac autonomic modulation in patients with pulmonary normotension. We aimed to observe how parameters of linear and nonlinear heart rate variability are changed pre- and postoperatively in patients with pulmonary normotension undergoing off-pump CABG.</AbstractText>Fifteen-minute ECG recordings were collected before and after off-pump CABG in 54 patients with multivessel coronary artery disease and pulmonary normotension to determine linear (TP, HF, LF, LF:HF ratio) and nonlinear detrended fluctuation analysis (alpha1, alpha2) and fractal dimension (average, high and low) parameters of heart rate variability. Arrhythmia was monitored preoperatively in 24-hour Holter recordings and postoperatively by continuous monitoring and clinical assessment.</AbstractText>Deterioration from simple (Lown I-II) to complex (Lown III-V) ventricular arrhythmia was observed in 19 patients, and improvement from complex to simple arrhythmia in five patients (P = 0.022). Patients with postoperative deterioration of ventricular arrhythmia had preoperatively significantly lower values of TP, HF and LF (P = 0.024-0.043) and postoperatively significantly higher values on the low fractal dimension index (P = 0.031) than patients with postoperative improvement of arrhythmia.</AbstractText>Patients experiencing postoperative deterioration of ventricular arrhythmia already have impaired autonomic regulation before surgery. Higher postoperative values on the low fractal dimension index indicate that sympathetic predominance with or without concomitant vagal withdrawal is the underlying neurogenic mechanism contributing to ventricular arrhythmia.</AbstractText> |
6,522 | Use of the trendelenburg position in the porcine model improves carotid flow during cardiopulmonary resuscitation. | Cardiopulmonary resuscitation (CPR) is now widely used as a treatment for ventricular fibrillation, though numerous studies have shown the outcome of standard CPR to be dismal. Alternative methods of CPR, including interposed abdominal compression, constant aortic occlusion, and the use of intrathoracic pressure regulator, have been shown to increase cardiac output and affect the mortality rate of CPR.</AbstractText>Here we suggest the Trendelenburg position as yet another method of increasing cardiac output and therefore improving the effectiveness of chest compressions. We hypothesized that the use of the Trendelenburg position during CPR would increase cardiac output as measured by carotid blood flow.</AbstractText>We anaesthetized six pigs and measured their pre-arrest carotid flow rate for two minutes. We then induced ventricular fibrillation in those pigs and performed open-chest CPR on them. Post-arrest carotid blood flow was measured for two minutes each at 0 (supine position), 10, 20, and 30 degrees of head-down tilt in each pig. The mean carotid flow for each degree of tilt was compared to mean carotid flow at 0 degrees of tilt using a paired student t-test.</AbstractText>We found an increase of up to 1.4-fold in carotid blood flow during CPR in the Trendelenburg position, though only 20 and 30 degrees of Trendelenburg showed a statistically significant increase from the 0 degrees of tilt in pigs.</AbstractText>The Trendelenburg position can lead to increased blood flow through the carotid arteries during CPR in this pig model. Future studies should investigate whether this increased blood flow through the carotid arteries leads to improved brain perfusion and better neurologic outcomes.</AbstractText> |
6,523 | Targeting of cardiac autonomic plexus for modulation of intracardiac neural tone. | Ventricular rate control is considered as an initial choice of therapy in many patients with atrial fibrillation (AF). We could previously show that electrostimulation of the right inferior ganglionated plexus (RIGP), which supplies the AV node, instantly decreases ventricular rate during AF. This study describes the development of a technique to reliably implant a chronic lead inside the RIGP.</AbstractText>In nine mongrel dogs with AF, the RIGP was identified by neuromapping with probatory high-frequency stimulation (20 Hz) over steerable electrode catheters until a significant ventricular rate slowing was achieved. Then an active fixation, permanent pacemaker lead was fixed closed to the mapping catheter left in place as anatomical marker. Initially (n = 4) available guiding catheters and steerable lead stylets were employed to navigate and anchor the lead, which resulted in repetitive screw-in attempts. Therefore, a guiding catheter was developed, which allowed angiography, lead advancement through its lumen, and probatory neurostimulation over its tip. This tool allowed lead delivery within 40 min (n = 5). Neurostimulation via the permanent lead elicited negative dromotropic effects with stimulation frequency, voltage, and impulse duration as determinants of stimulation efficacy.</AbstractText>Active fixation of a permanent pacing lead inside the RIGP is feasible without thoracotomy. Thereby, ventricular rate control during AF can be achieved with stimulus voltages applied for myocardial electrostimulation.</AbstractText> |
6,524 | Regional frequency variation during human ventricular fibrillation. | Quantifying the regional frequency variation in ventricular fibrillation (VF) may lead to focal strategies in treating human VF. We hypothesized that during human VF there are quantifiable regional frequency variations in the ventricles and they relate to underlying fixed myocardial substrate. In eight myopathic human hearts, we studied 35 VF episodes. The electrograms during VF were acquired simultaneously from the epicardium and endocardium using 2 electrode arrays each consisting of 112 electrodes. Regional characterization was performed using a ratio parameter derived from the dominant frequency analysis of the electrograms. The findings were related to the anatomical substrate using bipolar voltage maps. The results of the analysis indicate that LV had a larger dominant frequency (DF) span than RV (p=0.0111) while there was no significant difference (p=0.1488) in the DF span between LV freewall (FW) and septum (SE). Correlation of areas of abnormal myocardium with the dominant frequency feature matched only in 50% of the cases indicating that ion channel heterogeneity and time-varying physiological factors may play an important role in maintaining VF. |
6,525 | Incidence of ventricular arrhythmias in patients on long-term support with a continuous-flow assist device (HeartMate II). | The incidence of ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients supported with a continuous-flow left ventricular assist device (LVAD) has not been investigated in detail. In 23 consecutive recipients of a HeartMate II, we analyzed the incidence of VT/VF during a total of 266 months of follow-up. Sustained VT or VF occurred in 52% of the patients, with the majority of arrhythmias occurring in the first 4 weeks after LVAD implantation. VT/VF requiring implantable cardioverter-defibrillator (ICD) shock or external defibrillation occurred in 8 patients and significant hemodynamic instability ensued in 3 patients. There were no clear predictors of VT/VF, and it is argued that prophylactic ICD implantation should be considered in patients supported with a continuous-flow LVAD. |
6,526 | Unexpected complications of transapical aortic valve implantation. | Recent series have reviewed the results of transapical aortic valve implantation (TAVI). However, specific problems of this new procedure are not well-described. Unexpected complications due to the procedure and their management are reported.</AbstractText>Eighteen patients underwent TAVI using the Edwards Sapien bioprosthesis (Edwards Lifesciences Inc, CA) between September 2007 and June 2008 due to contraindications of conventional surgery (n = 5) or high operative risk (n = 13). The system was introduced through 2 purse string sutures in the apex under echocardiographic and fluoroscopic control.</AbstractText>The implantation success rate and initial procedural success were 100%. There was no intraoperative death and no stroke. During the procedure, two cases of ventricular fibrillation consequent to rapid pacing were treated by cardioversion. Acute mitral regurgitation due to traction of the subvalvular apparatus by the guidewire and acute aortic regurgitation from pressure on a bioprosthesis cusp by the guidewire were diagnosed by transesophageal echocardiography and reversed by the removal of the guidewire. Another case of aortic regurgitation was due to incomplete deployment of the bioprosthesis and was managed by a "valve after valve" procedure. Two patients died on postoperative day 2 from left ventricular failure. In one patient the postmortem study showed, despite correct implantation of the bioprosthesis, a hematoma of the septum with a small ventricular septal defect. The total in-hospital death was 27.7% (5 patients). There was no periprocedural bleeding but in one patient delayed rupture of the apex (36 hours after the procedure) necessitated emergency surgery. A false aneurysm of the apex appeared 3 months after surgery in another patient. Closure of the apex was performed through sternotomy and cardiopulmonary bypass with an uneventful follow-up.</AbstractText>The TAVI is associated with incidents and complications different to those encountered in conventional aortic valve surgery. Recognizing their existence contributes to elucidating their mechanisms and to propose solutions to avoid or treat them.</AbstractText> |
6,527 | Survival of cardiorespiratory arrest after coronary artery bypass grafting or aortic valve surgery. | Study objectives were to (1) report the clinical profile of and outcome for patients who experience a cardiorespiratory arrest after coronary artery bypass grafting or aortic valve replacement, and (2) identify factors associated with improved probability of survival.</AbstractText>We identified 108 consecutive patients who had cardiorespiratory arrest after coronary artery bypass grafting or aortic valve replacement between April 1999 and June 2008. We studied the characteristics of arrests and survivors, and performed a multivariate logistic analysis to determine features associated with survival to hospital discharge.</AbstractText>Cardiac arrest (n = 86) was more common than respiratory arrest (n = 13; unknown cause, n = 9). Cardiorespiratory arrest occurred with decreasing frequency from the day of surgery. Ventricular fibrillation or tachycardia was the dominant mechanism of cardiac arrest (70% versus 17% for asystole versus 13% for pulseless electrical activity), and the principal causes were postoperative myocardial infarction (n = 46; 53%) and tamponade or bleeding (n = 21; 24%). Resternotomy was performed in 45 patients (52%), cardiopulmonary bypass reinstituted in 14 (16%), and additional grafts constructed in 5 (6%). The causes of respiratory arrest were mainly pulmonary (n = 8) and neurologic (n = 5). Survival to hospital discharge was better for respiratory arrest (69%) than for cardiac arrest (50%). Older age, ejection fraction less than 0.30, and postoperative myocardial infarction decreased the probability of survival.</AbstractText>Ventricular fibrillation or tachycardia was the most common mechanism, and myocardial infarction, the predominant precipitating cause of cardiac arrest after coronary artery bypass grafting or aortic valve replacement. Despite aggressive resuscitation, outcome is poor. Young patients with good left ventricular function had a better probability of survival if they did not suffer a postoperative myocardial infarction.</AbstractText> |
6,528 | Sinus rhythm restoration by catheter ablation in patients with long-lasting atrial fibrillation and congestive heart failure: impact of the left ventricular ejection fraction improvement on the implantable cardioverter defibrillator insertion indication. | In the setting of congestive heart failure (CHF), atrial fibrillation (AF) ablation can improve clinical status and the left ventricular ejection fraction (LVEF) value. However, the impact of AF ablation on the implantable cardioverter defibrillator (ICD) indication has never been specifically addressed.</AbstractText>Study subject were six CHF (mean age 61.1 +/- 6.9 years, mean LVEF 25.8 +/- 7.3%) patients refractory to conventional medical treatment with long-lasting AF unresponsive to external cardioversion. Five patients had an idiopathic dilated cardiomyopathy (DCM) and one had an ischaemic cardiomyopathy (ICM). Their New York Heart Association (NYHA) class was III-IV. Two patients had renal insufficiency. No patient had left ventricular delay. All patients underwent AF ablation. LVEF and NYHA class were dramatically improved in the five DCM patients. New York Heart Association class, but not the LVEF, was improved in the ICM patient. A redo ablative procedure was undertaken in four of five DCM patients and in the ICM patient due to arrhythmia recurrence. Left ventricular ejection fraction and NYHA were improved again in the DCM patients (56 +/- 4.4%, I-II, respectively) and led to ICD indication preclusion. The LVEF remained low in the ICM patient (30%) and led to ICD insertion. Sinus rhythm has been stable during the 18.1 +/- 5.7 months follow-up period.</AbstractText>Atrial fibrillation ablation in CHF patients can improve both the clinical status of patients and their LVEF, especially among those affected by DCM. The LVEF improvement has the potential to preclude the indication for a primary prevention ICD insertion.</AbstractText> |
6,529 | Long-term follow-up free of ventricular fibrillation recurrence after resuscitated cardiac arrest in a myotonic dystrophy type 1 patient. | Cardiac involvement in myotonic dystrophy type 1 (DM1) is frequent with increased incidence of conduction disturbances and sudden cardiac death when compared with general population. We describe a 38-year-old man in whom the diagnosis of DM1 was made 8 years after occurrence of cardiac arrest owing to ventricular fibrillation and discuss management of DM1 patients at risk for sudden cardiac death. |
6,530 | Changes in plasma natriuretic peptide levels in patients with atrial fibrillation after cardioversion. | The aim of the study was to assess changes in plasma natriuretic peptide (NP) levels after spontaneous or electrical cardioversion (CV) in patients with paroxysmal or persistent atrial fibrillation (AF).</AbstractText>Patients with paroxysmal or persistent AF with normal left ventricular function and controlled heart rate, referred for electrical CV, were enrolled prospectively. NP concentrations were measured by means of radioimmunoassay method.</AbstractText>We studied 23 patients with paroxysmal and 77 with persistent AF, spontaneously or electrical cardioverted to sinus rhythm. The mean plasma NP levels were increased in AF patients, ANP: 249±88.3 pg/ml and 258±89.7 pg/ml vs 67±21.2 pg/ml; (p<0.001) and BNP: 99.6±29.8 pg/ml and 82.3±33 pg/ml vs 37.5±13 pg/ml; in the paroxysmal, persistent, and control group, respectively. The mean ANP and BNP levels decreased after sinus restoration from 249.0±88.3 pg/ml to 70.1±13 pg/ml, and from 99.6±29.8 pg/ml to 37.4±8.4 pg/ml, respectively, in the paroxysmal group; from 257.7±89.7 pg/ml to 150.0±87.2 pg/ml and from 82.3±33 pg/ml to 63.7±28.6 pg/ml in the persistent AF group. NP levels remained stable for the next 30 days in the group of patients who remained in sinus rhythm.</AbstractText>Plasma NP concentrations are significantly reduced or normalized after sinus rhythm restoration in patients with paroxysmal and persistent AF and remain stable within 4 weeks of follow-up, provided that AF does not recur.</AbstractText>Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,531 | The potential beneficial effects of beta adrenergic blockade in the treatment of ventricular fibrillation. | Cardiac arrest remains a major medical emergency in Western societies, with ventricular fibrillation being the initial rhythm in a significant proportion of cases. Adrenaline is generally accepted to improve the resuscitation outcome, since it improves coronary and cerebral blood flow during cardiopulmonary resuscitation, but several detrimental effects have been associated with its use, most of which are thought to be mediated by its beta adrenergic properties. Several animal studies suggest that beta adrenergic blockade during resuscitation, is associated with increased rates of resuscitation and improved post-resuscitation myocardial function. This article reviews the presence and function of beta-adrenoceptor subtypes in the intact and diseased human myocardium, as well as the differences observed in beta(1)- and beta(2) adrenoceptor subtypes in different species. |
6,532 | Successful resuscitation of a patient in asystole after a TASER injury using a hypothermia protocol. | New studies have shown the benefit of initiating a hypothermia protocol in the survivors of cardiac arrest. Although the data have shown an improved neurologic end point in patients initially in ventricular fibrillation or pulseless ventricular tachycardia, there is still debate about whether patients initially in other rhythms would benefit from hypothermia after return of spontaneous circulation. This is a report of a 17-year-old male found to be in asystole after sustaining a TASER injury, who was treated with a hypothermia protocol after return of spontaneous circulation and left the hospital with intact neurologic function. |
6,533 | Shortening of cardiopulmonary resuscitation time before the defibrillation worsens the outcome in out-of-hospital VF patients. | The purpose of the study is to investigate the influence of cardiopulmonary resuscitation (CPR) time before the first defibrillation.</AbstractText>The present study retrospectively analyzed the Utstein template records from April 1, 2002, to June 30, 2005. Patients who had out-of-hospital-witnessed cardiac arrest caused by cardiac disease and who presented with ventricular fibrillation (VF) as the initial cardiac rhythm were included in the study. Before April 1, 2003, the emergency medical technician (EMT) needed to obtain telephone permission before attempting defibrillation, and CPR was continued until permission was received (CPR first). On and after April 1, 2003, the EMT was immediately able to attempt a defibrillation without obtaining permission (shock first).</AbstractText>In 143 patients who had out-of-hospital-witnessed VF, 43 patients and 100 patients were treated with the CPR-first strategy and the shock-first strategy, respectively. The duration of CPR before the first defibrillation was longer in the CPR-first group than that in the shock-first group. The CPR-first group showed a higher rate of favorable neurologic outcome 30 days after (28% vs 14%; P = .048) and 1 year after cardiac arrest (26% vs 11%; P = .033) than those of the shock-first group. In the patients with witnessed VF, a stepwise multiple logistic regression analysis showed the CPR-first strategy to improve the neurologic outcome.</AbstractText>In patients with out-of-hospital-witnessed VF, sufficient CPR before the first defibrillation is considered to improve the neurologic outcome in comparison to the performance of immediate defibrillation.</AbstractText> |
6,534 | Prearrest signs of shock and respiratory insufficiency in out-of-hospital cardiac arrests witnessed by crew of the emergency medical service. | The objective of this study is to determine whether prearrest shock and respiratory insufficiency influence outcome in patients with emergency medical service-witnessed out-of-hospital cardiac arrest.</AbstractText>Analysis of data from a cardiac arrest database and data from the ambulance charts was performed. For the purpose of the study, shock was defined as prearrest heart rate below 40 or above 140/min, systolic blood pressure as below 90 mm Hg, and respiratory insufficiency as respiratory rate above 36 or oxygen saturation below 90%. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.</AbstractText>Of a total of 303 patients, 81% had prearrest shock or respiratory insufficiency. Mortality was higher in these patients indicated by fewer with return of spontaneous circulation (43% vs 75%, P < .001), and lower survival to hospital admission (31% vs 71%, P < .001) and to discharge (13% vs 59%, P < .001). Independent predictors of mortality were age (OR, 1.04; CI, 1.0-1.06), initial rhythm other than ventricular fibrillation or ventricular tachycardia (OR, 32.9; CI, 10.9-99.0), and respiratory insufficiency (OR, 4.2; CI, 1.4-12.5).</AbstractText>Shock and respiratory depression are common among patients with out-of-hospital cardiac arrest witnessed by the emergency medical service, and these patients have a high mortality when compared with patients without shock or respiratory failure.</AbstractText> |
6,535 | [In-hospital cardiopulmonary resuscitation at Landspitali University Hospital in Reykjavik]. | Survival after in-hospital cardiac arrest has not been previously reported in Iceland and the purpose of this study was to examine the outcomes of in-hospital resuscitation over a two year period.</AbstractText>There are resuscitation teams on each of the two campuses of the University Hospital in Reykjavik. Since the beginning of 2006, the resuscitation teams have compiled their reports in a structured form, Utstein style.</AbstractText>During 2006 and 2007 resuscitation teams were activated on a total of 311 occasions. Of those, there was need for a full cardiopulmonary resuscitation because of cardiac arrest of in patients in 80 cases (26%). Return of spontaneous circulation was achieved or the patient survived to be transferred to the intensive care unit in 55 (69%) of the 80 cases. Survival to discharge was 33%. Survival to discharge was better if the arrest occurred between 8 AM and 4 PM during daytime (50%), than outside of regular working hours (23%, p=0.02). The survival was better if ventricular tachycardia or fibrillation was the first rhythm encountered (50%) than if the initial rhythm turned out to be asystole or pulseless electrical activity (12%, p=0.002). Those who survived resuscitation were generally younger than those who did not (p=0.002).</AbstractText>The outcomes were similar to those reported at institutions in our neighboring countries. The survival rate was lower if the cardiac arrest occurred outside of regular working hours and if ventricular tachycardia or fibrillation was the first encountered rhythm.</AbstractText> |
6,536 | A meta-analysis of the prognostic significance of atrial fibrillation in chronic heart failure. | Atrial fibrillation (AF) is one of the commonest sustained arrhythmias in chronic heart failure (CHF), although the prognostic implications of the presence of AF in CHF remain controversial. We have therefore performed this meta-analysis to study the effects of the presence of AF on mortality in CHF patients.</AbstractText>A systematic MEDLINE search for all randomized trials and observational studies in which the influence of AF on CHF mortality was investigated and meta-analysis of the mortality data was performed. A total of 16 studies were identified of which 7 were randomized trials and 9 were observational studies including 30,248 and 23,721 patients, respectively. An adjusted meta-analysis of the data revealed that the presence of AF is associated with an adverse effect on total mortality with an odds ratio (OR) of 1.40 [95% confidence interval (CI) 1.32-1.48, P < 0.0001] in randomized trials and an OR of 1.14 (95% CI 1.03-1.26, P < 0.05) in observational studies. This increase in mortality associated with the presence of AF was observed in subgroups of CHF patients with both preserved and impaired left ventricular (LV) systolic function.</AbstractText>In conclusion, meta-analysis of 16 studies involving 53,969 patients suggests that the presence of AF is associated with an adverse prognosis in CHF irrespective of LV systolic function.</AbstractText> |
6,537 | Mitral regurgitation associated with mitral annular dilation in patients with lone atrial fibrillation: an echocardiographic study. | Whether and how lone atrial fibrillation (AF) is associated with functional mitral regurgitation (MR) remain unclear.</AbstractText>We studied 12 lone AF patients without left ventricular (LV) dysfunction and/or dilatation, who underwent mitral valve annuloplasty for functional mitral regurgitation (MR). Ten lone AF patients without MR served as controls.</AbstractText>Lone AF Patients with MR had a greater mitral valve annular area and left atrial area than those without MR. There were no differences in LV volumes or LV ejection fraction.</AbstractText>Therefore, we concluded that left atrial dilation and corresponding mitral annular dilation may cause MR in lone AF patients without LV dysfunction and/or dilatation.</AbstractText> |
6,538 | Hypothermia after cardiac arrest: expanding the therapeutic scope. | Therapeutic hypothermia for 12 to 24 hrs following resuscitation from out-of-hospital cardiac arrest is now recommended by the American Heart Association for the treatment of neurological injury when the initial cardiac rhythm is ventricular fibrillation. However, the role of therapeutic hypothermia is uncertain when the initial cardiac rhythm is asystole or pulseless electrical activity, or when the cardiac arrest is primarily due to a noncardiac cause, such as asphyxia or drug overdose. Given that survival rate in these latter conditions is very low, it is unlikely that clinical trials will be undertaken to test the efficacy of therapeutic hypothermia in this setting because of the very large sample size that would be required to detect a significant difference in outcomes. Therefore, in patients with anoxic brain injury after nonventricular fibrillation cardiac arrest, clinicians will need to balance the possible benefit of therapeutic hypothermia with the possible side effects of this therapy. Given that the side effects of therapeutic hypothermia are generally easily managed in the critical care setting, and there is benefit for anoxic brain injury demonstrated in laboratory studies, consideration may be given to treat comatose post-cardiac arrest patients with therapeutic hypothermia in this setting. Because the induction of therapeutic hypothermia has become more feasible with the development of simple intravenous cooling techniques and specialized equipment for improved temperature control in the critical care unit, it is expected that therapeutic hypothermia will become more widely used in the management of anoxic neurological injury whatever the presenting cardiac rhythm. |
6,539 | Ventricular fibrillation frequency from implanted cardioverter defibrillator devices. | The dominant frequency (DF) of ventricular fibrillation (VF) provides a measure of cycle length that may relate to the underlying complexity of the arrhythmia. Dominant frequency analysis may therefore provide insights into VF mechanisms, and potentially guide future therapies. Dominant frequency analysis can be undertaken on stored electrograms (EGMs) from implanted cardioverter defibrillator devices (ICDs). Demonstration of the reproducibility of the DF during separate VF events is necessary before using this tool.</AbstractText>We identified 82 patients receiving a Medtronic ICD who had two episodes of VF induced during ICD testing. We extracted EGMs recorded during both episodes and determined DF using the fast Fourier transform. The mean DF for the population was 4.7 +/- 0.6 Hz, corresponding to a cycle length of 213 ms. First and second episodes of VF were very highly correlated (interclass correlation = 0.87, P < 0.01) demonstrating that DF was highly reproducible. The 18 patients on Class III agents had a significantly lower DF than the remaining 63 (4.4 +/- 0.4 vs. 4.8 +/- 0.6 Hz, P < 0.01, n = 18). However, the DF of patients with ischaemic heart disease (n = 34) did not differ when compared with dilated cardiomyopathy patients (n = 25) (4.7 +/- 0.6 vs. 4.6 +/- 0.4 Hz, P = 0.3).</AbstractText>The DF of short intervals of induced VF is highly reproducible and is sensitive to pharmacological interventions that extend effective refractory period. Such estimates of DF may therefore have clinical utility and in patients with ICDs provide a means of investigating mechanisms underlying the initiation and early phases of VF.</AbstractText> |
6,540 | Defibrillation testing in patients with atrial fibrillation. | Implantable cardioverter defibrillator implantation in patients with atrial fibrillation (AF) is complicated by the need for anticoagulation during defibrillation testing. In this retrospective study, we evaluated the factors associated with successful cardioversion of AF during ventricular defibrillation testing and the safety of our local anticoagulation protocol. |
6,541 | Novel use of a vascular plug to anchor an azygous vein ICD lead. | We describe the case of a young patient with severe hypertrophic cardiomyopathy and marginal defibrillation thresholds (DFTs) at implant of a standard transvenous implantable cardioverter-defibrillator (ICD) system. The patient subsequently experienced multiple failed ICD shocks during a prolonged episode of spontaneous ventricular tachycardia/fibrillation. Placement of a second single-coil shocking lead in the azygous vein resulted in acceptable DFTs, but the new lead migrated superiorly within hours of the procedure. To stabilize the lead position, a vascular plug was placed in the distal azygous vein, and the shocking lead screw was actively fixated to the meshwork of the device. Subsequent testing confirmed both adequate defibrillation and stable lead position. |
6,542 | Nocturnal Arrhythmias across a spectrum of obstructive and central sleep-disordered breathing in older men: outcomes of sleep disorders in older men (MrOS sleep) study. | Rates of cardiac arrhythmias increase with age and may be associated with clinically significant morbidity. We studied the association between sleep-disordered breathing (SDB) with nocturnal atrial fibrillation or flutter (AF) and complex ventricular ectopy (CVE) in older men.</AbstractText>A total of 2911 participants in the Outcomes of Sleep Disorders in Older Men Study underwent unattended polysomnography. Nocturnal AF and CVE were ascertained by electrocardiogram-specific analysis of the polysomnographic data. Exposures were (1) SDB defined by respiratory disturbance index (RDI) quartile (a major index including all apneas and hypopneas), and ancillary definitions incorporating (2) obstructive events, obstructive sleep apnea (OSA; Obstructive Apnea Hypopnea Index quartile), or (3) central events, central sleep apnea (CSA; Central Apnea Index category), and (4) hypoxia (percentage of sleep time with <90% arterial oxygen percent saturation). Multivariable logistic regression analyses were performed.</AbstractText>An increasing RDI quartile was associated with increased odds of AF and CVE (P values for trend, .01 and <.001, respectively). The highest RDI quartile was associated with increased odds of AF (odds ratio [OR], 2.15; 95% confidence interval [CI], 1.19-3.89) and CVE (OR, 1.43; 95% CI, 1.12-1.82) compared with the lowest quartile. An increasing OSA quartile was significantly associated with increasing CVE (P value for trend, .01) but not AF. Central sleep apnea was more strongly associated with AF (OR, 2.69; 95% CI, 1.61-4.47) than CVE (OR, 1.27; 95% CI, 0.97-1.66). Hypoxia level was associated with CVE (P value for trend, <.001); those in the highest hypoxia category had an increased odds of CVE (OR, 1.62; 95% CI, 1.23-2.14) compared with the lowest quartile.</AbstractText>In this large cohort of older men, increasing severity of SDB was associated with a progressive increase in odds of AF and CVE. When SDB was characterized according to central or obstructive subtypes, CVE was associated most strongly with OSA and hypoxia, whereas AF was most strongly associated with CSA, suggesting that different sleep-related stresses may contribute to atrial and ventricular arrhythmogenesis in older men.</AbstractText> |
6,543 | Comparison of neurological outcomes following witnessed out-of-hospital ventricular fibrillation defibrillated with either biphasic or monophasic automated external defibrillators. | Biphasic waveform defibrillation results in higher rates of termination of fibrillation than monophasic waveform defibrillation but has not been shown to improve survival outcomes.</AbstractText>To compare the effectiveness of a biphasic automated external defibrillator (AED) with a monophasic AED for witnessed out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF).</AbstractText>In a prospective population-based cohort study, adults with witnessed VF OHCA were treated with either monophasic or biphasic waveform AED shocks. The primary outcome measure was neurologically favourable 1-month survival, defined as a Cerebral Performance Categories score of 1 or 2.</AbstractText>Of 366 adults with witnessed OHCA of presumed cardiac aetiology, 74 (20%) had VF. Termination of VF with the first shock tended to occur more frequently after biphasic AED shocks (36/44 (82%) vs 20/30 (67%), p = 0.14). Return of spontaneous circulation (ROSC) occurred more frequently after biphasic AED shocks (29/44 (66%) vs 8/30 (27%), p = 0.001). Neurologically favourable 1-month survival was also more frequent in the biphasic group (10/44 (23%) vs 1/30 (3%), p = 0.04). The median time interval from the first shock to the second shock was 67 s in the monophasic group and 24 s in the biphasic group (p = 0.001).</AbstractText>Treatment with biphasic AED shocks improved the likelihood of ROSC and neurologically favourable 1-month survival after witnessed VF compared with monophasic AED shocks. In addition to waveform differences, a shorter time interval from the first shock to the second shock could account for the better outcomes with biphasic AED.</AbstractText> |
6,544 | Update on medical management of atrial fibrillation in the modern era. | The management of atrial fibrillation involves control of the ventricular response rate, anticoagulation to reduce the risk of stroke and attempts to maintain sinus rhythm. The approach to patients with atrial fibrillation has become increasingly complex as therapeutic options have expanded. The ultimate reasons to treat atrial fibrillation include improvement in symptoms, reduction in adverse outcomes and improvement in survival. Despite increasing interest in non pharmacological approaches to treat and potentially cure atrial fibrillation, drugs remain the primary method to treat most patients. This review updates the present state-of-the-art regarding medical management of atrial fibrillation based on present and emerging evidence. |
6,545 | Postshunt hemochromatosis leading to cardiogenic shock in a patient presenting for orthotopic liver transplant: a case report. | In this case report, we have presented a patient whose liver transplant course was greatly affected by a previously undiagnosed disease process that ultimately led to an unexpected perioperative death.</AbstractText>A 52-year-old woman with idiopathic hepatoportal sclerosis presented for liver transplantation 2 years postmesocaval shunt placement. Lab and pathology studies at the time of liver biopsy and shunt placement were negative for iron deposition. Preoperative workup was negative for cardiac disease. At the outset of her liver transplant, the patient developed refractory hypotension secondary to cardiogenic shock. Intraoperative transesophageal echocardiography and postoperative transthoracic echocardiography demonstrated dilated cardiomyopathy with severely depressed systolic function. Upon succumbing to ventricular fibrillation cardiac arrest, an autopsy revealed hemochromatosis of the heart, pancreas, kidneys, adrenals, and explanted liver.</AbstractText>Dilated cardiomyopathy, congestive heart failure, and other unexpected disease processes resulting from hemochromatosis can greatly influence the care of postshunt liver failure patients.</AbstractText> |
6,546 | BNP/NT-proBNP and cardiac pacing: a review. | Natriuretic peptide (NP) levels (B-type natriuretic peptide [BNP] and N-terminal proBNP) are now widely used in clinical practice and cardiovascular research all over the world and have been incorporated into many cardiovascular guidelines for heart failure (HF). The roles of NP levels are evolving rapidly not only in diagnosis, therapy monitoring, and risk stratification of HF, but also in differential diagnosis of acute dyspnea, predicting death and rehospitalization in HF patients. NP assays have been applied in permanent cardiac pacing in recent years, whereas it is still not well known how NP levels change and whether NP levels can predict HF in permanent cardiac pacing. Therefore, this article reviews the role of NP levels in permanent cardiac pacing, mainly including NP changes in different cardiac pacing modes and cardiac resynchronization therapy. |
6,547 | Ventricular arrhythmia inducibility predicts subsequent ICD activation in nonischemic cardiomyopathy patients: a DEFINITE substudy. | We evaluated whether electrophysiologic (EP) inducibility predicts the subsequent occurrence of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.</AbstractText>Inducibility of ventricular arrhythmias has been widely used as a risk marker to select implantable cardioverter defibrillator (ICD) candidates, but is believed not to be predictive in nonischemic cardiomyopathy patients.</AbstractText>In DEFINITE, patients randomized to the ICD arm, but not the conventional arm, underwent noninvasive EP testing via the ICD shortly after ICD implantation using up to three extrastimuli at three cycle lengths plus burst pacing. Inducibility was defined as monomorphic or polymorphic VT or VF lasting 15 seconds. Patients were followed for a median of 29 +/- 14 months (interquartile range = 2-41). An independent committee, blinded to inducibility status, characterized the rhythm triggering ICD shocks.</AbstractText>Inducibility, found in 29 of 204 patients (VT in 13, VF in 16), was associated with diabetes (41.4% vs 20.6%, P = 0.014) and a slightly higher ejection fraction (23.2 +/- 5.9 vs 20.5 +/- 5.7, P = 0.021). In follow-up, 34.5% of the inducible group (10 of 29) experienced ICD therapy for VT or VF or arrhythmic death versus 12.0% (21 of 175) noninducible patients (hazard ratio = 2.60, P = 0.014).</AbstractText>In DEFINITE patients, inducibility of either VT or VF was associated with an increased likelihood of subsequent ICD therapy for VT or VF, and should be one factor considered in risk stratifying nonischemic cardiomyopathy patients.</AbstractText> |
6,548 | The influence of left ventricle diastolic function on natriuretic peptides levels in patients with atrial fibrillation. | The diagnosis of the impaired left ventricle (LV) diastolic function during atrial fibrillation (AF) using traditional methods is very difficult. Natriuretic peptides seem to be useful for assessment of diastolic function in patients with AF.</AbstractText>To evaluate the influence of LV diastolic dysfunction on natriuretic peptides concentrations and to assess the diagnostic value of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in patients with AF and impaired LV diastolic function.</AbstractText>The study included 42 patients (23 males, 19 females), aged 58.6 +/- 8.2 years with nonvalvular persistent AF with preserved LV systolic function who were converted into sinus rhythm by DC cardioversion (CV) and maintained sinus rhythm for at least 30 days. Echocardiography (ECG), ANP, and BNP level measurements were taken at baseline 24 hours before CV and 24 hours and 30 days after CV. On the 30th day following CV in patients with sinus rhythm, Doppler ECG was performed to assess LV diastolic function.</AbstractText>Thirty days after CV, normal LV diastolic function in 15 patients and impaired diastolic function in 27 patients was diagnosed: 20 with impaired LV relaxation and seven with impaired LV compliance. During AF and 24 hours, and 30 days after sinus rhythm restoration, significantly higher ANP and BNP levels were observed in patients with LV diastolic dysfunction as compared to the subgroup with normal LV diastolic function. The average values of ANP during AF in patients with normal and impaired diastolic function were 167.3 +/- 70.1 pg/mL and 298.7 +/- 83.6 pg/mL, respectively (P < 0.001), and the average values of BNP in the above mentioned subgroups were 49.5 +/- 14.7 pg/mL and 145.6 +/- 49.6 pg/mL respectively (P < 0.001). While comparing the diagnostic value of both natriuretic peptides it was noted that BNP was a more specific and sensitive marker of impaired LV diastolic function. ANP value >220.7 pg/mL measured during AF identified patients with impaired LV diastolic function with 85% sensitivity and 90% specificity. BNP value >74.7 pg/mL proved 95% sensitive and 100% specific in the diagnosing of such a group.</AbstractText>The increase of ANP/BNP concentration in patients with AF results not only from the presence of AF, but also reflects the impaired LV diastolic function. Natriuretic peptides, especially BNP, may be useful in diagnosing LV diastolic dysfunction in patients with AF.</AbstractText> |
6,549 | QT interval disturbances in hospitalized elderly patients. | The QT interval reflects the total duration of ventricular myocardial repolarization. Its prolongation is associated with increased risk of polymorphic ventricular tachycardia, or torsade de pointes, which can be fatal.</AbstractText>To assess the prevalence of both prolonged and short QT interval in patients admitted to an acute geriatric ward.</AbstractText>This retrospective study included the records over 6 months of all patients hospitalized in an acute geriatric ward. Excluded were patients with pacemaker, bundle branch block and slow or rapid atrial fibrillation. The standard 12 lead electrocardiogram of each patient was used for the QT interval evaluation.</AbstractText>We screened the files of 422 patients. QTc prolongation based on the mean of 12 ECG leads was detected in 115 patients (27%). Based on lead L2 only, QTc was prolonged in 136 (32%). Associated factors with QT prolongation were congestive heart failure and use of hypnotics. Short QTwas found in 30 patients (7.1%) in lead L2 and in 19 (4.5%) by the mean 12 leads. Short QT was related to a higher heart rate, chronic atrial fibrillation and schizophrenia.</AbstractText>Our study detected QT segment disturbances in a considerable number of elderly patients admitted acutely to hospital. Further studies should confirm these results and clinicians should consider a close QT interval follow-up in predisposed patients.</AbstractText> |
6,550 | Arrhythmia and acute coronary syndrome suppression and cardiac resuscitation management with bretylium. | It is well known that electric shock can both initiate and terminate ventricular fibrillation. Refractory ventricular fibrillation (RVF) may often be an iatrogenic paradoxical result of early, frequent, excessive salvos of DC current countershocks and inappropriate off-label drug use, particularly aggressive epinephrine administration. Evidence suggests that the current advanced cardiac life support pharmacology protocol for cardiac resuscitation may contribute to disappointing survival in patients with out-of-hospital cardiac arrest. Controlled studies and new theoretical consideration suggest the protocol may induce RVF. In contrast, studies suggest that immediate adequate intravenous bretylium administration therapy together with sustained effective chest compressions can induce chemical defibrillation or facilitate electrical defibrillation as well as reduce the intensity, or even need for potentially heart-damaging countershock, where early frequent excessive current shocks are likely to increase refractory arrhythmia as demonstrated in animals and in humans. Salvos of shocks do not allow time between shocks for uniform recovery of normal electrical parameters needed to restore a stable heart rhythm. This may occur by inadvertently administering shock during the vulnerable period of the cardiac cycle. There are compelling existing data to demonstrate that bretylium and cardiopulmonary resuscitation (CPR) delivered before initiating shock therapy is likely to provide the best outcome in cardiac arrest. But, most importantly, adequate CPR chest compressions administered while bretylium is being infused also provide the opportunity to wash out electrically destabilizing electrolytes that have leaked from or are abnormally transported by functionally damaged membranes of fibrillation-induced ischemic myocytes. This may cause abnormal compartment redistribution of electrolytes that may facilitate RVF by heterogeneously partially depolarizing ischemic myocytes. Although efforts have been made to provide hard science for advanced life support, the guidelines are a product of consensus, the give and take of collegiality and intuition rather than rigorous controlled studies. Bretylium has a direct antifibrillatory action normalizing myocyte membrane currents, which restores intracompartmental normal electrolyte balance. In addition, adrenergic blockade by bretylium dilates coronary arteries, increasing effective O2 delivery by CPR. The free and aggressive use of epinephrine is toxic. Catechalomines cause coronary spasm and puts myocardial metabolism into damaging hypermetabolic overdrive to support the "fight or flight reflex" rapidly depleting adenosine triphosphate needed for cardiac electrical and mechanical recovery. Moreover, the value of epinephrine to resuscitation has never been demonstrated in a controlled human study, whereas its potential damage has been largely ignored. Epinephrine's potential deleterious actions that might compromise resuscitation are well established and reviewed here. |
6,551 | Pathological remodeling of cardiac gap junction connexin 43-With special reference to arrhythmogenesis. | A dysfunction of the cardiac gap junction, which contributes to electrical cell-to-cell coupling is one of essential factors known to generate arrhythmias. The function of the gap junction depends on the regulation of connexin which composes the gap junction channel. A dysfunction of the gap junction is possibly caused by the down-regulation of connexin. In this review, the relationship between pathological remodeling of connexin 43 (Cx43) and susceptibility of the heart to the ventricular fibrillation, which is a lethal ventricular tachyarrhythmia, is addressed. A suppression of the PKA-mediated phosphorylation or an augmentation of the PKC-mediated phosphorylation of Cx43 induces the downward remodeling of Cx43. Factors regarding downward remodeling of Cx43, such as hypoxia (including intracellular Ca overload and intracellular acidosis), angiotensin II or an activation of PKCvarepsilon make the heart more susceptible to the ventricular fibrillation, while factors regarding upward remodeling of Cx43, such as cyclic AMP or an activation of PKA, lower susceptibility. As a result, from a clinical point of view, angiotensin II antagonists (synthesis inhibitors or receptor blockades), PKC inhibitors or PKA activators are thus considered to provide a therapeutic approach for the treatment of the initiation or advancement of the ventricular fibrillation. |
6,552 | Atrial fibrillation and quality of life after pacemaker implantation for sick sinus syndrome: data from the Mode Selection Trial (MOST). | In the Mode Selection Trial (MOST) of 2,010 patients with sinus node dysfunction, dual-chamber-paced patients had less atrial fibrillation (AF) and heart failure and had slightly improved health-related quality of life (QOL) compared with rate modulated right ventricular-paced patients. Our objective was to assess the impact of AF on QOL within MOST.</AbstractText>We analyzed serial QOL measures (Short Form-36, Specific Activity Scale, time trade-off) in 3 groups: (1) those without AF; (2) those with paroxysmal AF (PAF), but not chronic AF (CAF); and (3) those with CAF. We carried forward the last known QOL before crossover for all subsequent time points in patients randomized to rate modulated right ventricular pacing who crossed over to dual-chamber pacing for severe pacemaker syndrome.</AbstractText>Three hundred seventeen patients (15.8%) had AF in the year after implantation, 206 patients within 3 months (191 PAF, 15 CAF), and another 159 (124 PAF, 35 CAF) between 3 and 12 months. There were no significant differences among groups in individual Short Form-36 subscales or time trade-off scores at 12 months as compared with baseline or 3 months. Cardiovascular health status was better at 12 months as compared with baseline or 3 months in those without AF.</AbstractText>Atrial fibrillation after pacemaker implantation in elderly patients with sick sinus syndrome was not a major determinant of QOL. However, there was a trend toward better cardiovascular functional status in patients without AF.</AbstractText> |
6,553 | Improvement of P wave dispersion after cardiac resynchronization therapy for heart failure. | The purpose of this study is to investigate the effect of cardiac resynchronization therapy (CRT) on P wave maximum duration (PWM) and P wave dispersion (PWD) in patients with advanced heart failure.</AbstractText>Forty-six patients (33 men; mean age, 60 +/- 11 years) with CRT were enrolled in the present study. PWM and PWD were measured using 12-lead surface electrocardiography (ECG) at a paper speed of 50 mm/s and 20 mm/mV. Serial ECG, echocardiography, clinical assessment, and device interrogations were performed at baseline and 3 months after CRT.</AbstractText>After 3 months of follow-up, PWM and PWD values were significantly decreased (129.6 +/- 11.3 to 120.7 +/- 10.7 milliseconds, P < .001; 42.6 +/- 8.0 to 32.3 +/- 10.1 milliseconds; P < .001, respectively). It showed a significant reduction in left atrial diameter (LAD) (46.5 +/- 5.2 to 44.9 +/- 5.6 mm, P = .021) and an improvement in left ventricular ejection fraction (LVEF) (29.0% +/- 7.5% to 36.2% +/- 8.0%, P < .001). The decrease of PWM and PWD was positively correlated with the reduction of LAD and negatively correlated with the improvement of LVEF. The reduction in atrial fibrillation burden was observed after 3 months of follow-up.</AbstractText>Cardiac resynchronization therapy decreases PWM and PWD along with an improvement of LVEF and a reduction of LAD. Further studies are needed to evaluate the clinical implications of decrease of PWD on prevention of atrial fibrillation.</AbstractText> |
6,554 | Effect of biventricular pacing during a ventricular sensed event. | Loss of biventricular (BiV) pacing occurs during ventricular sensed events such as frequent ventricular ectopy, nonsustained ventricular tachycardia, and intrinsic atrioventricular nodal conduction, such as in atrial fibrillation. Ventricular sense response (VSR) pacing, a novel cardiac resynchronization therapy pacing strategy, maintains BiV pacing during these sensed ventricular events. Patients who underwent echocardiographic optimization after BiV pacemaker implantation were enrolled, and aortic velocity-time integrals (VTIs) were recorded and compared during intrinsic conduction without pacing, optimized BiV pacing, and intrinsic conduction with VSR pacing alone. Thirty-two patients were enrolled (mean age 68 +/- 11 years, 78% men), with a mean baseline QRS duration of 164 +/- 24 ms and a mean left ventricular ejection fraction of 23 +/- 10%. The mean aortic VTI during intrinsic conduction with VSR pacing was 16.5 +/- 3.6 cm, compared with 15.3 +/- 3.4 cm during intrinsic conduction without pacing (p <0.001). The mean aortic VTI with optimized BiV pacing was 17.3 +/- 3.6 cm, significantly better (p <0.001) compared with intrinsic conduction without pacing. Improvements in aortic VTI were higher with optimized BiV pacing compared with VSR pacing alone (p = 0.02). In the subgroup of patients with left bundle branch block-type activation, the hemodynamic improvements realized with VSR pacing were similar to optimized BiV pacing. Mean aortic VTI improvements with VSR were similar in patients with ischemic and nonischemic cardiomyopathy. In conclusion, a cardiac resynchronization therapy algorithm that maintains BiV pacing during a ventricular sensed event appears to have an aortic VTI response that is significantly better compared with intrinsic conduction without pacing. |
6,555 | Re-expression of alpha skeletal actin as a marker for dedifferentiation in cardiac pathologies. | Differentiation of foetal cardiomyocytes is accompanied by sequential actin isoform expression, i.e. down-regulation of the 'embryonic' alpha smooth muscle actin, followed by an up-regulation of alpha skeletal actin (alphaSKA) and a final predominant expression of alpha cardiac actin (alphaCA). Our objective was to detect whether re-expression of alphaSKA occurred during cardiomyocyte dedifferentiation, a phenomenon that has been observed in different pathologies characterized by myocardial dysfunction. Immunohistochemistry of alphaCA, alphaSKA and cardiotin was performed on left ventricle biopsies from human patients after coronary bypass surgery. Furthermore, actin isoform expression was investigated in left ventricle samples of rabbit hearts suffering from pressure- and volume-overload and in adult rabbit ventricular cardiomyocytes during dedifferentiation in vitro. Atrial goat samples up to 16 weeks of sustained atrial fibrillation (AF) were studied ultrastructurally and were immunostained for alphaCA and alphaSKA. Up-regulation of alphaSKA was observed in human ventricular cardiomyocytes showing down-regulation of alphaCA and cardiotin. A patchy re-expression pattern of alphaSKA was observed in rabbit left ventricular tissue subjected to pressure- and volume-overload. Dedifferentiating cardiomyocytes in vitro revealed a degradation of the contractile apparatus and local re-expression of alphaSKA. Comparable alphaSKA staining patterns were found in several areas of atrial goat tissue during 16 weeks of AF together with a progressive glycogen accumulation at the same time intervals. The expression of alphaSKA in adult dedifferentiating cardiomyocytes, in combination with PAS-positive glycogen and decreased cardiotin expression, offers an additional tool in the evaluation of myocardial dysfunction and indicates major changes in the contractile properties of these cells. |
6,556 | Postoperative atrial fibrillation - what do we really know? | Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery, occurring in 20% to 60% of patients. Advanced age, history of atrial fibrillation (AF), heart failure, peripheral arterial disease and chronic obstructive pulmonary disease are predictors of POAF. The pathogenesis of AF seems to be multifactorial, and includes electrical and structural remodeling as well as inflammation (a systemic response caused by cardiopulmonary bypass and cardiotomy). Numerous pharmacologic agents can decrease the incidence of POAF. It is also necessary to evaluate an agent's ability to decrease stroke, mortality, length of stay and hospital costs. Currently, the use of beta-blockers with adjunctive amiodarone has been shown to reduce POAF and several of its complications. Two therapeutic choices exist in patients with POAF: rate control and rhythm control. The decision which is more important to target should be based on the symptoms of the individual patient. Unlike in patients with chronic AF, POAF is generally transient, and the risks of anticoagulation may outweigh the benefits. Surgical ablation techniques and ablation devices have progressed considerably. This made the procedures quicker and simpler, and therefore feasible in virtually all clinical contexts. In turn, this has raised the issue of post-ablation arrhythmias. Although relapsing AF is generally addressed conservatively, it may require ablation, frequently transseptal. Further research is needed to identify the predictors of POAF and the most effective pharmacological and invasive methods for the prevention and treatment of POAF. |
6,557 | Early and comprehensive management of atrial fibrillation: executive summary of the proceedings from the 2nd AFNET-EHRA consensus conference 'research perspectives in AF'. | Atrial fibrillation (AF) causes important mortality and morbidity on a population-level. So far, we do not have the means to prevent AF or AF-related complications adequately. Therefore, over 70 experts on atrial fibrillation convened for the 2nd AFNET/EHRA consensus conference to suggest directions for research to improve management of AF patients (Appendix 1). The group defined three main areas in need for research in AF: 1. better understanding of the mechanisms of AF; 2. Improving rhythm control monitoring and management; and 3. comprehensive cardiovascular risk management in AF patients. The group put forward the hypothesis that successful therapy of AF and its associated complications will require comprehensive therapy. This applies e.g. to the "old" debate of "rate versus rhythm control", since rhythm control is generally added to underlying (continued) rate control therapy, but also to the emerging debate of "antiarrhythmic drugs versus catheter ablation", of which both may be needed in most patients to maintain sinus rhythm, but also to therapy of conditions that predispose to AF and contribute to cardiovascular complications such as stroke, cognitive decline, heart failure, and acute coronary syndromes. We call for research initiatives aiming at a better understanding of the different causes of AF and its complications, and at development and validation of mechanism-based therapies. The future of AF therapy may require a combination of management of underlying and concomitant conditions, early and comprehensive rhythm control therapy, adequate control of ventricular rate and cardiac function, and continuous therapy to prevent AF-associated complications (e.g. antithrombotic therapy). The reasons for these suggestions are detailed in this paper. |
6,558 | Noninvasive risk stratification after myocardial infarction: rationale, current evidence and the need for definitive trials. | Despite advances in therapies for myocardial infarction (MI), death attributed to a cardiac arrest from ventricular tachycardia (VT) or ventricular fibrillation (VF) remains an important problem. The implantable cardioverter defibrillator (ICD) is effective in preventing death from VT/VF, but reliably identifying which post-MI patients would benefit from an ICD remains a major challenge. Beyond the initial post-MI period, the presence of significant left ventricular (LV) dysfunction, alone or in combination with the induction of sustained VT/VF during invasive testing, is the only proven means of selecting patients for a prophylactic ICD. However, these approaches identify only a fraction of those at risk. Furthermore, most patients with significant LV dysfunction after MI have a low, near-term risk of VT/VF. Noninvasive risk stratification tools have been developed to better identify patients likely to benefit from an ICD. To date, none of these tools has been proven useful in this regard. The factors leading to a cardiac arrest are complex, and a single test is unlikely to reliably predict risk. Noninvasive assessment of cardiac structure, conduction and repolarization along with autonomic modulation appear to be useful in predicting the risk of a cardiac arrest after MI, particularly when assessed in combination. However, randomized trials assessing the efficacy of ICD therapy in patients identified as being at risk are required. Until such data are available, significant LV dysfunction alone and in combination with the induction of VT/VF during invasive testing in the nonacute post-MI period remain the only proven methods to guide prophylactic ICD therapy.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Exner</LastName><ForeName>Derek</ForeName><Initials>D</Initials><AffiliationInfo><Affiliation>Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Ablerta. [email protected]</Affiliation></AffiliationInfo></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D016428">Journal Article</PublicationType><PublicationType UI="D016454">Review</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>England</Country><MedlineTA>Can J Cardiol</MedlineTA><NlmUniqueID>8510280</NlmUniqueID><ISSNLinking>0828-282X</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D001341" MajorTopicYN="N">Autonomic Nervous System</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D002986" MajorTopicYN="Y">Clinical Trials as Topic</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D016757" MajorTopicYN="N">Death, Sudden, Cardiac</DescriptorName><QualifierName UI="Q000517" MajorTopicYN="Y">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D017147" MajorTopicYN="Y">Defibrillators, Implantable</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D004562" MajorTopicYN="N">Electrocardiography</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D019317" MajorTopicYN="Y">Evidence-Based Medicine</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D009203" MajorTopicYN="N">Myocardial Infarction</DescriptorName><QualifierName UI="Q000175" MajorTopicYN="Y">diagnosis</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName><QualifierName UI="Q000628" MajorTopicYN="Y">therapy</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D009206" MajorTopicYN="N">Myocardium</DescriptorName><QualifierName UI="Q000473" MajorTopicYN="N">pathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D011379" MajorTopicYN="N">Prognosis</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D018570" MajorTopicYN="N">Risk Assessment</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D012307" MajorTopicYN="N">Risk Factors</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D013318" MajorTopicYN="N">Stroke Volume</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D013997" MajorTopicYN="N">Time Factors</DescriptorName></MeshHeading></MeshHeadingList><OtherAbstract Type="Publisher" Language="fre">Malgré les avancées des traitements de l’infarctus du myocarde (IM), les décès attribués à un arrêt cardiaque imputable à une tachycardie ventriculaire (TV) ou à une fibrillation ventriculaire (FV) demeurent un problème important. Le défibrillateur cardiaque implantable (DCI) est efficace pour prévenir les décès causés par une TV ou une FV, mais il demeure très difficile de dépister avec fiabilité les patients ayant subi un IM qui en profiteraient. Après la période initiale suivant l’IM, la présence d’une dysfonction ventriculaire gauche (VG) importante, seule ou associée à l’induction d’une TV ou d’une FV pendant les examens effractifs, représente le seul moyen démontré de sélectionner les patients à qui installer un DCI prophylactique. Cependant, ces approches ne permettent de repérer qu’une fraction des patients vulnérables. De plus, la plupart des patients présentant une dysfonction VG importante après un IM on un faible risque de TV ou de FV à court terme. Il existe des outils de stratification non effractifs du risque pour mieux dépister les patients susceptibles de profiter d’un DCI, mais jusqu’à présent, on n’a pu démontrer l’utilité d’aucun d’entre eux. Les facteurs entraînant un arrêt cardiaque sont complexes, et un seul test est peu susceptible de prédire le risque avec fiabilité. L’évaluation non effractive de la structure cardiaque, de la conduction et de la repolarisation, conjointement avec la modulation autonome, semble utile pour prédire le risque d’arrêt cardiaque après un IM, notamment lorsqu’ils sont évalués conjointement. Cependant, des essais aléatoires s’imposent pour évaluer l’efficacité du DCI chez les patients dépistés comme vulnérables. Tant que ces données ne seront pas disponibles, une dysfonction VG importante, seule et en association avec l’induction d’une TV ou d’une FV pendant l’examen effractif au cours de la période non aiguë suivant l’IM, demeure le seul moyen démontré d’orienter l’installation prophylactique d’un DCI. |
6,559 | CPR degradation diagram. | During untreated ventricular fibrillation (VF), before CPR is applied, different bodily systems deteriorate at different rates. This paper describes the times when the EEG disappears, when respiratory arrest occurs, and when PD-PEA occurs. It also describes the frequency of VF waves over a 7-min period and how the frequency increases with good CPR. |
6,560 | [Takotsubo syndrome from original description up to now]. | Stress-induced cardiomyopathy, also known as takotsubo syndrome, imitates an acute ST elevation myocardial infarction or an acute coronary syndrome, but without concomitant coronary artery disease. It mainly affects postmenopausal women, but no established epidemiologic data of this syndrome are available to date. Furthermore, the underlying etiologies are still largely unknown. The most frequently described trigger is strong emotional stress. Supportive therapy with aspirin, beta-blockers and angiotensin-converting enzyme inhibitors is recommended. The abnormal kinetics usually reverse or improve within 4-5 weeks. Compared with acute myocardial infarction, takotsubo cardiomyopathy carries a favorable prognosis. However, severe complications, including ventricular fibrillation and cardiogenic shock, may still occur. |
6,561 | Management of left ventricular diastolic heart failure: is it only blood pressure control? | Diastolic heart failure (DHF) is the most common form of heart failure (HF) seen by clinicians today in practice. With the increasing prevalence of DHF, the need for greater spectrum of proven therapies in this condition is clear.</AbstractText>There are few data available to guide the therapy of these patients, and no treatment has been shown to improve survival in DHF. The results of the Hong Kong DHF trial, the first comparative study between an angiotensin converting enzyme inhibitor (ACEI) and an angiotensin receptor blocker (ARB), again did not provide evidence for a superior effect of ACE inhibitors or ARBs in patients with diastolic heart failure.</AbstractText>Traditionally, treatments for congestive HF with decreased ejection fraction have been used to treat DHS, without much proof of benefit. The high mortality and morbidity of these patients underscore the urgent need to find ways to improve outcomes for these patients. Consequently, the care of these patients should be redirected toward screening and treatment of crucial comorbidities such as hypertension, coronary artery disease, atrial fibrillation, obesity, diabetes, and chronic kidney disease.</AbstractText> |
6,562 | Significance of early onset and progressive increase of activation delay during premature stimulation in Brugada syndrome. | The relationship between the activation delay during programmed stimulation and the inducibility of ventricular fibrillation (VF) and filtered QRS duration on signal-averaged ECG (SAECG) were assessed in patients with Brugada syndrome (BS).</AbstractText>The activation delay was assessed using the interval between the stimulus and the QRS complex during programmed stimulation in 25 patients with BS and 10 with idiopathic ventricular tachycardia (controls). The mean increase of delay (MID) was used to characterize the conduction curves. The filtered QRS duration (fQRSd) in leads V(2) (RfQRSd) and V(5) (LfQRSd) were also evaluated using SAECG. Both MIDs at the right ventricular outflow tract (RVOT) were significantly greater in symptomatic and asymptomatic BS patients than in the control group (symptomatic, 7.1 +/-2.7 ms vs control, 2.5 +/-1.2 ms, P<0.001, asymptomatic, 7.3 +/-3.3 ms vs control, P<0.001, respectively). The MID correlated with the His-ventricular interval; however, there were no significant correlations between the MID and RfQRSd or RfQRSd - LfQRSd.</AbstractText>The MID, which indicates an increase of the St-QRS during premature stimulation, was much greater in patients with BS (regardless of clinical symptoms) than in the control group, especially in the RVOT, which might be related to the easy inducibility of VF from the RVOT.</AbstractText> |
6,563 | Antiarrhythmic activity of phytoadaptogens in short-term ischemia-reperfusion of the heart and postinfarction cardiosclerosis. | A course of treatment (16 mg/kg orally during 5 days) by Aralia mandshurica or Rhodiola rosea extracts reduced the incidence of ischemic and reperfusion ventricular arrhythmias during 10-min ischemia and 10-min reperfusion. Extracts of Eleutherococcus senticosus, Leuzea carthamoides, and Panax ginseng did not change the incidence of ischemic and reperfusion arrhythmias. Chronic treatment by aralia, rhodiola, and eleutherococcus elevated the ventricular fibrillation threshold in rats with postinfarction cardiosclerosis. Ginseng and leuzea did not change this parameter in rats with postinfarction cardiosclerosis. |
6,564 | Assessment of the ion channel-blocking profile of the novel combined ion channel blocker AZD1305 and its proarrhythmic potential versus dofetilide in the methoxamine-sensitized rabbit in vivo. | AZD1305 is a novel antiarrhythmic agent under clinical evaluation for management of atrial fibrillation. This study assessed its ion channel-blocking potency by the whole cell patch-clamp technique in vitro and its proarrhythmic liability in anesthetized methoxamine-sensitized rabbits in comparison with dofetilide. AZD1305 predominantly blocked the hERG, the L-type calcium and the hNav1.5 currents in a concentration-dependent manner. In vivo AZD1305 increased the QT interval (from 145 +/- 8 to 196 +/- 18 ms, P < 0.01) without inducing ventricular extrasystoles or torsades de pointes (TdP). In contrast, dofetilide prolonged the QT interval from 161 +/- 3 to 256 +/- 15 ms (P < 0.001) and caused TdP in 12/17 rabbits (P < 0.01 vs. AZD1305). During AZD1305 and dofetilide infusion, the QTend-peak interval maximally increased by 14 +/- 4 and 30 +/- 6 ms (P < 0.05 vs. AZD1305) and the beat-by-beat QT interval variability (quantified as the short-term variability, STV) changed from 2 +/- 0.8 to 2 +/- 0.3 ms (NS) and from 2 +/- 0.2 to 12 +/- 1.1 ms (P < 0.001), respectively. Following dofetilide-induced TdP, 6 rabbits each were injected with saline or AZD1305. In contrast to saline, AZD1305 abbreviated the QT interval (from 275 +/- 25 to 216 +/- 9 ms, P < 0.05), reduced the STV to 1 +/- 0.1 ms (P < 0.001) and suppressed TdP in all 6 rabbits (P < 0.01 vs. saline). In conclusion, AZD1305 can be characterised as a combined ion channel blocker that delays repolarization without increasing beat-by-beat variability of repolarization (BVR) or inducing TdP whereas selective IKr blockade by dofetilide prolongs the QT interval and eventually increases BVR resulting in TdP. |
6,565 | Brugada syndrome whose ST-segment changes were enhanced by antihistamines and antiallergenic drugs. | We describe a case of Brugada syndrome, in which a coved type ST-segment elevation was enhanced by antihistamines and antiallergenic drugs. The patient had been treated with four kinds of antihistamines and antiallergenic drugs. The twelve-lead ECG exhibited a coved type ST-segment elevation in leads V(1) and V(2), and their enhancement was induced by pilsicainide. After discontinuing those drugs, the ST segment elevation in leads V(1) and V(2) became reduced. An ICD implantation was selected for the therapy since ventricular fibrillation was induced. Our report discusses the possible contribution of antihistamines and antiallergenic drugs to the Brugada type ST-segment changes. |
6,566 | Bench study of the accuracy of a commercial AED arrhythmia analysis algorithm in the presence of electromagnetic interferences. | This paper presents a bench study on a commercial automated external defibrillator (AED). The objective was to evaluate the performance of the defibrillation advisory system and its robustness against electromagnetic interferences (EMI) with central frequencies of 16.7, 50 and 60 Hz. The shock advisory system uses two 50 and 60 Hz band-pass filters, an adaptive filter to identify and suppress 16.7 Hz interference, and a software technique for arrhythmia analysis based on morphology and frequency ECG parameters. The testing process includes noise-free ECG strips from the internationally recognized MIT-VFDB ECG database that were superimposed with simulated EMI artifacts and supplied to the shock advisory system embedded in a real AED. Measurements under special consideration of the allowed variation of EMI frequency (15.7-17.4, 47-52, 58-62 Hz) and amplitude (1 and 8 mV) were performed to optimize external validity. The accuracy was reported using the American Heart Association (AHA) recommendations for arrhythmia analysis performance. In the case of artifact-free signals, the AHA performance goals were exceeded for both sensitivity and specificity: 99% for ventricular fibrillation (VF), 98% for rapid ventricular tachycardia (VT), 90% for slow VT, 100% for normal sinus rhythm, 100% for asystole and 99% for other non-shockable rhythms. In the presence of EMI, the specificity for some non-shockable rhythms (NSR, N) may be affected in some specific cases of a low signal-to-noise ratio and extreme frequencies, leading to a drop in the specificity with no more than 7% point. The specificity for asystole and the sensitivity for VF and rapid VT in the presence of any kind of 16.7, 50 or 60 Hz EMI simulated artifact were shown to reach the equivalence of sensitivity required for non-noisy signals. In conclusion, we proved that the shock advisory system working in a real AED operates accurately according to the AHA recommendations without artifacts and in the presence of EMI. The results may be affected for specificity in the case of a low signal-to-noise ratio or in some extreme frequency setting. |
6,567 | Which factors influence spontaneous state transitions during resuscitation? | The clinical state (i.e. ventricular fibrillation/tachycardia: VF/VT, asystole: ASY, pulseless electrical activity: PEA, or return of spontaneous circulation, ROSC) during cardiopulmonary resuscitation determines patient management. We investigate how spontaneous transitions (i.e. not forced by DC shock) between these states are influenced by factors like age, gender, bystander CPR, CPR quality, proportion of time spent in a state, or the number of state transitions.</AbstractText>Detailed recordings from CPR attempts in 304 out-of-hospital cardiac arrests in Akershus (Norway), Stockholm (Sweden), and London (UK) were obtained from modified Heartstart 4000 defibrillators. Spontaneous state transitions were studied using a non-parametric intensity regression method that can handle dynamic factors like the state history properly.</AbstractText>The initial state tended to preserve itself, as did cumulative time in any state. Recent DC shock, bystander CPR, location, response time, gender, compression depth, and ventilation rate were important for some transitions. More ventilation during PEA might possibly avert development to ASY and favour ROSC; otherwise observed variations in CPR quality had little impact.</AbstractText>Using a novel intensity regression approach we studied the influence of various factors on spontaneous (i.e. non-shock) state transitions during CPR. State development was largely determined by the initial state, the proportion of time spent in a state, and the transition frequency; all probably reflecting the underlying aetiology.</AbstractText> |
6,568 | Factors associated with a change in functional outcome between one month and six months after cardiac arrest: a retrospective cohort study. | The appropriate time point of evaluation of functional outcome in cardiac arrest survivors remains a matter of debate. In this cohort study we posed the hypothesis that there are no significant changes in Cerebral Performance Categories (CPC) between one month and six months after out-of hospital cardiac arrest. If changes were present we aimed to identify reasons for these changes.</AbstractText>Based on a cardiac arrest registry, a potential change in CPC and mortality between one month and six months after cardiac arrest was analysed. Variables that were associated with these changes were identified.</AbstractText>Thirty percent of 681 patients showed a significant change in functional outcome and mortality between one month and six months after out-of hospital cardiac arrest, 12% improved in CPC, 1% deteriorated, 17% died. The only factor that was associated with an improvement in CPC in the multivariate analysis was time to restoration of spontaneous circulation (ROSC) (RRR 1.04, 95% CI 1.01-1.06, per minute). We could not find any significant factors associated with a deterioration of CPC. Factors that were associated with mortality were age (RRR 1.03, 95% CI 1.01-1.06) and ventricular fibrillation as initial cardiac rhythm (RRR 0.34, 95% CI 0.16-0.71).</AbstractText>There is a relevant change of functional outcome even one month after out-of hospital cardiac arrest. Especially when studies compare patient groups with unequal arrest times, and an unequal distribution of initial cardiac rhythms a follow-up period longer than one month should be considered for the final outcome evaluation after cardiac arrest.</AbstractText> |
6,569 | Association of intramyocardial high energy phosphate concentrations with quantitative measures of the ventricular fibrillation electrocardiogram waveform. | Quantitative measures of the ventricular fibrillation (VF) electrocardiogram (ECG) have been correlated with the success of rescue shocks, making them ideal measures for guiding resuscitative interventions. Correlation of intramyocardial energy stores with the change in quantitative VF ECG measures would provide mechanistic insight into their utility. We sought to investigate the relationship between intramyocardial energy stores and four quantitative ECG measures.</AbstractText>Eighteen mixed-breed, domestic swine were sedated, anaesthetized and paralyzed. Swine were block randomized into three groups receiving 5, 10, or 15 min of untreated VF. Thoracotomy was performed and the heart was delivered. VF was induced by a 100 mA transthoracic shock while ECG was recorded. Biopsies of myocardial tissue were taken from the left and right ventricles after the prescribed duration of VF. Adenosine triphosphate (ATP) and adenosine diphosphate (ADP) concentrations in the tissue samples were measured. ECG data immediately prior to each biopsy were analyzed by each of four quantitative ECG methods: Scaling Exponent (ScE), Median Slope (MS), Amplitude Spectrum Area (AMSA), and logarithm of the Absolute Correlation (LAC). ATP and ADP concentrations of VF duration groups were compared. ATP and ADP concentrations were regressed against each quantitative ECG measure.</AbstractText>ATP concentrations differed between VF duration groups, but ADP concentrations differed only between 5 and 10 min groups. A significant association existed between ATP and three quantitative measures--ScE, MS, and AMSA--but no significant relationship was found for ADP.</AbstractText>Intramyocardial ATP levels correlate with quantitative measures of the ECG during ventricular fibrillation.</AbstractText> |
6,570 | Surface ECG organization analysis to predict paroxysmal atrial fibrillation termination. | The aim of this work is to predict non-invasively if an AF episode terminates spontaneously or not by analyzing the increase of atrial activity organization prior to paroxysmal atrial fibrillation (PAF) termination. Sample entropy was selected as non-linear organization index. Synthetic PAF signals were used to evaluate the notable impact of noise in AA organization estimation. Three strategies to reduce noise, ventricular residues and enhance the atrial activity main features were proposed. The best prediction results were obtained through main atrial wave (MAW) organization estimation. The MAW can be considered as the fundamental waveform associated to the AA. The 92% of the terminating and non-terminating analyzed PAF episodes were correctly classified. Thereby, it can be concluded that the MAW non-linear analysis from the surface ECG is a reliable and useful tool to predict spontaneous PAF termination. |
6,571 | Technical and practical aspects of remote monitoring of implantable cardioverter-defibrillator patients in Poland - preliminary results. | The aim of remote monitoring of implantable cardioverter-defibrillators (ICD) is to increase the patient's safety by early detection of technical or medical malfunctions and decrease the number of follow-up visits.</AbstractText>To evaluate the feasibility and reliability of internet-based home monitoring of ICD recipients in Poland.</AbstractText>Twenty-seven patients with ICD with remote monitoring options were evaluated; 20 (74%) patients had a single chamber ICD, 6 (22%) patients had a dual chamber ICD and one had an ICD with a resynchronisation therapy option. Medical and technical events reported by the remote monitoring system as well as interruptions in monitoring longer than 14 days were analysed.</AbstractText>The patients were followed for 12.7 +/- 10.5 months. Two of them died because of heart failure (6 and 13 months after ICD implantation, respectively). The remote monitoring system reported medical events in 13 (48%) patients. In total, we received 32 event reports (from 1 to 19 per patient, mean 2.6) which were generated due to the detection of ventricular tachycardia (VT) (17 events in 9 patients), ventricular fibrillation (VF) (9 episodes in 6 patients), ineffective defibrillation with the maximal energy (5 reports in 3 patients) and supraventricular tachycardia in the VT detection window (1). Two patients had more than 3 VT/VF episodes during 24 h. There were no reports on technical abnormalities of the ICD system. Interruptions in home monitoring longer than 14 days occurred in 5 (18.5%) patients and lasted 2 to 14 weeks (mean 2.8 +/- 7.1). The longest break was caused by the patient's stay abroad. The remaining interruptions were caused by: journeys (5 episodes), hospitalisations (4), and a temporary stay in a place without sufficient GSM coverage (3). During the follow-up period there were no interruptions in monitoring caused by transmitter or ICD failure. All data received by the home monitoring system were confirmed during the follow-up visits.</AbstractText>Remote monitoring of ICD recipients in Poland does not present technical difficulties and enables early detection of serious events in ICD patients.</AbstractText> |
6,572 | Cognitive disorders in elderly patients with permanent atrial fibrillation. | Atrial fibrillation (AF) is a risk factor for development of thromboembolic events with an annual stroke rate of 4.5%. In subjects over 80 years AF is the single leading cause of major stroke. Moreover, about 25% of patients with AF in the absence of neurological deficits have tomographic signs of one or more silent cerebral infarcts.</AbstractText>To investigate whether cognitive function in patients with permanent AF is significantly worse than in patients with sinus rhythm.</AbstractText>We included subjects aged > 65 years, without previous cerebrovascular events or dementia, with permanent arrhythmia lasting > 12 months. The AF group comprised 51 patients, aged 75.8 years. The control group consisted of 43 patients with sinus rhythm. The main points of the study protocol were: clinical history recording, physical examination, biochemical analyses, standard 12-lead ECG and transthoracic echocardiography. Cognitive status was assessed by Mini Mental State Examination (MMSE).</AbstractText>Patients had established AF with a median duration of 4.9 years (range 1-21 years). Of the 51 patients, 51% had hypertension, 37% coronary artery disease, 12% presented sick sinus syndrome or atrioventricular advanced block with a VVI pacemaker implanted. There were no significant differences between the two groups though AF patients presented left ventricular hypertrophy and history of myocardial infarction more frequently. Patients in the sinus group had a lower-risk profile and received antithrombotic therapy less frequently than the AF group. However, a significant proportion of patients, particularly in the AF group received less than optimal thromboembolic prophylactic treatment with anticoagulants. Cognitive status was found to be significantly lower in the AF group, compared with the sinus rhythm group: 24.8 +/- 3.1 vs. 27.1 +/- 2.6 (p < 0.05). There were 43% patients with cognitive impairment in the AF group and 14% in the sinus rhythm group.</AbstractText>Permanent AF in patients aged over 65 years seems to be associated with lower MMSE score compared with subjects with sinus rhythm. Cognitive impairment in older patients is a multifactorial disorder. One of the causes of low cognitive function in these patients appears to be permanent AF. Further prospective clinical trials should help determine the possible role of inadequate anticoagulant treatment, and its association with the deterioration of cognitive function in AF patients.</AbstractText> |
6,573 | Ventricular reverse remodeling early after mitral valve repair for severe chronic mitral regurgitation with atrial fibrillation. | Chronic mitral regurgitation (MR) results in volume overload followed by left ventricular (LV) and left atrial remodeling. The aim of this study was to investigate the relation of clinical, echocardiographic findings and N-terminal B-type natriuretic peptide (NT-proBNP) to LV reverse remodeling (LVRR) early after valve repair for severe chronic MR concomitant with modified maze procedure for atrial fibrillation (AF).</AbstractText>We retrospectively evaluated 60 patients who were surgically treated for severe chronic MR and AF. Plasma NT-proBNP and echocardiographic measurements were performed before surgery, before discharge and 12 months after surgery. Echocardiogram was additionally performed at 6 months. LVRR was assessed by looking at regression of LV mass index (LVMI) using echocardiography.</AbstractText>Fifty-two patients (87%) were classified in the LVRR group, defined as having a postoperative reduction in LVMI. The remaining patients were classified in the non-LVRR group. The non-LVRR group was older (p = 0.004), had a significantly higher ratio of patients with hypertension (p = 0.022), higher NT-proBNP levels (p = 0.007) and lower ejection fraction (p = 0.034) compared to the LVRR group. In multivariate analysis, age (odds ratio 0.874, p = 0.013) and NT-proBNP levels (odds ratio 0.185, p = 0.040) were independent predictors of LVRR.</AbstractText>Preoperative lower NT-proBNP levels and younger age may predict LVRR early after surgical correction of chronic MR with AF.</AbstractText>Copyright 2009 S. Karger AG, Basel.</CopyrightInformation> |
6,574 | Predictors of stroke in patients with severe systolic dysfunction in sinus rhythm: role of echocardiography. | Congestive heart failure in sinus rhythm ranks second after atrial fibrillation (AF) among cardiogenic risk-factors for stroke. Clinical and echocardiographic predictors of stroke in this high-risk population remain poorly defined.</AbstractText>Retrospective screening of 1886 consecutive patients with severe systolic dysfunction (LVEF ≤35%) at a tertiary medical center echocardiography database (Nov 2005-Sep 2008) identified 83 patients in sinus rhythm with cardioembolic stroke. Patients with AF on follow-up, prosthetic valve, ventricular arrhythmia and lack of consensus between reviewing neurologists were excluded (n=10). Consecutive age and gender-matched controls in sinus rhythm formed GpII (n=73).</AbstractText>The incidence of stroke was 3.9% (73/1886) over 35 months in this study. There were no significant differences in prevalence of established clinical risk-factors for stroke. There was a significantly higher prevalence of LV non-compaction (p=0.02), aneurysm (p<0.01), spontaneous echo-contrast (p<0.01) and pulmonary hypertension (p<0.001) in GpI.</AbstractText>LV non-compaction, aneurysm, spontaneous echo-contrast and pulmonary hypertension are associated with an increased risk of stroke. While anticoagulation of these high-risk subgroups appears reasonable, further study in a prospective randomized clinical trial merits consideration.</AbstractText>Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,575 | Robotic magnetic navigation for ablation of human arrhythmias: initial experience. | Magnetic navigation system (MNS) (Niobe, Stereotaxis, Saint-Louis, Missouri, USA) allows remote control of a radiofrequency ablation catheter using a steerable magnetic field and a catheter advancement system.</AbstractText>We report our initial experience of ablation of human arrhythmias using the MNS.</AbstractText>Eighty-four patients (mean age 54+/-17years; 39 women) had an electrophysiologic study followed by ablation with the MNS using non-irrigated 4, 8 and 3.5mm-tip catheters with three distal magnets. All patients were symptomatic, with commonly-accepted indications for ablation: atrioventricular nodal re-entrant tachycardia (AVNRT; n=37); typical atrial flutter (n=15); accessory pathway (n=12); atypical atrial flutter (n=7); ventricular tachycardia (n=7); atrial tachycardia (n=3); paroxysmal atrial fibrillation (n=3). Electroanatomical mapping was used for atrial flutter, atrial fibrillation, atrial tachycardia and ventricular tachycardia procedures (29 patients, 34%).</AbstractText>Ablation was performed successfully in 69 (82%) patients. In 15 patients (18%), MNS technique was unsuccessful: seven typical atrial flutters, four accessory pathways, two left atrial flutters after atrial fibrillation ablation, one ventricular tachycardia and one AVNRT; in all these cases except one typical atrial flutter and two left atrial flutters, success was obtained by switching to the manual technique by means of an irrigated catheter. Total fluoroscopy time was 14+/-11minutes; operator exposure fluoroscopy time was 1.5+/-0.6minutes; procedure time was 169+/-72minutes.</AbstractText>MNS ablation is a feasible treatment for various human arrhythmias, with a high success rate. Mapping with a magnetic catheter is safe. However, magnetic ablation of typical atrial flutter remains challenging, probably because of insufficient pressure for cavotricuspid isthmus ablation.</AbstractText> |
6,576 | Effectiveness of cardiac resynchronization therapy in heart failure patients with valvular heart disease: comparison with patients affected by ischaemic heart disease or dilated cardiomyopathy. The InSync/InSync ICD Italian Registry. | To analyse the effectiveness of cardiac resynchronization therapy (CRT) in patients with valvular heart disease (a subset not specifically investigated in randomized controlled trials) in comparison with ischaemic heart disease or dilated cardiomyopathy patients.</AbstractText>Patients enrolled in a national registry were evaluated during a median follow-up of 16 months after CRT implant. Patients with valvular heart disease treated with CRT (n = 108) in comparison with ischaemic heart disease (n = 737) and dilated cardiomyopathy (n = 635) patients presented: (i) a higher prevalence of chronic atrial fibrillation, with atrioventricular node ablation performed in around half of the cases; (ii) a similar clinical and echocardiographic profile at baseline; (iii) a similar improvement of LVEF and a similar reduction in ventricular volumes at 6-12 months; (iv) a favourable clinical response at 12 months with an improvement of the clinical composite score similar to that occurring in patients with dilated cardiomyopathy and more pronounced than that observed in patients with ischaemic heart disease; (v) a long-term outcome, in term of freedom from death or heart transplantation, similar to patients affected by ischaemic heart disease and basically more severe than that of patients affected by dilated cardiomyopathy.</AbstractText>In 'real world' clinical practice, CRT appears to be effective also in patients with valvular heart disease. However, in this group of patients the outcome after CRT does not precisely overlap any of the two other groups of patients, for which much more data are currently available.</AbstractText> |
6,577 | Application of constrained independent component analysis algorithms in electrocardiogram arrhythmias. | The extraction of the atrial activity in atrial fibrillation episodes is a must for clinical purposes. During atrial fibrillation arrhythmia, the independent atrial and ventricular signals are superposed in the electrocardiogram, fulfilling the independent component analysis (ICA) model. We propose three new algorithms that constrain the classical ICA solution to fit the spectral content of the atrial component. This constraint allows the statement of the problem in terms of semiblind source extraction instead of blind source separation (BSS), in the sense that we only recover one source and we exploit the prior information about the sources in the extraction process.</AbstractText>The methods used are extensions of classical BSS methods based on second and higher order statistics. We exploit the prior assumption about the sources in order to obtain the source extraction algorithms that are focused on the extraction of the atrial component. The material corresponds to 10 synthetic recordings in order to measure and compare the quality of the different algorithms and 66 real recordings coming from two different databases, one public database from Physionet and one database from the Clinical University Hospital, Valencia, Spain.</AbstractText>We have analyzed the performance of the three new algorithms and compared it with the performance of the traditional ICA algorithms. In the case of the synthetic data, it is possible to obtain the mean square error, so the comparison is easier. The new methods outperform the non-constrained versions in addition to simplifying the solution, since they do not need to recover all the components in order to estimate the atrial activity, i.e., the new methods are focused on the extraction of the atrial activity, so the extraction is stopped after the atrial signal is recovered.</AbstractText>We have shown that the ICA only version of the algorithms can be improved and adapted to fulfill the prior information about the characteristics of the atrial activity. This modification allows us to obtain new algorithms that have the following advantages compared to ICA only based solutions: they exploit prior information during the extraction, not in the postprocessing identification of the atrial signal; they extract only the interesting clinical signal instead of all the components; they outperform the ICA only version of the algorithm, improving the estimation of the atrial signal.</AbstractText> |
6,578 | Brugada-like EKG pattern and myocardial effects in a chronic propofol abuser. | Cases of death are reported due to medical use of propofol, whereas deaths due to recreational purpose are unusual.</AbstractText>A 26-year-old Caucasian man, physician trainee in anesthesiology, was referred to an intensive care unit. The man was found unconscious in his bed with a butterfly-needle canalized into the vein of the left forearm and connected to an empty syringe. Transferred to the local hospital, the patient was monitored, and EKG showed typical Brugada features in V1-V3. Profound hypotension and metabolic acidosis were registered. Half an hour after admission, the patient developed prolonged QT interval, idioventricular rhythm, and ventricular fibrillation. Strong positive reaction for tumor necrosis factor alpha in cardiac myocytes and a diffuse apoptotic process in the heart specimens were observed. The multiple needle marks on the hands and forearms, and the propofol concentration in the hair examined (0.73 microg/g), led us to believe that the young man was a long-term propofol abuser.</AbstractText>Development of the EKG pattern of ST-segment elevation in leads V1-V3 may be the first indicator of electrical instability and high risk for imminent sudden death. Whether this finding applies to other patients poisoned with propofol is unclear, but the association of sudden death and the acquired EKG pattern has been observed in other disease states.</AbstractText>This article describes a fatal propofol-related death case because of recreational purpose; the EKG pattern, the cardiac morphology, and the expression of tumor necrosis factor alpha and apoptosis in cardiac tissue specimens are discussed to elucidate the mechanism of death.</AbstractText> |
6,579 | Aconite poisoning. | Aconitine and related alkaloids found in the Aconitum species are highly toxic cardiotoxins and neurotoxins. The wild plant (especially the roots and root tubers) is extremely toxic. Severe aconite poisoning can occur after accidental ingestion of the wild plant or consumption of an herbal decoction made from aconite roots. In traditional Chinese medicine, aconite roots are used only after processing to reduce the toxic alkaloid content. Soaking and boiling during processing or decoction preparation will hydrolyze aconite alkaloids into less toxic and non-toxic derivatives. However, the use of a larger than recommended dose and inadequate processing increases the risk of poisoning.</AbstractText>A Medline search (1963-February 2009) was conducted. Key articles with information on the use of aconite roots in traditional medicine, active (toxic) ingredients, mechanisms of toxicity, toxicokinetics of Aconitum alkaloids, and clinical features and management of aconite poisoning were reviewed.</AbstractText>The cardiotoxicity and neurotoxicity of aconitine and related alkaloids are due to their actions on the voltage-sensitive sodium channels of the cell membranes of excitable tissues, including the myocardium, nerves, and muscles. Aconitine and mesaconitine bind with high affinity to the open state of the voltage-sensitive sodium channels at site 2, thereby causing a persistent activation of the sodium channels, which become refractory to excitation. The electrophysiological mechanism of arrhythmia induction is triggered activity due to delayed after-depolarization and early after-depolarization. The arrhythmogenic properties of aconitine are in part due to its cholinolytic (anticholinergic) effects mediated by the vagus nerve. Aconitine has a positive inotropic effect by prolonging sodium influx during the action potential. It has hypotensive and bradycardic actions due to activation of the ventromedial nucleus of the hypothalamus. Through its action on voltage-sensitive sodium channels in the axons, aconitine blocks neuromuscular transmission by decreasing the evoked quantal release of acetylcholine. Aconitine, mesaconitine, and hypaconitine can induce strong contractions of the ileum through acetylcholine release from the postganglionic cholinergic nerves.</AbstractText>Patients present predominantly with a combination of neurological, cardiovascular, and gastrointestinal features. The neurological features can be sensory (paresthesia and numbness of face, perioral area, and the four limbs), motor (muscle weakness in the four limbs), or both. The cardiovascular features include hypotension, chest pain, palpitations, bradycardia, sinus tachycardia, ventricular ectopics, ventricular tachycardia, and ventricular fibrillation. The gastrointestinal features include nausea, vomiting, abdominal pain, and diarrhea. The main causes of death are refractory ventricular arrhythmias and asystole and the overall in-hospital mortality is 5.5%.</AbstractText>Management of aconite poisoning is supportive, including immediate attention to the vital functions and close monitoring of blood pressure and cardiac rhythm. Inotropic therapy is required if hypotension persists and atropine should be used to treat bradycardia. Aconite-induced ventricular arrhythmias are often refractory to direct current cardioversion and antiarrhythmic drugs. Available clinical evidence suggests that amiodarone and flecainide are reasonable first-line treatment. In refractory cases of ventricular arrhythmias and cardiogenic shock, it is most important to maintain systemic blood flow, blood pressure, and tissue oxygenation by the early use of cardiopulmonary bypass. The role of charcoal hemoperfusion to remove circulating aconitine alkaloids is not established.</AbstractText>Aconite roots contain aconitine, mesaconitine, hypaconitine, and other Aconitum alkaloids, which are known cardiotoxins and neurotoxins. Patients present predominantly with neurological, cardiovascular, and gastrointestinal features. Management is supportive; the early use of cardiopulmonary bypass is recommended if ventricular arrhythmias and cardiogenic shock are refractory to first-line treatment.</AbstractText> |
6,580 | ONTARGET, TRANSCEND, and PRoFESS: new-onset diabetes, atrial fibrillation, and left ventricular hypertrophy. | Prevention of diabetes represents an important therapeutic goal in current cardiovascular risk reduction strategies. Blockade of the renin-angiotensin system has been shown to markedly reduce the incidence of new-onset diabetes in different patient populations. Recent results from three large clinical endpoint trials with the angiotensin-II receptor blocker telmisartan regarding new-onset diabetes, atrial fibrillation, and left ventricular hypotrophy will be discussed. |
6,581 | Right ventricular rapid pacing in catheter ablation of atrial fibrillation: a novel application for cryoballoon pulmonary vein isolation. | Cryoballoon ablation (Arctic Front, Cryocath) represents a novel technology for pulmonary vein isolation (PVI). The initial phase of a freeze is crucial for cryolesion formation which is determined by local temperature depending on blood flow. We investigated the impact of right ventricular rapid pacing (RVRP) on temperature kinetics in patients (pts) with paroxysmal atrial fibrillation (PAF).</AbstractText>Right ventricular rapid pacing was performed from the RV apex. Absolute minimal temperature (MT, degrees C), temperature slopes [time (s) to 80% MT; dT/dt), area under the curve (AUC) and arterial blood pressure (ABP, mmHg) were compared (group I: with RVRP vs. group II: without RVRP). RVRP (mean duration 55 +/- 7 s) was performed in 11 consecutive PAF pts (41 PVs, age 58 +/- 9 years, LA size 44 +/- 6 mm, normal ejection fraction). Only freezes with identical balloon positions were analyzed (11/41 PVs). RVRP (cycle length 333 +/- 3 ms) induced a significant drop in ABP (group I: 45 +/- 3 mmHg vs. group II: 100 +/- 18 mmHg, p < 0.001). MT was not different between group I and group II (-45.0 +/- 4.4 vs. -44.3 +/- 3.4 degrees C, p = 0.46), whereas slope (38.0 +/- 4.6 s vs. 51.6 +/- 14.4 s, p = 0.0034) and AUC (1090 +/- 4.6 vs. 1181 +/- 111.2, p = 0.02) was significantly changed. In one pt, a ventricular tachycardia was induced. PVI was achieved in 41/41 PVs.</AbstractText>Right ventricular rapid pacing significantly accelerates cryoballoon cooling during the initial phase of a freeze possibly suggesting improved cryolesions.</AbstractText> |
6,582 | The effect of myocardial revascularization on malignant ventricular arrhythmias in coronary artery disease. | Malignant ventricular arrhythmia in coronary artery disease (CAD) is a severe life-threatening disease and a risk factor for sudden cardiac death. Myocardial revascularization influences the arrhythmogenic substrate of the malignant ventricular arrhythmia in the secondary prevention of sudden cardiac death. Its effectivity remains controversial.</AbstractText>The aim of this study is to assess the inducibility of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients after myocardial revascularization and to compare the effectivity of complete and incomplete revascularization.</AbstractText>Fifty patients with documented sustained VT or VF and CAD were examined in our department.</AbstractText>Conservatively treated patients were significantly older than revascularized patients (68 +/- 8 versus 62 +/- 9 years, p<0.05). We registered a trend towards a lower inducibility of malignant ventricular arrhythmias in the revascularized group and completely revascularized subgroup, but without statistical significance. Incompletely revascularized patients comprised only of men (100% versus 66.6%, p<0.05). Fewer ICDs were implanted in the completely revascularized group (55.6% versus 92.3%, p<0.05).</AbstractText>Myocardial revascularization has little effect on the inducibility of malignant ventricular arrhythmias after myocardial revascularization. Complete revascularization significantly decreases the need of ICD implantation when compared to incomplete one (Tab. 3, Fig. 4, Ref. 24). Full Text (Free, PDF) www.bmj.sk.</AbstractText> |
6,583 | Therapeutic hypothermia after out-of-hospital cardiac arrest with the target temperature 34-35 degrees C. | The objective of this study was to evaluate the impact of mild hypothermia (34-35 degrees C) on the final neurological outcome in patients after resuscitation from out-of-hospital cardiac arrest.</AbstractText>Forty three patients, admitted at University Hospital Brno after the out-of-hospital cardiac arrest, were included in the cohort study. The inclusion criteria were out-of-hospital cardiac arrest resulting from ventricular fibrillation or non-perfusing ventricular tachycardia as well as recovery of spontaneous circulation within 60 minutes after first symptoms. Blanketrol II (Cinncinnatti Sub Zero, USA) water mattresses were used for cooling the patients. The temperature was maintained at 34-35 degrees C for 24 hours. Favorable neurological outcome was defined as a Pittsburgh cerebral-performance category 1 (good recovery) or 2 (moderate disability) on five-category scale.</AbstractText>The required temperature was reached in all patients; the cooling rate was 0.8 +/- 0.3 degrees C/hour. The time between the restoration of circulation and reaching the temperature of 35 degrees C was 119 +/- 32 minutes. The time induce the hypothermia (with the core body temperature below 35 degrees C) was 26 +/- 2 hours. Good outcome at hospital discharge was achieved in 21 out of 43 (49%) patients. Ten patients died in the hospital and two patients died after the discharge from the hospital, with the overall 6 months mortality being 28%.</AbstractText>The study confirmed feasibility, safety and possible efficacy of the mild hypothermia (34-35 degrees C) patients after the cardiac arrest. To evaluate whether the target temperature 34-35 degrees C is as beneficial as 32-34 degrees C; a randomised controlled trial design should be used (Tab. 4, Fig. 2, Ref. 17). Full Text (Free, PDF) www.bmj.sk.</AbstractText> |
6,584 | Predictors of appropriate implantable cardioverter-defibrillator therapy during long-term follow-up of patients with coronary artery disease. | Indications for implantable cardioverter defibrillators (ICDs) are expanding. Defining long-term predictors of ICD therapies might help to identify those patients who will benefit most from implantation of an ICD. The objective of this study was to examine long-term predictors of appropriate ICD therapy among patients with coronary disease at high risk of sudden cardiac death. An analysis of 245 patients with coronary disease, who had been implanted with an ICD for primary or secondary prevention of sudden cardiac death, was performed. Time to appropriate ICD therapy, defined as antitachycardia pacing or shock, was evaluated by the Kaplan-Meier method. Cox regression analysis was performed to determine hazard ratios for factors predicting appropriate ICD therapies. During a mean (SD) follow-up of 41 (33) months, 115 patients (53%) experienced appropriate ICD therapy. Independent predictors of appropriate ICD therapy included advanced age, left ventricular ejection fraction (LVEF) < 35%, and impaired renal function, with covariate-adjusted hazard ratios of 1.36 per 10 years (95% CI, 1.11 - 1.66; P = 0.003), 1.78 (95% CI, 1.21 - 2.63; P = 0.004), and 1.59 (95% CI, 1.00 - 2.54; P = 0.050), respectively. Remote myocardial infarction (> 6 months prior to ICD implantation) was associated with higher probability of appropriate ICD therapy among patients with LVEF > 35% (adjusted HR 2.68 [95% CI, 1.05 - 6.86; P = 0.04]), but not among patients with LVEF < 35% (adjusted HR 1.09 [95% CI, 0.58 - 2.04; P = 0.79]). Left ventricular ejection fraction, advanced age, and renal impairment are long-term predictors of appropriate ICD therapy in patients with coronary disease at high risk of sudden cardiac death. Patients with an ejection fraction above 35% have few arrhythmic events early after the myocardial infarction but appropriate therapies become more frequent late after the myocardial infarction, possibly due to progression of the disease. |
6,585 | Torsade de pointes associated with recurrent ampulla cardiomyopathy in a patient with idiopathic ACTH deficiency. | We describe here a patient with torsade de pointes associated with recurrent ampulla cardiomyopathy, who was later proven to suffer from idiopathic AC TH deficiency. A 70-year-old man was admitted to our hospital for bacterial pneumonia. A cardiac examination performed on admission revealed ampulla cardiomyopathy, which improved spontaneously as the pneumonia was cured. Two months after discharge, he was transferred to our hospital for relapse of the pneumonia. After the second admission, the pneumonia subsided with antibiotic treatment and his general condition ameliorated gradually. However, on the 20(th) hospital day, he was found lying on the floor in a prone position in cardiopulmonary arrest. Cardiac telemetry monitoring showed torsade de pointes worsening to ventricular fibrillation, and immediate cardiac defibrillation was performed. The electrocardiogram after successful defibrillation showed inverted T waves in the chest leads with long QT intervals, and subsequent emergent coronary catherization revealed the recurrence of ampulla cardiomyopathy. Thereafter, endocrinological examinations for the diagnosis of sustained hyponatremia demonstrated secondary adrenal insufficiency caused by idiopathic AC TH deficiency. The cardiomyopathy resolved promptly after steroid hormone replacement without relapse as did the hyponatremia. Patients with ampulla cardiomyopathy or ventricular fibrillation without apparent etiology should be examined for adrenal function. If begun as soon as adrenal insufficiency is diagnosed, immediate steroid replacement therapy can prevent the deterioration and relapse of cardiac involvement. |
6,586 | Relation of disease pathogenesis and risk factors to heart failure with preserved or reduced ejection fraction: insights from the framingham heart study of the national heart, lung, and blood institute. | The contributions of risk factors and disease pathogenesis to heart failure with preserved ejection fraction (HFPEF) versus heart failure with reduced ejection fraction (HFREF) have not been fully explored.</AbstractText>We examined clinical characteristics and risk factors at time of heart failure onset and long-term survival in Framingham Heart Study participants according to left ventricular ejection fraction < or =45% (n=314; 59%) versus >45% (n=220; 41%) and hierarchical causal classification. Heart failure was attributed to coronary heart disease in 278 participants (52%), valvular heart disease in 42 (8%), hypertension in 140 (26%), or other/unknown causes in 74 (14%). Multivariable predictors of HFPEF (versus HFREF) included elevated systolic blood pressure (odds ratio [OR]=1.13 per 10 mm Hg; 95% confidence interval [CI], 1.04 to 1.22), atrial fibrillation (OR=4.23; 95% CI, 2.38 to 7.52), and female sex (OR=2.29; 95% CI, 1.35 to 3.90). Conversely, prior myocardial infarction (OR=0.32; 95% CI, 0.19 to 0.53) and left bundle-branch block QRS morphology (OR=0.21; 95% CI, 0.10 to 0.46) reduced the odds of HFPEF. Long-term prognosis was grim, with a median survival of 2.1 years (5-year mortality rate, 74%), and was equally poor in men and women with HFREF or HFPEF.</AbstractText>Among community patients with new-onset heart failure, there are differences in causes and time-of-onset clinical characteristics between those with HFPEF versus HFREF. In people with HFREF, mortality is increased when coronary heart disease is the underlying cause. These findings suggest that heart failure with reduced left ventricular systolic function and heart failure with preserved left ventricular systolic function are partially distinct entities, with potentially different approaches to early detection and prevention.</AbstractText> |
6,587 | Hypertension to heart failure: a pathophysiological spectrum relating blood pressure, drug treatments and stroke. | Hypertension is a leading cause of major adverse cardiovascular outcomes, including heart attacks and stroke. The most visible manifestation of target organ damage related to hypertension is left ventricular hypertrophy (LVH). LVH eventually predisposes to systolic and diastolic heart failure, and is associated with an even greater risk of stroke. Electrocardiography and echocardiography are usually used to quantify LVH, but cardiac MRI may be a more reproducible and accurate modality. Regression in LVH is associated with improved cardiovascular outcomes. Treatments aimed at LVH regression include restriction of salt, regular exercise and weight reduction. Blockade of the renin-angiotensin-aldosterone system is particularly effective in preventing cardiovascular and cerebrovascular events, and is often associated with the regression of LVH, a decrease in left atrial size and a reduced incidence of new-onset atrial fibrillation, which could all contribute towards a decrease in vascular events. Overall, a reduction in blood pressure is still the most important factor in prevention of disease progression, and early treatment averts the risk of subsequent heart failure and stroke. |
6,588 | Antipsychotic-induced sudden cardiac death: examination of an atypical reaction. | Following the publication of a recent study, which linked antipsychotics to sudden cardiac death, the safety of both typical and atypical antipsychotics has once again been questioned. Sudden cardiac death resulting from ventricular arrhythmias remains a significant public health concern, with over 300,000 deaths per year in the US alone. Long QT syndrome (LQTS) is an important cause of sudden cardiac death in which both congenital and acquired lesions in cardiac ionic channels impair myocardial repolarization and predispose the heart to developing lethal ventricular rhythms, including torsade de pointes, which may degenerate into ventricular fibrillation. Congenital LQTS is a relatively rare condition; however, acquired LQTS and arrhythmogenesis occurring through the unwanted pharmacological effects of a wide range of medications has become one of the largest problems facing the pharmaceutical industry today. This article examines recent findings linking antipsychotics to ventricular arrhythmias and explores potential new strategies to reduce the incidence of drug-induced sudden cardiac death. |
6,589 | [Phytoadaptogens-induced phenomenon similar to ischemic preconditioning]. | The course administration (16 mg/kg per os for 5 days) of extracts of Panax ginseng or Rhodiola rosea induced a decrease in the infarction size/the area at risk (IS AAR) ratio during a 45-min local ischemia and a 2-hr reperfusion in artificially ventilated chloralose-anaesthetized rats. Single administration of ginseng or Rhodiola 24 h before ischemia did not affect the IS/AAR ratio. Chronic administration of Extracts of Eleutherococcus senticosus, Leuzea carthamoides and Aralia mandshurica had no effect on the IS/AAR ratio. Pretreatment with extract ofAralia mandshurica prevented appearance of ventricular arrhythmias during first 10 min coronary artery occlusion. Pretreatment with extract of Rhodiola rosea decreased the incidence of ventricular fibrillation during ischemia. Single administration of extracts of Panax ginseng or Rhodiola rosea in a dose of 16 mg/kg had no effect on the IS/AAR ratio. The authors conclude that extracts of ginseng or Rhodiola exhibit a powerful cardioprotective effect. Extract of Aralia exhibit a strong antiarrhythmic effect. Extracts of ginseng and Rhodiola do not mimic phenomena of ischemia preconditioning. |
6,590 | Reduction in myocardial infarct size at 48 hours after brief intravenous infusion of ATL-146e, a highly selective adenosine A2A receptor agonist. | This study was undertaken to determine whether the myocardial infarct-sparing effect of ATL-146e, a selective adenosine A(2A) receptor agonist, persists without a rebound effect for at least 48 h and to determine the optimal duration of ATL-146e treatment in anesthetized dogs. Reperfusion injury after myocardial infarction (MI) is associated with inflammation lasting 24-48 h that contributes to ongoing myocyte injury. We previously showed that an ATL-146e infusion, starting just before reperfusion, decreased inflammation and infarct size in dogs examined 2 h after MI without increasing coronary blood flow. In the present study, adult dogs underwent 90 min of left anterior descending coronary artery occlusion. Thirty minutes before reperfusion, ATL-146e (0.01 microg x kg(-1) x min(-1); n = 21) or vehicle (n = 12) was intravenously infused and continued for 2.5 h (protocol 1) or 24 h (protocol 2). At 48 h after reperfusion hearts were excised and assessed for histological risk area and infarct size. Infarct size based on triphenyltetrazolium chloride (TTC) staining as a percentage of risk area was significantly smaller in ATL-146e-treated vs. control dogs (16.7 +/- 3.7% vs. 33.3 +/- 6.2%, P < 0.05; protocol 1). ATL-146e reduced neutrophil accumulation into infarcted myocardium of ATL-146e-treated vs. control dogs (30 +/- 7 vs. 88 +/- 16 cells/high-power field, P < 0.002). ATL-146e infusion for 24 h (protocol 2) conferred no significant additional infarct size reduction compared with 2.5 h of infusion. A 2.5-h ATL-146e infusion initiated 30 min before reperfusion results in marked, persistent (48 h) reduction in infarct size as a percentage of risk area in dogs with a reduction in infarct zone neutrophil infiltration. No significant further benefit was seen with a 24-h infusion. |
6,591 | Sample entropy of the main atrial wave predicts spontaneous termination of paroxysmal atrial fibrillation. | Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. In the first stages of the disease, AF may terminate spontaneously and it is referred as paroxysmal atrial fibrillation (PAF). In this respect, the prediction of PAF termination or maintenance could avoid unnecessary therapy and contribute to take the appropriate decisions on its management. The aim of this work is to predict non-invasively the spontaneous termination of PAF episodes by analyzing the variation of atrial activity (AA) organization. The organization increases as a consequence of the decrease in the number of reentries wandering the atrial tissue before termination. The analysis has been carried out by applying sample entropy, which is a non-linear organization estimator, to surface electrocardiogram (ECG) recordings. Synthetic signals were used in order to evaluate the notable impact of noise in AA organization estimation. Therefore, to reduce noise, ventricular residues and enhance the fundamental features of AA, the main atrial wave (MAW) was extracted making use of selective filtering. Through MAW organization estimation applied to real ECGs, 95% (19 out of 20) of the learning PAF recordings and 90% (27 out of 30) of the test episodes were correctly predicted. As a consequence, the MAW organization analysis from surface ECGs can be considered as a promising tool to predict spontaneous PAF termination. |
6,592 | Arrhythmia detection in single- and dual-chamber implantable cardioverter defibrillators: the more leads, the better? | The implantable cardioverter defibrillator (ICD) offers life-saving therapies for primary and secondary prevention of sudden cardiac death in high-risk patients. However, ICD detection algorithms consistently misclassify a substantial proportion of supraventricular rhythms, thus carrying the risk for inappropriate therapies. Although single-chamber ICD (Sc-ICD) discrimination tools have been reported to provide high specificity in rejecting sinus tachycardia and atrial fibrillation with a relatively low ventricular rate, accurate recognition of atrial fibrillation with faster ventricular rates, atrial tachycardias, atrial flutter, and some reentrant tachycardias is still an issue. Dual-chamber ICDs (Dc-ICDs) are supposed to overcome specificity issues by enhancing detection algorithms with information derived from the atrial and ventricular timing relationship. The initial promise of Dc-ICDs was to improve detection specificity without compromising sensitivity, and to translate this advantage over Sc-ICDs in a more selective use of aggressive therapies. Despite this solid background, superiority of Dc- over Sc-ICDs has never been convincingly demonstrated. The present review focuses on the efficacy of contemporary ICD arrhythmia discrimination tools and appraises the so far reported evidence supporting the superiority of Dc-ICDs in preventing inappropriate therapies. |
6,593 | Fluconazole-induced recurrent ventricular fibrillation leading to multiple cardiac arrests. | This case report describes the successful management of a patient with diabetic ketoacidosis, who developed torsades de pointes leading to nine cardiac arrests secondary to intravenous fluconazole administration on a background of hypokalaemia and hypocalcaemia. |
6,594 | Prehospital resuscitated cardiac arrest patients: role for induced hypothermia. | This article is a support paper for the National Association of EMS Physicians' position paper on induced therapeutic hypothermia in resuscitated cardiac arrest patients. Induced hypothermia is one of the newest treatments aimed at increasing the dismal neurologically intact survival rate for out-of-hospital cardiac arrest patients. Two landmark studies published in 2002 by the New England Journal of Medicine led to the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care IIa recommendation of cooling unconscious adult patients with return of spontaneous circulation after out-of-hospital cardiac arrest due to ventricular fibrillation to 32 degrees C to 34 degrees C for 12 to 24 hours. Despite many limitations of those studies, the AHA also suggests that this therapy may be beneficial for patients with non-ventricular fibrillation arrests. However, the literature is lacking in answers with regard to the best methods to utilize in cooling patients. While avoiding delay in the initiation of cooling seems logical, the literature is also lacking evidence indicating the ideal time at which to implement cooling. Furthermore, it remains unclear as to which patients may benefit from induced hypothermia. Finally, the literature provides no evidence to support mandating induced hypothermia in the prehospital setting. Given limited prehospital resources, sometimes consisting of only two providers, attention first needs to be given to providing the basic care with the utmost skill. Once the basics are being delivered expertly, consideration can be given to the use of prehospital cooling for the resuscitated cardiac arrest patient in the setting of continued cooling in the hospital. |
6,595 | The effect of paramedic experience on survival from cardiac arrest. | We hypothesized that paramedics with more experience would be more successful at treating patients in ventricular fibrillation (VF) cardiac arrest than those with less experience. We conducted a study examining the relationship between the years of experience of paramedics and survival from out-of-hospital cardiac arrest.</AbstractText>This retrospective cohort study examined all witnessed, out-of-hospital VF cardiac arrests (n = 699) that occurred between January 1, 2002, and December 31, 2006. Logistic regression was used to determine the odds of survival and the 95% confidence intervals (95% CIs) relating to the number of years of experience that each of the treating paramedics had.</AbstractText>We found that every additional year of experience of the medic in charge of implementing procedures such as intravenous line insertions, intubations, and provision of medications was associated with a 2% increase in the likelihood of survival of the patient (95% CI: 1.00-1.04). The number of years of experience of the paramedic who did not perform procedures but instead was in charge of treatment decisions was not significantly associated with survival (odds ratio [OR] 1.01, 95% CI: 0.99-1.03). When we combined both paramedics' years of experience, we saw a 1% increase in the odds of survival for every additional year of experience (95% CI: 1.00-1.03).</AbstractText>This study suggests that the amount of experience of the paramedic who performed procedures on cardiac arrest patients was associated with increased rates of survival. However, we did not find an association between survival from VF and the number of years of experience of the paramedic who made treatment decisions.</AbstractText> |
6,596 | Prompt advanced life support improves survival from ventricular fibrillation. | To determine whether the interval between the arrival of basic life support (BLS) providers and the arrival of advanced life support (ALS) providers is associated with patient outcome after cardiac arrest.</AbstractText>We conducted a retrospective cohort study of all witnessed, out-of-hospital ventricular fibrillation (VF) cardiac arrests between January 1, 1991, and December 31, 2007. Eligible patients (n = 1,781) received full resuscitation efforts from both BLS and ALS providers.</AbstractText>The BLS-to-ALS arrival interval was a significant predictor of survival to hospital discharge (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.93-0.99); the likelihood of survival decreased by 4% for every minute that ALS arrival was delayed following BLS arrival. Other significant predictors of survival were whether the arrest occurred in public (OR 1.48, 95% CI 1.19-1.85), whether a bystander administered cardiopulmonary resuscitation (CPR) (OR 1.34, 95% CI 1.07-1.68), and the interval between the 9-1-1 call and BLS arrival (OR 0.78, 95% CI 0.73-0.83).</AbstractText>We found that a shorter BLS-to-ALS arrival interval increased the likelihood of survival to hospital discharge after a witnessed, out-of-hospital VF cardiac arrest. We conclude that ALS interventions may provide additional benefits over BLS interventions alone when utilized in a well-established, two-tiered emergency medical services (EMS) system already optimized for rapid defibrillation. The highest priorities in any EMS system should still be early CPR and early defibrillation, but timely ALS services can supplement these crucial interventions.</AbstractText> |
6,597 | The relative role of refractoriness and source-sink relationship in reentry generation during simulated acute ischemia. | During acute myocardial ischemia, reentrant episodes may lead to ventricular fibrillation (VF), giving rise to potentially mortal arrhythmias. VF has been traditionally related to dispersion of refractoriness and more recently to the source-sink relationship. Our goal is to theoretically investigate the relative role of dispersion of refractoriness and source-sink mismatch in vulnerability to reentry in the specific situation of regional myocardial acute ischemia. The electrical activity of a regionally ischemic tissue was simulated using a modified version of the Luo-Rudy dynamic model. Ischemic conditions were varied to simulate the time-course of acute ischemia. Our results showed that dispersion of refractoriness increased with the severity of ischemia. However, no correlation between dispersion of refractoriness and the width of the vulnerable window was found. Additionally, in approximately 50% of the reentries, unidirectional block (UDB) took place in cells completely recovered from refractoriness. We examined patterns of activation after premature stimulation and they were intimately related to the source-sink relationship, quantified by the safety factor (SF). Moreover, the isoline where the SF dropped below unity matched the area where propagation failed. It was concluded that the mismatch of the source-sink relationship, rather than solely refractoriness, was the ultimate cause of the UDB leading to reentry. The SF represents a very powerful tool to study the mechanisms responsible for reentry. |
6,598 | Amiodarone for pediatric resuscitation: a word of caution. | Intravenous administration of amiodarone has recently been recommended for use during pediatric resuscitation of pediatric patients with ventricular fibrillation or pulseless ventricular tachycardia. We present two pediatric patients who received amiodarone for polymorphic ventricular tachycardia, although they were ultimately determined to have congenital long QT syndrome. Amiodarone is contraindicated in this setting and may have exacerbated the ventricular arrhythmia. |
6,599 | Giant coronary aneurysm in adult Kawasaki disease: angiographic, 64-slice coronary MDCT and cardiac MRI appearances. | Kawasaki disease is a small-to-medium-vessel vasculitis that preferentially affects infants and young children. This condition is rare in adults, and therefore the diagnosis can easily be missed in a patient presenting to a primary care clinic. We report an unusual case of a patient who presented with ventricular fibrillation on a background of adult Kawasaki disease.</AbstractText>To identify the advantages of using coronary multidetector computed tomography (MDCT) and cardiac magnetic resonance imaging (MRI) in diagnosing adult Kawasaki disease.</AbstractText>We studied a 52-year-old patient with Kawasaki disease using coronary angiography, cardiac MDCT and MRI.</AbstractText>Invasive coronary angiography demonstrated an occluded right coronary artery (RCA) and appearances suspicious for a calcified giant RCA aneurysm. The full extent of the aneurismal RCA was depicted with MDCT. Cardiac MRI revealed a chronic inferior segment myocardial infarction representing an arrhythmia substrate.</AbstractText>Our case highlights the increasing utility of contrast-enhanced cardiac MRI and MDCT in the diagnosis of this rare condition in adults.</AbstractText> |
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