Unnamed: 0 int64 0 2.34M | titles stringlengths 5 21.5M | abst stringlengths 1 21.5M |
|---|---|---|
14,400 | Implantable cardioverter defibrillator lead placement in the middle cardiac vein after tricuspid valve surgery. | Pacing and defibrillation with an implantable cardioverter defibrillator (ICD) after tricuspid valve surgery can be challenging if right ventricular (RV) lead placement is contraindicated or safe lead placement in the RV apex is impossible.</AbstractText>In six patients for whom RV lead placement and repeat thoracotomy were contraindicated, ventricular pacing and sensing were achieved with bipolar leads placed in the lateral branch of the coronary sinus or in the atrialized portion of the RV or without helix exposure of the pace-sense electrodes of the defibrillator leads. After cannulation of the middle cardiac vein (MCV), a defibrillator coil lead was delivered there and placed in the farthest apical position. An 'active can' pulse generator was implanted in the left retromammary region. Biphasic shocks were delivered between the MCV coil, SVC coil, and the 'active can', or between the MCV coil, azygous vein coil, and the 'active can'. All six patients underwent successful implantation. All patients had a defibrillation safety margin of at least 10 J (at least two successful shocks at 25 J). During follow-up, one patient received a successful internal shock for ventricular fibrillation, and two received successful overdrive ventricular pacing for ventricular tachycardia. Three patients underwent defibrillation threshold testing to evaluate safety margins. No late complications have been reported at 60 months' follow-up.</AbstractText>Defibrillator coil lead placement in the MCV is a safe alternative to epicardial lead placement via a thoracotomy in selected patients for whom RV lead placement is contraindicated or impossible.</AbstractText> |
14,401 | The clinical significance of ventricular arrhythmias during an exercise test in non-competitive and competitive athletes. | Sudden death in athletes can occur during sport activities and is presumably related to ventricular arrhythmias. There are no guidelines concerning athletes who develop ventricular arrhythmias during an exercise test. It is unclear whether they should be allowed to continue with their competitive activity or not.</AbstractText>To investigate the long-term follow-up of athletes with ventricular arrhythmias during an exercise test.</AbstractText>From a database of 56,462 athletes we identified 192 athletes, less than 35 years old, who had ventricular arrhythmias during an exercise test. Ninety athletes had > or = 3 ventricular premature beats (group A) and 102 athletes had ventricular couplets or non-sustained ventricular tachycardia during an exercise test (group B). A control group of 92 athletes without ventricular arrhythmias was randomly selected from the database (group C).</AbstractText>All athletes, except one who died from a dilated cardiomyopathy, were alive during a follow-up period of 70 +/- 25 months. An abnormal echocardiogram was obtained in seven athletes from group A (10%), four from group B (5%), and one from group C (3%) (not significant). An abnormal echocardiogram was more likely to be present in competitive athletes (P = 0.001) and in female athletes (P = 0.01).</AbstractText>Our results showed that ventricular arrhythmias during exercise are more commonly associated with cardiovascular abnormalities in young competitive athletes and in female athletes. When present, they necessitate a thorough investigation and follow-up.</AbstractText> |
14,402 | Chronic oral amiodarone but not dronedarone therapy increases ventricular defibrillation threshold during acute myocardial ischemia in a closed-chest animal model. | Dronedarone, a recently approved antiarrhythmic drug, has been shown to have fewer side effects than amiodarone, particularly with regard to thyroid and neurologic events. Since the effects of either drug on ventricular defibrillation threshold during ischemia are unknown, the aim of this study was to compare the effects of dronedarone and amiodarone on defibrillation efficacy during ischemia in a closed-chest animal model. Dronedarone (30 mg·kg·d) and amiodarone (20 mg·kg·d) were administered orally for 3 weeks to 19 and 21 pigs, respectively. A control group (no treatment) comprised 19 pigs. A 2-lead endovascular defibrillation system was used. Each biphasic shock was delivered after 8 seconds of ventricular fibrillation. A step-up/step-down protocol was used to calculate mean defibrillation threshold before and 10 minutes after coronary artery occlusion using an angioplasty balloon in the left descending artery. At basal state, defibrillation threshold did not differ between the control (20.8 ± 4.8 J), amiodarone (21.2 ± 2 J), and dronedarone (19.5 ± 3 J) groups. After ischemia, the amiodarone group had a significantly higher defibrillation threshold than the control group (29.6 ± 3 J vs. 21.8 ± 5 J, respectively; P = 0.015), but the dronedarone (22.8 ± 4 J) and control groups had similar defibrillation threshold values. These data indicate that oral dronedarone treatment, unlike oral amiodarone, does not affect defibrillation threshold during ischemia in pigs. |
14,403 | Myocardial protection in beating heart cardiac surgery: I: pre- or postconditioning with inhibition of es-ENT1 nucleoside transporter and adenosine deaminase attenuates post-MI reperfusion-mediated ventricular fibrillation and regional contractile dysfunction. | To determine the role of the p-nitrobenzylthioinosine-sensitive equilibrative nucleoside transporter 1 (es-ENT1) in postmyocardial infarction reperfusion injury-mediated ventricular fibrillation and regional dysfunction. We used erythro-9 (2-hydroxy-3-nonyl)-adenine and p-nitrobenzylthioinosine to inhibit both adenosine deamination and transport in a canine model of off pump acute myocardial infarction.</AbstractText>Anesthetized adult dogs (n = 37), instrumented to monitor the percentage of systolic segmental shortening and wall thickening using sonomicrometry, underwent 90 minutes of left anterior descending coronary artery occlusion and 120 minutes of reperfusion. Myocardial coronary blood flow, adenosine triphosphate pool, infarct size, and the incident of ventricular fibrillation and cardioversion were also measured. The dogs received an intravenous infusion of the vehicle (control) or 100 μM of erythro-9 (2-hydroxy-3-nonyl)-adenine and 25 μM p-nitrobenzylthioinosine before ischemia (preconditioning group) or just before reperfusion (postconditioning group).</AbstractText>In the control group, adenosine triphosphate depletion was associated with the accumulation of more inosine than adenosine during ischemia and washed out during reperfusion. Myocardial adenosine and inosine were the major nucleosides in the pre- and postconditioning groups during ischemia and remained detectable during reperfusion. In both groups, recovery of systolic segmental shortening and wall thickening and a reduction in the incidence of ventricular fibrillation (P < .05 vs the control group) coincided with retention of myocardial nucleosides. The infarct size in the 3 groups was not significantly different, independent of myocardial blood flow during ischemia.</AbstractText>Preconditioning or postconditioning with erythro-9 (2-hydroxy-3-nonyl)-adenine/p-nitrobenzylthioinosine significantly reduced the incidence of ventricular fibrillation and cardioversion and attenuated regional contractile dysfunction mediated by postmyocardial infarction reperfusion injury. It is concluded that p-nitrobenzylthioinosine-sensitive equilibrative nucleoside transporter 1 played a major role in these events.</AbstractText>Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
14,404 | Association between family risk of stroke and myocardial infarction with prevalent risk factors and coexisting diseases. | Familial transmission of stroke and myocardial infarction (MI) is partially mediated by transmission of cerebrovascular and cardiovascular risk factors. We examined relationships between family risk of stroke and MI with risk factors for these phenotypes.</AbstractText>A cross-sectional association between the stratified log-rank family score for stroke and MI with prevalent risk factors was assessed in the REasons for Geographic And Racial Differences in Stroke (REGARDS) cohort.</AbstractText>Individuals in the fourth quartile of stratified log-rank family scores for stroke were more likely to have prevalent risk factors including hypertension (OR, 1.43; 95% CI, 1.30-1.58), left ventricular hypertrophy (OR, 1.42; 95% CI, 1.16-1.42), diabetes (OR, 1.26; 95% CI, 1.12-1.43), and atrial fibrillation (OR, 1.23; 95% CI, 1.03-1.45) compared with individuals in the first quartile. Likewise, individuals in the fourth quartile of stratified log-rank family scores for MI were more likely to have prevalent risk factors including hypertension (OR, 1.57; 95% CI, 1.27-1.94) and diabetes (OR, 1.29; 95% CI, 1.12-1.43) than the first quartile. In contrast to stroke, the family risk score for MI was associated with dyslipidemia (OR, 1.38; 95% CI, 1.23-1.55) and overweight/obesity (OR, 1.22; 95% CI, 1.10-1.37).</AbstractText>Family risk of stroke and MI is strongly associated with the majority of risk factors associated with each disease. Family history and genetic studies separating nonspecific contributions of intermediate phenotypes from specific contributions to the disease phenotype may lead to a more thorough understanding of transmission for these complex disorders.</AbstractText> |
14,405 | [Management of severe accidental hypothermia]. | Accidental hypothermia is an environmental condition with basic principles of classification and resuscitation that apply to mountain, sea or urban scenarios. Along with coagulopathy and acidosis, hypothermia belongs to the lethal triad of trauma victims requiring critical care. A customized healthcare chain is involved in its management, extending from on site assistance to intensive care, cardiac surgery and/or the extracorporeal circulation protocols. A good classification of the degree of hypothermia preceding admission contributes to improve management and avoids inappropriate referrals between hospitals. The most important issue is to admit hypothermia victims in asystolia or ventricular fibrillation to those hospitals equipped with the medical technology which these special clinical scenarios require. This study attempts to establish the foundations for optimum management of accidental hypothermia from first emergency care on site to treatment in hospital including, resuscitation and rewarming with extracorporeal circulation. |
14,406 | Mitral valve repair for severe mitral regurgitation secondary to lone atrial fibrillation. | Significant mitral regurgitation (MR) may arise from isolated annular dilatation secondary to lone atrial fibrillation (AF) and associated atrial remodelling. The aim of the present study is to assess the outcome of surgery for this condition.</AbstractText>Between November 2007 and July 2011, 20 patients underwent mitral valve (MV) repair for severe MR secondary to AF. The median age of patients was 77.5 years (45-82 years) and the mean pre-operative duration of AF was 84.6 ± 92 months. The left ventricle was moderately (ejection fraction 30-50%; n = 6) or severely (<30%; n = 1) impaired in seven patients pre-operatively. Mean logistic EuroSCORE was 8.1 ± 5.9 and mean follow-up was 18.0 ± 12.5 months.</AbstractText>All operations were elective. Concomitant anti-arrhythmic procedures (maze procedure, pulmonary vein isolation) or left atrial (LA) appendage amputation were performed in all patients; tricuspid valve repair was undertaken in 12 patients and coronary artery bypass grafting in 2 patients. Ring annuloplasty was performed in all patients. The median ring size was 30 mm (range 24-36 mm). On-table transoesophageal echocardiography post-repair showed mild residual MR in two patients and no MR in the remainder. There were no cases of systolic anterior motion. There was one re-exploration for bleeding. No patients required haemofiltration or suffered from stroke and deep sternal wound infections. There was no in-hospital mortality. At discharge mean left ventricular (LV) end-diastolic diameter was 4.8 ± 0.7 cm compared with 5.6 ± 0.7 cm pre-operatively (P < 0.005), while mean LV end-systolic diameter was 3.2 ± 0.8 cm when compared with 4.0 ± 0.7 cm pre-operatively (P < 0.005). The mean LA size was 5.2 ± 1.0 cm when compared with 6.1 ± 1.6 cm pre-operatively (P = 0.03). There was mild MR in two patients, but none in the rest. The mean MV area was 3.0 ± 0.7 cm(2). The mean systolic pulmonary artery pressure was 40.4 ± 15.5 mmHg when compared with 54.1 ± 12.2 mmHg pre-operatively (P = 0.02). Seventeen patients (85%) were in NYHA class I/II at latest follow-up (P < 0.0001 vs pre-operatively). During follow-up, there were no thrombo-embolic complications, re-operation, endocarditis or deaths.</AbstractText>MV annuloplasty for annular dilatation secondary to AF has a good mid-term outcome.</AbstractText> |
14,407 | Therapeutic potential of marine n-3 fatty acids in CABG patients. | Dietary intake of marine n-3 polyunsaturated fatty acids (PUFA) has beneficial effects in various cardiac disorders. Few studies have, however, investigated the therapeutic potential of n-3 PUFA in patients undergoing coronary artery bypass grafting (CABG). Five heterogeneous randomized studies on n-3 PUFA for prevention of postoperative atrial fibrillation have yielded conflicting results. Increased venous graft patency rates following CABG were seen in another study in patients treated with n-3 PUFA. Finally, supplements with n-3 PUFA postoperatively have been associated with a lower risk of repeat revascularization and lower mortality in patients with poor ventricular function. Data are still few, and more studies are needed to clarify the therapeutic potential of n-3 PUFA in patients undergoing CABG. |
14,408 | [C-reactive protein and non-valvula atrial fibrillation combining with thrombosis]. | To investigate the alteration of plasma C-reactive protein(CRP) count in patients with non-valvula atrial fibrillation combining thrombosis.</AbstractText>A total of 154 patients with non-valvula atrial fibrillation were divided into thrombus group (n = 46) and non-thrombus group (n = 108) in accordance with transesophageal echocardiography (TEE) results. The concentration of CRP by scattering turbidimetry, D-dimer by immunoturbidmetry, left atrium diameter (LAd), fraction shortening (FS) and left ventricular ejection fraction (LVEF) by TEE or echocardiography were detected. Logistic multi-factors regression analysis was performed.</AbstractText>There were significant differences in CRP [(5.77 ± 6.37) mg/L vs (1.73 ± 2.39) mg/L, P = 0.003], LAd [(59.86 ± 10.70) mm vs (47.97 ± 13.19) mm, P < 0.001] and LVEF [(58.75 ± 8.28)% vs (64.10 ± 6.75)%, P < 0.001] between thrombus group and non-thrombus group. The results of logistic regression analysis found CRP ≥ 1.33 mg/L (OR 2.856, 95%CI 1.235 - 6.600, P = 0.014) and LAd ≥ 54.5 mm (OR 4.236, 95%CI 1.877 - 9.562, P = 0.001) were independent risk factors of patients with non-valvula atrial fibrillation combining with thrombosis.</AbstractText>CRP and LAd are independent risk factors for patients with non-valvula atrial fibrillation combining with thrombosis. Inflammation may involve with the formation of thrombosis.</AbstractText> |
14,409 | Relationship between left atrial volume and atrial fibrillation following coronary artery bypass grafting. | Atrial fibrillation (AF) is a common complication of coronary artery bypass grafting (CABG). However, limited information is available about the role of preoperative echocardiographic left atrial evaluation to predict AF occurrence after CABG. Thus, we prospectively compared the ability of echocardiographic measurements of left atrial volume to predict AF in this setting.</AbstractText>From January to December 2009, 220 patients (75% males, 66.8 ± 10.0 years) met the inclusion criteria of our study (isolated and elective CABG, no valve surgery, no permanent AF, or other chronic atrial arrhythmias). The day before CABG a complete echocardiographic evaluation was performed with left atrial volume measurements. The primary endpoint of the study was postoperative AF (POAF) lasting >30 seconds.</AbstractText>POAF was observed in 61 patients (27.7%). POAF patients showed increased left atrial M-mode anteroposterior dimension (41.2 ± 6.4 mm vs. 43.6 ± 7.3 mm; p = 0.020) and increased left atrial volume (59.0 ± 18.3 mL vs. 70.6 ± 28.1 mL; p = 0.0004). Left atrial volume was an independent risk factor for POAF (OR 10.03; 95% CI 10.01 to 10.05; p = 0.01), along with postoperative bleeding with hemoglobin levels below 8 g/dL (OR 20.84; 95% CI 10.12 to 70.19; p = 0.03) and preoperative left ventricular ejection fraction below 40% (OR 10.08; 95% CI 10.01 to 10.15; p = 0.02). Conversely, preoperative statin therapy exerted a protective role (OR 0.30; 95% CI 0.12 to 0.74; p = 0.009).</AbstractText>Preoperative echocardiographic evaluation of patients with isolated CABG demonstrated that left atrium volume measurements were independently correlated to the occurrence of POAF. Further investigations should focus on the opportunity to target prophylactic antiarrhythmic treatments to patients with large left atrial volumes.</AbstractText>© 2012 Wiley Periodicals, Inc.</CopyrightInformation> |
14,410 | Methylphenidate and risk of serious cardiovascular events in adults. | The authors sought to determine whether use of methylphenidate in adults is associated with elevated rates of serious cardiovascular events compared with rates in nonusers.</AbstractText>This was a cohort study of new users of methylphenidate based on administrative data from a five-state Medicaid database and a 14-state commercial insurance database. All new methylphenidate users with at least 180 days of prior enrollment were identified. Users were matched on data source, state, sex, and age to as many as four comparison subjects who did not use methylphenidate, amphetamines, or atomoxetine. A total of 43,999 new methylphenidate users were identified and matched to 175,955 nonusers. Events of primary interest were 1) sudden death or ventricular arrhythmia, 2) stroke, 3) myocardial infarction, and 4) a composite endpoint of stroke or myocardial infarction.</AbstractText>The age-standardized incidence rate per 1,000 person-years of sudden death or ventricular arrhythmia was 2.17 (95% CI=1.63-2.83) in methylphenidate users and 0.98 (95% CI=0.89-1.08) in nonusers, for an adjusted hazard ratio of 1.84 (95% CI=1.33-2.55). Dosage was inversely associated with risk. Adjusted hazard ratios for stroke, myocardial infarction, and the composite endpoint of stroke or myocardial infarction did not differ statistically from 1.</AbstractText>Although initiation of methylphenidate was associated with a 1.8-fold increase in risk of sudden death or ventricular arrhythmia, the lack of a dose-response relationship suggests that this association may not be a causal one.</AbstractText> |
14,411 | Ultra-short course of low-dose amiodarone-induced post-operative fatal pulmonary toxicity. | A 58-year-old male diabetic patient with severe left ventricular dysfunction and pulmonary arterial hypertension successfully underwent coronary artery by pass grafting (CABG) and was extubated 48 hours after surgery. Patient had atrial fibrillation on 3rd post-operative day requiring loading dose of amiodarone followed by maintenance dose to control the arrhythmia. On 4th post operative day patient became tachypnoiec and required higher concentration of oxygen to maintain SpO2 >90%. There was new infiltrates on the x-ray, which was more on right side. Initially treated as pulmonary infection and antifailure measures. The patient did not respond and the lesions progressed to opaque hemithorax by the 10th postoperative day. On 11th POD he was reintubated due to respiratory distress. After excluding pulmonary infections, pulmonary oedema, embolism and vascular obstruction, the possibility of drug induced pulmonary toxicity was considered. Hence amiodarone was withdrawn and steroid was initiated. There was good radiological and gas exchange improvement and he was extubated the following day. After one week course of steroids the infiltrates cleared and oxygenation also improved. Post CABG patients are prone for acute amiodarone toxicity and high index of suspicion is needed to diagnose this early so that fatal complication can be averted by timely intervention. |
14,412 | Incidence of asymptomatic cerebral microthromboembolism after atrial fibrillation ablation guided by complex fractionated atrial electrogram. | The incidence of cerebral thromboembolism after pulmonary vein isolation (PVI) ranges from 2% to 14%. This study investigated the incidence of cerebral thromboembolism after complex fractionated atrial electrogram (CFAE) ablation with or without PVI.</AbstractText>One hundred consecutive atrial fibrillation (AF) patients (50 paroxysmal and 50 persistent, including 10 longstanding) who underwent CFAE ablation combined with (n = 41, PVI+CFAE group) or without (n = 59, CFAE group) PVI were studied. Coronary angiography (CAG) was conducted with AF ablation in 5 cases in which coronary artery stenosis was suspected on 3D-computed tomography. PVI was performed before CFAE ablation without circular catheter during AF. After termination of AF, additional ablation was performed to complete PVI with a circular catheter. All patients underwent cerebral magnetic resonance imaging (MRI) including diffusion-weighted MRI and T2-weighted MRI the day after ablation.</AbstractText>New thromboembolism was detected in 7.0%, and there was no significant difference between the 2 strategies (7.3% in PVI+CFAE group, 6.8% in CFAE group). CHADS2 score (1.6 ± 1.0 vs 0.8 ± 0.9, P < 0.05), left atrial volume (LAV; 83.8 ± 27.1 vs 67.8 ± 21.8, P < 0.05), and left ventricular ejection fraction (LVEF, 53.1 ± 9.2 vs 65.1 ± 9.7, P < 0.01) were significantly different when comparing patients with or without thromboembolism. In multivariate analysis, LVEF (odds ratio [OR], 0.92; 95% confidence interval [CI], 0.84-0.99; P < 0.05) and concomitant CAG (OR 18.82; 95% CI, 1.77-200.00; P < 0.05) were important predictors of new cerebral thromboembolism.</AbstractText>The incidence of cerebral microthromboembolism after CFAE ablation was not greater than previous reports in PVI. Cautious management is required during AF ablation, especially in the patients with low LVEF.</AbstractText>© 2012 Wiley Periodicals, Inc.</CopyrightInformation> |
14,413 | Clinical predictors of Fidelis lead failure: report from the Canadian Heart Rhythm Society Device Committee. | Approximately 268,000 Fidelis leads were implanted worldwide until distribution was suspended because of a high rate of early failure. Careful analyses of predictors of increased lead failure hazard are required to help direct future lead design and also to inform decision making on lead replacement. We sought to perform a comprehensive analysis of all potential predictors in a multicenter study.</AbstractText>A total of 3169 Sprint Fidelis leads were implanted in 11 centers with a total of 251 failures. Lead failure rates at 3, 4, and 5 years were 5.3%, 10.6%, and 16.8%, respectively. The rate of lead failure continues to accelerate (P<0.001). There were 4 independent predictors of failure: center, sex, access vein, and previous lead failure. Women had a higher hazard of failure (hazard ratio 1.51; 95% confidence interval, 1.14-2.04; P=0.005). Both axillary and subclavian access increased the hazard of failure (P=0.007); hazard ratio for axillary was 1.94, (95% confidence interval, 1.23-3.04) and for subclavian 1.63 (95% confidence interval, 1.08-2.46). Previous lead failure increased the hazard of a subsequent Fidelis failure with a hazard ratio of 3.12 (95% confidence interval, 1.80-5.41; P<0.001).</AbstractText>The rate of Fidelis failure continues to increase over time, with failures approaching 17% at 5 years. Women, patients with leads inserted via the subclavian or axillary vein, and those with a previous lead fracture were at greatest risk of Fidelis failure. Our data suggest that Fidelis replacement should be strongly considered at the time of generator replacement.</AbstractText> |
14,414 | Dingxin recipe ( ) prevents ischemia/reperfusion-induced arrhythmias via up-regulating prohibitin and suppressing inflammatory responses. | To identify the underlying mechanisms of the protective effects of Dingxin Recipe (: , DXR), a Chinese compound prescription that has been used clinically in China for more than 20 years, on ischemia/reperfusion (I/R)-induced arrhythmias in rat model.</AbstractText>A total of 30 rats were randomly divided into three groups: sham group, I/R group, and DXR-pretreated I/R (DXR-I/R) group. Rats in the DXR-DXRI/R group were intragastrically administrated with DXR (12.5 g/kg per day) for consecutive 7 days, while rats I/in the sham and I/R groups were administrated with normal saline. Arrhythmias were introduced by I/R and electrocardiograms (ECG) were recorded. Two-dimensional (2-D) polyacrylamide gel electrophoresis and matrix-matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used to identify assisted differentially expressed proteins. Immunohistochemistry, real-time quantitative polymerase chain reaction (RQ-RQPCR), Western blot, and enzyme-linked immunosorbent assay (ELISA) were performed to analyze proteins PCR), obtained in the above experiments.</AbstractText>DXR significantly reduced the incidence and mean duration of ventricular tachycardia and ventricular fibrillation and dramatically decreased the mortality, as well as arrhythmia score, compared with those of the I/R group. Among successfully identified proteins, prohibitin (PHB) and heart fatty acid binding protein (hFABP) were up-regulated in DXR-pretreated I/R rats compared with those of the I/R rats. In addition, compared with the I/R group, the level of glutathione (GSH) was elevated accompanied by reduced expressions of interleukin-6 (IL-6) and neutrophil infiltration in I/R rats with DXR pretreatment.</AbstractText>DXR could alleviate I/R-induced arrhythmias, which might be related to increased expression of PHB. The enhanced expression of PHB prevented against the depletion of GSH and consequently inhibited apoptosis of cardiomyocytes. Furthermore, up-regulation of PHB might ameliorate I/R-induced cell death and leakage of hFABP by suppressing neutrophil infiltration and IL-6 expressions.</AbstractText> |
14,415 | Unrecognized failure of a narrow caliber defibrillation lead: the role of defibrillation threshold testing in identifying an unprotected individual. | In this case report we describe a short circuit in the Riata 1570 defibrillator lead (Riata 1570, St. Jude Medical, St. Paul, MN, USA) that was unsuspected owing to normal lead parameters until defibrillator threshold testing at the time of elective generator change. On this occasion, the short circuit manifested as unsuccessful defibrillation of ventricular fibrillation with immediate battery depletion. This report adds weight to existing concerns over narrow caliber leads, it draws attention to the possibility of lead malfunction despite unremarkable interrogation, and lastly it highlights the potential role of routine defibrillator threshold testing, particularly at elective generator change (an issue that remains sparingly addressed in the existing literature). |
14,416 | Near elimination of ventricular pacing in SafeR mode compared to DDD modes: a randomized study of 422 patients. | SafeR performance versus DDD/automatic mode conversion (DDD/AMC) and DDD with a 250-ms atrioventricular (AV) delay (DDD/LD) modes was assessed toward ventricular pacing (Vp) reduction.</AbstractText>After a 1-month run-in phase, recipients of dual-chamber pacemakers without persistent AV block and persistent atrial fibrillation (AF) were randomly assigned to SafeR, DDD/AMC, or DDD/LD in a 1:1:1 design. The main endpoint was the percentage of Vp (%Vp) at 2 months and 1 year after randomization, ascertained from device memories. Secondary endpoints include %Vp at 1 year according to pacing indication and 1-year AF incidence based on automatic mode switch device stored episodes.</AbstractText>Among 422 randomized patients (73.2±10.6 years, 50% men, sinus node dysfunction 47.4%, paroxysmal AV block 30.3%, bradycardia-tachycardia syndrome 21.8%), 141 were assigned to SafeR versus 146 to DDD/AMC and 135 to DDD/LD modes. Mean %Vp at 2 months was 3.4±12.6% in SafeR versus 33.6±34.7% and 14.0±26.0% in DDD/AMC and DDD/LD modes, respectively (P<0.0001 for both). At 1 year, mean %Vp in SafeR was 4.5±15.3% versus 37.9±34.4% and 16.7±28.0% in DDD/AMC and DDD/LD modes, respectively (P<0.0001 for both). The proportion of patients in whom Vp was completely eliminated was significantly higher in SafeR (69%) versus DDD/AMC (15%) and DDD/LD (45%) modes (P<0.0001 for both), regardless of pacing indication. The absolute risk of developing permanent AF or of remaining in AF for >30% of the time was 5.4% lower in SafeR than in the DDD pacing group (ns).</AbstractText>In this selected patient population, SafeR markedly suppressed unnecessary Vp compared with DDD modes.</AbstractText>©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.</CopyrightInformation> |
14,417 | Arrhythmogenic difference between the left and right atria in a canine ventricular pacing-induced heart failure model of atrial fibrillation. | The detail of biatrial activation during sustained atrial fibrillation (AF) has not been investigated until now.</AbstractText>Five dogs with right ventricular pacing-induced congestive heart failure (CHF) and five normal dogs were included. Biatrial endocardiac mapping was performed using noncontact mapping system.</AbstractText>Noncontact mapping of the right atrium (RA) showed CHF dogs had a higher frequency of focal discharge from Bachmann's bundle, sinoatrial region, and crista terminalis. CHF dogs also had a higher frequency of wave break, wave fusion, and reentry. CHF dogs had greater effective refractory period (ERP) dispersion. Noncontact mapping of the left atrium (LA) showed CHF dogs had more frequent focal discharge from left superior pulmonary vein (PV), right superior PV, and left atrial appendage. CHF dogs had a higher frequency of wave break, wave fusion, and reentry. CHF dogs had greater ERP dispersion. Comparison between RA and LA showed LA had a higher frequency of focal discharge, wave break, wave fusion, and leading circle reentry than the RA. LA also had greater ERP dispersion than RA.</AbstractText>CHF dogs had a higher frequency of focal discharge and reentry, suggesting that CHF provided an arrhythmogenic substrate. LA had a higher frequency of focal discharge and reentry, suggesting that LA is more important to maintain AF.</AbstractText>©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.</CopyrightInformation> |
14,418 | Continuous-flow left ventricular assist device support in patients with advanced heart failure: points of interest for the daily management. | Today, continuous-flow left ventricular assist devices (cf-LVADs) are implanted more often in patients with end-stage heart failure. Because of greater durability they can be implanted for an extended period of time. As a result of increased numbers of patients on cf-LVAD support, healthcare professionals should be aware of the potential complications inherent to this therapy. Both bleeding and thrombosis may occur, and also complications related either to the device itself or to the ensuing altered haemodynamics, valvular pathology, and rhythm disturbances such as ventricular tachycardias and fibrillation. Accurate clinical evaluation, together with an electrocardiogram and, if necessary, combined with an echocardiogram, is obligatory in these situations. This review summarizes common complications complemented by a few clinical cases. |
14,419 | Electromechanical and structural alterations in the aging rabbit heart and aorta. | Aging increases the risk for arrhythmias and sudden cardiac death (SCD). We aimed at elucidating aging-related electrical, functional, and structural changes in the heart and vasculature that account for this heightened arrhythmogenic risk. Young (5-9 mo) and old (3.5-6 yr) female New Zealand White (NZW) rabbits were subjected to in vivo hemodynamic, electrophysiological, and echocardiographic studies as well as ex vivo optical mapping, high-field magnetic resonance imaging (MRI), and histochemical experiments. Aging increased aortic stiffness (baseline pulse wave velocity: young, 3.54 ± 0.36 vs. old, 4.35 ± 0.28 m/s, P < 0.002) and diastolic (end diastolic pressure-volume relations: 3.28 ± 0.5 vs. 4.95 ± 1.5 mmHg/ml, P < 0.05) and systolic (end systolic pressure-volume relations: 20.56 ± 4.2 vs. 33.14 ± 8.4 mmHg/ml, P < 0.01) myocardial elastances in old rabbits. Electrophysiological and optical mapping studies revealed age-related slowing of ventricular and His-Purkinje conduction (His-to-ventricle interval: 23 ± 2.5 vs. 31.9 ± 2.9 ms, P < 0.0001), altered conduction anisotropy, and a greater inducibility of ventricular fibrillation (VF, 3/12 vs. 7/9, P < 0.05) in old rabbits. Histochemical studies confirmed an aging-related increased fibrosis in the ventricles. MRI showed a deterioration of the free-running Purkinje fiber network in ventricular and septal walls in old hearts as well as aging-related alterations of the myofibrillar orientation and myocardial sheet structure that may account for this slowed conduction velocity. Aging leads to parallel stiffening of the aorta and the heart, including an increase in systolic stiffness and contractility and diastolic stiffness. Increasingly, anisotropic conduction velocity due to fibrosis and altered myofibrillar orientation and myocardial sheet structure may contribute to the pathogenesis of VF in old hearts. The aging rabbit model represents a useful tool for elucidating age-related changes that predispose the aging heart to arrhythmias and SCD. |
14,420 | Use of beta-blockers for the treatment of cardiac arrest due to ventricular fibrillation/pulseless ventricular tachycardia: a systematic review. | Advanced Life Support guidelines recommend the use of epinephrine during Cardiopulmonary Resuscitation (CPR), as to increase coronary blood flow and perfusion pressure through its alpha-adrenergic peripheral vasoconstriction, allowing minimal rises in coronary perfusion pressure to make defibrillation possible. Contrasting to these alpha-adrenergic effects, epinephrine's beta-stimulation may have deleterious effects through an increase in myocardial oxygen consumption and a reduction of subendocardial perfusion, leading to postresuscitation cardiac dysfunction.</AbstractText>The present paper consists of a systematic review of the literature regarding the use of beta-blockade in cardiac arrest due to ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT).</AbstractText>Studies were identified through MEDLINE electronic databases research and were included those regarding the use of beta-blockade during CPR.</AbstractText>Beta-blockade has been extensively studied in animal models of CPR. These studies not only suggest that beta-blockade could reduce myocardial oxygen requirements and the number of shocks necessary for defibrillation, but also improve postresuscitation myocardial function, diminish arrhythmia recurrences and prolong survival. A few case reports described successful beta-blockade use in patients, along with two prospective human studies, suggesting that it could be safe and effectively used during cardiac arrest in humans.</AbstractText>Even though the existing literature points toward a beneficial effect of beta-blockade in patients presenting with cardiac arrest due to VF/pulseless VT, high quality human trials are still lacking to answer this question definitely.</AbstractText>Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,421 | Ventricular flutter triggered by fever in a patient with Brugada syndrome. | Brugada syndrome is a clinical-electrocardiographic entity predisposing to malignant ventricular arrhythmias. The typical arrhythmia is polymorphic ventricular tachycardia, which can potentially degenerate to ventricular fibrillation. Monomorphic ventricular tachycardia is uncommon. Our group is reporting the case of a 39-year-old man with known Brugada syndrome who developed ventricular flutter while febrile. Fever has previously been shown to unmask Brugada changes and to induce ventricular arrhythmias. The appearance of monomorphic ventricular tachycardia potentially attributable to sodium-channel dysfunction further confounds the mechanism of arrhythmogenesis in Brugada syndrome. This curious occurrence further underlines the likely complex nature of arrhythmogenesis in Brugada syndrome. |
14,422 | Feasibility and safety of dabigatran versus warfarin for periprocedural anticoagulation in patients undergoing radiofrequency ablation for atrial fibrillation: results from a multicenter prospective registry. | The purpose of this study was to evaluate the feasibility and safety of periprocedural dabigatran during atrial fibrillation (AF) ablation.</AbstractText>AF ablation requires optimal periprocedural anticoagulation for minimizing bleeding and thromboembolic complications. The safety and efficacy of dabigatran as a periprocedural anticoagulant for AF ablation are unknown.</AbstractText>We performed a multicenter, observational study from a prospective registry including all consecutive patients undergoing AF ablation in 8 high-volume centers in the United States. All patients receiving dabigatran therapy who underwent AF ablation on periprocedural dabigatran, with the dose held on the morning of the procedure, were matched by age, sex, and type of AF with an equal number of patients undergoing AF ablation with uninterrupted warfarin therapy over the same period.</AbstractText>A total of 290 patients, including 145 taking periprocedural dabigatran and an equal number of matched patients taking uninterrupted periprocedural warfarin, were included in the study. The mean age was 60 years with 79% being male and 57% having paroxysmal AF. Both groups had a similar CHADS(2) score, left atrial size, and left ventricular ejection fraction. Three thromboembolic complications (2.1%) occurred in the dabigatran group compared with none in the warfarin group (p = 0.25). The dabigatran group had a significantly higher major bleeding rate (6% vs. 1%; p = 0.019), total bleeding rate (14% vs. 6%; p = 0.031), and composite of bleeding and thromboembolic complications (16% vs. 6%; p = 0.009) compared with the warfarin group. Dabigatran use was confirmed as an independent predictor of bleeding or thromboembolic complications (odds ratio: 2.76, 95% confidence interval: 1.22 to 6.25; p = 0.01) on multivariate regression analysis.</AbstractText>In patients undergoing AF ablation, periprocedural dabigatran use significantly increases the risk of bleeding or thromboembolic complications compared with uninterrupted warfarin therapy.</AbstractText>Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,423 | Detection and prediction of the onset of human ventricular fibrillation: an approach based on complex network theory. | Ventricular fibrillation is a life-threatening cardiac arrhythmia which deserves quick and reliable detection as well as prediction from human electrocardiogram time series. We constructed networks of human ventricular time series with the visibility graph approach to study the network subgraph phenomenon and motif ranks. Our results show that different dominant motifs exist as an effective indicator in distinguishing ventricular fibrillations from normal sinus rhythms of a subject. We verify the reliability of our findings in a large database with different time lengths and sampling frequencies, and design an onset predictor of ventricular fibrillations with reliable verifications. |
14,424 | Cardiac resynchronization therapy with or without anatomical reverse remodeling does not affect defibrillation threshold. | Recent clinical trials have documented beneficial reverse-remodeling effects with cardiac resynchronization therapy (CRT). The aim of this study was to investigate the effect of CRT with or without reverse anatomical remodeling of the left ventricle on defibrillation threshold (DFT) levels in a prospective and consecutive group of patients with class II-IV systolic heart failure.</AbstractText>Study population consisted of 29 patients (14 women and 15 men; mean age 61±11 years old). All patients underwent baseline (within 24-hours of cardiac resynchronization therapy-defibrillator [CRT-D] implantation) and 6-month follow-up DFT testing. Reverse anatomical remodeling of the left ventricle was defined as ≥15% reduction in left ventricular end-systolic volume at the end of 6 months of follow-up compared to baseline.</AbstractText>Baseline, average DFT was 8.8±5.9 J. Left ventricular end-diastolic volume was the only predictor of baseline DFT level (P=0.02) among the baseline demographics. Safety margin of at least 10 J was achieved in all patients. Average DFT at the end of 6 months of biventricular pacing was 9.2±6.9 J. One patient (3.4%) failed to have a safety margin of 10 J. Reverse anatomical remodeling was observed in 14 (48%) patients and did not have any effect on DFT level. There were no complications related to DFT testings.</AbstractText>Baseline average DFT in patients undergoing CRT-D was ≤10 J in our study. CRT-D with or without anatomical reverse remodeling does not affect DFT at the end of 6 months of follow-up. High DFT level at the end of 6 months of follow-up is rare (3.4%) among patients with current CRT-D devices.</AbstractText>©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.</CopyrightInformation> |
14,425 | Estimating outcomes of astronauts with myocardial infarction in exploration class space missions. | We estimate likelihood of presenting rhythms and survival to hospital discharge outcome after acute cardiac ischemia with arrhythmia and/or myocardial infarction (AMI) during long-duration space missions (LDSM) using selected terrestrial cohorts in medical literature. Medical scenarios were risk-stratified by coronary artery calcium score (CAC) and Framingham risk factors (FRF).</AbstractText>AMI with and without sudden cardiac arrest (SCA) likelihoods and clinically significant rhythm scenarios and associated outcomes in "astronaut-like" cohorts were derived from two prospective trials identified by an evidence-based literature review. Results are presented using an event sequence diagram and event time line. The association of increasing CAC scores and FRF with AMI and SCA outcomes was calculated.</AbstractText>Low AMI likelihoods are estimated in individuals with CAC scores of zero or < 100 and a low number of FRF. Survival rate to hospital discharge after out of hospital SCA in a large urban environment study was 5.2%. EMS-witnessed ventricular tachycardia and/or ventricular fibrillation survival rate of 37.5% represents < 1% of all urban out of hospital AMI, and these patients have a high proportion of known ischemic cardiovascular and pulmonary disease "disqualifying for spaceflight."</AbstractText>Multiple factors may be expected to delay or defeat rapid access to "chain of survival" resources during LDSM, lowering survival rates below urban levels of 5.2%. Low CAC and FRF reflect lower risk for AMI events. Zero CAC was associated with the lowest risk of AMI after 3.5 yr of follow-up. Quantifiable incidence and outcome characterization suggests AMI in LDSM outcomes will be relatively independent of in-flight medical resources.</AbstractText> |
14,426 | Propofol-induced coved-type electrocardiogram during catheter ablation of paroxysmal atrial fibrillation. A case of Brugada syndrome? | We report a case of a young man with paroxysmal atrial fibrillation, in whom a characteristic coved-type Brugada pattern developed during catheter ablation performed under sedation with propofol. After immediate discontinuation of the propofol infusion, coved-type ST-segment elevation gradually resolved and no ventricular arrhythmias occurred. An ajmaline challenge failed to unmask a coved-type electrocardiogram and genetic testing was negative for ion channel mutations related to Brugada syndrome. |
14,427 | Indications for cardiac resynchronization therapy: 2011 update from the Heart Failure Society of America Guideline Committee. | Cardiac resynchronization therapy (CRT) improves survival, symptoms, quality of life, exercise capacity, and cardiac structure and function in patients with New York Heart Association (NYHA) functional class II or ambulatory class IV heart failure (HF) with wide QRS complex. The totality of evidence supports the use of CRT in patients with less severe HF symptoms. CRT is recommended for patients in sinus rhythm with a widened QRS interval (≥150 ms) not due to right bundle branch block (RBBB) who have severe left ventricular (LV) systolic dysfunction and persistent NYHA functional class II-III symptoms despite optimal medical therapy (strength of evidence A). CRT may be considered for several other patient groups for whom evidence of benefit is clinically significant but less substantial, including patients with a QRS interval of ≥120 to <150 ms and severe LV systolic dysfunction who have persistent mild to severe HF despite optimal medical therapy (strength of evidence B), some patients with atrial fibrillation, and some with ambulatory class IV HF. Several evidence gaps remain that need to be addressed, including the ideal threshold for QRS duration, QRS morphology, lead placement, degree of myocardial scarring, and the modality for evaluating dyssynchrony. Recommendations will evolve over time as additional data emerge from completed and ongoing clinical trials. |
14,428 | Does terfenadine-induced ventricular tachycardia/fibrillation directly relate to its QT prolongation and Torsades de Pointes? | Terfenadine has been reported to cause cardiac death. Hence, we investigated its pro-arrhythmic potential in various in vitro models.</AbstractText>Pro-arrhythmic effects of terfenadine were investigated in rabbit isolated hearts and left ventricular wedge preparations. Also, using whole-cell patch-clamp recording, we examined its effect on the human ether-à-go-go-related gene (hERG) current in HEK293 cells transfected with hERG and on the I(Na) current in rabbit ventricular cells and human atrial myocytes.</AbstractText>Terfenadine concentration- and use-dependently inhibited I(Na) in rabbit myocytes and in human atrial myocytes and also inhibited the hERG. In both the rabbit left ventricular wedge and heart preparations, terfenadine at 1 µM only slightly prolonged the QT- and JT-intervals but at 10 µM, it caused a marked widening of the QRS complex, cardiac wavelength shortening, incidences of in-excitability and non-TdP-like ventricular tachycardia/fibrillation (VT/VF) without prolongation of the QT/JT-interval. At 10 µM terfenadine elicited a lower incidence of early afterdepolarizations versus non- Torsades de Pointes (TdP)-like VT/VF (100% incidence), and did not induce TdPs. Although the concentration of terfenadine in the tissue-bath was low, it accumulated within the heart tissue.</AbstractText>Our data suggest that: (i) the induction of non-TdP-like VT/VF, which is caused by slowing of conduction via blockade of I(Na) (like Class Ic flecainide), may constitute a more important risk for terfenadine-induced cardiac death; (ii) although terfenadine is a potent hERG blocker, the risk for non-TdP-like VT/VF exceeds the risk for TdPs; and (iii) cardiac wavelength (λ) could serve as a biomarker to predict terfenadine-induced VT/VF.</AbstractText>© 2012 Janssen Pharmaceutica NV. British Journal of Pharmacology © 2012 The British Pharmacological Society.</CopyrightInformation> |
14,429 | Determinants of mortality in patients with heart failure and atrial fibrillation during long-term follow-up. | Heart failure (HF) and atrial fibrillation (AF) often occur together. Both are independently associated with an increased mortality. Clinical parameters associated with mortality in patients with HF such as left ventricular ejection fraction (LV-EF) and New York Heart Association (NYHA) functional class are influenced by AF. If these parameters are still determinants of mortality when HF is complicated by AF, or if other parameters determine mortality in this case is unknown.</AbstractText>We studied 173 consecutive HF patients (mean age 67 +/- 12 years, 30% female) in New York Heart Association (NYHA) functional class 2.6 +/- 0.8 with left ventricular systolic dysfunction (ejection fraction 45%) and AF. Mortality was 42% after a mean follow-up of 41 months. Age (OR 1.04, CI 1.01-1.07, P = 0.003), chronic obstructive pulmonary disease (OR 2.07, Cl 1.15-3.73, P = 0.015), elevated serum creatinine at admission (OR 1.25, Cl 1.01-1.54, P = 0.033), prolongation of QRS duration (OR 1.02, CI 1.01-1.54, P= 0.001), decreased serum sodium at admission (OR 0.94, Cl 0.89-0.99, P = 0.026) and oral anticoagulation (OR 0.59, Cl 0.36-0.99, P = 0.046) were independently associated with mortality when assessed with multivariable Cox proportional hazard analysis. Importantly, mortality was not associated with NYHA functional class or left ventricular ejection fraction (LVEF).</AbstractText>Elevated creatinine levels, decreased serum sodium levels, prolongation of QRS duration and the presence of COPD are associated with long-term mortality after hospitalization in patients with HF and AF. Oral anticoagulation is associated with better survival. LVEF and NYHA functional class are no reliable mortality markers in this patient population.</AbstractText> |
14,430 | Aging reduces left atrial performance during adrenergic stress in middle aged and older patients. | During adrenergic stress, the influence of age on left atrial (LA) function is unknown. We hypothesized that aging decreases LA total emptying fraction (LAEF) during maximal adrenergic stress. The aim of the study was to determine the influence of aging on LA function during adrenergic stress in middle aged and older patients.</AbstractText>We enrolled 167 middle aged and elderly participants, and measured LA and left ventricular (LV) volumes using a multi-slice three-dimensional cine white blood cardiovascular magnetic resonance (CMR) technique before and during intravenous dobutamine infused to achieve 80% of the maximum heart rate response for age. Paired sample t-test was used to detect differences in LA and LV volumes between baseline and peak dose stage of dobutamine stress CMR, and multivariable linear regression was used to identify predictors of LA function.</AbstractText>Participants averaged 68 ± 8 years in age, 53% were men, 25% exhibited coronary artery disease, 35% had diabetes, 9% had a remote history of atrial fibrillation, 90% had hypertension, and 11% had inducible LV wall motion abnormalities indicative of ischemia during dobutamine CMR. Increasing age correlated with LA volumes (maximal and minimal) and inversely correlated with LAEF at rest and after peak adrenergic stress. Age was an independent predictor of LAEF during adrenergic stress, even after accounting for gender, LV volumes, and other co-morbidities including inducible ischemia.</AbstractText>Age is associated with a decrease in LA function during adrenergic stress even after adjusting for co-morbidities associated with cardiovascular disease and LV function.</AbstractText> |
14,431 | Predictors of local venous complications resulting from electrophysiological procedures. | Thromboembolic complications resulting from radiofrequency catheter ablation (RFCA) have an overall incidence of 0.6%. Multiple intracardiac catheters are often necessary for electrophysiological study and RFCA therapy. Therefore, the placement of multiple venous sheaths in one femoral vein is always required for multiple intracardiac catheter insertion. The safety of the placement of multiple separate venous sheaths has been studied previously in a non-randomized study, but the placement of multiple sheaths via one venous line has not been fully studied.</AbstractText>A randomized clinical trial was conducted with a total of 200 patients. We studied the safety of placing multiple sheaths via one venous line, and the effect of heparin on deep vein thrombosis (DVT) and on in situ thrombosis. DVT was not seen in our patients. We observed a significant decrease in the rate of in situ thrombosis in patients who received heparin during the procedure (28% vs 11%, p = 0.04). The type of cannulation changed the in situ thrombosis rate independently of the heparinization protocol. The rate of in situ thrombosis was higher when placing sheaths via one venous line regardless of the heparinization protocol used (16% vs 6%, p = 0.1 for the group on heparin, and 38% vs 18%, p = 0.04 for the other group). In the group cannulated with only one venous line (100 patients), heparinization significantly decreased the rate of in situ thrombosis (16% vs 38%, p = 0.023), but there was an insignificant decrease in the separate cannulation group (6% vs 18%, p = 0.12). Advanced age had no effect on thrombosis. Surprisingly, there was a significantly greater rate of in situ thrombosis (not DVT) among women than among men (26% vs 11%, p = 0.01), regardless of the heparinization protocolor the type of cannulation.</AbstractText>Given the local venous complications and DVT after electrophysiological procedures, heparinization is not necessary for right-sided electrophysiological procedures. In situ thrombosis is a minor complication that can be reduced by heparinization in patients undergoing one-line cannulation and in women during longer procedures.</AbstractText> |
14,432 | Single-heartbeat electromechanical wave imaging with optimal strain estimation using temporally unequispaced acquisition sequences. | Electromechanical Wave Imaging (EWI) is a non-invasive, ultrasound-based imaging method capable of mapping the electromechanical wave (EW) in vivo, i.e. the transient deformations occurring in response to the electrical activation of the heart. Optimal imaging frame rates, in terms of the elastographic signal-to-noise ratio, to capture the EW cannot be achieved due to the limitations of conventional imaging sequences, in which the frame rate is low and tied to the imaging parameters. To achieve higher frame rates, EWI is typically performed by combining sectors acquired during separate heartbeats, which are then combined into a single view. However, the frame rates achieved remain potentially sub-optimal and this approach precludes the study of non-periodic arrhythmias. This paper describes a temporally unequispaced acquisition sequence (TUAS) for which a wide range of frame rates are achievable independently of the imaging parameters, while maintaining a full view of the heart at high beam density. TUAS is first used to determine the optimal frame rate for EWI in a paced canine heart in vivo and then to image during ventricular fibrillation. These results indicate how EWI can be optimally performed within a single heartbeat, during free breathing and in real time, for both periodic and non-periodic cardiac events. |
14,433 | Conversion of Persistent Atrial Fibrillation After Radiofrequency Ablation by Ibutilide. | Ablation of peristent AF remains challenging with questions unanswered about what the ideal next step after pulmonary venous isolation should be. Ibutilide is a highly effective class III agent for cardioversion of acute-onset atrial flutter and fibrillation, with limited clinical use due to risks of ventricular pro-arrhythmias. However, results from the on-going MAGIC-AF trial may re-invigorate its role in clinical electrophysiology as an invaluable adjunct to facilitate controlled substrate modification during ablation of persistent AF. |
14,434 | Left Atrial Diastolic Dysfunction following Catheter Ablation of Atrial Fibrillation. | Radiofrequency catheter ablation (RFCA)-induced thermal injury may cause and/or worsen left atrial (LA) diastolic dysfunction leading to pulmonary hypertension and heart failure in patients with atrial fibrillation (AF), the incidence of which is probably more common than is generally realized. Biplane 2-dimensional echocardiography coupled with tissue Doppler (velocity) imaging and Doppler-derived strain (rate) imaging can be applied to provide quantitative assessment of the LA function (both systolic and diastolic) relative to pulmonary venous circulation and left ventricular function. Information so obtained is useful for guiding follow-up management of patients undergoing RFCA of AF. |
14,435 | A Novel Transgenic Mouse Model of Cardiac Hypertrophy and Atrial Fibrillation. | Cardiac hypertrophy is a major risk factor for the development of atrial fibrillation (AF). However, there are few animal models of AF associated with cardiac hypertrophy. In this study, we describe the in vivo electrophysiological characteristics and histopathology of a mouse model of cardiac hypertrophy that develops AF. Myostatin is a well-known negative regulator of skeletal muscle growth that was recently found to additionally regulate cardiac muscle growth. Using cardiac-specific expression of the inhibitory myostatin pro-peptide, we generated transgenic (TG) mice with dominant-negative regulation of MSTN (DN-MSTN). One line (DN-MSTN TG13) displayed ventricular hypertrophy, as well as spontaneous AF on the surface electrocardiogram (ECG), and was further evaluated. DN-MSTN TG13 had normal systolic function, but displayed atrial enlargement on cardiac MRI, as well as atrial fibrosis histologically. Baseline ECG revealed an increased P wave duration and QRS interval compared with wild-type littermate (WT) mice. Seven of 19 DN-MSTN TG13 mice had spontaneous or inducible AF, while none of the WT mice had atrial arrhythmias (p<0.05). Connexin40 (Cx40) was decreased in DN-MSTN TG13 mice, even in the absence of AF or significant atrial fibrosis, raising the possibility that MSTN signaling may play a role in Cx40 down-regulation and the development of AF in this mouse model. In conclusion, DN-MSTN TG13 mice represent a novel model of AF, in which molecular changes including an initial loss of Cx40 are noted prior to fibrosis and the development of atrial arrhythmias. |
14,436 | Ejection fraction and outcomes in patients with atrial fibrillation and heart failure: the Loire Valley Atrial Fibrillation Project. | Heart failure (HF) increases the risk of stroke and thrombo-embolism (TE) in non-valvular atrial fibrillation (NVAF), and is incorporated in stroke risk stratification scores. We aimed to establish the role of ejection fraction (EF) in risk prediction in patients with NVAF and HF.</AbstractText>Patients with NVAF, history of HF, and measured EF were included in a retrospective analysis. Patients with HF and preserved ejection fraction (HFPEF) were defined as those with clinical HF and EF ≥50% in this study. Among 7156 patients with NVAF, 1276 (17.8%) patients with HF and measured EF were included. Of these, 747/1276 (58.5%) patients were on vitamin K antagonists. The stroke/TE event rate per 100 person-years was 1.05 [95% confidence interval (CI) 0.87-1.25]. Patients with HFPEF were more likely to be female (P < 0.001), older (P < 0.001), and hypertensive (P < 0.001), and less likely to have prior vascular disease (P < 0.001). There were no differences in rates of stroke (P = 0.17) and stroke/TE (P = 0.11) between patients with HFPEF and those with HF and reduced EF. There were no significant differences in rates of all-cause mortality when patients were stratified by EF. In multivariate analyses, only previous stroke (hazard ratio 2.36, 95% CI 1.45-3.86) and vascular disease (1.57, 1.07-2.30) increased the risk of stroke/TE amongst NVAF patients with HF, but EF <35% did not (0.75, 0.44-1.30).</AbstractText>In NVAF patients with HF, there were no differences in rates of stroke, TE, or death between EF categories. Only previous stroke and vascular disease (and not decreased EF) independently increased risk of stroke/TE in multivariate analyses.</AbstractText> |
14,437 | Rapid recovery from congestive heart failure following successful radiofrequency catheter ablation in a patient with late onset of Wolff-Parkinson-White syndrome. | A 56-year-old man was admitted because of palpitations and dyspnea. A 12-lead electrocardiogram showed irregular wide QRS complex tachycardia with a slur at the initial portion of the QRS complex. He had preexisting long-standing persistent atrial fibrillation, but early excitation syndrome had never been noted. Chest X-ray showed heart enlargement and pulmonary congestion. He was diagnosed with late onset of Wolff-Parkinson-White syndrome, and congestive heart failure was probably caused by rapid ventricular response of atrial fibrillation through the accessory pathway. Emergency catheter ablation for the accessory pathway was undertaken, and heart failure was dramatically improved. |
14,438 | Electrophysiologic characteristics and catheter ablation of ventricular tachyarrhythmias among patients with heart failure on ventricular assist device support. | Ventricular tachyarrhythmias (VT) are common among ventricular assist device (VAD) recipients, yet electrophysiologic (EP) characteristics and catheter ablation outcomes remain uncharacterized.</AbstractText>To evaluate the EP characteristics and catheter ablation outcomes for VTs among heart failure patients on VAD support.</AbstractText>The Cleveland Clinic registry of consecutive patients undergoing VAD placement in 1991-2010 with medically refractory, symptomatic VT referred for EP study and catheter ablation.</AbstractText>Among 611 recipients of VAD (mean age 53.3 ± 12.4 years, 80% men), 21 patients (3.4%) were referred for 32 EP procedures, including 11 patients (52%) presenting with implantable cardioverter-defibrillator therapy (13 shocks, 26 antitachycardia pacing). Data from 44 inducible tachycardias (mean cycle length 339 ± 59 ms) demonstrated monomorphic VT (n = 40, 91%; superior axis 52%, right bundle branch block morphology 41%) and polymorphic ventricular tachycardia (PMVT)/ventricular fibrillation (n = 4, 8%). Electroanatomic mapping of 28 tachycardias in 20 patients demonstrated reentrant VT related to intrinsic scar (n = 21 of 28, 75%) more commonly than the apical inflow cannulation site (n = 4 of 28, 14%), focal/microreentry VT (n = 2 of 28, 7%), or bundle branch reentry (n = 1 of 28, 3.5%). Catheter ablation succeeded in 18 of 21 patients (86%). VT recurred in 7 of 21 patients (33%) at a mean of 133 ± 98 days, and 6 patients (29%) required repeat procedures, with subsequent recurrence in 4 of 21 patients (19%).</AbstractText>Catheter ablation of VT is effective among recipients of VAD. Intrinsic myocardial scar, rather than the apical device cannulation site, appears to be the dominant substrate.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,439 | Paroxysmal atrial fibrillation with silent episodes: intermittent versus continuous monitoring. | Asymptomatic atrial fibrillation (AF) presents the same risk for cardioembolic events as symptomatic AF. Intermittent ECG recordings may be helpful in detecting asymptomatic paroxysmal arrhythmias. The objective of this study was to compare short intermittent heart rhythm recordings with or without symptoms with continuous ECG recordings.</AbstractText>Twenty-two patients with diagnosed symptomatic paroxysmal AF participated. Patients used a handheld transtelephonic ECG device for a 30-day period performing two registrations of 10 seconds per day. Additionally patients were asked to make registrations if arrhythmia symptoms occurred. Patients also performed a 24-hour ambulatory continuous ECG recording during a single twenty-four hours period of the 30 day period. AF was defined as an irregular ventricular rhythm without visible p-waves for at least 10 seconds.</AbstractText>1425 intermittent ECG recordings were performed. AF episodes were diagnosed in 18 (82%) patients compared with 7 (32%) patients using continuous ECG, (p = 0.001). All patients with AF detected by continuous monitoring were also detected by intermittent recordings. Of the episodes, 16% were judged as symptomatic.</AbstractText>Short-term ECG registrations over extended time periods seem to be a more sensitive tool, compared with short continuous ECG recordings, for detection of AF episodes.</AbstractText> |
14,440 | Efficacy and safety of vernakalant in patients with atrial flutter: a randomized, double-blind, placebo-controlled trial. | Vernakalant is a novel, relatively atrial-selective antiarrhythmic agent for conversion of atrial fibrillation (AF) to sinus rhythm. This study examined the safety and efficacy of vernakalant in converting atrial flutter (AFL) to sinus rhythm.</AbstractText>This was a phase 2/3, randomized, double-blind, placebo-controlled trial. Adults with AFL received either a 10 min infusion of 3.0 mg/kg vernakalant (n = 39) or placebo (n = 15). If AFL or AF persisted at the end of a 15 min observation period, a second 10 min infusion of 2.0 mg/kg vernakalant or placebo was administered. The primary efficacy outcome was the proportion of patients who had treatment-induced conversion of AFL to sinus rhythm for a minimum duration of 1 min within 90 min after the start of the first infusion. No patient in the placebo group met the primary outcome. Only one patient receiving vernakalant (1 of 39, 3%) converted to sinus rhythm. A reduced mean absolute ventricular response rate occurred within 50 min in patients receiving vernakalant (mean change from baseline -8.2 b.p.m.) vs. patients receiving placebo (-0.2 b.p.m.) (P = 0.037). A post-hoc analysis revealed that vernakalant increased AFL cycle length by an average of 55 ms, whereas the AFL cycle length was unchanged in the placebo group (P < 0.001). There was no occurrence of 1 : 1 atrio-ventricular conduction. Dysgeusia and sneezing were the most common treatment-related adverse events, consistent with previous reports.</AbstractText>Vernakalant did not restore sinus rhythm in patients with AFL. Vernakalant modestly slowed AFL and ventricular response rates, and was well tolerated.</AbstractText> |
14,441 | Potassium-channel mutations and cardiac arrhythmias--diagnosis and therapy. | The coordinated generation and propagation of action potentials within cardiomyocytes creates the intrinsic electrical stimuli that are responsible for maintaining the electromechanical pump function of the human heart. The synchronous opening and closing of cardiac Na(+), Ca(2+), and K(+) channels corresponds with the activation and inactivation of inward depolarizing (Na(+) and Ca(2+)) and outward repolarizing (K(+)) currents that underlie the various phases of the cardiac action potential (resting, depolarization, plateau, and repolarization). Inherited mutations in pore-forming α subunits and accessory β subunits of cardiac K(+) channels can perturb the atrial and ventricular action potential and cause various cardiac arrhythmia syndromes, including long QT syndrome, short QT syndrome, Brugada syndrome, and familial atrial fibrillation. In this Review, we summarize the current understanding of the molecular and cellular mechanisms that underlie K(+)-channel-mediated arrhythmia syndromes. We also describe translational advances that have led to the emerging role of genetic testing and genotype-specific therapy in the diagnosis and clinical management of individuals who harbor pathogenic mutations in genes that encode α or β subunits of cardiac K(+) channels. |
14,442 | Cannabinoid 1 (CB1) receptor mediates WIN55, 212-2 induced hypothermia and improved survival in a rat post-cardiac arrest model. | The nonselective Cannabinoid (CB) receptor agonist, WIN55, 212-2, was demonstrated to induce hypothermia and improve post-resuscitation outcomes in a rat post-cardiac arrest model. The present study was to explore the potential mechanisms of WIN55, 212-2 on thermoregulation following resuscitation and to investigate which class of CB receptors was involved in WIN55, 212-2-induced hypothermia.</AbstractText>Ventricular fibrillation (VF) was induced and untreated for 6 min in 20 male Sprague-Dawley rats. Defibrillation was attempted after 8min of Cardiopulmonary resuscitation (CPR). Five min post-resuscitation, resuscitated animals were randomized to receive an intramuscular injection of selective CB1 receptors antagonist, SR141716A (5 mg kg(-1)); selective CB2 receptors antagonist SR144528 (5 mg kg(-1)); or placebo. Thirty min after injection, animals received continuous intravenous infusion of WIN55, 212-2 (1.0 mgkg(-1) h(-1)) for 4h while control animals received placebo. The identical temperature environment was maintained in all animals.</AbstractText>In animals treated with WIN55, 212-2, blood temperatures decreased progressively from 37 °C to 34 °C within 4h. This hypothermic effect was completely blocked by CB1 but not CB2 antagonist. Accordingly, significantly better cardiac output, ejection fraction and myocardial performance index, reduced neurological deficit scores, improved microcirculation and longer duration of survival were observed in WIN55, 212-2-treated animals, which were also completely abolished by pretreatment with CB1 antagonist.</AbstractText>Pharmacologically induced hypothermia with WIN55, 212-2 improved post-resuscitation myocardial and cerebral function, associated with a significantly increased duration of survival in a rat post-cardiac arrest model. The hypothermic and resulted beneficial effects of WIN55, 212-2 were mediated through CB1 receptors.</AbstractText>Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,443 | Discrete subaortic stenosis 37 years after repair of a ventricular septal defect. | Discrete subaortic stenosis (DSS) is uncommon in adults after surgical correction of congenital heart defects. There are only a few published reports on the occurrence of DSS in adults. We present an adult case with DSS after repair of a ventricular septal defect (VSD). The case was a 44-year old female patient who underwent VSD closure at 7 years of age. Thirty-seven years later, she presented with congestive heart failure associated with severe subaortic membranous stenosis and atrial fibrillation (AF) that required surgical repair. We report successful surgical treatment of this adult patient with DSS and AF 37 years after repair of a VSD. |
14,444 | Cardioprotective effect of dipeptidyl peptidase-4 inhibitor during ischemia-reperfusion injury. | Dipeptidyl peptidase-4 (DPP-4) inhibitor is a new anti-diabetic drug for type-2 diabetes mellitus patients. Despite its benefits on glycemic control, the effects of DPP-4 inhibitor on the heart during ischemia-reperfusion (I/R) periods are not known. We investigated the effect of DPP-4 inhibitor on cardiac electrophysiology and infarct size in a clinically relevant I/R model in swine and its underlying cardioprotective mechanism.</AbstractText>Fourteen pigs were randomized to receive either DPP-4 inhibitor (vildagliptin) 50mg or normal saline intravenously prior to a 90-min left anterior descending artery occlusion, followed by a 120-min reperfusion period. The hemodynamic, cardiac electrophysiological and arrhythmic parameters, and the infarct size were determined before and during I/R. Rat cardiac mitochondria were used to study the protective effects of DPP-4 inhibitor on cardiac mitochondrial dysfunction caused by severe oxidative stress induced by H2O2 to mimic the I/R condition.</AbstractText>Compared to the saline group, DPP-4 inhibitor attenuated the shortening of the effective refractory period (ERP), decreased the number of PVCs, increased the ventricular fibrillation threshold (VFT) during the ischemic period, and also decreased the infarct size. In cardiac mitochondria, DPP-4 inhibitor decreased the reactive oxygen species (ROS) production and prevented cardiac mitochondrial depolarization caused by severe oxidative stress.</AbstractText>During I/R, DPP-4 inhibitor stabilized the cardiac electrophysiology by preventing the ERP shortening, decreasing the number of PVCs, increasing the VFT, and decreasing the infarct size. This cardioprotective effect could be due to its prevention of cardiac mitochondrial dysfunction caused by severe oxidative stress during I/R.</AbstractText>Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,445 | Polymorphic ventricular tachycardia in a patient with herpes encephalitis. | We present a patient with polymorphic ventricular tachycardia and subsequent ventricular fibrillation with acquired long QT syndrome secondary to herpes encephalitis. |
14,446 | Growth differentiation factor-15, a novel biomarker related with disease severity in patients with hypertrophic cardiomyopathy. | The growth differentiation factor 15 (GDF-15) has been shown up-regulated in stress conditions and to have regulatory actions in myocyte hypertrophy. We hypothesized that GDF-15 could be related to disease severity and functional status in patients with hypertrophic cardiomyopathy (HCM).</AbstractText>We performed a study which includes 102 consecutive outpatient HCM subjects, 73% males, aged 47.1±14.6 years. A complete history and clinical examination was performed, including 12-lead electrocardiogram, echocardiography, symptom-limited treadmill exercise, 24-hour ECG-Holter monitoring, and magnetic resonance with Gadolinium. Several biomarkers, associated with myocardial remodeling and damage, were compared to GDF-15 levels. The assays were performed with commercial ELISAs or standardized methods when available. There was a significant association between GDF-15 levels and comorbidities, being higher in hypertension (p=0.001), diabetes (p=0.030), atrial fibrillation (p=0.012), dyspnea (p=0.020) and NYHA≥II functional class (p=0.037). GDF-15 levels were positively correlated with clinical variables (age, worse exercise capacity and mild renal dysfunction) and biomarkers of interstitial remodeling, such as metalloproteinase-2 (r: 0.40; p=0.009), N-terminal pro-B-type natriuretic peptide (r: 0.28; p=0.049), high-sensitivity troponin T (r: 0.30; p=0.003) and von Willebrand factor (r: 0.33; p=0.001). Multivariate analysis was assessed to estimate the involvement of these different factors in the GDF-15 levels, confirming the independent implication of severe dyspnea and functional status.</AbstractText>The present results show that higher levels of GDF-15 are associated to conditions of severe disease in HCM. Hence, GDF-15 is suggested as a novel marker related to the severity and could represent a further useful tool in monitoring functional capacity of HCM patients.</AbstractText>Copyright © 2011 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.</CopyrightInformation> |
14,447 | Amiodarone (Nexterone) injection for the treatment and prophylaxis of frequently recurring ventricular fibrillation. | Intravenous (IV) amiodarone is the most used and effective drug to manage life-threatening ventricular arrhythmias. However, its administration is associated with important adverse effects, the most frequent of which is hypotension. Nexterone® is a novel IV amiodarone formulation, proved to be devoid of hypotensive effects in clinical studies and may represent an improved and safer instrument in this setting.</AbstractText>The Medline Database was searched for articles on the efficacy and safety of IV amiodarone in ventricular arrhythmias and cardiac arrest. This article summarizes the key findings of the most relevant studies conducted so far, with a special attention to the limitations of the currently available IV amiodarone and the potential advantages of the recently approved Nexterone. The role given to IV amiodarone in the guidelines on Advanced Cardiovascular Life Support is also reported and discussed.</AbstractText>Available studies demonstrated a convincing efficacy of IV amiodarone in ventricular arrhythmias and cardiac arrest. The new formulation seems to resolve concerns about tolerability. However, despite proven antiarrhythmic efficacy of the drug, no improved survival was showed in different settings. The search for an antiarrhythmic drug able to impact on hard endpoint as survival to hospital discharge is therefore far from being concluded.</AbstractText> |
14,448 | Atrial fibrillation: established and innovative methods of evaluation and treatment. | 5% to 8% of 70-year-olds and some 10% of persons over age 80 have atrial fibrillation (AF).</AbstractText>Selective literature review.</AbstractText>New scoring schemes (CHA(2)DS(2)-VASc score, HAS-BLED score) have been introduced to enable more accurate estimation of the risk of stroke and hemorrhage in patients with AF. These scores are calculated on the basis of clinical data (left ventricular dysfunction, hypertension, age, diabetes, prior stroke, vascular diseases, sex, renal or hepatic dysfunction, bleeding, labile INR values, consumption of medications and alcohol) and are used to determine the potential indication for, and appropriate type of, anticoagulation in the individual AF patient. Hemodynamically unstable patients with rapid AF should undergo DC cardioversion at once. Patients with permanent AF should be given beta-blockers, calcium antagonists, or digitalis for rate control, with a target rate below 110/minute. A recently introduced drug, dronedarone, is used for rhythm control and has relatively few side effects. Patients with AF and impaired left ventricular function should be given amiodarone. Rhythm control has not been found to prolong life any more than rate control. Patients with a CHA(2)DS(2)-VASc score of 2 or above should be orally anticoagulated. Those with a score of 1 can be treated with aspirin (75 to 325 mg daily); those with a score of 0 do not need antithrombotic treatment. A HAS-BLED score of 3 or above is associated with a high risk of bleeding. Pulmonary vein isolation is an established method of treating symptomatic AF, with a success rate of 60% to 80%. Surgical procedures are possible in AF patients who need additional cardiac surgery.</AbstractText>The treatment strategy for AF must be individualized on the basis of the patient's clinical manifestations. The mainstay of treatment is anticoagulation; the indication for anticoagulation depends on the patient's age, underlying disease, and left ventricular function.</AbstractText> |
14,449 | Effects of testosterone on norepinephrine release in isolated rat heart. | The effects of testosterone on norepinephrine release were investigated in the isolated rat hearts. Sprague-Dawley male rats (n=120) were randomized to testosterone and control groups. The rats in testosterone group were perfused with modified Krebs-Henseleit buffer containing different concentrations of testosterone (0.1, 1.0, 10.0, and 100.0 nmol/L, respectively). Myocardial ischemia was induced by globally stopping the perfusion flow. Exocytotic norepinephrine release was induced by electrical field stimulation at 5 V (effective voltage) and 6 Hz (pulse width of 2 ms) for 1 min. The overflow of norepinephrine was determined by high pressure liquid chromatography and electrochemical detection (HPLC-EC). Following acute ischemia, testosterone (1.0, 10.0 and 100.0 nmol/L) significantly reduced norepinephrine release (P<0.01), and the norepinepherine overflow was similar between the control and 0.1 nmol/L testosterone group (P>0.05). Electrical stimulation of the ventricle evoked norepinepherine release, and this was diminished by the perfusion with testosterone at the concentrations of 1.0, 10.0 and 100.0 nmol/L (P<0.01). It is suggested that testosterone suppresses ischemia- and electrical stimulation-induced norepinepherine release in the isolated rat hearts. |
14,450 | [Evaluation of clinical and demographic characteristics and their association with length of hospital stay in patients admitted to cardiac intensive care unit with the diagnosis of acute heart failure]. | Despite increasing incidence, data regarding clinical and demographic characteristics of patients with acute heart failure (AHF) admitted to cardiac intensive care unit (ICU) are inconclusive. The aim of this study was to assess the presentation characteristics and factors determining the length of hospital stay in this particular patient population.</AbstractText>We conducted a single-center, prospective study involving 150 patients hospitalized to cardiac ICU with the primary diagnosis of AHF. Chi-square and Student t tests were used for the analysis of categorical and continuous variables, respectively. Linear regression analysis (LRA) was used to determine the factors affecting the length of hospital stay.</AbstractText>Forty-nine percent of the patients had new-onset AHF and 25% had preserved left ventricular ejection fraction (LVEF). In 25.3% of all patients and 46.6% of the patients with new-onset HF the precipitating factor was acute coronary syndrome. Atrial fibrillation and valvular heart disease as precipitating factors were more common in patients with preserved EF, when compared to low EF group. LRA showed that presence of anemia [β=1.62; 95% CI 0.08-3.15; p=0.039)] and severe mitral regurgitation (β=2.55; 95% CI 0.06-5.05; p=0.045) and systolic blood pressure (β=-0.03; 95% CI -0.06 - -0.002; p=0.039) and blood urea nitrogen (β=0.034; 95% CI 0.006 - 0.06; p=0.016) were the independent predictors of length of stay.</AbstractText>Underlying cardiovascular risk factors, comorbidities and precipitating pathologies were diverse and highlighted the inhomogeneous characteristics of AHF syndromes. However, in-hospital mortality was high and initial clinical presentation characteristics were significantly associated with in-hospital outcome.</AbstractText> |
14,451 | Prediction protocol for neurological outcome for survivors of out-of-hospital cardiac arrest treated with targeted temperature management. | To identify patients who can obtain the full benefit from targeted temperature management (TTM) after out-of-hospital cardiac arrest.</AbstractText>We performed a retrospective observational study of comatose patients treated with TTM after an out-of-hospital cardiac arrest from January 2006 to February 2011. Neurological outcome was evaluated with the Glasgow-Pittsburgh Cerebral Performance category (CPC) at discharge and predictors were determined.</AbstractText>Of 66 patients studied, 40 (60.6%) survived to neurologically intact discharge (CPC 1 or 2). According to multivariate analysis, predictors of good neurological outcome included arrest-to-first cardiopulmonary resuscitation attempt interval ≤5 min, ventricular fibrillation or ventricular tachycardia in the first monitored rhythm, absence of re-arrest before leaving the emergency department, arrest-to-return of spontaneous circulation interval ≤30 min and recovery of pupillary light reflex, which were identifiable in the emergency department. Based on this analysis, we developed a seven-point score (5-R score). If the score was ≥5, it predicted good neurological outcome with a sensitivity of 82.5% (95% confidence interval [CI], 67.2-92.7%) and specificity of 92.3% (95% CI, 74.9-99.1%). The negative predictive value of a score ≥4 was 100% (95% CI, 81.5-100%). Our prediction model was validated internally by a bootstrapping technique.</AbstractText>The prediction protocol using the 5-R score was associated with good neurological outcome of patients treated with TTM. Therefore, it could be helpful in clinical decision making on whether to initiate cooling.</AbstractText>Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,452 | Unusual case of right atrial reinfarction. | It is well known that atrial infarctions are rare comparing to the ventricular. They cannot easily be verified on ECG and the standard autopsy technique does not include a detailed review of the atrial wall, so the atrial infarction often remains undiagnosed. A 63-year-old male was treated and died in an intensive care unit due to decompensated liver insufficiency and cardiac disease following long-lasting alcohol abuse. At autopsy, the extreme cardiomegaly was found, severe atherosclerosis of the anterior descending branch of left coronary artery. The posterior wall of the right atrium was thickened (cca 9 mm) in diameter of cca 3 × 3 cm, and this area was yellowish in the luminal part, while the central part was filled with dark red blood. A detailed dissection of the coronary arteries showed the complete occlusion of the atrial branch of the right coronary artery wreath as far as the place of sinoatrial artery branching, which corresponded anatomically to the described area of infarction on the posterior wall of the right atrium. Histopathological examination of the previously described area of the posterior wall of the right atrium, showed four zones of heart muscle changes: 1. zone of partially preserved structure of the heart muscle, 2. zone of cellular (immature) connective tissue, 3. areas of bleeding in cellular connective tissue, and 4. zone of acellular (old) connective tissue. These histopathological changes indicated that the posterior wall of the right atrium was affected by myocardial necrosis in at least two and possibly more times. It is reasonable to think that bleeding in the third zone of the posterior wall of the right atrium contributed greatly to the death due to the anatomical proximity to the sinoatrial node. It was confirmed by the existence of bradycardia with a prolonged PR interval, PR segment elevation in D1 and aVL lead and PR depression in the D3 lead on the ECG. These ECG changes appeared immediately before asystolia and the death of the patient, but not ventricular fibrillation or electromechanical dissociation due to ventricular infarction. The presented case shows that detailed autopsy examination of atrial wall and blood vessels can sometimes be crucial in disclosing the cause and mode of death if the ischemia and necrosis attack only the atrial wall, especially in the region of the heart conduction system. |
14,453 | Right intra-atrial catheter placement for hemodialysis in patients with multiple venous failure. | The purpose of this study is to evaluate the efficacy and safety of direct right atrial catheter insertion for hemodialysis in patients with multiple venous access failure. We retrospectively evaluated the charts of 27 patients with multiple venous access failure who had intra-atrial dialysis catheter placement between October 2005 and October 2010 in our clinic. Permanent right atrial dialysis catheters were placed through a right anterior mini-thoracotomy under intratracheal general anesthesia in all patients. Demographics of the cases, the patency rates of hemodialysis via atrial catheterization, existence of any catheter thrombosis, and catheter-related infections were documented and used in statistical analysis. Seventeen women (63%) and 10 men (37%) with the mean age of 59.0 ± 7.1 years (47-71) were enrolled in this study. Chronic renal failure was diagnosed for the mean of 78.9 ± 24.3 months (33-130). Five patients (18.5%) died. Ventricular fibrillation and myocardial infarction were the causes of death in the early postoperative period in two patients. Two of the remaining three patients died because of cerebrovascular events, and one patient died because of an unknown cause. Ten patients (37%) had been using anticoagulate agents (warfarin) because of concomitant disorders such as deep vein thrombosis, operated valve disease, and arrhythmias. Catheter thrombosis and malfunction was determined in three cases (11.1%). Intra-atrial hemodialysis catheterization is a safe and effective life-saving measure for the patients with multiple venous failure and without any possibility of peritoneal dialysis or renal transplantation. |
14,454 | Early increase in blood glucose in patients resuscitated from out-of-hospital ventricular fibrillation predicts poor outcome. | To describe the trend of blood glucose immediately after successful resuscitation from out-of-hospital ventricular fibrillation.</AbstractText>Data from cardiac arrest registry supplemented with blood glucose data were analyzed in this population-based observational study. Between 2005 and 2009, a total of 170 adult patients survived to hospital admission after resuscitation from bystander-witnessed cardiac arrest of cardiac origin and ventricular fibrillation as an initial rhythm.</AbstractText>Sufficient data for analysis were available in 134 (79%) patients, of whom 87 (65% [95% CI 57-73]) survived to hospital discharge in Cerebral Performance Category 1 or 2. Blood glucose did not change significantly between prehospital (10.5 ± 4.1 mmol/L) and admission (10.0 ± 3.7 mmol/L) in survivors (P = 0.3483), whereas in nonsurvivors, blood glucose increased from 11.8 ± 4.6 to 13.8 ± 3.3 mmol/L (P = 0.0025).</AbstractText>Patients who are resuscitated from out-of-hospital ventricular fibrillation, but whose outcome is unfavorable are characterized by significant increase of blood glucose in the ultraacute postresuscitation phase.</AbstractText> |
14,455 | The natural history of preclinical diastolic dysfunction: a population-based study. | Preclinical diastolic dysfunction (PDD) has been broadly defined as subjects with left ventricular diastolic dysfunction, without the diagnosis of congestive heart failure (HF) and with normal systolic function. Our objective was to determine the risk factors associated with the progression from PDD (stage B) HF to symptomatic (stage C) HF.</AbstractText>Using the resources of the Rochester Epidemiology Project, all residents of Olmsted County, MN, who underwent echocardiography between January 1, 2004, and December 31, 2005, and had grade 2-4 diastolic dysfunction and ejection fraction ≥50% were identified. Patients with a diagnosis of HF before or within 30 days of the echocardiogram were excluded. Patients were also excluded if they had a diagnosis of atrial fibrillation or severe mitral or aortic valve regurgitation at the time of the echocardiogram. A total of 388 patients met the inclusion criteria. The mean age of the cohort was 67±12 years, with a female (57%) predominance. Prevalence of renal insufficiency (estimated glomerular filtration rate <60 mL/min per 1.73 m(2)) was 34%. The 3-year cumulative probabilities of development of (stage C) HF, development of atrial fibrillation, cardiac hospitalization, and mortality were 11.6%, 14.5%, 17.7%, and 10.1% respectively. In multivariable Cox proportional hazard regression analysis, we determined that age, renal dysfunction, and right ventricular systolic pressure were independently associated with the development of HF.</AbstractText>This population-based study demonstrated that in PDD (stage B) HF, there was a moderate degree of progression to symptomatic (stage C) HF over 3 years, and renal dysfunction was associated with this progression independent of age, sex, hypertension, coronary disease, and ejection fraction.</AbstractText> |
14,456 | Device troubleshooting: cross connection of ventricular leads in a patient with decreased right ventricular electrical activity. | A patient with cardiac sarcoidosis showed low R-wave amplitude in the entire right ventricle (RV). To troubleshoot this, a left ventricular (LV) lead was implanted in the coronary vein. The pace/sense terminal of the defibrillation lead was connected to LV:IS-1 of the defibrillator. Conversely, the LV lead was connected to RV:IS-1. Induced ventricular fibrillation was successfully terminated without any undersensing. |
14,457 | Atrial burst pacing with biphasic and monophasic waveforms for atrial fibrillation. | Biphasic pacing is a novel mode of pacing that was suggested to increase cardiac conduction velocity as compared with cathodal monophasic pacing. We aimed to evaluate the safety and efficacy of rapid atrial pacing to convert atrial fibrillation (AF) to normal sinus rhythm.</AbstractText>Multiple biphasic (anodal/cathodal), reverse biphasic (cathodal/anodal), and monophasic (cathodal) atrial pacing therapies were performed among 12 patients undergoing left atrial catheter ablation for AF. The efficacy end point was successful conversion of AF to sinus rhythm, and safety end point no induction of ventricular arrhythmias. Patients were paced at three cycle lengths (100, 200, and 333 msec) for 60 seconds at three locations (right and left atrial appendages and coronary sinus).</AbstractText>Among the 66 biphasic (anodal/cathodal) pacing procedures one procedure in a patient with chronic AF, which involved pacing at the left atrial appendage with a cycle length of 200 msec, led to conversion of AF to sinus rhythm. None of the 66 monophasic pacing procedures or the 66 reverse biphasic (cathodal/anodal) pacing procedures was associated with AF termination. None of the biphasic pacing procedures was associated with induction of ventricular arrhythmias.</AbstractText>Rapid atrial pacing using a variety of waveforms at the cycle length and output used in the current study was found to be safe. There was a single success in converting a chronic AF to sinus rhythm.</AbstractText>© 2012, Wiley Periodicals, Inc.</CopyrightInformation> |
14,458 | [Arrhythmogenic effects of alcohol]. | Acute or chronic excessive consumption of alcohol can cause cardiac arrhythmias, particularly supraventricular tachyarrhythmias. Experimental and clinical data show that chronic excessive alcohol ingestion has a destructive role on cardiac tissue, which significantly deteriorates the rhythm and contractile activity, manifested by the appearance of cardiac arrythmias and dilated cardiomyopathy.</AbstractText>The aim of this study was to evaluate and analyze the ECG changes and disturbances of cardiac rhythm and conduction in patients after an acute or chronic excessive consumption of alcohol.</AbstractText>The study included 187 patients (184 males and 3 females). Each patient followed biochemical and hematological analysis as well as paraclinical investigation measurements.</AbstractText>The most common types of arrhythmia were permanent atrial fibrillation (61%). Paroxysmal atrial fibrillation and supraventricular extrasystoles were found in patients without significant echocardiographic deteriorations. These arrhythmias appeared after an excessive alcohol drinking and paroxysmal atrial fibrillation was converted to normal sinus rhythm after a short period of abstinence or after pharmacologic therapy. Ventricular arrhythmias (ventricular extrasystoles, non-sustained ventricular tachycardia-4.7%, torsada de point-1.5%) were less frequent. Conduction disturbance (left bundle branch-LBBB 6.3%, right bundle branch-RBBB 10%) were found in patients who had a history of consuming >150 g/day of alcohol for >10 years, with dilated heart chambers and systolic ventricular function much more deteriorated (symptomatic stage of heart failure).</AbstractText>Excessive alcohol consumption may lead to cardiac arrhythmias in patients with existing heart disease as well as in healthy individuals.</AbstractText> |
14,459 | Integration of intracardiac echocardiographic imaging of the left atrium with electroanatomic mapping data for pulmonary vein isolation: first-in-Greece experience with the CartoSound™ system and brief literature review. | Intracardiac echocardiography (ICE) offers the ability to image the left atrium in order to reconstruct a three-dimensional model that can be integrated with electroanatomic data to guide pulmonary vein isolation. We report a case series representing the first-in-Greece experience with the CartoSound module.</AbstractText>Patients with paroxysmal or persistent atrial fibrillation (AF) referred for pulmonary vein isolation were included in this case-series. The SoundStar ICE catheter was used to trace left atrial and pulmonary vein contours from the right atrium, the right ventricular outflow tract and the coronary sinus.</AbstractText>Eight patients (age 66.3 ± 1.6 years) are presented in this case-series report. Six of them (75%) had paroxysmal AF and the rest were in persistent AF for less than one year. The time for ICE imaging and left atrium three-dimensional reconstruction decreased from a median of 20.5 minutes (interquartile range 19.3-23.3) for the chronologically first four cases to a median of 16.5 minutes (interquartile range 14.517.0) for the chronologically last four cases (p=0.02). The procedure was completed in all cases. No significant periprocedural complications were encountered. Acute success, with restoration of sinus rhythm, was achieved in both patients with persistent AF. Seven of the eight patients (87.5%) were AF-free in 48-hour Holter recordings one week after the procedure.</AbstractText>ICE integration into three-dimensional electroanatomic reconstruction of the left atrium provides reliable guidance for pulmonary vein isolation. It appears that this modality is a sound alternative to magnetic resonance and computed tomography image data registration, although randomized comparisons are lacking.</AbstractText> |
14,460 | Modeling defibrillation of the heart: approaches and insights. | Cardiac defibrillation, as accomplished nowadays by automatic, implantable devices (ICDs), constitutes the most important means of combating sudden cardiac death. While ICD therapy has proved to be efficient and reliable, defibrillation is a traumatic experience. Thus, research on defibrillation mechanisms, particularly aimed at lowering defibrillation voltage, remains an important topic. Advancing our understanding towards a full appreciation of the mechanisms by which a shock interacts with the heart is the most promising approach to achieve this goal. The aim of this paper is to assess the current state-of-the-art in ventricular defibrillation modeling, focusing on both numerical modeling approaches and major insights that have been obtained using defibrillation models, primarily those of realistic ventricular geometry. The paper showcases the contributions that modeling and simulation have made to our understanding of the defibrillation process. The review thus provides an example of biophysically based computational modeling of the heart (i.e., cardiac defibrillation) that has advanced the understanding of cardiac electrophysiological interaction at the organ level and has the potential to contribute to the betterment of the clinical practice of defibrillation. |
14,461 | Left atrial volume and function in patients with Behcet's disease assessed by real-time three-dimensional echocardiography. | Behçet's disease (BD), a multisystemic inflammatory disorder, has been associated with a number of cardiovascular dysfunctions, including endomyocardial fibrosis of the right heart, atrial fibrillation, ventricular arrhythmias and sudden cardiac death. The incidence and nature of cardiac involvement in BD are not yet clearly documented. Our aim was to evaluate left atrial (LA) volume and functions using real-time three-dimensional echocardiography (RT3DE) in Behcet's patients without any cardiac symptom.</AbstractText>The study included 40 BD (16 females, 24 males and mean age of 33±7 years) and 30 healthy (11 females, 19 males and mean age of 35±6 years) subjects. All the patients' demographic parameters such as age, gender, and duration of BD were recorded. All the individuals underwent comprehensive 2D echocardiography examination, and RT3DE was performed to assess LA volumes and mechanical functions. LA maximum volume (Vmax) and before atrial contraction volume (Vpre A), LA active stroke volume and total stroke volumes (TSV), total emptying and active emptying fractions and expansion index were significantly higher in Behcet's disease patients when compared with the controls (P<0.0001 for all). LA passive emptying fraction was significantly lower in the patients with BD than in the controls (41±7 vs. 44±5, P=0.039). There were positive correlations between TSV and high-sensitive C-reactive protein level (r=0.413, P=0.008), TSV, and disease duration (r=0.417, P<0.007).</AbstractText>Our study has shown that LA mechanical functions and volumes are impaired in BD. These results may be an early form of subclinical cardiac involvement in patients with BD who have no clinical evidence for cardiovascular disease.</AbstractText> |
14,462 | Predictors of long-term benefit of cardiac resynchronization therapy in patients with right bundle branch block. | The aims of this study were: (i) to characterize consecutive cardiac resynchronization therapy (CRT) recipients with right bundle branch block (RBBB) in comparison with left bundle branch block (LBBB) and (ii) to identify independent predictors of long-term outcome among CRT recipients with RBBB. The presence of RBBB has been associated with poorer prognosis after CRT compared with LBBB; however, little is known about the differences in cardiac mechanics between RBBB and LBBB patients. Furthermore, predictors of favourable outcome after CRT in patients with RBBB have not been identified.</AbstractText>Five hundred and sixty-one consecutive CRT recipients (89 with RBBB and 472 with LBBB) underwent echocardiography before and 6 months after CRT to determine left ventricular (LV) size and function, and interventricular and LV dyssynchrony (as measured by tissue Doppler imaging). Long-term follow-up to identify a composite endpoint of all-cause mortality or heart failure hospitalization was available. Right bundle branch block patients exhibited a higher prevalence of male gender, ischaemic heart disease, atrial fibrillation, and lower exercise capacity when compared with LBBB patients, despite smaller LV volumes. In addition, the extent of both interventricular and LV dyssynchrony was less in RBBB patients. Six months after CRT, RBBB patients also showed limited LV reverse remodelling. At long-term follow-up, LV dyssynchrony and mitral regurgitation were identified as independent predictors of all-cause mortality or heart failure hospitalization among RBBB patients.</AbstractText>Left ventricular dyssynchrony may be an important determinant of outcome following CRT in patients with RBBB and may help in the selection of CRT candidates.</AbstractText> |
14,463 | [Progress in cardiac electrophysiology and arrhythmias]. | This article contains a review of the most important publications in the field of cardiac electrophysiology and arrhythmias that have appeared in the last year. Publications were selected because they reported important scientific developments or significant improvements in the devices or invasive techniques used for the treatment of arrhythmias. |
14,464 | A randomized trial of compression first or analyze first strategies in patients with out-of-hospital cardiac arrest: results from an Asian community. | It is still under debate whether a period of cardiopulmonary resuscitation should be performed prior to rhythm analysis for defibrillation for out of hospital cardiac arrests (OHCA). This study compared outcomes of OHCA treated by "compression first" (CF) versus "analyze first" (AF) strategies in an Asian community with low rates of shockable rhythms.</AbstractText>This randomized trial was conducted in Taipei City between February 2008 and December 2009. Dispatches of suspected OHCA that activated advanced life support teams were randomized into the CF and AF strategies. Patients assigned to CF strategy received 10 cycles of CPR prior to analysis by automatic external defibrillator. The primary outcome was sustained (>2 h) return of spontaneous circulation (ROSC) and secondary outcome was survival to hospital discharge.</AbstractText>We included 289 cases in the final analysis after exclusion by pre-specified criteria, 141 were allocated to CF strategy and 148 to AF strategy. Baseline characteristics were similar. Thirty-seven (26.2%) of those receiving CF strategy and 49 (33.1%) of the AF strategy achieved sustained ROSC (p=0.25). In a post-hoc analysis of patients who achieved ROSC, those that received CF strategy were more likely to be discharged alive from the hospital (16/37=43.2% vs. 11/49=22.4%, p=0.02).</AbstractText>In this study population of low rates of shockable rhythms, there was no difference in ROSC for CF or AF strategies. Considering the EMS operation situations, a period of paramedic-administered CPR for up to 10 cycles prior to rhythm analysis could be a feasible strategy in this community.</AbstractText>Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,465 | Atrial electrical and structural remodeling associated with longstanding pulmonary hypertension and right ventricular hypertrophy in humans. | Pulmonary hypertension (PH) is common to a range of cardiopulmonary conditions and is associated with atrial arrhythmias. However, little is known of the isolated atrial effects of PH and right atrial dilatation (RA) in humans. To avoid the confounding effects of PH-associated disease states, we performed detailed electrophysiological (EP) and electroanatomic (EA) mapping of the RA in patients with idiopathic PH.</AbstractText>Eight PH patients (mean pulmonary arterial [PA] pressure 39.0 ± 15.8 mmHg) and 16 age-matched controls (mean PA pressure 11.5 ± 4.1 mmHg, P < 0.0001) were studied. Corrected sinus node recovery times (cSNRT), atrial effective refractory periods (ERPs), conduction delay at the crista terminalis (CT), and inducibility of atrial fibrillation (AF) were evaluated. EA mapping (pacing cycle length 600 and 300 milliseconds) was performed to determine RA global and regional voltage, conduction velocities, atrial activation times, fractionated electrograms and double potentials. Patients with PH demonstrated a prolongation in cSNRT without significant change in atrial ERP and an increase in AF inducibility. PH was associated with lower tissue voltage (1.8 ± 0.4 mV in PH vs 2.2 ± 0.4 mV in controls, P = 0.02), increased low voltage areas (13.7 ± 8.2% in PH vs 6.2 ± 3.7% in controls, P < 0.01) and the presence of electrically silent areas. Conduction velocities were slower (global 67.3 ± 5.6 cm/s vs 92.8 ± 4.0 cm/s, P < 0.001) and fractionated electrograms and double potentials were more prevalent (14.7 ± 4.4% vs 6.3 ± 4.1, P < 0.01) in PH compared with controls, respectively.</AbstractText>Idiopathic PH is associated with RA remodeling characterized by: generalized conduction slowing with marked regional abnormalities; reduced tissue voltage; and regions of electrical silence. These changes provide important insights into the isolated effects of PH fundamental to a range of clinical conditions associated with AF.</AbstractText>© 2012 Wiley Periodicals, Inc.</CopyrightInformation> |
14,466 | Studying semblances of a true killer: experimental model of human ventricular fibrillation. | It is unknown whether ventricular fibrillation (VF) studied in experimental models represents in vivo human VF. First, we examined closed chest in vivo VF induced at defibrillation threshold testing (DFT) in four patients with ischemic cardiomyopathy pretransplantation. We examined VF in these same four hearts in an ex vivo human Langendorff posttransplantation. VF from DFT was compared with VF from the electrodes from a similar region in the right ventricular endocardium in the Langendorff using two parameters: the scale distribution width (extracted from continuous wavelet transform) and VF mean cycle length (CL). In a second substudy group where multielectrode phase mapping could be performed, we examined early VF intraoperatively (in vivo open chest condition) in three patients with left ventricular cardiomyopathy. We investigated early VF in the hearts of three patients in an ex vivo Langendorff and compared findings with intraoperative VF using two metrics: dominant frequency (DF) assessed by the Welch periodogram and the number of phase singularities (lasting >480 ms). Wavelet analysis (P = 0.9) and VF CL were similar between the Langendorff and the DFT groups (225 ± 13, 218 ± 24 ms; P = 0.9), indicating that wave characteristics and activation rate of VF was comparable between the two models. Intraoperative DF was slower but comparable with the Langendorff DF over the endocardium (4.6 ± 0.1, 5.0 ± 0.4 Hz; P = 0.9) and the epicardium (4.5 ± 0.2, 5.2 ± 0.4 Hz; P = 0.9). Endocardial phase singularity number (9.6 ± 5, 12.1 ± 1; P = 0.6) was lesser in number but comparable between in vivo and ex vivo VF. VF dynamics in the limited experimental human studies approximates human in vivo VF. |
14,467 | Intramural optical mapping of V(m) and Ca(i)2+ during long-duration ventricular fibrillation in canine hearts. | Intramural gradients of intracellular Ca(2+) (Ca(i)(2+)) Ca(i)(2+) handling, Ca(i)(2+) oscillations, and Ca(i)(2+) transient (CaT) alternans may be important in long-duration ventricular fibrillation (LDVF). However, previous studies of Ca(i)(2+) handling have been limited to recordings from the heart surface during short-duration ventricular fibrillation. To examine whether abnormalities of intramural Ca(i)(2+) handling contribute to LDVF, we measured membrane voltage (V(m)) and Ca(i)(2+) during pacing and LDVF in six perfused canine hearts using five eight-fiber optrodes. Measurements were grouped into epicardial, midwall, and endocardial layers. We found that during pacing at 350-ms cycle length, CaT duration was slightly longer (by ≃10%) in endocardial layers than in epicardial layers, whereas action potential duration (APD) exhibited no difference. Rapid pacing at 150-ms cycle length caused alternans in both APD (APD-ALT) and CaT amplitude (CaA-ALT) without significant transmural differences. For 93% of optrode recordings, CaA-ALT was transmurally concordant, whereas APD-ALT was either concordant (36%) or discordant (54%), suggesting that APD-ALT was not caused by CaA-ALT. During LDVF, V(m) and Ca(i)(2+) progressively desynchronized when not every action potential was followed by a CaT. Such desynchronization developed faster in the epicardium than in the other layers. In addition, CaT duration strongly increased (by ∼240% at 5 min of LDVF), whereas APD shortened (by ∼17%). CaT rises always followed V(m) upstrokes during pacing and LDVF. In conclusion, the fact that V(m) upstrokes always preceded CaTs indicates that spontaneous Ca(i)(2+) oscillations in the working myocardium were not likely the reason for LDVF maintenance. Strong V(m)-Ca(i)(2+) desynchronization and the occurrence of long CaTs during LDVF indicate severely impaired Ca(i)(2+) handling and may potentially contribute to LDVF maintenance. |
14,468 | Combined cardiac magnetic resonance imaging and C-reactive protein levels identify a cohort at low risk for defibrillator firings and death. | Annually, ≈80,000 Americans receive guideline-based primary prevention implantable cardioverter-defibrillators (ICDs), but appropriate firing rates are low. Current selection criteria for ICDs rely on left ventricular ejection fraction, which lacks sensitivity and specificity. Because scar-related myocardial tissue heterogeneity is a substrate for life-threatening arrhythmias, we hypothesized that cardiac magnetic resonance identification of myocardial heterogeneity improves risk stratification through (1) its association with adverse cardiac events independent of clinical factors and biomarker levels and (2) its ability to identify particularly high- and low-risk subgroups.</AbstractText>In 235 patients with chronic ischemic and nonischemic cardiomyopathy with a left ventricular ejection fraction of ≤35% undergoing clinically indicated primary prevention ICD implantation, gadolinium-enhanced cardiac magnetic resonance was prospectively performed to quantify the amount of heterogeneous myocardial tissue (gray zone [GZ]) and dense core scar. Serum high-sensitivity C-reactive protein (hsCRP) and other biomarkers were assayed. The primary end point was appropriate ICD shock for ventricular tachycardia/fibrillation or cardiac death, which occurred in 45 (19%) patients at a 3.6-year median follow-up. On univariable analysis, only diuretics, hsCRP, GZ, and core scar were associated with outcome. After multivariable adjustment, GZ and hsCRP remained independently associated with outcome (P<0.001). Patients in the lowest tertile for both GZ and hsCRP (n=42) were at particularly low risk (0.7% per year event rate), whereas those in the highest tertile for both GZ and hsCRP (n=32) had an event rate of 16.1% per year, P<0.001.</AbstractText>In a cohort of primary prevention ICD candidates, combining a myocardial heterogeneity index with an inflammatory biomarker identified a subgroup with a very low risk for adverse cardiac events, including ventricular arrhythmias. This novel approach warrants further investigation to confirm its value as a clinical risk stratification tool. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00181233.</AbstractText> |
14,469 | Assessment of left atrial mechanics in patients with atrial fibrillation: comparison between two-dimensional speckle-based strain and velocity vector imaging. | Two-dimensional (2D) speckle tracking-derived left atrial (LA) strain (ε) facilitates comprehensive evaluation of LA contractile, reservoir, and conduit function; however, its dependence on the individual software used for assessment has not been evaluated. The aim of this study was to compare LA ε derived from two different speckle-tracking software technologies, Velocity Vector Imaging (VVI) and 2D speckle-tracking echocardiography (STE).</AbstractText>VVI-derived and 2D STE-derived global longitudinal LA ε and ε rate (SR) were directly compared in 127 patients (mean age, 62 ± 10 years) with atrial fibrillation. Peak negative, peak positive, and total ε (corresponding to LA contractile, conduit, and reservoir function) were measured during sinus rhythm. Late negative (LA contraction), peak positive (left ventricular systole), and early negative (left ventricular early diastole) SR were also measured.</AbstractText>The measurement of LA ε and SR by both software was feasible in high proportions of patients (93% with VVI and 93% with 2D STE). The average analysis of ε(negative) was -7.24 ± 3.87% by VVI and -7.30 ± 3.37% by 2D STE (P = .84). The average analysis of ε(positive) was 14.52 ± 5.82% by VVI and 10.74 ± 4.51% by 2D STE (P < .01). The average analysis of ε(total) was 21.76 ± 7.39% by VVI and 18.04 ± 5.98% by 2D STE (P < .01). VVI-derived and 2D STE-derived ε(positive), ε(negative), and ε(total) had good correlations with one another (R = 0.79, R = 0.75, and R = 0.80), with low mean differences. Late negative, peak positive, and early negative SR were correlated less well (R = 0.78, R = 0.71, and R = 0.67).</AbstractText>LA ε measurement using both VVI and 2D STE is feasible in a large proportion of patients in clinical practice. VVI and 2D STE provide comparable LA ε and SR measurements for LA contractile function.</AbstractText>Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
14,470 | Association of heart rate variability with arrhythmic events in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia. | Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is associated with an increased risk of sudden cardiac death (SCD). Risk stratification of ARVC/D patients, however, remains an unresolved issue. In this study we investigated whether heart rate variability (HRV) can be helpful in identifying ARVC/D patients with increased risk of arrhythmic events.</AbstractText>We studied 30 consecutive patients (17 males; 45.4 ± 18 years) with ARVC/D, diagnosed according to guideline criteria; 15 patients (50%) had received an implantable cardioverter defibrillator (ICD) for primary SCD prevention. HRV was assessed on 24-h ECG Holter monitoring. The primary endpoint was the occurrence of major arrhythmic events (SCD, sustained ventricular tachycardia (VT), ICD therapy for sustained VT or ventricular fibrillation (VF)). During the follow-up period (19 ± 7 months), no deaths occurred, but 5 patients (17%) experienced arrhythmic events (4 VTs and 1 VF, all in the ICD group). All HRV parameters were significantly lower in patients with, compared with those without, arrhythmic events. Low-frequency amplitude was the most significant HRV variable associated with arrhythmic events in univariate Cox regression analysis (P=0.017), and was the only significant predictor of arrhythmic events in multivariable regression analysis (hazard ratio 0.88, P=0.047), together with unexplained syncope (hazard ratio 16.1, P=0.039).</AbstractText>Our data show that among ARVC/D patients HRV analysis might be helpful in identifying those with increased risk of major arrhythmic events.</AbstractText> |
14,471 | Radiofrequency catheter ablation in children with supraventricular tachycardias: intermediate term follow up results. | Radiofrequency (RF) catheter ablation represents an important advance in the management of children with cardiac arrhythmias and has rapidly become the standard and effective line of therapy for supraventricular tachycardias (SVTs) in pediatrics. The purpose of this study was to evaluate the intermediate term follow up results of radiofrequency catheter ablation in treatment of SVT in pediatric age group.</AbstractText>A total of 60 pediatric patients (mean age = 12.4 ± 5.3 years, ranged from 3 years to 18 years; male: female = 37:23; mean body weight was 32.02 ± 12.3 kg, ranged from 14 kg to 60 kg) with clinically documented SVT underwent an electrophysiologic study (EPS) and RF catheter ablation at Children's Hospital Mansoura University, Mansoura, Egypt during the period from January 2008 to December 2009 and they were followed up until October 2011.</AbstractText>The arrhythmias included atrioventricular reentrant tachycardia (AVRT; n = 45, 75%), atrioventricular nodal reentrant tachycardia (AVNRT; n = 6, 10%), and atrial tachycardia (AT; n = 9, 15%). The success rate of the RF catheter ablation was 93.3% for AVRT, 66.7% for AVNRT, and 77.8% for AT, respectively. Procedure-related complications were infrequent (7/60, 11.7%), (atrial flutter during RF catheter ablation (4/60, 6.6%); ventricular fibrillation during RF catheter ablation (1/60, 1.6%); transient complete heart block during RF catheter ablation (2/60, 3.3%)). The recurrence rate was 8.3% (5/60) during a follow-up period of 34 ± 12 months.</AbstractText>RF catheter ablation is an effective and safe method to manage children with SVT.</AbstractText> |
14,472 | [Amiodarone and thyroid dysfunction]. | Amiodarone is a structural analogue of thyroid hormone, and some of its anti-arrhythmic actions and toxicity are attributable to its interaction with nuclear receptors of thyroid hormones. Being highly lipophilic, amiodarone is concentrated in many tissues and is eliminated, consequently, very slowly. It is preferably employed to manage life-threatening arrhythmias, including ventricular fibrillation and unstable ventricular tachycardia. Other indications include atrial fibrillation and flutter, severe congestive heart failure, prevention of atrial fibrillation recurrence, and even in emergency medical situations to prevent sudden cardiac death. The aim of this review is to provide an updated approach on amiodarone and its influence on thyroid physiology and to discuss and analyze in depth its potential and not infrequent thyroidal adverse effects such as hypothyroidism and thyrotoxicosis. |
14,473 | Automatic continuous ECG monitoring system for over-drug detection in Brugada Syndrome. | This paper is concerned with the automatic control of drug administration in patients suffering from Brugada Syndrome (BS). Drugs such as flecainide, procainamide, ajmaline and pilsicainide should be administrated under carefully controlled electrocardiogram (ECG) monitoring given that the treatment must be stopped if some ECG disturbing conditions appear. These conditions are, among others the development of premature ventricular contraction (PVC), atrial fibrillation (AF) and the widening of the QRS wave. The proposed system can detect these abnormalities by using a pattern recognition approach based on Hidden Markov Models (HMM) with features extracted from three scales of the Wavelet Transform (WT). Performances higher than 98% were reached regarding the classification of normal and abnormal pulses. The system was trained and tested mainly in data from the standard MIT-BIH arrhythmia database. |
14,474 | Detection and removal of ventricular ectopic beats in atrial fibrillation recordings via principal component analysis. | Ectopic beats are early heart beats with remarkable large amplitude that provoke serious disturbances in the analysis of electrocardiograms (ECG). These beats are very common in atrial fibrillation (AF) and are the source of important residua when the QRST is intended to be removed. Given that QRST cancellation is a binding step in the appropriate analysis of atrial activity (AA) in AF, a method for ventricular ectopic beats cancellation is proposed as a previous step to the application of any QRST removal technique. First, the method discriminates between normal and ectopic beats with an accuracy higher than 99% through QRS morphological characterization. Next, the most similar ectopic beats to the one under cancellation are clustered and serve to get their eigenvector matrix by principal component analysis. Finally, the highest variance eigenvector is used as cancellation template. The reduction ectopic rate (RER) has been defined to evaluate the method's performance by using templates generated with 5, 10, 20, 40 or 80 ectopics. Optimal results were reached with the 5 most similar complexes, yielding a RER higher than 5.5. In addition, a decreasing RER trend was noticed as the number of considered ectopics for cancellation increased. As conclusion, given that ectopics presented a remarkable variability in their morphology, the proposed cancellation approach is a robust ectopic remover and can notably facilitate the later application of any QRST cancellation technique to extract the AA in the best conditions. |
14,475 | Interpretation of coarse-graining of Lempel-Ziv complexity measure in ECG signal analysis. | Lempel-Ziv (LZ) complexity measure has been applied to classify ventricular tachycardia (VT) and ventricular fibrillation (VF). The coarse-graining process plays a crucial role in the LZ complexity measure analysis, which directly affects the separating performance of VT and VF in ECG signal analysis. The question of different coarse-graining approaches interpretability in ECG signal analysis and their influence on the performance of ECG classification have not yet been previously addressed in the literature. In this paper, we present four coarse-graining process approaches, K-Means, Mean, Median and Mid-point. Our test shows that K-Means algorithm is superior to the other three approaches in VT and VF separation rate, Particularly, optimum performance is achieved at a 8-second window length. |
14,476 | Time-domain ECG signal analysis based on smart-phone. | In this paper, a time domain algorithm architecture is presented and implemented on a smart-phone for ECG signal analysis. Using the QRS detection algorithm suggested by Pan-Tompkins and the beat classification method, the heart beats are detected and classified as normal beats and premature ventricular contractions (PVCs). Subsequently, a computationally efficient method is presented to separate ventricular tachycardia (VT) and ventricular fibrillation (VF). This method utilizes Lempel and Ziv complexity analysis combined with K-means algorithm for the coarse-graining process. In addition, a new classification rule is presented to recognize VT and VF in our study. The proposed system provides fairly good performance when applied to the MIT-BIH Database. This algorithm architecture can be efficiently used on the mobile platform. |
14,477 | Wavelet-based features for characterizing ventricular arrhythmias in optimizing treatment options. | Ventricular arrhythmias arise from abnormal electrical activity of the lower chambers (ventricles) of the heart. Ventricular tachycardia (VT) and ventricular fibrillation (VF) are the two major subclasses of ventricular arrhythmias. While VT has treatment options that can be performed in catheterization labs, VF is a lethal cardiac arrhythmia, often when detected the patient receives an implantable defibrillator which restores the normal heart rhythm by the application of electric shocks whenever VF is detected. The classification of these two subclasses are important in making a decision on the therapy performed. As in the case of all real world process the boundary between VT and VF is ill defined which might lead to many of the patients experiencing arrhythmias in the overlap zone (that might be predominately VT) to receive shocks by the an implantable defibrillator. There may also be a small population of patients who could be treated with anti-arrhythmic drugs or catheterization procedure if they can be diagnosed to suffer from predominately VT after objectively analyzing their intracardiac electrogram data obtained from implantable defibrillator. The proposed work attempts to arrive at a quantifiable way to scale the ventricular arrhythmias into VT, VF, and the overlap zone arrhythmias as VT-VF candidates using features extracted from the wavelet analysis of surface electrograms. This might eventually lead to an objective way of analyzing arrhythmias in the overlap zone and computing their degree of affinity towards VT or VF. A database of 24 human ventricular arrhythmia tracings obtained from the MIT-BIH arrhythmia database was analyzed and wavelet-based features that demonstrated discrimination between the VT, VF, and VT-VF groups were extracted. An overall accuracy of 75% in classifying the ventricular arrhythmias into 3 groups was achieved. |
14,478 | Ventricular fibrillation risk estimation for conducted electrical weapons: critical convolutions. | The TASER® Conducted Electrical Weapon (CEW) is used by law enforcement agencies about 900 times per day worldwide and has been shown to reduce suspect and officer injuries by about 65%. However, since a CEW delivers rapid electrical pulses through injected probes, the risk of inducing ventricular fibrillation (VF) has been considered. Animal studies have shown that the tip of the probe must come within a few millimeters of the surface of the heart for the CEW to induce VF in a typical animal application. Early calculations of the CEW VF risk in humans used sophisticated 3-D chest models to determine the size of the probe landing areas that had cardiac tissue within a given distance of the inner surface of the ribs. This produced a distribution of area (cm(2)) vs. mm of depth. Echocardiography was then used to determine the shortest distance from the skin surface to the cardiac surface. This produced a population distribution of skin-to-heart (STH) distances. These 2 distributions were then convolved to arrive at a probability of inducing VF for a typical human CEW application. With 900, 000 probe-mode field uses to date, epidemiological results have shown that these initial VF risk estimates were significant overestimates. We present model refinements that take into account the gender and body-mass-index (BMI) of the target demographics and produce VF risk estimates concordant with the epidemiological results. The risk of VF is estimated at 0.4 per million uses with males. |
14,479 | Ventricular fibrillation threshold of rapid short pulses. | The risk of VF (ventricular fibrillation) from continuous AC utility (50/60 Hz) power has been well quantified and is reflected in accepted standards. Similarly, the required charge for a single pulse delivered during the T-wave of the ECG is also quantified. However, there are no studies that deal with the VF risk of a train of multiple short pulses such as those used in electric fences and conducted electrical weapons (CEWs). We studied 5 swine with an electrode placed through the anterior chest such that the tip was 10 mm from the epicardium. A return electrode was attached remotely to the lower abdomen. Five-second trains of 100 μs pulses at rates of 10-70 PPS (pulses per second) were delivered with gradually increasing charges until VF was induced. The VF threshold was also determined for 60 Hz AC current. As expected, the VF charge threshold decreased with increasing rates. For pulse rates between 10-30 PPS, the aggregate current (= charge • pulse rate) was constant at the VF threshold. The VF threshold in terms of AC RMS current was 7.4 ± 1.9 times the aggregate current VF threshold for the rapid short pulses. These results may have utility for setting safety standards for electric fences and for CEWs such as TASER® CEWs. This also allows for the risk assessment of CEWs by comparison to international electrical safety standards. The output of these weapons appears to be well below the VF risk limits as set by these standards. |
14,480 | Predicting refibrillation from pre-shock waveforms in optimizing cardiac resuscitation. | Ventricular fibrillation (VF) is a lethal cardiac arrhythmia that if untreated within minutes of its occurrence will lead to sudden cardiac death. Defibrillation using electric shocks is the only choice of treatment to restore the heart to normal rhythm especially in out-of-the-hospital VF incidents. Refibrillation (i.e., recurrence of VF) is a common and significant problem in cardiac resuscitation as it negatively impacts the survival rates. In such refibrillation cases administration of anti-arrhythmic drugs could improve the shock outcomes or prevent refibrillation. In cases of prolonged VF, cardio pulmonary resuscitation (CPR) prior to the shocks have been shown to improve the survival rates. The proposed work using wavelet analysis of the pre-shock VF electrograms attempts to predict the shock outcomes as successful, refibrillation, and unsuccessful categories. This feedback in real-time would be of immense assistance to the Emergency Medical Services (EMS) personnel in choosing the right combination of therapies (i.e., shock, CPR, pharmacology interventions) in improving the shock outcomes. Using a real-word database of 34 pre-shock VF electrograms obtained from Toronto area EMS personnel, the proposed method achieved classification accuracies of 76.5% and 75% for a two level binary classification of the three groups. |
14,481 | Relating spatial heterogeneities to rotor formation in studying human ventricular fibrillation. | Ventricular fibrillation (VF) occurs due to disorganized electrical activity in the ventricles. This leads to rapid uncoordinated contractions of the ventricles and sudden cardiac death if not treated within minutes of its occurrence. The mechanism of VF initiation and maintenance is still elusive, however the mother rotor and multiple wavelet theories attempt to explain the mechanism behind this lethal arrhythmia. In mother rotor theory, VF is believed to be maintained by high frequency periodic sources called rotors that could be tracked using the phase progression along and through the myocardium using spatio-temporal electrical mapping of the heart. There are exiting works including our previous works that have related the formation of these rotors to anatomical and physiological heterogeneities observed in the myocardium. In this study we performed an correlation exercise of the locations of rotors with scar boundary maps and dominant frequency maps and elucidated this relation using human VF data acquired from isolated human hearts. The results suggest that in 14 rotors over 6 human hearts that we studied, all rotors co-localized to boundary zones of scar and low-high dominant frequency locations. The mean variance of the dominant frequency over the spatial location of the rotor was found to be 0.55 with average minimum of 4.15 Hz to a maximum of 5.71 Hz. This results in human VF data strongly suggest that boundary zones of healthy-non-healthy tissues and low-high frequency boundaries form a favorite substrate for rotor formation. |
14,482 | Targeting cardiac fibrosis: a new frontier in antiarrhythmic therapy? | Cardiac fibrosis is known to alter cardiac conduction and promote reentry. Recent evidence indicates that fibrosis characterized by increased interstitial collagen accumulation and increased myofibroblast proliferation also promotes enhanced automaticity and early afterdepolarizations (EADs) causing triggered activity. Fibrosis then becomes an effective therapeutic target for the management of lethal cardiac arrhythmias. While oxidative stress with hydrogen peroxide (H(2)O(2)) is shown to readily promote EADs and triggered activity in isolated rat and rabbit ventricular myocytes however, this same stress fails to cause EADs in well-coupled, non-fibrotic hearts due to source-to-sink mismatches arising from cell-to-cell coupling. The triggered activity in the aged fibrotic hearts causes focal ventricular tachycardia (VT) that degenerates within seconds to ventricular fibrillation (VF) after the emergence of spatially discordant action potential duration alternans leading to wavebreak, reentry and VF. Computer simulations in 2D tissue incorporating variable degrees of fibrosis showed that intermediate (but not mild or very severe) fibrosis promoted EADs and TA. Human studies have shown that myocardial fibrosis was an independent predictor for arrhythmias including sustained VT and VF. A variety of drug classes including, torsemide, a loop diuretic, that inhibits the enzyme involved in the myocardial extracellular generation of collagen type I molecules and the inhibitors of the renin-angiotensin-aldosterone system (RAAS), the mineralocorticoid receptors and endothelin receptors reduce cardiac fibrosis with reduction of myocardial stiffness and improved ventricular function. It is hoped that in the near future effective antifibrotic drug regimen would be developed to reduce the risk of fibrosis related VT and VF. |
14,483 | Relation of components of the metabolic syndrome to left ventricular geometry in hispanic and non-hispanic black adults. | Left ventricular (LV) hypertrophy is an independent predictor of increased cardiovascular morbidity and mortality. It remains unclear whether components of the metabolic syndrome are associated with LV hypertrophy.</AbstractText>Accordingly, we analyzed echocardiograms in 192 consecutive ambulatory patients referred for echocardiography from October to December 2004. Patients were excluded if they had atrial fibrillation, significant valvular heart disease or failed to cooperate for echocardiogram. Of these, 126 (66%) patients met Adult Treatment Panel (ATP) III diagnostic criteria for the metabolic syndrome. 29% had any 3 metabolic syndrome components, 18% had any 4 metabolic syndrome components and 17% had all 5 metabolic syndrome components. In analyses of variance adjusted for age and sex, LV mass and LV mass adjusted to its allometric relation to height(2.7) (LV mass/height(2.7)) were higher in patients with metabolic syndrome compared to those without metabolic syndrome (237 g [228-239 95%CI] vs. 224 g [206-239 95%CI] p=0.005 and 62 g/m(2.7) [59-65 95%CI] vs. 56 g/m(2.7) [52-60 95%CI] p=0.014, respectively). The prevalence of LV hypertrophy using prognostically-validated gender-specific partition values for LV mass/height(2.7) was significantly higher in metabolic syndrome patients than in those without metabolic syndrome (81 v. 58%, p<0.001). There was a step-wise increase in LV mass/height(2.7) in those with no metabolic syndrome components to those with increasing number of metabolic syndrome components (Figure, p<0.001). In this study of high-risk patients, the significant independent predictors of LV hypertrophy were only high blood pressure (OR=3.2, p=0.008) and increased waist circumference (OR=2.8, p=0.006) with no interaction between blood pressure and waist circumference.</AbstractText>Metabolic syndrome is associated with higher LV mass and prevalence of LV hypertrophy. Increasing number of metabolic syndrome components is associated with step-wise increases in LV mass. Identification of LV hypertrophy in metabolic syndrome patients may provide an additional prognostic tool to further risk-stratify these patients.</AbstractText> |
14,484 | Characteristics of induced ventricular fibrillation cycle length in symptomatic Brugada syndrome patients. | Limited information is available on the ventricular fibrillation (VF) spectrum in Brugada syndrome (BS) patients. We clarified differences in the VF cycle length (CL) using fast-Fourier transformation (FFT) analysis in symptomatic and asymptomatic BS patients.</AbstractText>VF was induced by pacing from the right ventricular (RV) apex and/or RV outflow tract (RVOT) for >8s. A 4096-point FFT analysis of results from 28 male BS patients (51.1 ± 13.7 years old) was performed. Dominant frequency (DF) from phases 1 (4s) to 6 was obtained at 2-s intervals. The average DF from surface and intracardiac electrograms (ECG: DF(ECG); ICE: DF(ICE,), respectively) was compared between symptomatic and asymptomatic patients. Symptomatic patients had a significantly shorter effective refractory period at a CL of 600 ms at the RVOT than asymptomatic patients. DF(ECG) significantly increased with phase (5.64 ± 0.32 Hz in phase 1 to 6.16 ± 0.52 Hz in phase 6) and was significantly higher in symptomatic patients than in asymptomatic patients. DF(ICE) had the same characteristics as DF(ECG).</AbstractText>Induced VF in BS patients can be characterized using FFT analysis. Our data support the hypothesis that symptomatic patients have a significantly shorter VF CL than asymptomatic patients.</AbstractText> |
14,485 | 96 hours ECG monitoring for patients with ischemic cryptogenic stroke or transient ischaemic attack. | Atrial fibrillation (AF) is intermittent in 30% of patients with cardioembolic stroke and, therefore, might not be seen in a single standard ECG recording. The aim of this study was to evaluate if prolonged ECG monitoring (96 h) finds episodes of intermittent AF beyond the 24 h ECG monitoring in patients with cryptogenic stroke or transient ischemic attack (TIA). We prospectively evaluated consecutive patients affected by cryptogenic stroke or TIA who had sinus rhythm on a 12-lead ECG on admission, and during ECG monitoring performed in the acute phase (for at least 24 h). Patients had continuous 96 h Holter ECG monitoring within 30 days from stroke onset. 114 patients were included in the study (mean age 63.1 ± 15.1, 59 males). AF was found in 29 patients (24.3%). In 20 patients, AF was found in the first 24 h of recording, and in nine patients after 24 h. In addition, several other dysrhythmias such as supraventricular ectopic activity (33), ventricular tachycardia (10), sinus pause (4) and sinus-atrial block (1) were found. In patients with cryptogenic stroke or TIA, 96 h ECG monitoring detected a high rate of AF. One-third of AF was seen beyond 24 h of ECG monitoring. |
14,486 | Unmasking of J waves during right coronary angiography in patients with spontaneous coronary spasms and ventricular fibrillation. | We encountered two consecutive cases with spontaneous ST elevation due to right coronary spasms and subsequent ventricular fibrillation (VF). Their 12-lead ECGs on anterior chest pain showed elevation of ST-segments in the inferior leads, but coronary angiography (CAG) revealed no significant stenosis. Both cases showed dramatically evolving J waves in the inferior leads during the right CAG, but it was not observed during angiography of the left CAG. Neither Brugada-type ECG nor long-QT was evident. In summary, J waves can be produced without ST-segment elevation, and contrast media-induced J waves might be related to the arrhythmogenesis of subsequent VF evoked by right coronary spasms. |
14,487 | Molecular mechanisms of therapeutic hypothermia on neurological function in a swine model of cardiopulmonary resuscitation. | To explore the molecular mechanisms by which mild hypothermia following resuscitation improves neurological function in a porcine model of cardiac arrest.</AbstractText>Thirty-three inbred Chinese Wuzhishan (WZS) minipigs were used. After 8 min of untreated ventricular fibrillation (VF), the surviving animals (n=29) were randomly divided into two groups including serum group (n=16) and molecular group (n=13). Serum group animals were used to measure porcine-specific tumour necrosis factor-alpha (TNF-α), interleukin (IL-6, IL-10), matrix metalloproteinase (MMP9), Aquaporin-4 (AQP4), tissue inhibitor to metalloproteinase-1 (TIMP1), neuron-specific enolase (NSE) and S100B at 0.5 h, 6 h, 12 h, 24 h and 72h recovery by enzyme-linked immunosorbent assay (ELISA). Molecular group animals were used to measure cerebral cortex messenger RNA (mRNA) and protein expression of nuclear factor-κB (NF-κB), MMP9 and AQP4 by real-time (RT) quantitative polymerase chain reaction (PCR) and Western blotting at 24 h and 72 h recovery. Animals were further divided into either normothermia or hypothermia groups. Hypothermia (33°C) was maintained for 12 h using an endovascular cooling device. Swine neurologic deficit scores (NDS) were used to evaluate neurological function at 24-h and 72-h recovery.</AbstractText>Twenty-nine of the 33 (87.9%) animals were successfully resuscitated. The hypothermia group exhibited higher survival rates at 24 h (75%) and 72 h (62.5%) compared to the normothermia group (37.5% and 25%, respectively). Hypothermia markedly inhibited expression of NF-κB, TNF-α, MMP9 and NSE, and promoted expression of TIMP1 (P<0.01). The mean NDS at 24-h and 72-h recovery was 112.5 and 61, respectively, in the hypothermic group, and 230 and 207.5, respectively, in the normothermia group.</AbstractText>Brain protection induced by hypothermia involves inhibition of inflammatory and brain edema pathways.</AbstractText>Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,488 | United States national prevalence of electrocardiographic abnormalities in black and white middle-age (45- to 64-Year) and older (≥65-Year) adults (from the Reasons for Geographic and Racial Differences in Stroke Study). | A United States national sample of 20,962 participants (57% women, 44% blacks) from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study provided general population estimates for electrocardiographic (ECG) abnormalities among black and white men and women. The participants were recruited from 2003 to 2007 by random selection from a commercially available nationwide list, with oversampling of blacks and those from the stroke belt, with a cooperation rate of 49%. The measurement of risk factors and 12-lead electrocardiograms (centrally coded using Minnesota code criteria) showed 28% had ≥1 major ECG abnormality. The prevalence of abnormalities was greater (≥35%) for those ≥65 years old, with no differences between blacks and whites. However, among men <65 years, blacks had more major abnormalities than whites, most notably for atrial fibrillation, major Q waves, and left ventricular hypertrophy. Men generally had more ECG abnormalities than women. The most common ECG abnormalities were T-wave abnormalities. The average heart rate-corrected QT interval was longer in women than in men, similar in whites and blacks, and increased with age. However, the average heart rate was greater in women than in men and in blacks than in whites and decreased with age. The prevalence of ECG abnormalities was related to the presence of hypertension, diabetes, blood pressure, and age. In conclusion, black men and women in the United States have a significantly greater prevalence of ECG abnormalities than white men and women at age 45 to 64 years; however, these proportions, although larger, tended to equalize or reverse after age 65. |
14,489 | Prognostic value of tricuspid annular tissue Doppler velocity in heart failure with atrial fibrillation. | Right ventricular function is associated with long-term outcomes of heart failure (HF), particularly with atrial fibrillation (AF). The aim of this study was to evaluate the prognostic value of Doppler tissue imaging at the mitral and tricuspid annuli in patients with HF and AF.</AbstractText>In this prospective observational study, 457 patients (mean age, 67 years; 283 men) referred for HF with AF were enrolled and underwent conventional echocardiography including pulsed-wave Doppler tissue imaging. Systolic (s') and early diastolic (e') velocities of the tricuspid and mitral annuli were recorded from the apical four-chamber view. The development of clinical adverse events during the follow-up period was defined as the composite of cardiac death and readmission for HF.</AbstractText>During the follow-up period (median, 20 months), 37 patients reached the primary end point (nine deaths and 28 cases of HF). Patients with cardiac events were significantly older and more often had previous HF admissions and diuretic use, higher New York Heart Association classes, and greater average ratios of peak early diastolic mitral inflow to annular velocity. Additionally, Doppler tissue imaging of s' and e' at the tricuspid, septal, and lateral mitral annuli were all reduced. Multivariate analysis showed that tricuspid s' and septal e' remained significant predictors of cardiac events. By Kaplan-Meier analysis, the occurrence of cardiac events was more frequent when tricuspid s' was <9.0 cm/sec (P < .001) and when septal e' was <7.3 cm/sec (P < .001).</AbstractText>In patients with HF and AF with a high risk for cardiac events, tricuspid s' and septal e' can be independent risk predictors of outcomes.</AbstractText>Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
14,490 | Worsening dyspnea in a man with 2 hearts. | We report a case of dyspnea in a 71-year-old man who underwent heterotopic heart transplantation in 2003. At presentation, electrocardiography showed ventricular fibrillation of the native heart and then a progression to both donor and recipient hearts. Synchronized electrical cardioversion restored sinus rhythm and relieved the patient from his symptoms. |
14,491 | The involvement of gap junctions in the delayed phase of the protection induced by cardiac pacing in dogs. | The present study has examined the role of GJ (gap junctions) in the delayed anti-arrhythmic effect of cardiac pacing, with particular reference to the time-course changes in Cx43 (connexin43) expression both after pacing (4×5 min, at a rate of 240 beats/min) and 24 h later, when the dogs were subjected to a 25 min occlusion and reperfusion of the LAD (left anterior descending coronary artery). Compared with the SP (sham-paced) controls (n=20), in dogs paced 24 h previously (n=16) there were reductions in arrhythmia severity [e.g. number of VPB (ventricular premature beats) during occlusion 294±78 compared with 63±25; survival from the combined ischaemia/reperfusion insult 20% compared with 78%], and in other ischaemic changes [epicardial ST-segment, TAT (total activation time) and tissue impedance]. Pacing also prevented the ischaemia-induced structural impairment of the intercalated discs, and preserved GJ permeability and Cx43 phosphorylation, without modifying Cx43 protein content. Following cardiac pacing the membrane and total Cx43 protein contents were unchanged up to 6 h, but were significantly reduced 12 h later (preceded by a down-regulation of Cx43 mRNA at 6 h), and returned to normal by 24 h. Interestingly, dogs that were subjected to ischaemia 12 h after cardiac pacing showed increased arrhythmia generation. We conclude that cardiac pacing results in time-dependent changes in Cx43 expression, which may alter GJ function and influence arrhythmia generation during a subsequent ischaemia/reperfusion insult. This effect is manifested in protection 24 h after pacing, but of potential clinical interest is the finding that there is a time interval after pacing during which an ischaemic event may generate severe ventricular arrhythmias. |
14,492 | [Comparative study between landiolol and amiodarone for therapeutic efficacy after open heart surgery]. | Tachyarrhythmia, especially atrial fibrillation, remains as a common complication after open heart surgery and sometimes leads to fatal condition. Many reports showed that landiolol (ultra short-acting beta one blocker) and amiodarone were effective against postoperative atrial fibrillation (POAF). However, there were few comparative studies between these 2 drugs as prophylactic agents, and no report mentioned the therapeutic efficacy. Our study suggests that landiolol be the 1st choice for rate control of tachyarrhythmia because of easy dose adjustment and mild side effects. Amiodarone may be useful for the patients whose left ventricular function is poor. |
14,493 | Atrial fibrillation management in Asia: from the Asian expert forum on atrial fibrillation. | Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is associated with increased morbidity and mortality. AF has a slightly lower incidence and prevalence in Asian populations than in Western populations, but the associated relative risk of stroke and mortality is similar. Patients with AF in Asia have similar disease profiles and CHADS2 score distributions compared to those in the West, with the exception of a slightly higher prevalence of valvular heart diseases in Asia. Acute ventricular rate control should be the initial consideration in patients with AF and rapid ventricular rate. Anti-arrhythmic drugs have only a modest long-term effect on maintenance of sinus rhythm, and clinical trials in both the West and the East show that chronic rhythm control is not superior to chronic rate control in terms of cardiovascular outcomes, most likely because the benefit of anti-arrhythmic drugs in these trials was often offset by proarrhythmic effects. ECG-driven trials for AF should be replaced by outcome-driven ones. ATHENA is the largest outcome trial to confirm the superiority of a new anti-arrhythmic drug in improving cardiovascular outcomes. The choice of anti-arrhythmic drugs for AF should be based on both safety and efficacy in improving cardiovascular outcomes. For long-term rate control, a lenient strategy with a ventricular rate of less than 110bpm may be adequate, but more strict rate control may be required if patients continue to complain of symptoms. Catheter ablation should be reserved for patients who remain symptomatic despite optimal medical therapy. |
14,494 | Hypothermia therapy: neurological and cardiac benefits. | Due to its protective effect on the brain and the myocardium, hypothermia therapy (HT) has been extensively studied in cardiac arrest patients with coma as well as in patients presenting with acute myocardial infarction (MI). In the setting of cardiac arrest, randomized studies have shown that HT decreases mortality and improves neurological outcomes. Subsequent guidelines have therefore recommended cooling (32°C to 34°C) for 12 to 24 h in unconscious adult patients with spontaneous circulation after out-of-hospital cardiac arrest due to ventricular fibrillation. Observational studies have also confirmed the feasibility of this therapy in clinical practice and support its early application in patients with nonventricular fibrillation cardiac arrest and in post-resuscitation circulatory shock. In patients with acute MI, available clinical evidence does not yet support HT as the standard of care, because no study to date has shown a clear net benefit in such a cohort. After a brief review of the mechanisms of action for HT, we provide a review of the clinical evidence, cooling techniques, and potential adverse effects associated with HT in the setting of post-cardiac arrest patient and acute MI. |
14,495 | Characteristics of electrocardiographic repolarization in acute myocardial infarction complicated by ventricular fibrillation. | Some de- and re-polarization patterns can reflect an increased risk of ventricular tachyarrhythmias. We studied whether some electrocardiographic (ECG) patterns are able to predict the development of ventricular fibrillation (VF) during acute myocardial infarction (MI).</AbstractText>We compared the patterns of ST-T segment of 78 patients who developed VF during acute MI (patient with VF) vs 170 comparable patients with acute MI but with no VF complications.</AbstractText>Of the VF group, 47 developed out-of-hospital VF and 31 developed VF after their admission to the hospital. A steep downsloping ST segment toward a negative T wave with or without a short, flat, or rising portion at the initial portion was observed in 69.2% of the 78 patients: 61.3% in patients with pre-VF and 74.5% in patients with post-VF, vs 9.4% of patients who did not develop VF (P < .0001). In 90.6% of the latter, a typical upward-concave or convex "ischemic" pattern of the ST segment was observed. Thus, the characteristic ST-T patterns were highly associated with VF with a specificity greater than 90%.</AbstractText>A steep downsloping ST segment may characterize the ECGs of patients who develop VF during acute MI.</AbstractText>Copyright © 2012 Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,496 | Role of inflammation in early atrial fibrillation recurrence. | Outcome of rhythm control in atrial fibrillation (AF) is still poor due to various mechanisms involved in the initiation and perpetuation of AF. Differences in timing of AF recurrence may depend on different types of mechanisms. The aim of this study was to assess the mechanisms involved in early AF recurrence in patients with short-lasting AF.</AbstractText>Patients with short-lasting persistent AF undergoing rhythm control (n= 100) were included. Markers of mechanisms involved in the initiation and perpetuation of AF were assessed, including clinical factors, echocardiographic parameters, and biomarkers. Primary endpoint was early AF recurrence (recurrence <1 month). Secondary endpoint was progression to permanent AF. Median total AF history was short: 4.2 months. Early AF recurrences occurred in 30 patients (30%) after a median of 6 (inter-quartile range 2-14) days. Baseline log(2) interleukin (IL)-6 [adjusted hazard ratio (HR) 1.3, 95% confidence interval (CI) 1.0-1.7, P= 0.02] and present or previous smoking (adjusted HR 3.6, 95% CI 1.2-10.9, P= 0.03) were independently associated with early AF recurrence, suggesting that inflammation played an important role in early recurrences. Atrial fibrillation became permanent in 29 patients (29%). Baseline transforming growth factor-β1, left ventricular ejection fraction, and early AF recurrence were independently associated with progression to permanent AF.</AbstractText>In patients with short-lasting AF, early AF recurrence seemed to be associated with inflammation as represented by IL-6. Treatment aimed against inflammation may therefore prevent early AF recurrences, which can improve rhythm control outcome.</AbstractText> |
14,497 | Epidemiology of out-of hospital pediatric cardiac arrest due to trauma. | To determine the epidemiology and survival of pediatric out-of-hospital cardiac arrest (OHCA) secondary to trauma.</AbstractText>The CanAm Pediatric Cardiac Arrest Study Group is a collaboration of researchers in the United States and Canada sharing a common goal to improve survival outcomes for pediatric cardiac arrest. This was a prospective, multicenter, observational study. Twelve months of consecutive data were collected from emergency medical services (EMS), fire, and inpatient records from 2000 to 2003 for all OHCAs secondary to trauma in patients aged ≤18 years in 36 urban and suburban communities supporting advanced life support (ALS) programs. Eligible patients were apneic and pulseless and received chest compressions in the field. The primary outcome was survival to discharge. Secondary measures included return of spontaneous circulation (ROSC), survival to hospital admission, and 24-hour survival.</AbstractText>The study included 123 patients. The median patient age was 7.3 years (interquartile range [IQR] 6.0-17.0). The patient population was 78.1% male and 59.0% African American, 20.5% Hispanic, and 15.7% white. Most cardiac arrests occurred in residential (47.1%) or street/highway (37.2%) locations. Initial recorded rhythms were asystole (59.3%), pulseless electrical activity (29.1%), and ventricular fibrillation/tachycardia (3.5%). The majority of cardiac arrests were unwitnessed (49.5%), and less than 20% of patients received chest compressions by bystanders. The median (IQR) call-to-arrival interval was 4.9 (3.1-6.5) minutes and the on-scene interval was 12.3 (8.4-18.3) minutes. Blunt and penetrating traumas were the most common mechanisms (34.2% and 25.2%, respectively) and were associated with poor survival to discharge (2.4% and 6.5%, respectively). For all OHCA patients, 19.5% experienced ROSC in the field, 9.8% survived the first 24 hours, and 5.7% survived to discharge. Survivors had triple the rate of bystander cardiopulmonary resuscitation (CPR) than nonsurvivors (42.9% vs. 15.2%). Unlike patients sustaining blunt trauma or strangulation/hanging, most post-cardiac arrest patients who survived the first 24 hours after penetrating trauma or drowning were discharged alive. Drowning (17.1% of cardiac arrests) had the highest survival-to-discharge rate (19.1%).</AbstractText>The overall survival rate for OHCA in children after trauma was low, but some trauma mechanisms are associated with better survival rates than others. Most OHCA in children is preventable, and education and prevention strategies should focus on those overrepresented populations and high-risk mechanisms to improve mortality.</AbstractText> |
14,498 | Cardiac movement identified on prehospital echocardiography predicts outcome in cardiac arrest patients. | The prognostic value of emergency echocardiography (EE) in the management of cardiac arrest patients has previously been studied in an in-hospital setting. These studies mainly included patients who underwent cardiopulmonary resuscitation (CPR) by emergency medicine technicians at the scene and who arrived at the emergency department (ED) still in a state of cardiac arrest. In most European countries, cardiac arrest patients are normally treated by physician-staffed emergency medical services (EMS) teams on scene. Transportation to the ED while undergoing CPR is uncommon.</AbstractText>To evaluate the ability of EE to predict outcome in cardiac arrest patients when it is performed by ultrasound-inexperienced emergency physicians on scene.</AbstractText>We performed a prospective, observational study of nonconsecutive, nontrauma, adult cardiac arrest patients who were treated by physician-staffed urban EMS teams on scene. Participating emergency physicians (EPs) received a two-hour course in EE during CPR. After initial procedures were accomplished, EE was performed during a rhythm and pulse check. A single subxiphoid, four-chamber view was required for study enrollment. We defined sonographic evidence of cardiac kinetic activity as any detected motion of the myocardium, ranging from visible ventricular fibrillation to coordinated ventricular contractions. The CPR had to be continued for at least 15 minutes after the initial echocardiography. No clinical decisions were made based on the results of EE.</AbstractText>Forty-two patients were enrolled in the study. The heart could be visualized successfully in all patients. Five (11.9%) patients survived to hospital admission. Of the 32 patients who had cardiac standstill on initial EE, only one (3.1%) survived to hospital admission, whereas four out of 10 (40%) patients with cardiac movement on initial EE survived to hospital admission (p = 0.008). Neither asystole on initial electrocardiogram nor peak capnography value, age, bystander CPR, or downtime was a significant predictor of survival. Only cardiac movement was associated with survival, and cardiac standstill at any time during CPR resulted in a positive predictive value of 97.1% for death at the scene.</AbstractText>Our results support the idea of focused echocardiography as an additional criterion in the evaluation of outcome in CPR patients and demonstrate its feasibility in the prehospital setting.</AbstractText> |
14,499 | Serum potassium levels and mortality in acute myocardial infarction. | Clinical practice guidelines recommend maintaining serum potassium levels between 4.0 and 5.0 mEq/L in patients with acute myocardial infarction (AMI). These guidelines are based on small studies that associated low potassium levels with ventricular arrhythmias in the pre-β-blocker and prereperfusion era. Current studies examining the relationship between potassium levels and mortality in AMI patients are lacking.</AbstractText>To determine the relationship between serum potassium levels and in-hospital mortality in AMI patients in the era of β-blocker and reperfusion therapy.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PATIENTS" NlmCategory="METHODS">Retrospective cohort study using the Cerner Health Facts database, which included 38,689 patients with biomarker-confirmed AMI, admitted to 67 US hospitals between January 1, 2000, and December 31, 2008. All patients had in-hospital serum potassium measurements and were categorized by mean postadmission serum potassium level (<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 4.5-<5.0, 5.0-<5.5, and ≥5.5 mEq/L). Hierarchical logistic regression was used to determine the association between potassium levels and outcomes after adjusting for patient- and hospital-level factors.</AbstractText>All-cause in-hospital mortality and the composite of ventricular fibrillation or cardiac arrest.</AbstractText>There was a U-shaped relationship between mean postadmission serum potassium level and in-hospital mortality that persisted after multivariable adjustment. Compared with the reference group of 3.5 to less than 4.0 mEq/L (mortality rate, 4.8%; 95% CI, 4.4%-5.2%), mortality was comparable for mean postadmission potassium of 4.0 to less than 4.5 mEq/L (5.0%; 95% CI, 4.7%-5.3%), multivariable-adjusted odds ratio (OR), 1.19 (95% CI, 1.04-1.36). Mortality was twice as great for potassium of 4.5 to less than 5.0 mEq/L (10.0%; 95% CI, 9.1%-10.9%; multivariable-adjusted OR, 1.99; 95% CI, 1.68-2.36), and even greater for higher potassium strata. Similarly, mortality rates were higher for potassium levels of less than 3.5 mEq/L. In contrast, rates of ventricular fibrillation or cardiac arrest were higher only among patients with potassium levels of less than 3.0 mEq/L and at levels of 5.0 mEq/L or greater.</AbstractText>Among inpatients with AMI, the lowest mortality was observed in those with postadmission serum potassium levels between 3.5 and <4.5 mEq/L compared with those who had higher or lower potassium levels.</AbstractText> |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.