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7,700 | Heart rate variability measures during sinus rhythm predict cycle length entropy during atrial fibrillation. | Several noninvasive measures of cardiac risk such as heart rate variability (HRV) cannot be used in patients with atrial fibrillation (AF). One promising exception is the measure of ventricular cycle length entropy (VCLE) where initial data suggest that a reduction in VCLE portends an increased risk of cardiac death in patients with chronic AF. In this study, we hypothesized that measures of short-term HRV during sinus rhythm would correlate with measures of cycle length entropy during paroxysms of AF.</AbstractText>We tested 25 Holter recordings of paroxysmal AF from the Physionet AF Prediction Database. We calculated HRV parameters including standard deviation of all NN intervals (SDNN), the root mean square root of the differences between adjacent NN intervals (RMSSD), standard deviation of 5-minute averages of NN intervals (SDANN), percentage of adjacent NN interval differences >50 ms (pNN50), and interbeat correlation coefficient (ICC) from 30 minutes of normal sinus rhythm, and entropy measures (the Shannon Informational Entropy [ShEn] and Average of Approximate Entropy [ApEn]) from 5 minutes of AF that occurred during the same 24-hour monitor. Pairwise correlations were used to assess associations, as regression residuals were normally distributed.</AbstractText>The mean entropy measures during AF were: ShEn: 4.78 +/- 0.82, ApEn: 0.198 +/- 0.21. When assessed during the 30 minutes immediately preceding AF onset, ICC showed a significant negative correlation with both ShEn (r =-0.65, P < 0.001) and ApEn (r =-0.60, P < 0.01). RMSSD also correlated with both ShEn (r = 0.41, P = 0.04) and ApEn (r = 0.39, P = 0.05), but other HRV measures showed no correlation with VCLE during AF.</AbstractText>Reductions in RMSSD or increases in ICC, two short-term HRV measures that are known to reflect parasympathetic function in sinus rhythm, are correlated with reductions in the entropy of ventricular response intervals during AF. Our findings suggest that entropy during AF may be modulated, in part, by vagal innervation.</AbstractText> |
7,701 | Long-term clinical efficacy and risk of catheter ablation for atrial fibrillation in the elderly. | The number of elderly patients with atrial fibrillation (AF) is increasing rapidly, and the safety and efficacy of catheter ablation in this demographic group has not been established.</AbstractText>Over a 7-year period we studied 1,165 consecutive patients undergoing 1,506 AF ablation procedures using a consistent ablation protocol that included proximal ostial pulmonary vein (PV) isolation and focal ablation of non-PV AF triggers. Outcome was analyzed for three distinct age groups: <65 years (group 1; n = 948 patients), 65-74 years (group 2; n = 185 patients), and > or =75 years (group 3; n = 32 patients) based on the age at the initial procedure.</AbstractText>There was no significant difference in AF control (89% in group 1, 84% in group 2, and 86% in group 3, P = NS) during a mean follow-up of 27 months. Major complication rates were also comparable (1.6% in group 1, 1.7% in group 2, 2.9% in group 3, P = NS) between the three groups. There was no difference in the left atrial size, percentage with left ventricular ejection fraction <50%, or percentage with paroxysmal versus more persistent forms of atrial fibrillation. However, older patients were more likely to be women (20% in group 1, 34% in group 2, and 56% in group 3, P < 0.001) and have hypertension and/or structural heart disease (56% in group 1 vs 68% in group 2 vs 88% in group 3; P < 0.001). There was a strong trend demonstrating that older patients were less likely to undergo repeat ablation (26% vs 27% vs 9%) to achieve AF control and more likely to remain on antiarrhythmic drugs (20% vs 29% vs 37%; P < 0.05).</AbstractText>Elderly patients with AF undergoing catheter ablation therapy are represented by a higher proportion of women and have a higher incidence of hypertension/structural heart disease. To achieve a similar level of AF control, there appears to be no increased risk from the ablation procedure, but elderly patients are more likely to remain on antiarrhythmic drugs.</AbstractText> |
7,702 | Future directions in cardiac resynchronization therapy. | Cardiac resynchronization therapy (CRT) reduces symptoms and improves mortality in patients with moderate to severe chronic heart failure (New York Heart Association class III-IV) in sinus rhythm with reduced left ventricular ejection fraction and with wide QRS on the surface electrocardiogram as evidence of ventricular dyssynchrony. CRT's benefit in patients with atrial fibrillation, mild heart failure, or a conventional indication for antibradycardia pacing is being assessed. Moreover, the PROSPECT trial assessed whether the response rate to CRT might increase if, in addition to wide QRS, mechanical dyssynchrony criteria were required. The RethinQ study examined whether patients with narrow QRS but with mechanical dyssynchrony benefit from CRT. Finally, whether patients with heart failure with preserved left ventricular function also may benefit from CRT remains to be studied. |
7,703 | Factors predicting the time until atrial fibrillation recurrence after concomitant left atrial ablation. | Treatment of atrial fibrillation, a risk factor for morbidity and mortality, by left atrial ablation is a less complex procedure which is increasingly performed in conjunction with surgery for various heart diseases. Although restoration of sinus rhythm is effective initially, atrial fibrillation may recur. We investigated factors predicting the time until its recurrence.</AbstractText>Between January 2003 and December 2005, 162 consecutive patients (52.5% male, age 69+/-8.7 years) with permanent atrial fibrillation underwent concomitant left atrial ablation and isolated or combined mitral valve surgery (42.6%), isolated or combined aortic valve surgery (32.1%), and isolated or combined coronary artery bypass grafting (24.1%). Ablation was performed by microwave (n=93, 57.4%) or radiofrequency (n=69, 42.6%) technology. Follow-up was after 3, 6, 12 months and yearly thereafter. Predictive values of variables for postoperative atrial fibrillation were examined using techniques of univariate and multivariate survival analysis (proportional hazards regression).</AbstractText>Eight patients died perioperatively and 13 during follow-up (not ablation related). Two patients were lost to follow-up. At last follow-up (19+/-11.3 months), 86 patients (62%) were in stable sinus rhythm, 73 (52%) without antiarrhythmic drugs, and 43 (31%) were in atrial fibrillation. Predictors for the time until recurrence of atrial fibrillation in a multivariate model were preoperative atrial fibrillation duration (hazard ratio 1.005, 95% confidence interval 1.003-1.007, p<0.001) and left atrial diameter (hazard ratio 1.056, 95% confidence interval 1.020-1.093, p=0.002). Overall, sinus rhythm conversion rate was 75% when preoperative atrial fibrillation duration was less than 2 years, but 42% in longer lasting atrial fibrillation with left atrial dilatation (>50mm). Age, gender, primary heart disease, history of thromboembolism or cardioversion, presence of concomitant diseases, EuroScore, left ventricular size and function, aortic cross-clamp time, ablation technology, and treatment with antiarrhythmic drugs did not predict rhythm outcome.</AbstractText>Preoperative atrial fibrillation duration and left atrial diameter predict the time until atrial fibrillation recurrence after concomitant left atrial ablation, whereas age, type of primary cardiac surgery, ablation technology and antiarrhythmic therapy do not.</AbstractText> |
7,704 | Ventricular tachyarrhythmia as a primary presentation of sarcoidosis. | Sarcoidosis is a multisystem, granulomatous disease with occasional cardiac manifestations. The clinical course of patients with ventricular tachyarrhythmias as a primary presentation of sarcoidosis is mostly unknown.</AbstractText>We describe nine patients (four males and five females) in whom sarcoidosis manifested as ventricular tachycardia (VT). The age of the patients was 53 +/- 10 years (range 33-68). The disease was diagnosed by endomyocardial biopsy in eight patients and by lymph node biopsy in one patient. The presenting arrhythmia varied from non-sustained VT to incessant VT and ventricular fibrillation. All patients received implantable cardioverter defibrillator (ICD) and anti-arrhythmic medication. High-dose steroid treatment was used in eight cases. During the follow-up (50 +/- 34 months), five patients underwent appropriate ICD therapies and non-sustained VT episodes were detected in four patients. Two patients developed incessant VT, which was treated by catheter ablation. One patient was referred for heart transplantation.</AbstractText>Our data indicate that sarcoidosis can manifest as VT without any detectable systemic findings. This makes sarcoidosis an important diagnostic consideration in patients with VT of unknown origin. Arrhythmia control in cardiac sarcoidosis is difficult, and all modern treatments including high-dose steroids, anti-arrhythmic drugs, ICD, and catheter ablation are needed to suppress the arrhythmias.</AbstractText> |
7,705 | Effects of garlic on the induction of ventricular fibrillation. | Previous studies have shown that oral and intravenous administrations of garlic provide a significant antiarrhythmic effect and improve defibrillation efficacy. We tested the hypothesis that garlic could decrease the inducibility of ventricular arrhythmia.</AbstractText>Twenty-one pigs (25-30 kg) were divided into three groups. In each group, the ventricular fibrillation threshold (VFT) and the upper limit of vulnerability (ULV) were determined. After the control VFT and ULV values were obtained, solutions containing 20 mg/kg (group 1, n = 7) and 40 mg/kg (group 2, n = 7) of garlic (1.3% allicin) were administered intravenously. The VFT and ULV were determined again at the end of garlic infusion. In group 3 (n = 7), 100 mL of normal saline was administered instead of garlic.</AbstractText>The VFT values in groups 1 and 2 were not different from the control VFT. The ULV in group 1 was not different from the control ULV. However, the ULV in group 2 (328 +/- 58 V, 8 +/- 3 J) was significantly lower than the control ULV (415 +/- 24 V, 13 +/- 2 J), thus accounting for the reduction of approximately 21% by peak voltage and approximately 38% by energy. The effective refractory period and diastolic pacing threshold were not altered after garlic infusion. Saline did not alter VFT or ULV.</AbstractText>Garlic cannot alter the VFT, but it significantly decreases the ULV in a dose-dependent pattern, indicating that it can reduce the range of the stimulation strength between the VFT and ULV (vulnerability window) during the vulnerable period of a cardiac cycle.</AbstractText> |
7,706 | Prevention and management of perioperative arrhythmias in the thoracic surgical population. | Although bradyarrhythmias or malignant ventricular tachyarrhythmias have been reported in less than 1% of patients following noncardiac surgery, rapid atrial arrhythmias more frequently affect the elderly who undergo thoracic operations. This article focuses on new issues leading to the improved understanding of the pathophysiology and mechanisms of postoperative atrial arrhythmias. It discusses new risk factors and a prediction rule for postthoracotomy atrial fibrillation (AF), reviews prophylaxis and acute therapeutic interventions for postthoracotomy AF, and highlights the most recent recommendations of the American Heart Association Task Force on the management of patients who have AF with emphasis on preventing thromboembolic events. |
7,707 | Analysis of benign ventricular tumors: long-term outcome after resection. | We sought to compare clinical and pathologic characteristics of ventricular tumors and to detect whether differences exist in short- and long-term survival after resection.</AbstractText>From 1964 to 2005, 323 patients had cardiac surgery for resection of primary cardiac tumors; 53 (16%) patients had primary ventricular tumors. We randomly sampled 53 characteristics of ventricular tumors.</AbstractText>Patients with ventricular tumors were younger than those with atrial tumors (34.8 vs 54.6 years; P < .0001). New York Heart Association functional status was similar at presentation, although patients with atrial tumors had increased risk of atrial fibrillation (P < .05), thromboembolic events (P = .04), and mitral stenosis (P = .008) at the time of presentation. Patients with ventricular tumors had an increased incidence of myocardial invasion (14% vs 2%; P = .02) and had significantly longer cardiopulmonary bypass (80 vs 65 minutes; P < .05) and crossclamp (52 vs 39 minutes; P = .03) times. Operative mortality was 4% and 0% in the ventricular and atrial groups, respectively (P = not significant). Follow-up was obtained in 89% of patients at a mean follow-up time of 7.21 years. A Kaplan-Meier survival plot demonstrated no difference in survival characteristics of both groups. At follow-up, 81% and 74% of ventricular and atrial tumors, respectively, were minimally symptomatic (New York Heart Association class I/II; P = .13). Patients with atrial and ventricular tumors had a 6% and 0% tumor recurrence rate, respectively (P = .12).</AbstractText>Surgical resection for ventricular tumors is effective and results in excellent long-term outcome. Early surgical treatment should be strongly considered in patients with primary ventricular tumors.</AbstractText> |
7,708 | Ventricular late potentials: a critical overview and current applications. | More than 450 000 Americans die suddenly each year from sustained ventricular tachycardia (VT) or fibrillation. Overall, event rates in Europe are similar to those in the United States. A correct risk stratification is essential to reduce the incidence of sudden cardiac death. Ventricular late potentials (VLPs) represent delayed conduction through a diseased myocardium and consist of the presence of electrical activity after the end of the standard QRS. The VLPs are potential substrates for reentry VT.</AbstractText>The VLPs were found highly predictive of cardiac events, in particular, arrhythmic events, in patients with acute myocardial infarction. The weakness of VLPs is the low positive predictive value, especially as a single technique. However, their negative predictive value for arrhythmic events is very high. The VLPs are observed in more than 50% of patients with arrhythmogenic right ventricular cardiomyopathy, and are actually considered a helpful diagnostic tool in this setting. In patients with syncope of unknown cause, VLP analysis, combined with patient history and other diagnostic tests, can help identify or exclude a mechanism of VT as a cause of the syncope.</AbstractText>The VLP assessment offers a practical and low-cost tool to the clinical cardiologist to recognize the possible electrophysiologic substrate underlying life-threatening ventricular arrhythmias. The strength of VLPs is their high negative predictive value. When positive, VLPs still help better stratify the arrhythmic risk of patients in several clinical settings.</AbstractText> |
7,709 | Repolarization heterogeneity in the right ventricular outflow tract: correlation with ventricular arrhythmias in Brugada patients and in an in vitro canine Brugada model. | Brugada syndrome (BrS) is characterized by repolarization abnormality with ST-segment elevation in the right ventricular outflow tract (RVOT).</AbstractText>Although action potential (AP) heterogeneity is associated with induction of ventricular arrhythmias (VA) in BrS, clinical evidence and its experimental correlations are still absent and are the focus of this study.</AbstractText>We evaluated repolarization heterogeneity in 15 patients with BrS using body surface mapping and in 8 pairs of isolated canine RVOT and right ventricular anteroinferior (RVAI) preparations having drug-induced BrS using optical mapping.</AbstractText>Patients had large J-ST-segment elevation and long QT interval in the RVOT at baseline. Administration of pilsicainide (1 mg/kg) exaggerated J-ST-segment elevation, caused simultaneous long and short QT intervals in the RVOT, and induced polymorphic ventricular tachycardia (VT) and T wave alternans (TWA). Dispersion of QT within the RVOT after pilsicainide was greater in patients that had syncope or ventricular fibrillation than those that did not. Ventricular arrhythmias originated from the RVOT along with local electrocardiogram changes and TWA. Repolarization heterogeneity was much less in areas outside the RVOT. Inducing BrS increased AP heterogeneity (with and without spike-and-dome) within the RVOT epicardium. Phase 2 reentry and TWA originated from the epicardium in 88% and 50% of RVOT preparations, respectively. In contrast, the RVOT endocardium and RVAI had little AP heterogeneity, with neither reentry nor TWA.</AbstractText>The instability and heterogeneity of repolarization within the epicardium of the RVOT seem to be associated with arrhythmogenesis in both patients and in the in vitro tissue models of BrS.</AbstractText> |
7,710 | High amplitude T-wave alternans precedes spontaneous ventricular tachycardia or fibrillation in ICD electrograms. | T-wave alternans (TWA) increases acutely prior to ventricular tachycardia (VT) or fibrillation (VF) in animal studies, suggesting that it may provide a warning for VT/VF in implantable cardioverter defibrillator (ICD) patients. Clinically, measurement of surface ECG TWA requires preprocessing the input signal to reduce noise and/or analyzing more sinus beats than are recorded in ICDs as pre-onset, stored intracardiac electrograms (EGMs) before VT/VF. Our objective was to measure TWA from the few sinus EGMs stored in ICDs before spontaneous VT/VF in humans.</AbstractText>The purpose of this study was to evaluate the technical feasibility of measuring TWA from pre-onset ICD EGMs and to measure EGM TWA before spontaneous VT/VF in humans.</AbstractText>We developed a method to measure EGM TWA as a simple average (AVE) of peak-to-peak alternans. Using simulation, we determined the effect of ICD signal processing on EGM TWA for durations comparable to those in pre-onset EGMs. We then applied this method to pre-onset ICD EGMs that preceded 101 episodes of sustained VT/VF in 10 patients. In 6 of these patients, EGM recordings in atrial pacing and sinus rhythm provided control data.</AbstractText>In simulation, the AVE method discriminated input TWA differences > or = 15 microV. In patients, EGM TWA was 78 +/- 62 microV prior to VT/VF vs. 13 +/- 10 microV in control recordings (p< .0001). Eighty percent of pre-onset measurements exceeded 30 microV, while 95% of control measurements were less than 30 microV.</AbstractText>A simple averaging method can measure TWA preceding VT/VF in stored ICD EGMs. Pilot data indicate that high-amplitude EGM TWA usually precedes spontaneous VT/VF and is infrequent in control recordings. They provide a rationale for developing ICD technology to measure EGM TWA continuously, both to warn patients and to initiate pacing algorithms to prevent VT/VF.</AbstractText> |
7,711 | Post-infarction ventricular arrhythmias originating in papillary muscles. | The aim of this study was to define the role of papillary muscles (PAPs) in post-infarction ventricular arrhythmias.</AbstractText>Papillary muscles have been implicated in arrhythmogenesis; however, their role in post-infarction ventricular arrhythmias has not been well-defined.</AbstractText>In a series of 9 patients (age 65 +/- 9 years, ejection fraction 0.36 +/- 0.1) with post-infarction ventricular arrhythmias, electroanatomic mapping in conjunction with intracardiac echocardiography demonstrated that 1 of the PAPs was involved in the arrhythmia. Magnetic resonance imaging with delayed enhancement (DEMRI) was performed in all patients without contraindications. A consecutive series of 9 patients (age 64 +/- 8 years, ejection fraction 0.32 +/- 0.14) with ventricular arrhythmias that did not originate from the PAP served as a control group and also underwent DEMRI.</AbstractText>Heterogeneous uptake of gadolinium during magnetic resonance imaging was observed more frequently in arrhythmogenic PAPs than in PAPs that were not involved in ventricular arrhythmias (p = 0.01). The PAPs in the control patients did not take up contrast or show homogeneous contrast uptake. Radiofrequency ablation eliminated all arrhythmias originating from PAPs. Echocardiography after the ablation showed no new or worsened mitral regurgitation.</AbstractText>Papillary muscles that lie within an infarct zone might give rise to ventricular arrhythmias. Heterogeneous uptake of gadolinium in magnetic resonance images might be predictive of arrhythmogenic PAPs. Radiofrequency catheter ablation of ventricular tachycardia and ventricular ectopy arising in a PAP has a high success rate.</AbstractText> |
7,712 | Cerebrovascular risk factors and incident depression in community-dwelling elderly. | The 'vascular depression' hypothesis suggests that late-life depression results from vascular brain damage. We studied the longitudinal association between cerebrovascular risk factors and incident depression in a large population-based study.</AbstractText>Two thousand nine hundred and thirty-one persons with the age of > or =61 years were followed up. Data on a comprehensive set of cerebrovascular risk factors were collected at baseline. Participants received a psychiatric assessment 5 years later to establish DSM-IV diagnoses.</AbstractText>Only current smoking and antihypertensive drug use were independently associated with incident depressive symptoms. Diabetes mellitus and the Framingham stroke risk score were related to incident depressive disorder. No relation with depression was observed for cholesterol, diastolic and systolic blood pressure, history of cardiovascular disease, atrial fibrillation, left ventricular hypertrophy or the use of statins and anticoagulants.</AbstractText>These results moderately support the 'vascular depression' hypothesis.</AbstractText> |
7,713 | Brugada syndrome with complete right bundle branch block disclosed by a febrile illness. | The characteristic of right-bundle branch block (RBBB) pattern in Brugada syndrome (BS) is an atypical pattern without a wide S wave in left leads. We present a case of a patient with BS who had a typical ECG pattern of complete RBBB (CRBBB) with a wide S wave in the left leads which was disclosed by a febrile illness. Our observations suggest that physicians should be careful to evaluate ECG change in response to a febrile state, even if the ECG shows a typical CRBBB pattern with deep and wide S waves in the left leads. |
7,714 | Comparison of the Cerebral Performance Category score and the Health Utilities Index for survivors of cardiac arrest. | The Cerebral Performance Category score is an easy to use but unvalidated measure of functional outcome after cardiac arrest. We evaluate the comparability of results from the Cerebral Performance Category scale versus those of the validated but more complex Health Utilities Index scale for health-related quality of life.</AbstractText>This prospective substudy of the Ontario Prehospital Advanced Life Support (OPALS) Study included adult out-of-hospital cardiac arrest patients treated in 20 cities. This prospective cohort study included all survivors of out-of-hospital adult cardiac arrest enrolled in phase II (rapid basic life support with defibrillation) and phase III (advanced life support) of the OPALS Study, as well as the intervening run-in phase. Survivors were interviewed at 12 months for Cerebral Performance Category Score and the Health Utilities Index Mark 3 (Health Utilities Index).</AbstractText>Of 8,196 eligible out-of-hospital cardiac arrest patients between 1995 and 2002, 418 (5.1%) survived to discharge, and 305 (3.7%) completed the Health Utilities Index interview and had Cerebral Performance Category scored at 12 months. The 305 patients had the following data: mean age 63.9 years; male 78.0%; paramedic-witnessed arrest 25.6%; bystander cardiopulmonary resuscitation 32.1%; initial rhythm ventricular fibrillation/ventricular tachycardia 86.9%, Cerebral Performance Category 1 267, Cerebral Performance Category 2 26, Cerebral Performance Category 3 12. Overall, the median scores (interquartile range) were Cerebral Performance Category 1 (1 to 1) and Health Utilities Index 0.84 (0.61 to 0.97). The Cerebral Performance Category score ruled out good quality of life (Health Utilities Index >0.80), with a sensitivity of 100% (95% confidence interval [CI] 98% to 100%) and specificity 27.1% (95% CI 20% to 35%); thus, when the Cerebral Performance Category score was 2 or 3, it was unlikely that the Health Utilities Index score would be good. The Cerebral Performance Category score had sensitivity 55.6% (95% CI 42% to 67%) and specificity 96.8% (95% CI 94% to 98%) for predicting poor quality of life (Health Utilities Index >0.40); ie, when Cerebral Performance Category was 1, it was highly unlikely that the Health Utilities Index score would be poor. The weighted kappa was 0.39 and the interclass correlation was 0.51.</AbstractText>This represents the largest study yet conducted of the performance of the Cerebral Performance Category score in 1-year survivors of out-of-hospital cardiac arrest. Overall, the Cerebral Performance Category score classified patients well for their quality of life, ruling out a good Health Utilities Index score with high sensitivity and ruling in poor Health Utilities Index score with high specificity. The Cerebral Performance Category is an important tool in that it indicates broad functional outcome categories that are useful for a number of key clinical and research applications but should not be considered a substitute for the Health Utilities Index.</AbstractText> |
7,715 | Clinical and echocardiographic measures governing thromboembolism destination in atrial fibrillation. | Although infrequent, embolic occlusion to non-cerebral arteries may result in limb loss, organ failure, and death. The aim of this study was to define clinical and echocardiographic characteristics determining thromboembolism destination in non-valvular atrial fibrillation. An inception cohort of individuals (n=72) were identified with incident peripheral embolism in the setting of non-valvular atrial fibrillation (1995-2005). A randomly selected group of atrial fibrillation related stroke patients (n=100) were identified for comparison. Arteries of the extremities were the most common site of embolism (85%); lower extremity involvement was twice as common compared with the upper extremity. Clinical features distinguishing peripheral embolism from stroke included age>75, heart failure and hypertension. Severe left ventricular dysfunction, spontaneous echo contrast and left atrial thrombus were 2-3 fold more common in peripheral embolism patients. Mean CHADS-2 scores were low and comparable for both groups. By multivariate analysis, age>5 years (hazard ratio [HR] 2.3, 95% confidence interval [CI] 1.3-3.9; p=0.05) was predictive of peripheral embolism. After adjustment for age>75 years, severe left atrial enlargement (HR 1.8, 95% CI 0.99-3.1; p=0.055) and CHADS score (HR 1.2, 95% CI 0.99-1.6; p=0.06) were of borderline significance. In conclusion, several clinical and echocardiographic measures distinguish the clinical presentation of thromboembolism in non-valvular atrial fibrillation. Small emboli are destined to lodge in the cerebral circulation as a result of hydrodynamic, anatomic, and physical factors. Advanced age, atrial enlargement and other co-morbidities may increase the propensity for the formation of larger thrombi which may bypass the carotid orifice merely as a function of size. |
7,716 | Serum transforming growth factor-beta1 as a risk stratifier of sudden cardiac death. | Sudden cardiac death prematurely claims the lives of some 7 million each year worldwide. It occurs primarily in patients with an underlying structural cardiac abnormality, and regardless of the type of the underlying pathology (heart failure, dilated and hypertrophic cardiomyopathies, myocardial infarction and aging), death is almost always caused by ventricular tachycardia (VT) which rapidly degenerates to ventricular fibrillation (VF). Implantable cardioverter defibrillator is an effective but expensive therapy for preventing SCD, and finding a reasonably specific, sensitive and cost-effective risk stratification tool for patients at high risk of sudden cardiac death will have great clinical utility in preventing premature sudden cardiac death. Increased myocardial fibrosis has been shown to develop in a wide range of cardiac diseases all manifesting increased risk of VT and VF. Clinical and experimental studies attribute a major role for fibrosis in the initiation of VT, VF and sudden cardiac death. Transforming growth factor-beta1 (TGF-beta1) has been shown to promote myocardial tissue fibrosis and perhaps more importantly in cardiac conditions associated with increased myocardial fibrosis are shown to be positively correlated with increased serum levels of TGF-beta1. In the present hypothesis we suggest that monitoring the serum levels of TGF-beta1 may be a cost-effective risk stratifier to identify patients at high risk of sudden cardiac death caused by VT and VF. |
7,717 | Vernakalant--a promising therapy for conversion of recent-onset atrial fibrillation. | This paper reviews the pharmacology, electrophysiology, efficacy and safety of intravenous and oral vernakalant hydrochloride (RSD-1235), a novel antiarrhythmic drug that has relative atrial selectivity by blocking potassium channels that are present in the atria and not the ventricle. In addition, this drug has important rate-dependent sodium channel blocking properties.</AbstractText>Currently, there few commercially approved intravenous antiarrhythmic agents for the conversion of atrial fibrillation. Intravenously, vernakalant has been demonstrated to be useful in terminating over 50% of recent-onset atrial fibrillation (< 7 days duration) with minimal ventricular proarrhythmic effects. Intravenous vernakalant is not effective in terminating atrial flutter. Oral vernakalant is currently undergoing study and appears to be effective in suppressing atrial fibrillation recurrences after cardioversion of persistent atrial fibrillation.</AbstractText><AbstractText Label="RESULTS/CONCLUSION" NlmCategory="CONCLUSIONS">Intravenous vernakalant has the potential to be an important agent in the conversion of atrial fibrillation and oral vernakalant may be a useful drug for the suppression of atrial fibrillation recurrences.</AbstractText> |
7,718 | Paroxysmal atrial fibrillation in critically ill patients with sepsis. | The objective of this retrospective cohort study was to describe the incidence of paroxysmal atrial fibrillation and to determine its risk factors and effect on outcome in critically ill patients with sepsis. The study included 81 patients with sepsis admitted to an intensive care unit. In all, 25 patients (31%) developed paroxysmal atrial fibrillation. Advanced age, history of paroxysmal atrial fibrillation, higher severity of illness at intensive care unit admission, and lower left ventricular ejection fraction were risk factors for paroxysmal atrial fibrillation. Multiple logistic regression analysis showed that paroxysmal atrial fibrillation was independently associated with 28-day mortality (odds ratio = 3.284; 95% confidence interval, 1.126-9.574). The incidence of paroxysmal atrial fibrillation is high in critically ill patients with sepsis. It occurs more frequently in patients with advanced age, history of paroxysmal atrial fibrillation, high severity of illness, and lower left ventricular ejection fraction and is associated with increased mortality. |
7,719 | Less invasive intracardiac surgery performed without aortic clamping. | Aortic clamping and cardioplegia delivery add complexity to performing intracardiac procedures through a right minithoracotomy. Recent publications have shown excellent patient outcomes after mitral valve (MV) procedures undertaken through thoracotomy on the fibrillating heart. We reviewed our experience with this approach.</AbstractText>From March 2000 to September 2006, 100 patients underwent MV repair (n = 42), MV annuloplasty (n = 28), MV replacement (n = 18), atrial septal defect closure (n = 10), tricuspid valve repair (n = 1), and left atrial myxoma excision (n = 1). A modified maze procedure (n = 4) or left minimally invasive direct coronary bypass grafting (MIDCABG) (n = 2) was combined in six cases. The mean age was 57 +/- 11 years (range, 22 to 89); 27 patients were in New York Heart Association (NYHA) class III or IV; 24 cases were first or second time reoperations; 20 patients had a left ventricular ejection fraction of less than 0.3. All the operations were carried out on the fibrillating heart without cross-clamping the aorta through a right minithoracotomy using peripheral cannulation.</AbstractText>Mean fibrillation time was 73 +/- 31 minutes (range, 10 to 198 minutes). There was no conversion to sternotomy. Postoperative inotropic support was needed in 20 cases. One patient who underwent a third time reoperation died within 30 days of mesenteric ischemia (hospital mortality = 1%). Complications were the following: four reoperations for bleeding (4%); two strokes (2%). Postoperative median hospital length of stay was five days (range, 2 to 58 days). None of the patients has required MV reoperation after hospital discharge. Follow-up was complete. All survivors were in NYHA class I or II.</AbstractText>Ventricular fibrillation simplifies less invasive intracardiac procedures and carries lower complication rates and perioperative mortality compared with conventional surgery.</AbstractText> |
7,720 | Clinical significance of B-type natriuretic Peptide in the assessment of untreated hypertension. | Recent studies suggest that B-type natriuretic peptide (BNP) is an important predictor of cardiac events in hypertensive patients.</AbstractText>The relationship between the plasma BNP level and various clinical parameters was examined in 154 untreated hypertensive patients without heart failure or atrial fibrillation (mean age: 58.0+/-10.7; mean blood pressure: 164.5+/-15.2/99.1+/-9.7 mmHg; mean BNP: 32.7+/-36.7 pg/ml). First, the patients were divided into 2 groups based on BNP: normal (<18.5 pg/ml, mean 9.7+/-5.7, n=69); or elevated (>18.5 pg/ml, mean 51.4+/-40.4, n=85). The elevated BNP group had a significantly greater electrocardiographic voltage index (SV1+RV5; 3.7+/-1.2 vs 3.2+/-0.8 mV, p=0.0029), cardiothoracic ratio/chest radiography (CTR; 49.1 vs 46.9%, p=0.0037), left ventricular mass index (LVMI; 122.2+/-31.7 vs 103.1+/-26.4 g/m2, p=0.0005) and deceleration time (DT; 241+/-39 vs 208+/-30 ms, p=0.0001), as well as a smaller E-wave to A-wave (E/A ratio) (0.80+/-0.22 vs 0.96+/-0.28, p=0.0003), compared with the normal BNP group. There were no significant differences in casual blood pressure, body mass index, serum creatinine and ejection fraction between the 2 groups. Next, the patients were divided into 3 groups based on BNP: normal (<18.5, n=69), moderate (18.5 to 40, mean 27.0+/-5.7, n=43) and high (40<, mean 76.3+/-45.3, n=42). In the high BNP group, most clinical parameters indicated the most severe organ damage compared with other groups, including SV1+RV5, DT and LVMI. In all patients, logarithmic BNP was positively correlated with the age, pulse pressure, SV1+RV5, CTR, ventricular wall thickness, DT, LVMI and negatively correlated with hemoglobin, renin and E/A ratio. Using multiple regression analysis, renin and DT were significantly associated with BNP. No gender differences in the relationship between BNP and clinical parameters were found.</AbstractText>Results suggest that BNP is a useful indicator for the initial assessment of the severity of essential hypertension, detecting both cardiac hypertrophy and diastolic dysfunction, and may also be valuable for risk stratification.</AbstractText> |
7,721 | Comparison of rate and rhythm control in hypertension patients with atrial fibrillation. | Atrial fibrillation (AF) is a very common cardiac arrhythmia, and is associated with an increased mortality in patients with hypertension. Whether the best therapeutic approach for these patients is to restore sinus rhythm (SR) or to adequately control the ventricular rate is still controversial. The aim of this study is to compare both strategies in patients with hypertension.</AbstractText>Two hundred and twenty-one patients with hypertension and AF of duration >48 h were randomly assigned to either the rhythm (n=155) or rate (n=66) control group. Exercise capacity was improved in the rhythm control group in the 1st year of the study (p<0.0001). There were no statistically significant differences in the embolic event rate and the total mortality between the 2 groups at the end of the study (p=NS).</AbstractText>Although restoring and maintaining SR had a beneficial effect on exercise capacity in patients with hypertension and AF, no significant difference was found in terms of the total mortality and the embolic event rates. Thus, rate control is an acceptable primary strategy in patients with AF and hypertension.</AbstractText> |
7,722 | Reducing false alarm rates for critical arrhythmias using the arterial blood pressure waveform. | Over the past two decades, high false alarm (FA) rates have remained an important yet unresolved concern in the Intensive Care Unit (ICU). High FA rates lead to desensitization of the attending staff to such warnings, with associated slowing in response times and detrimental decreases in the quality of care for the patient. False arrhythmia alarms are commonly due to single channel ECG artifacts and low voltage signals, and therefore it is likely that the FA rates may be reduced if information from other independent signals is used to form a more robust hypothesis of the alarm's etiology.</AbstractText>A large multi-parameter ICU database (PhysioNet's MIMIC II database) was used to investigate the frequency of five categories of false critical ("red" or "life-threatening") ECG arrhythmia alarms produced by a commercial ICU monitoring system, namely: asystole, extreme bradycardia, extreme tachycardia, ventricular tachycardia and ventricular fibrillation/tachycardia. Non-critical ("yellow") arrhythmia alarms were not considered in this study. Multiple expert reviews of 5386 critical ECG arrhythmia alarms from a total of 447 adult patient records in the MIMIC II database were made using the associated 41,301 h of simultaneous ECG and arterial blood pressure (ABP) waveforms. An algorithm to suppress false critical ECG arrhythmia alarms using morphological and timing information derived from the ABP signal was then tested.</AbstractText>An average of 42.7% of the critical ECG arrhythmia alarms were found to be false, with each of the five alarm categories having FA rates between 23.1% and 90.7%. The FA suppression algorithm was able to suppress 59.7% of the false alarms, with FA reduction rates as high as 93.5% for asystole and 81.0% for extreme bradycardia. FA reduction rates were lowest for extreme tachycardia (63.7%) and ventricular-related alarms (58.2% for ventricular fibrillation/tachycardia and 33.0% for ventricular tachycardia). True alarm (TA) reduction rates were all 0%, except for ventricular tachycardia alarms (9.4%).</AbstractText>The FA suppression algorithm reduced the incidence of false critical ECG arrhythmia alarms from 42.7% to 17.2%, where simultaneous ECG and ABP data were available. The present algorithm demonstrated the potential of data fusion to reduce false ECG arrhythmia alarms in a clinical setting, but the non-zero TA reduction rate for ventricular tachycardia indicates the need for further refinement of the suppression strategy. To avoid suppressing any true alarms, the algorithm could be implemented for all alarms except ventricular tachycardia. Under these conditions the FA rate would be reduced from 42.7% to 22.7%. This implementation of the algorithm should be considered for prospective clinical evaluation. The public availability of a real-world ICU database of multi-parameter physiologic waveforms, together with their associated annotated alarms is a new and valuable research resource for algorithm developers.</AbstractText> |
7,723 | Optimal heart failure therapy and successful cardioversion in heart failure patients with atrial fibrillation. | Effectiveness, safety, and other factors associated with success of cardioversion (CV) of atrial fibrillation (AF) have not yet been evaluated in patients with reduced left ventricular ejection fraction. We studied 148 consecutive patients with left ventricular dysfunction (ejection fraction < or = 45%), who underwent electrical CV for AF in our department. The patients had New York Heart Association heart failure ranging from class II to IV. The overall CV success rate was 71%. We relied on univariate and multivariate regression and sought variables influencing success rate. Conversion success did not correlate with New York Heart Association class. Instead, we found that the greatest predictor was the degree of heart failure treatment. Patients receiving beta-blockers, angiotensin-converting enzyme inhibitors or angiotension receptor blockers, plus mineralocorticoid receptor blockers had the greatest chance for conversion success. Success was more likely in patients with coronary artery disease (91%) than in patients with nonischemic cardiomyopathy.</AbstractText>Cardioversion is a safe and effective method for the restoration of sinus rhythm in patients with AF and reduced left ventricular ejection fraction. Our findings underscore the value of aggressive heart failure treatment before CV in patients with AF.</AbstractText> |
7,724 | Brugada syndrome with marked conduction disease: dual implications of a SCN5A mutation. | A 51-year-old woman presented with an episode of syncope. Upon further review she was found to have a typical Brugada type pattern on her electrocardiogram. She did not have evidence for structural heart disease. At electrophysiological testing she was found to have marked infrahisian conduction disease and had easily inducible polymorphic ventricular tachycardia. She underwent implantation of a dual-chamber implantable cardioverter defibrillator (ICD) and family screening was recommended. Genetic analysis revealed a novel nonsense mutation in the gene encoding for the sodium channel (SCN5A). Five months after ICD implantation the patient had an episode of ventricular fibrillation documented on ICD interrogation. This case is unique as it is consistent with an overlap syndrome, namely both Brugada Syndrome and distal atrioventricular (AV) conduction disease secondary to a novel SCN5A mutation in a young female. This finding highlights the phenotypic heterogeneity of novel SCN5A mutations. |
7,725 | Stimulation rate and the optimal interventricular interval during cardiac resynchronization therapy in patients with chronic atrial fibrillation. | Optimization of cardiac resynchronization therapy (CRT) with respect to the interventricular (V-V) interval is mainly limited to pacing at a resting heart rate. We studied the effect of higher stimulation rates with univentricular and biventricular (BiV) pacing modes including the effect of the V-V interval optimization.</AbstractText>In 36 patients with heart failure and chronic atrial fibrillation (AF), the effects of right ventricular (RV), left ventricular (LV), simultaneous BiV, and optimized sequential BiV (BiVopt) pacing were measured. The effect of the pacing mode and the optimal V-V interval was determined at stimulation rates of 70, 90, and 110 ppm using invasive measurement of the maximum rate of left ventricular pressure rise (LV dP/dt(max)).</AbstractText>The average LV dP/dt (max) for all pacing modalities at stimulation rates of 70, 90, and 110 ppm was 781 +/- 176, 833 +/- 197, and 884 +/- 223 mmHg/s for RV pacing; 893 +/- 178, 942 +/- 186, and 981 +/- 194 mmHg/s for LV pacing; 904 +/- 179, 973 +/- 187, and 1052 +/- 206 mmHg/s for simultaneous BiV pacing; and 941 +/- 186, 1010 +/- 198, and 1081 +/- 206 mmHg/s for BiVopt pacing, respectively. In BiVopt pacing, the corresponding optimal V-V interval decreased from 34 +/- 29, 28 +/- 28, and21 +/- 27ms at stimulation rates of 70, 90, and 110 ppm, respectively. In two individuals, LV dP/dt(max) decreased when the pacing rate was increased from 90 to 110 ppm.</AbstractText>In patients with AF and heart failure, LV dP/dt(max) increases for all pacing modalities at increasing stimulation rates in most, but not all, patients. The rise in LV dP/dt(max) with increasing stimulation rates is higher in biventricular (BiV and BiVopt) than in univentricular (LV and RV) pacing. The optimal V-V interval at sequential biventricular pacing decreases with increasing stimulation rates.</AbstractText> |
7,726 | The impedance cardiogram recorded through two electrocardiogram/defibrillator pads as a determinant of cardiac arrest during experimental studies. | Laypersons are poor at emergency pulse checks (sensitivity 84%, specificity 36%). Guidelines indicate that pulse checks should not be performed. The impedance cardiogram (dZ/dt) is used to assess stroke volume. Can a novel defibrillator-based impedance cardiogram system be used to distinguish between circulatory arrest and other collapse states?</AbstractText>Animal study.</AbstractText>University research laboratory.</AbstractText>Twenty anesthetized, mechanically ventilated pigs, weight 50-55 kg.</AbstractText>Stroke volume was altered by right ventricular pacing (160, 210, 260, and 305 beats/min). Cardiac arrest states were then induced: ventricular fibrillation (by rapid ventricular pacing) and, after successful defibrillation, pulseless electrical activity and asystole (by high-dose intravenous pentobarbitone).</AbstractText>The impedance cardiogram was recorded through electrocardiogram/defibrillator pads in standard cardiac arrest positions. Simultaneously recorded electro- and impedance cardiogram (dZ/dt) along with arterial blood pressure tracings were digitized during each pacing and cardiac arrest protocol. Five-second epochs were analyzed for sinus rhythm (20 before ventricular fibrillation, 20 after successful defibrillation), ventricular fibrillation (40), pulseless electrical activity (20), and asystole (20), in two sets of ten pigs (ten training, ten validation). Standard impedance cardiogram variables were noncontributory in cardiac arrest, so the fast Fourier transform of dZ/dt was assessed. During ventricular pacing, the peak amplitude of fast Fourier transform of dZ/dt (between 1.5 and 4.5 Hz) correlated with stroke volume (r2 = .3, p < .001). In cardiac arrest, a peak amplitude of fast Fourier transform of dZ/dt of < or = 4 dB x ohm x rms indicated no output with high sensitivity (94% training set, 86% validation set) and specificity (98% training set, 90% validation set).</AbstractText>As a powerful clinical marker of circulatory collapse, the fast Fourier transformation of dZ/dt (impedance cardiogram) has the potential to improve emergency care by laypersons using automated defibrillators.</AbstractText> |
7,727 | Automatic home monitoring of implantable cardioverter defibrillators. | With the expanding indications for implantable cardioverter defibrillator (ICD) and reports of unexpected ICD failures, home monitoring (HM) was proposed to decrease follow-up workload and increase patient safety. Home monitoring implantable cardioverter defibrillators offer wireless, everyday transfer of ICD status and therapy data to a central HM Service Center, which notifies the attending physician of relevant HM events. We evaluated functionality and safety of HM ICDs.</AbstractText>A total of 260 patients with HM ICDs were monitored for a mean of 10 +/- 5 months. Time to HM events [medical (ventricular tachycardia/ventricular fibrillation) and technical (ICD system integrity)] since ICD implantation and since the latest in-clinic follow-up was analysed. Mean number of HM events per 100 patients per day was calculated, without and with a 2-day blanking period for re-notifying the same type of event. About 41.2% of the patients had HM events (38.1% medical, 0.8% technical, and 2.3% both types). Probability of any HM event after 1.5 years was 0.50 (95% confidence interval: 0.42-0.58). More than 60% of new HM event types occurred within the first month after follow-up. A mean of 0.86 event notifications was received per 100 patients per day or 0.45 with the 2-day blanking period.</AbstractText>Home monitoring is feasible and associated with an early detection of medical and technical events.</AbstractText> |
7,728 | [Drugs for cardiac arrest]. | After publication of the 2005 international recommendations on resuscitation, a French panel of experts on cardiac arrest published guidelines adapted to French practice. Despite the absence of placebo-controlled trials, adrenaline remains the standard vasopressor for cardiac arrest, at a dose of 1 mg about every 4 minutes. Amiodarone has replaced lidocaine in treatment of refractory ventricular fibrillation.No other drug is indicated during cardiopulmonary resuscitation,except for particular causes of cardiac arrest. Fibrinolysis should be considered only for cardiac arrest due to pulmonary embolism. Isotonic saline solution is recommended for infusions, and routine administration of sodium bicarbonate is not recommended. Intravenous access is necessary, but when unavailable rapidly,intraosseous is preferred to endotracheal delivery in adults and children |
7,729 | Myocardial delayed contrast enhancement in patients with arterial hypertension: initial results of cardiac MRI. | In arterial hypertension left ventricular hypertrophy comprises myocyte hypertrophy, interstitial fibrosis and structural alterations of the coronary microcirculation. MRI enables the detection of myocardial fibrosis, infarction and scar tissue by delayed enhancement (DE) after contrast media application. Aim of this study was to investigate patients with arterial hypertension but without known coronary disease or previous myocardial infarction to detect areas of DE.</AbstractText>Twenty patients with arterial hypertension with clinical symptoms of myocardial ischemia, but without history of myocardial infarction and normal coronary arteries during coronary angiography were investigated on a 1.0 T superconducting magnet (Gyroscan T10-NT, Intera Release 8.0, Philips). Fast gradient-echo cine sequences and T2-weighted STIR-sequences were acquired. Fifteen minutes after injection of Gadobenate dimeglumine inversion recovery gradient-echo sequences were performed for detection of myocardial DE. Presence or absence of DE on MRI was correlated with clinical data and the results of echocardiography and electrocardiography, respectively.</AbstractText>Nine of 20 patients showed DE in the interventricular septum and the anteroseptal left ventricular wall. In 6 patients, DE was localized intramurally and in 3 patients subendocardially. There was a significant correlation between myocardial DE and ST-segment depressions during exercise and between DE and left-ventricular enddiastolic pressure. Patients with intermittent atrial fibrillation showed a myocardial DE more often than patients without atrial fibrillation.</AbstractText>In our series, 45% of patients with arterial hypertension showed DE on cardiac MRI. In this clinical setting, delayed enhancement may be due to coronary microangiopathy. The more intramurally localization of DE, however, rather indicates myocardial interstitial fibrosis.</AbstractText> |
7,730 | Unusual cause of exercise-induced ventricular fibrillation in a well-trained adult endurance athlete: a case report. | The diseases responsible for sudden deaths in athletes differ considerably with regard to age. In young athletes, congenital malformations of the heart and/or vascular system cause the majority of deaths and can only be detected noninvasively by complex diagnostics. In contrast, in older athletes who die suddenly, atherosclerotic disease of the coronary arteries is mostly found. Reports of congenital coronary anomalies as a cause of sudden death in older athletes are rare.</AbstractText>A 48-year-old man who was a well-trained, long-distance runner collapsed at the finish of a half marathon because of a myocardial infarction with ventricular fibrillation. Coronary angiography showed an anomalous origin of the right coronary artery from the left sinus of Valsalva with minimal wall alterations. Multislice computed tomography of the coronary arteries confirmed these findings. Cardiomagnetic resonance imaging demonstrated a mild hypokinesia of the basal right- and left-ventricular posterior wall. An electrophysiological study showed an inducible temporary polymorphic ventricular tachycardia and an inducible ventricular fibrillation. The athlete was subsequently treated by acetylsalicylic acid 100 mg (0-1-0), bisoprolol 2.5 mg (1-0-0) and atorvastatin 10 mg (0-0-1) and was instructed to keep his training intensity under the 'individual anaerobic threshold'. Intense and long-lasting exercise under extreme environmental conditions, particularly heat, should also be avoided.</AbstractText>This case report presents a coronary anomaly as the most likely reason for an exercise-induced myocardial infarction with ventricular fibrillation in a well-trained 48-year-old endurance athlete. Therefore, coronary anomalies have also to be considered as a possible cause of cardiac problems in older athletes.</AbstractText> |
7,731 | Left atrial giant thrombus infected by Escherichia Coli. Case report. | Left atrial thrombi are mostly related to mitral valve disease. The differential diagnosis of clots and myxomas in the left atrium is mostly based on echocardiography. Infection of intracardiac thrombi is extremely rare and mostly reported in ventricular clots or aneurysms following myocardial infarction.</AbstractText>We present the case of a 65 year old female with a history of mitral valve disease and chronic atrial fibrillation who suffered repeated embolic strokes and a giant infected clot in the left atrium. Although the patient underwent prompt surgery with removal of the clot and valve replacement the complication of septic emboli to the CNS led her to death. To the best of our knowledge this is the second report of an infected left atrial thrombus.</AbstractText>The case is a representative example of a neglected and undertreated patient with catastrophic consequences. Anticoagulant therapy in patients with mitral valve disease and atrial fibrillation should be applied according the currently available guidelines and standards in order to avoid analogous paradigms in the future. Mitral valve substitution should be considered in patients with mitral valve disease presenting thromboembolic complications. Surgery should be considered as the treatment of choice in cases of organized left atrial thrombus and suspected tumor or infected mass.</AbstractText> |
7,732 | [Predictors of efficacy initial low energy of external rectilinear biphasic cardioversion in persistent atrial fibrillation]. | Rectilinear biphasic cardioversion (Bi-DC) has been shown to be very effective for restoration of sinus rhythm in patients with persistent atrial fibrillation (AF). There is, however, limited information on factors influencing effectiveness of the initial energy of 50 J for Bi-DC of atrial fibrillation.</AbstractText>Evaluation of efficacy of 50 J shock of Bi-DC for restoration sinus rhythm and development of point score system to predict high conversion rate of 50 J shock in persistent atrial fibrillation.</AbstractText>The study group was composed of 502 consecutive Bi-DC in-patients with persistent atrial fibrillation who underwent cardioversion according to the standard protocol (50 J --> 1 J/kg m.c. --> 2 J/kg m.c. --> 200 J). Factors influencing effectiveness of 50 J shock were defined.</AbstractText>Rectilinear biphasic cardioversion of shock of 50 J was successful in 157 (31%) patients. In multivariate analysis independent factors associated with efficacy of 50 J shock were: atrial fibrillation duration < 7 months (OR: 14.3, CI: 5.83 - 35.2, p < 0.001), left ventricular ejection fraction--LVEF > 40% (OR: 5.67, CI: 1.22 - 26.3, p = 0.027), body weight < 78 kg (OR: 3.17, CI: 1.52 - 6.59, p = 0.002), permanent pacemaker (OR: 2.98, CI: 1.20 - 7.40, p = 0.018), LA diameter < 4.5 cm (OR: 2.80, CI: 1.19 - 6.58, p = 0.02). A simplified point score system was developed to predict the chance for termination of atrial fibrillation (the score gives 5 points for atrial fibrillation duration < 7 months; 2 points for EF > 40%; 1 point for pacemaker, body weight < 78 kg and LA < 4.5 cm, each). High effectiveness (65%) of 50 J shock was achieved in patients with > 9 points of scoring system and 80% in this group when atrial fibrillation duration is shorter than 3 months. Effectiveness of 50 J shock was very low in the remaining group (0 points--0%; 1-3 points--5%; 4-6 points--21%; 7-8 points--34%, respectively).</AbstractText>The efficacy of initial shock of 50 J for termination of atrial fibrillation is limited and is not recommended for general population of patients with atrial fibrillation referred for Bi-DC. 50 J might be considered in patients with pacemakers without factors associated with failure of 50 J to terminate atrial fibrillation: atrial fibrillation duration > 7 months, lower LVEF increased LA diameter, body weight > 78 kg. The shock of 50 J is effective in more than 60% of patients, if they achieved 9 or 10 points in proposed score. The highest efficacy of 50 J shock (80%) is possible to reach in this group if atrial fibrillation duration is shorter than 3 months.</AbstractText> |
7,733 | Usefulness and predictive value of circulating NT-proBNP levels to stratify patients for referral and priority treatment in a specialized outpatient heart failure center. | Serum natriuretic peptide levels are useful diagnostic and prognostic markers in patients with acute decompensated heart failure, but have been little used to stratify urgency of treatment in the outpatient situation.</AbstractText>To examine the use of natriuretic peptide to guide priority of patient referral to a heart failure center.</AbstractText>We analyzed data from 70 consecutive patients with chronic heart failure (NYHA class 2-4) referred for first evaluation in a specialized outpatient heart failure center. Serum NT-proBNP was measured at the initial patient visit. We examined correlates and predictive value of mid- and upper tertile NT-proBNP for mortality in comparison with other known prognostic indicators using univariate and multivariate logistic regression analysis.</AbstractText>Mortality at 6 months was 26.0% in patients with upper tertile (> 1958 pg/ml) NT-proBNP, 8.7% in the middle tertile group and 0% in the lowest tertile (P=0.017). Patients with upper tertile serum NT-proBNP levels (group 3) had lower left ventricular ejection fraction, were more often in atrial fibrillation (P=0.04) and more often had renal failure (P=0.03). Age-adjusted logistic regression analysis identified upper tertile serum NT-proBNP level as the strongest independent predictor of 6 month mortality with a sixfold risk of early death (adjusted odds ratio 6.08, 95% confidence interval 1.58-47.13, P=0.04). NT-proBNP was a more powerful predictor of prognosis than ejection fraction and other traditional outcome markers.</AbstractText>In heart failure patients referred to an outpatient specialized heart failure center, an upper tertile NT-proBNP level identified patients at high risk for mortality. A single high > 550 pg/ml NT-proBNP measurement appears to be useful for selecting patients for care in a heart failure center, and a level > 2000 pg/ml for assigning patients to high priority management.</AbstractText> |
7,734 | Cardiac arrhythmias in Thai Acute Coronary Syndrome Registry. | The incidence of arrhythmic complications in Thai patients with acute coronary syndromes (ACS) has not been previously reported. The present study results will serve as the local database for future studies.</AbstractText>To evaluate the incidence of arrhythmic complications in ASC in Thai patients and to identify factors that may affect arrhythmia complications in ACS patients.</AbstractText>Data collected from 9,373 patients from the Thai acute coronary syndrome registry (TACSR) were analyzed. This registry includes patients who presented with ACS including ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI) and unstable angina (UA), within 14 days from the symptoms onset.</AbstractText>395 (4.2%) patients with an ACS presented after cardiac arrest. These patients were noted to have significantly higher in-hospital mortality (50.1%). The incidence of serious cardiac arrhythmia complications in the TACSR was 16.6%. Among them, 62.7% were sustained VT/VE 31.5% had second or third degree AV block, and 5.8% has both VT/VF and AV Block. The incidence of VT was higher in the younger age group, while AV block and arrhythmic death were higher in the older aged patients. Arrhythmias complicating ACS were associated with increased mortality risk. Congestive heart failure (CHF) within the first 48 hours, current use of tobacco and cardiac troponin elevation were associated with significantly higher arrhythmic complications during hospitalization.</AbstractText>Arrhythmias complicating ACS were associated with higher in hospital mortality. CHF within the first 48 hr, current tobacco use and cardiac troponin elevation were associated with significantly higher arrhythmic complications.</AbstractText> |
7,735 | Is use of temporary pacing wires following coronary bypass surgery really necessary? | Temporary epicardial pacing wires (TEPW) which are routinely used after coronary bypass grafting may result in significant complications. We sought to identify variables that predict TEPW implantation and thereby limit their use.</AbstractText>This prospective study enrolled 564 patients (296 underwent coronary artery bypass grafting with cardiopulmonary bypass [ONCAB] and 268 underwent off-pump coronary artery bypass grafting, OPCAB). TEPW were placed in patients with the intraoperative presence of one or more of the following criteria: sinus bradycardia, sinus arrest, nodal/junctional rhythms, atrioventricular block, bundle branch block, ventricular tachycardia, or onset of atrial fibrillation.</AbstractText>Only 31 (5.5%) patients [ONCAB: 20 (6.8%) (ventricular: 14, bichamber: 6); OPCAB: 11 (4.1%) (ventricular: 9, bichamber: 2)] had temporary epicardial pacing wires implanted intraoperatively. Indications for using temporary epicardial pacing wires for ONCAB were sinus bradycardia (8), nodal/junctional rhythms (3), atrioventricular block (3), atrial fibrillation (4), and bundle branch block (2), and for OPCAB were sinus bradycardia (8), nodal/junctional rhythms (2), and atrioventricular block (1). Mean duration for pacing was 22.4 h for the ONCAB group and 11.3 h for the OPCAB group. There were no temporary epicardial pacing wires associated complications. One paced OPCAB patient required a permanent pacemaker and 2 non-paced OPCAB patients required transvenous pacing wires. Univariate and multivariate analyses were also conducted to determine risk factors for TEPW.</AbstractText>TEPW implantation is overused in cardiac surgery and by identifying independent predictors for pacing we conclude that TEPW use should be limited to a select few.</AbstractText> |
7,736 | Therapeutic hypothermia with a novel surface cooling device improves neurologic outcome after prolonged cardiac arrest in swine. | Devices for rapid induction of mild hypothermia after cardiac arrest are needed. We hypothesized that the Life Recovery Systems' ThermoSuit System provides effective core cooling by pumping ice water over the skin surface and improves neurologic outcome after prolonged cardiac arrest.</AbstractText>Prospective experimental study.</AbstractText>University research laboratory.</AbstractText>Large White breed pigs (29 to 35 kg).</AbstractText>Swine were anesthetized and mechanically ventilated. Ten minutes of untreated ventricular fibrillation, 3 mins of basic life support, and 5 mins of advanced cardiac life support, including two 0.4 IU/kg doses of vasopressin, were followed by up to three countershocks. After restoration of spontaneous circulation, swine were randomized to two groups (normothermic control, hypothermia). The hypothermia group was cooled from a pulmonary artery temperature of 38.5 +/- 0.5 degrees C to 33.0 degrees C and kept for 14 hrs. At day 9 of the experiment, overall performance categories scores (1, normal; 2, slightly disabled; 3, severely disabled; 4, comatose; 5, dead, brain dead) and neurologic deficit scores (0%, normal; 100%, brain dead) were assessed. Data are presented as median and interquartile range; group comparison was done with a Mann-Whitney U test.</AbstractText>In total, 16 of 22 animals were randomized. Time to target temperature in the hypothermia group (n = 8) was 9.0 (5.3-11.9) mins (cooling rate 0.4 [0.3-0.8] degrees C/min), and all animals achieved an overall performance categories score of 1. In the control group, one swine achieved an overall performance categories score of 1, three achieved a score of 2, and four achieved a score of 3 (p = .002). Neurologic deficit score was 0% (0%-4%) in the hypothermia group and 39% (19%-55%) in the control group (p = .001). No harmful side effects could be observed.</AbstractText>The Life Recovery Systems' ThermoSuit System rapidly and safely induced mild therapeutic hypothermia. Hypothermia improved neurologic outcome in swine after cardiac arrest as compared with normothermia. Further studies are warranted to compare the device with established cooling methods.</AbstractText> |
7,737 | Prearrest administration of low-molecular-weight heparin in porcine cardiac arrest: hemodynamic effects and resuscitability. | Both animal and human studies demonstrate activation of coagulation during cardiac arrest. Prearrest anticoagulation is used routinely in many experimental studies. We studied the hemodynamic effects of prearrest anticoagulation with a low-molecular-weight heparin suitable for clinical use during cardiopulmonary resuscitation in pigs.</AbstractText>Randomized and blinded experimental animal study.</AbstractText>University hospital-affiliated research laboratory.</AbstractText>Sixteen female domestic pigs.</AbstractText>Three minutes before electrically induced ventricular fibrillation, enoxaparin 1 mg/kg or physiologic saline was blinded and administered intravenously. After 10 mins of untreated ventricular fibrillation, advanced cardiac life support was initiated with continuous mechanical chest compressions and interposed manual ventilation with 100% oxygen. Epinephrine was administered after 2 mins of advanced cardiac life support followed by attempted defibrillation 1 min thereafter. Advanced cardiac life support was continued for 10 mins following international guidelines. Electrocardiogram was recorded continuously and ventricular fibrillation waveform was analyzed (median slope). Animals with return of spontaneous circulation were observed for ten more minutes. Blood specimens were drawn for analysis of coagulation activation (thrombin-antithrombin complex) and drug effect (anti-factor Xa activity).</AbstractText>Six of eight (75%) pigs in each group achieved return of spontaneous circulation. Thrombin-antithrombin complex levels were significantly lower in pigs that received enoxaparin. There was no significant difference either in measured hemodynamics between the groups during advanced cardiac life support and after return of spontaneous circulation or in median slope values during ventricular fibrillation. Epinephrine caused a significant decrease in femoral and increase in cerebral cortical blood flow with no difference between the groups.</AbstractText>Prearrest anticoagulation with enoxaparin did not influence either hemodynamics during advanced cardiac life support and after return of spontaneous circulation or the frequency of return of spontaneous circulation in porcine cardiac arrest.</AbstractText> |
7,738 | Selective retrograde venous revascularization of the myocardium when PCI or CABG is impossible: investigation in a porcine model. | We investigated the possibility of nourishing the myocardium through selective retrograde coronary venous bypass grafting (CVBG) with an off-pump technique and evaluated various methods of monitoring the physiological effects of this procedure. In a porcine model, the left internal mammary artery (LIMA) was anastomosed to the left anterior descending coronary vein (LAD vein) in an off-pump procedure. The LAD vein was ligated proximal to the anastomosis. The LAD artery was ligated proximally. The physiological effects were monitored using microdialysis, tissue oxygen tension, blood flow in LIMA, blood samples, and hemodynamic and histological analyses. As controls, 5 pigs underwent surgery involving only LAD artery ligation without CVBG. CVBG with LAD ligation was performed in 16 pigs; 12 survived CVBG and were monitored for 2-2.5 hours while in sinus rhythm, a 75% salvage rate after an otherwise lethal LAD artery occlusion. Immediately after LAD artery ligation, the anterior wall of the left ventricle became cyanotic and hypokinetic. Over time it regained color and contractility as flow in the LIMA increased. Microdialysis showed a significant increase in lactate. Initially tissue oxygen tension decreased, but with time some recovery was seen. Cardiac troponin T was elevated. Histological analysis showed ischemic changes. In control pigs, microdialysis was performed for 1.5 hours up to LAD artery ligation, after which all pigs died in ventricular fibrillation arrest. No increase in lactate was observed. These results indicate that after LAD artery occlusion, CVBG can nourish the myocardium to a certain extent and prevent death in the majority of cases, although varying degrees of ischemia remain. |
7,739 | Evaluation of left ventricular long-axis function in cases of rheumatic pure mitral stenosis with atrial fibrillation. | Using tissue Doppler echocardiography, we evaluated left ventricular long-axis function in 65 mitral stenosis patients, 30 of whom were in sinus rhythm and 35 of whom were in chronic atrial fibrillation. There were 35 healthy control subjects. Conventional echocardiography was used to evaluate left ventricular diameters, left atrial diameters, left ventricular ejection fractions, and mitral valve areas. Tissue Doppler echocardiography was used to evaluate isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), ejection time (ET), and peak systolic myocardial velocities. The myocardial performance index was calculated with the formula (ICT+IRT)/ET. Mean and segmental left ventricular IRT and ICT values were significantly longer in mitral stenosis patients than in control subjects, but were similar in the sinus rhythm and atrial fibrillation subgroups. Ejection times were significantly lower in the mitral stenosis with atrial fibrillation group than in the mitral stenosis with sinus rhythm and control groups (P<0.001), but were similar when the sinus rhythm group was compared with the control group (P<0.05). Myocardial performance index values were higher in mitral stenosis patients, significantly so in those with atrial fibrillation when compared with the control group (P<0.001). Systolic velocity values were significantly lower in mitral stenosis patients, more markedly so in those with atrial fibrillation than in the control group (P<0.001). We conclude that patients with pure rheumatic mitral stenosis, most particularly when in combination with atrial fibrillation, have significantly impaired left ventricular long-axis function as evaluated by tissue Doppler echocardiography, although global systolic function may be normal. |
7,740 | Novel transient outward and ultra-rapid delayed rectifier current antagonist, AVE0118, protects against ventricular fibrillation induced by myocardial ischemia. | AVE0118 is a novel drug that blocks the transient outward current (Ito), the ultra rapid component of the delayed rectifier current (IKur), and the acetylcholine dependent potassium channel (IKach). The latter 2 channels are more abundant in atrial tissue. It is possible that AVE0118 could reduce regional differences in repolarization and thereby prevent malignant arrhythmias provoked by ischemia. To test this hypothesis, ventricular fibrillation was induced by a 2-minute occlusion of the left circumflex coronary artery during the last min of exercise in dogs with healed myocardial infarctions (n = 9). On a subsequent day, this exercise plus ischemia test was repeated after pretreatment with AVE0118 (1.0 mg/kg, IV). AVE0118 did not change QTc (Van de Water's correction) interval [245 +/- 6.0 ms (control) versus 242 +/- 2.3 ms (AVE)] and attenuated the dispersion of repolarization as measured by the duration of the descending portion of the T wave (Tpeak - Tend) induced by ischemia [ischemic changes: +11.1 +/- 2.4 ms (no drug) versus +2.2 +/- 3.7 ms (AVE)]. AVE0118 also significantly reduced the incidence of ventricular fibrillation, protecting 7 of 9 animals. Thus, AVE0118 abolished ischemically induced repolarization abnormalities and prevented malignant arrhythmias induced by ischemia without altering QTc interval. |
7,741 | Development and validation of diagnostic criteria for atrial flutter on the surface electrocardiogram. | There are no universally accepted ECG diagnostic criteria for atrial flutter (AFL), making its differentiation from "coarse" atrial fibrillation (AF) difficult.</AbstractText>To develop diagnostic criteria for AFL, we examined two sets of ECGs. Set 1 consisted of 100 ECGs (50 AF, AFL) with diagnoses confirmed by intracardiac recordings. Criteria evaluated were presence of F waves in the frontal plane leads, F waves in V(1), sawtooth F waves, rate, and regularity of ventricular response. Set 2 included 200 ECGs taken from the hospital database each of which had already been interpreted by a cardiologist as either AF (n = 100) or AFL (n = 100). Set 2 was blindly read by electrophysiologists whose consensus-diagnoses were compared to the diagnoses made by using the best criteria identified from the Set 1 data.</AbstractText>The criteria of frontal plane F waves, regular or partially regular ventricular response, and their combination had sensitivities of 92%, 98%, and 90% and specificities of 100%, 78%, and 100% in Set 1 for the diagnosis of AFL. In Set 2, concordance of electrophysiologist and cardiologist diagnoses was only 84%. The criteria of frontal plane Fwaves, regular or partially regular ventricular response, and their combination resulted in concordances with the cardiologist diagnoses of 85%, 85%, and 82% and with the electrophysiologist-consensus diagnoses of 90%, 89%, and 94% (P < 0.001).</AbstractText>The criteria of frontal plane F waves and regular or partially regular ventricular response aid in the proper diagnosis of AFL. Because management strategies may differ for AF and AFL, it is important to adopt a more rigorous diagnostic approach.</AbstractText> |
7,742 | Adverse effects of continuous ventricular pacing in patients with slower atrial fibrillation and normal left ventricular systolic function. | Both heart rate irregularity during chronic atrial fibrillation (AF) and ventricular desynchronization imposed by ventricular pacing may compromise ventricular function. We investigated whether heart rhythm regularization achieved through ventricular overdrive pacing (VP) gives additional benefit over rate control alone in patients with AF.</AbstractText>We studied 27 patients (mean age 72 +/- 7 years) with AF and normal left ventricular (LV) systolic function who were implanted with a common VVIR pacemaker. Cardiac function was assessed by using serial echocardiographic conventional, tissue Doppler imaging (TDI) and color M-Mode (CMM) examinations, together with B-type natriuretic peptide (BNP) measurements. Baseline data were obtained during AF (mean heart rate 58 +/- 5 beats/minute) with the pacemakers programmed to ventricular mere back-up pacing. These data were compared to the corresponding measurements following a 2-week VP period after the devises had been programmed to a lower rate of 70 beats/min, ensuring most of the time continuing VP.</AbstractText>Continuous VP compared to AF, reduced the LV cardiac index (2.28 +/- 0.44 l/min/m(2) vs 2.33 +/- 0.39 l/min/m(2), P < 0.05), increased the LV end-systolic volume (38 +/- 14 mL vs 35 +/- 11 mL, P < 0.05), and decreased the TDI-derived systolic and diastolic mitral velocity (8.1 +/- 1.8 cm/s vs 8.3 +/- 1.6 cm/s, and 8.1 +/- 1.8 cm/s vs 8.3 +/- 1.6 cm/s, respectively, both P < 0.05) and the CMM-derived transmitral early diastolic flow propagation velocity (37.6 +/- 9.2 vs 41.5 +/- 9.7, P < 0.05). Following VP, both ratios E/Ea and E/Vp showed a trend toward increase (P = NS), whereas BNP rose up to 25.5% (median value, from 111 pg/mL to 165 pg/mL, P < 0.01).</AbstractText>VP may be considered disadvantageous compared to slower AF.</AbstractText> |
7,743 | Multiple source surveillance incidence and aetiology of out-of-hospital sudden cardiac death in a rural population in the West of Ireland. | There is a paucity of published data on prospectively identified rates of out-of-hospital sudden cardiac death (SCD). We sought to determine the incidence, survival and aetiology of out-of-hospital SCD in the West of Ireland for the year 2005.</AbstractText>Data from emergency room resuscitation records were collected throughout the year from all hospitals in the West of Ireland and recorded according to pre-specified criteria. Hospital records of survivors were analysed. Simultaneously, autopsy reports from all pathology laboratories in the region were systematically reviewed and cases of SCD identified. Cardiac arrest associated with non-cardiac pathology was excluded. The population base was 414,277. There were 212 recorded cases of out-of-hospital SCD; 160 (75.5%) were male and the mean age was 63.3 years. The incidence rate was 51.2/100,000/year. The most common aetiology was coronary artery disease (161 cases; 75.9%). The majority of cases occurred in the home (152, 71.7%). Thirteen (6.1%) patients survived to admission of whom eight (3.8%) were alive at discharge. All survivors had ventricular fibrillation as the presenting rhythm.</AbstractText>The burden of SCD in the West of Ireland is considerable. The vast majority of cases occur in the home. Survival rates in this rural population cohort remain low.</AbstractText> |
7,744 | 3D and 4D echo--applications in EP laboratory procedures. | 3D echocardiography allows imaging and analysis of cardiovascular structures as they move in time and space, thus creating possibility for creation of 4D datasets (3D + time). Intracardiac echocardiography (ICE) further broadens the spectrum of echocardiographic techniques by allowing detailed imaging of intracardiac anatomy with 3D reconstructions. The paper reviews the current status of development of 3D and 4D echocardiography in electrophysiology. In ablation area, 3D echocardiography can enhance the performance of catheter ablation for complex arrhythmias such as atrial fibrillation. Currently, several strategies to obtain 3D reconstructions from ICE are available. One involves combination with electroanatomical mapping system; others create reconstruction from standard phased-array or single-element ICE catheter using special rotational or pull-back devices. Secondly, 3D echocardiography may be used for precise assessment of cardiac dyssynchrony before cardiac resynchronization therapy. Its reliable detection is expected to minimize number of non-responders to this treatment and optimize left ventricular lead positioning to get maximum hemodynamic benefit.</AbstractText>The main potential benefit of 3D and 4D echocardiography in electrophysiology lie in real-time guidance of complex ablation procedures and precise assessment of cardiac dyssynchrony.</AbstractText> |
7,745 | Intramural foci during long duration fibrillation in the pig ventricle. | For more than 50 years, it has been assumed that ventricular fibrillation (VF) is maintained solely by reentry in the working myocardium. This hypothesis has never been tested by recording VF with electrodes spaced sufficiently close to map activation sequences in 3D. We recorded the first 10 minutes of electrically induced VF from the anterior left ventricular (LV) free wall near the insertion of the anterior papillary muscle in 6 pigs. A 3D transmural unipolar electrode array consisting of a 9x9 array of needles with 2-mm spacing and 6 electrodes 2 mm apart on each needle was used for recordings. Automatic analyses were performed to recognize 3D reentry and foci. Our results showed that intramural reentry is present early but not late during VF in the mapped region. The incidence of reentry in working myocardium decreases almost to 0 after 3 minutes of VF. In contrast, intramural foci are present during early VF and, as VF continues, increase in incidence, so that by 10 minutes of VF, 27% of wavefronts arise from intramural foci. These results suggest that, particularly after the first 3 minutes of VF, mechanisms other than local reentry in the working myocardium maintain VF in the anterior LV free wall near the root of the anterior papillary muscle. Intramural foci may play an important role in later VF maintenance. It remains to be determined if these foci arise from Purkinje fibers attributable to abnormal automaticity, afterdepolarizations, or reentry. |
7,746 | Antiarrhythmogenic effect of reconstituted high-density lipoprotein against ischemia/reperfusion in rats. | This study analyzed the antiarrhythmogenic effect of reconstituted high-density lipoprotein (rHDL) against ischemia/reperfusion in vivo.</AbstractText>Recent studies have suggested that a reduction in the plasma HDL level may contribute to cardiac sudden death. Although there are currently only a few therapeutic strategies for increasing HDL, an exciting new therapeutic option, rHDL, has recently been developed to prevent coronary artery disease.</AbstractText>To analyze the suppression of reperfusion arrhythmia by rHDL (apolipoprotein A-I with 1-palmitoyl-2-oleoyl-phosphatidyl-choline), 92 male Wistar rats were divided into 10 groups: rats that had been pre-treated with or without rHDL, apolipoprotein A-I, or 1-palmitoyl-2-oleoyl-phosphatidyl-choline in the presence or absence of inhibitors of Akt protein kinase, nitric oxide (NO), or extracellular-signal-regulated kinase (ERK) administered intravenously before left coronary artery occlusion. We also used human coronary artery endothelial cells and adenosine triphosphate-binding cassette transporter (ABC) A1-, ABCG1-, or scavenger receptor class B, type I-transfected ldlA7 cells systems.</AbstractText>The duration of ventricular tachycardia or ventricular fibrillation after reperfusion in rHDL-pre-treated rats was much shorter than that in untreated rats. Apolipoprotein A-I or 1-palmitoyl-2-oleoyl-phosphatidyl-choline alone had no effect. The effect of rHDL was blocked by inhibitors of Akt, NO, and ERK. Plasma NO concentration in the rHDL group was significantly higher. In addition, rHDL activated phospho(p)-Akt, p-ERK, and p-endothelial NO synthesis in endothelial cells. The rHDL activated p-ERK in ABCA1- or ABCG1-transfected but not scavenger receptor class B, type I-transfected ldlA7 cells.</AbstractText>The rHDL-induced NO production, probably mediated by ABCA1 or ABCG1 through an Akt/ERK/NO pathway in endothelial cells, may suppress reperfusion-induced arrhythmias. The HDL-based therapy may hold the promise of reducing the incidence of such arrhythmias after ischemia/reperfusion.</AbstractText> |
7,747 | [Impact of atrial fibrillation on prognosis of chronic heart failure patients with left ventricular ejection fraction>or=0.5]. | To explore the prevalence, distribution type and impact of atrial fibrillation on prognosis of hospitalized patients with congestive heart failure (CHF) with left ventricular ejection fraction (LVEF)>or=0.50.</AbstractText>The medical records of 417 unselected consecutive patients with CHF were retrospectively reviewed. Patients were categorized as LVEF<0.50 or LVEF>or=0.50. And they were also categorized by the past history of atrial fibrillation and divided into three groups: paroxysmal atrial fibrillation, continuous atrial fibrillation and onset of atrial fibrillation after admission. Then the vicious events, the number of readmission due to CHF and the interval between discharge and readmission were observed and recorded.</AbstractText>Male patients were prevalent with CHF whose LVEF<0.50. The occurrence of acute myocardial infarction in the 1st year [15.6% (34/218)] was higher than that of CHF with LVEF>or=0.5 [8.0% (16/199), P<0.01]. The occurrence of cerebral stroke in patients with atrial fibrillation [24.3% (27/111)] was higher than that of patients without atrial fibrillation [8.4% (9/107), P<0.05). The numbers of acute coronary syndrome and cardiac death were also increased. In the patients with CHF whose LVEF>or=0.50 the incidence atrial fibrillation occurring after readmission was significantly higher than that of patient with CHF whose LVEF<0.50 (51 vs. 30, P<0.05). Atrial fibrillation could be found in nearly 2/3 of patients. And the number of readmission (2.78+/-1.79 vs. 2.00+/-1.35, P<0.01) was increased, while the interval between discharge and readmission [(117+/-107) days vs. (154+/-130) days, P<0.05] was shorter.</AbstractText>Atrial fibrillation occurs more likely in patients with CHF whose LVEF>or=0.50, leading to a shorter interval of readmission. Therefore the importance of treatment of atrial fibrillation should be emphasized.</AbstractText> |
7,748 | Implantable cardioverter defibrillator therapy: ten years experience in a medical center. | An implantable cardioverter defibrillator (ICD) is the therapy of choice for survivors of life-threatening ventricular tachyarrhythmias or sudden cardiac death. To date there is little data concerning the clinical features and outcome of ICD therapy among Taiwanese. This study identifies factors related to the outcome of ICD therapy over a ten-year period at this institution.</AbstractText>Forty-nine ICDs were implanted in 46 patients between August 1996 and January 2006. The mean follow-up duration was 32 +/- 21 months. Patient data, primary cardiac diagnosis, presenting cardiac arrhythmia, echocardiographic parameters, hemodynamic indexes, electrophysiologic findings, and follow-up observations were analyzed. The findings were compared to those of the Taiwan ICD Multicenter Registry (TIMR) Study and major secondary prevention ICD trials in the literature.</AbstractText>The patients in this study were comparable to those of TIMR but were younger and had better left ventricular ejection fractions (LVEF) than those in Western countries. Furthermore, higher mortality on follow-up was observed in patients with any of the following: LVEF < 35%, New York Heart Association (NYHA) functional class III or IV, a left atrial dimension > or = 55 mm, a left ventricular end diastolic dimension > or = 75 mm, an end systolic dimension > or = 60 mm, triple vessel disease, a prior anterior myocardial infarction, and amiodarone or diuretic therapy. Patients with structural heart disease other than ischemic heart disease or dilated cardiomyopathy had higher event recurrence rates.</AbstractText>Left ventricular function is a major determinant affecting the outcome in ICD recipients. Aggressive treatment for heart failure is warranted in these patients.</AbstractText> |
7,749 | Hypothermia and neurological outcome after cardiac arrest: state of the art. | Multi-centred studies in patients who remain comatose after cardiac arrest and also in newborn babies with perinatal asphyxia have clearly demonstrated that mild hypothermia (32-34 degrees C) can improve neurological outcome after post-anoxic injury. This represents a highly promising development in the field of neurocritical care. This review discusses the place of mild therapeutic hypothermia in the overall therapeutic strategy for cardiac arrest patients. Cooling should not be viewed in isolation but in the context of a 'treatment bundle,' which together can significantly improve outcome after cardiac arrest. Favourable outcomes of 50-60% are now routinely achieved in many centres in patients with witnessed arrest and an initial rhythm of ventricular fibrillation or ventricular tachycardia. These results have been achieved by combining a number of therapeutic strategies, including early and effective resuscitation with greater emphasis on continuing chest compressions throughout various procedures (including resumption of compressions immediately after defibrillation even if rhythm has been restored) as well as prevention of hypoxia and hypotension in all stages following restoration of spontaneous circulation. Regarding the use of hypothermia, early induction and proper management of side-effects are the key elements of successful implementation. Treatment should include the rapid infusion of 1500-3000 mL of cold fluids to induce hypothermia and prevent hypovolaemia and hypotension. Educational activities to increase awareness and acceptance of new therapeutic options and European Resuscitation Council guidelines are urgently required. |
7,750 | Drugs that interact with cardiac electro-mechanics: old and new targets for treatment. | The concept of mechano-electrical feedback was derived from the observation that a short stretch applied to the beating heart can invoke an electrical response in the form of an afterdepolarization or a premature ventricular beat. More recent work has identified stretch-activated channels whose specific inhibition might help to treat atrial fibrillation in the near future. But the interaction between electrical and mechanical function of the heart is a continuum from short-term (within milliseconds) to long-term (within weeks or months) effects. The long-term effects of pressure overload have been well-described on the molecular and cellular level, and substances that interact with these processes are used in clinical routine in the care of patients with cardiac hypertrophy and heart failure. These treatments help to prevent lethal arrhythmias (sudden death) and potentially atrial fibrillation. The intermediate interaction between mechanical and electrical function of the heart is less well-understood. Several recently identified regulatory mechanisms may provide novel antiarrhythmic targets associated with the "intermediate" response of the myocardium to stretch. |
7,751 | Anti-arrhythmic and vasopressor medications for the treatment of ventricular fibrillation in severe hypothermia: a systematic review of the literature. | To determine the rate of return of spontaneous circulation (ROSC) in animal models performing resuscitation from induced ventricular fibrillation (VF) in severe hypothermia (<30 degrees C).</AbstractText>A medical literature database search from 1966 to present was performed identifying placebo controlled trials using anti-arrhythmic or vasopressor medications to treat ventricular fibrillation in the setting of severe hypothermia.</AbstractText>7 controlled studies were identified (n=117) testing 6 combinations of resuscitative medications. ROSC rates for treatment versus control groups were as follows: amiodarone (6% vs. 18%, p=0.6, n=34), bretylium (35% vs. 35%, p=1.0, n=40), intermediate- and high-dose epinephrine (adrenaline) (36% vs. 27%, p=1.0, n=22), vasopressin (60% vs. 0%, p<0.0001, n=39), vasopressin and amiodarone (0% vs. 0%, p=NS, n=11), low-dose epinephrine and amiodarone (91% vs. 30%, p=0.0075, n=21). Cumulatively, among all studies administering vasopressors, the rate of ROSC was 62% in treatment groups contrasted to 17% in control groups (p<0.0001, n=77).</AbstractText>In controlled animal models of severe hypothermia, ROSC rates for induced ventricular fibrillation are higher with utilization of vasopressor medications. Current guidelines which recommend withholding these medications in the setting of hypothermic cardiac arrest should be re-evaluated.</AbstractText> |
7,752 | Liquid ventilation with perfluorocarbons facilitates resumption of spontaneous circulation in a swine cardiac arrest model. | Induced external hypothermia during ventricular fibrillation (VF) improves resuscitation outcomes. Our objectives were twofold (1) to determine if very rapid hypothermia could be achieved by intrapulmonary administration of cold perfluorocarbons (PFC), thereby using the lungs as a vehicle for targeted cardiopulmonary hypothermia, and (2) to determine if this improved resuscitation success.</AbstractText>Part 1: Nine female swine underwent static intrapulmonary instillation of cold perfluorocarbons (PFC) during electrically induced VF. Part 2: Thirty-three female swine in VF were immediately ventilated via total liquid ventilation (TLV) with pre-oxygenated cold PFC (-15 degrees C) or warm PFC (33 degrees C), while control swine received no ventilation during VF. All swine in both Parts 1 and 2 underwent VF arrest for 11 min, then defibrillation, ventilation and closed chest massage until resumption of spontaneous circulation (ROSC). The endpoint was continued spontaneous circulation for 1h without pharmacologic support.</AbstractText>Static intrapulmonary instillation of cold PFC achieved rapid cardiopulmonary hypothermia; pulmonary artery (PA) temperature of 33.5+/-0.2 degrees C was achieved by 10 min. Nine of 9 achieved ROSC. Hypothermia was achieved faster using TLV: at 6 min VF, cold TLV temperature was 32.9+/-0.4 degrees C vs. cold static instillation temperature 34.3+/-0.2 degrees C. Nine of 11 cold TLV swine achieved ROSC for 1h vs. 3 of 11 control swine (p=0.03). Warm PFC also appeared to be beneficial, with a trend toward greater achievement of ROSC than control (ROSC; warm PFC 8 of 11 vs. control 3 of 11, p=0.09).</AbstractText>Targeted cardiopulmonary intra-arrest moderate hypothermia was achieved rapidly by static intrapulmonary administration of cold PFC and more rapidly by total liquid ventilation with cold PFC; resumption of spontaneous circulation was facilitated. Warm PFC showed a trend toward facilitating ROSC.</AbstractText> |
7,753 | Dynamics and state transitions during resuscitation in out-of-hospital cardiac arrest. | The state or rhythm during resuscitation, i.e. ventricular fibrillation/tachycardia (VF/VT), asystole (ASY), pulseless electrical activity (PEA), or return of spontaneous circulation (ROSC) determines management. The state is unstable and will change either spontaneously (e.g. PEA-->ASY) or by intervention (e.g. VF-->ASY after DC shock); temporary ROSC may also occur. To gain insight into the dynamics of this process, we analyzed the state transitions over time using real-life data.</AbstractText>Detailed recordings from 304 episodes of attempted resuscitation from out-of-hospital cardiac arrests of presumed cardiac etiology were obtained from modified Heartstart 4000 defibrillators. State transitions were visualized and described, and analyzed in terms of a Markov probability model.</AbstractText>The median number of state transitions was 5 (range 1-39), and more transitions were observed with VF than PEA or asystole as the initial rhythm. Of 105 patients (35%) who regained ROSC at some point during CPR, only 65 (21%) achieved sustained ROSC; suggesting an unrealized survival potential. A 3-min transition probability matrix was estimated: for example, a patient early in VF has a probability of 31% to be in ASY, 32% of still being in VF, 5% to have temporary ROSC, and 2% to have sustained ROSC after 3 min.</AbstractText>The dynamics of resuscitation can be described in terms of state transitions and a Markov probability model. This framework enables prediction of short-term clinical development, supports informed decisions during CPR, and suggests a novel area for research.</AbstractText> |
7,754 | [Benefits of cardiac resynchronization therapy in patients with atrial fibrillation who have not undergone atrioventricular node ablation]. | The aim of this study was to compare the effects of cardiac resynchronization therapy on left ventricular function and reverse remodeling in patients in sinus rhythm with the effects in patients with atrial fibrillation who have not undergone atrioventricular node ablation. Echocardiographic and clinical parameters were evaluated at baseline and after 6 months of cardiac resynchronization therapy in 55 patients: 15 had atrial fibrillation and 40 were in sinus rhythm. Device programming was similar in the 2 groups, as were the reductions in QRS interval and echocardiographic measures of asynchrony observed after implantation. However, although significant improvements in end-systolic volume and ejection fraction were seen in both groups, reverse remodeling was greater in patients in sinus rhythm (reduction in end-systolic volume 30.9%+/-24.6% vs 12.5%+/-18.6%; P=.024), as was the relative increase in ejection fraction (15.4%+/-12.6% vs 5.0%+/-7.2%; P=.010). Cardiac resynchronization therapy in patients with atrial fibrillation who had not undergone atrioventricular node ablation resulted in significant improvements in ejection fraction and reverse remodeling, but these were less than those observed in patients in sinus rhythm. |
7,755 | [Changes in the spectral characteristics of ventricular fibrillation in lesions produced by radiofrequency ablation. An experimental study]. | Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions.</AbstractText>Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compared.</AbstractText>In the ablated zones, significant reductions were observed in the spectral density of the dominant (0.168+/-0.113 mV(2)/Hz vs 0.025+/-0.018 mV(2)/Hz; P< .001) and mean frequencies (0.053+/-0.057 mV(2)/Hz vs 0.012+/-0.016 mV(2)/Hz; P< .001), the normalized energy around the dominant frequency (0.860+/-0.570 vs 0.128+/-0.091; P< .001), and the standard deviation of the power spectrum (0.031+/-0.020 mV(2)/Hz vs 0.004+/-0.001 mV(2)/Hz; P< .001). There was no significant change in the dominant (16.2+/-5.6 vs 14.8+/-1.8 Hz) or mean frequency (17.7+/-3.4 vs 16.6+/-1.3 Hz). The spectral parameters that could be used in a multivariate model to identify the lesion were the standard deviation of the power spectrum and the spectral density of the mean frequency.</AbstractText>During ventricular fibrillation, the spectral parameters associated with spectral power and spectral energy were significantly altered in zones with radiofrequency lesions and could be used to identify those zones. There was no significant change in either the dominant or mean frequency in these zones.</AbstractText> |
7,756 | Diagnostic approach and treatment strategy in tachycardia-induced cardiomyopathy. | Due to the absence of differential guidelines for heart failure with tachyarrhythmia, it is difficult to diagnose tachycardia-induced cardiomyopathy (TIC) at the initial visit. Furthermore, clinical outcomes of rate versus rhythm control in TIC are unclear.</AbstractText>Because the etiology of TIC is different from dynamic cardiomyoplasty (DCMP), differential parameters may be present.</AbstractText>We assessed 21 patients with TIC (15 men; mean age, 50+/-14 years) and 21 control patients with idiopathic DCMP. We assessed clinical courses, echocardiographic parameters, as well as outcomes by treatment.</AbstractText>In the TIC group, the related tachyarrhythmias were atrial fibrillation (n=12), atrial flutter (n=5), atrial tachycardia (n=3) and paroxysmal supraventricular tachycardia (n=1). After treatment, all patients became asymptomatic and the ejection fraction (EF) improvement (DeltaEF>or=15%) was observed in all patients (left ventricular ejection fraction [LVEF], 30+/-11%initial versus 58+/-6%last). In the idiopathic DCMP group, no patient showed EF improvement (EF increase<or=5%), and 4 patients (19%) underwent heart transplantation. Left ventricle (LV) mass indices, volumes adjusted by BSA, and dimensions were smaller in the TIC group than in the idiopathic DCMP group. Of those, LV end-diastolic dimension was the only independent predictor of TIC in multiple regression analysis (odds ratio [OR] 0.742 per 1 mm, 95% confidence ratio [CI] 0.618 to 0.891, p=0.001). The Association of University Cardiologists (AUC) was 0.908 on receiver-operating characteristic (ROC) curve analysis and LV end-diastolic dimension<or=61% mm could predict TIC with a sensitivity of 100% and a specificity of 71.4%. After restoration of sinus rhythm (n=8), one experienced recurrent TIC after discontinuation of amiodarone. After control of heart rate (n=13), one experienced recurrent TIC due to poor control of heart rate (log-rank test, p=0.808). There were no differences in the echocardiographic parameters between the 2 groups before and after treatment except for the larger initial LV volumes in the rhythm control.</AbstractText>In patients presented as heart failure with tachyarrhythmia, initial echocardiographic parameters, especially LV end-diastolic dimension, help to differentiate TIC from idiopathic DCMP. Rate control was as effective as rhythm control for EF improvement and prognosis.</AbstractText>Copyright (c) 2008 Wiley Periodicals, Inc.</CopyrightInformation> |
7,757 | Comparison of standard and bicaval approach in orthotopic heart transplantation: 10-year follow-up. | The present study compared 86 patients who underwent orthotopic heart transplantation by bicaval and standard techniques.</AbstractText>Patients already followed in the first year after heart transplantation were studied at 10 years of follow-up, this time evaluating the prevalence of arrhythmias, conduction disturbances and mitral or tricuspid regurgitation.</AbstractText>The following arrhythmias were observed: atrial fibrillation (one patient from the standard group), ventricular premature beats and ventricular fibrillation (each in one patient from the bicaval group). Conduction disturbances were found in 25 patients in the standard group (48.1%) and in 19 patients in the bicaval group (55.9%, P = 0.515). Twenty patients had a mono- or bifascicular block in the standard group (38.5%) versus 19 patients in the bicaval group (55.9%); furthermore, five patients in the standard group (9.6%) and none in the bicaval group had a permanent pacemaker (Fisher's exact test: P = 0.074). Mitral regurgitation was present in 13 (26.5%) and five (16.1%) patients, respectively, in the standard and bicaval groups (Fisher's exact test: P = 0.411): it was grade 1 in 12 and five patients and grade 2 in one and zero patients, respectively. Tricuspidal regurgitation was observed in 26 (53.1%) and 13 (41.9%) patients, respectively, in the standard and bicaval groups (Fisher's exact test: P = 0.366): it was grade 1 in 23 and 13 patients and grade 2 in three and zero patients, respectively. Cumulative survival was 75% at 10 years from transplant in this relatively old population of patients (mean age = 58 years).</AbstractText>In conclusion, our data do not support any definite mandate for either of the surgical techniques.</AbstractText> |
7,758 | Direction of signal recording affects waveform characteristics of ventricular fibrillation in humans undergoing defibrillation testing during ICD implantation. | In cardiac arrest due to prolonged ventricular fibrillation (VF), defibrillation is more likely to result in a perfusing rhythm if chest compressions are performed first. Furthermore, the VF waveform can predict the shockability of VF and thus automated external defibrillators (AEDs) are being designed to analyze the VF waveform to direct therapies. However, it is unknown whether the VF waveform is dependent on recording direction, which could be altered by incorrect placement of AED patches.</AbstractText>VF was induced in 26 patients with ischemic cardiomyopathy and 19 patients with dilated cardiomyopathy and recorded in six limb leads. Frequency characteristics (mean, median, dominant frequency, and bandwidth) were computed as well as amplitude-based measures: amplitude spectral area (AMSA), slope, signal amplitude, and slope divide by signal amplitude (slope-amp).</AbstractText>Frequency characteristics were similar in all leads. However, AMSA, slope, and signal amplitude were significantly affected (P<0.001) by lead. In particular, for ischemic cardiomyopathy patients, between leads I and II, AMSA varied from 29.4+/-3.2 to 49.3+/-4.6 mV Hz (mean+/-SEM, P<0.001) and slope varied from 1.5+/-0.2 to 2.4+/-0.3 mV/s (P<0.001). Slope-amp was similar in all leads. There were no significant differences between ischemic and dilated cardiomyopathy patients.</AbstractText>Amplitude measures of VF are significantly affected by limb lead ECG recording direction. This work suggests that AED patches must be correctly and consistently placed if amplitude-based measures are used to decide whether to deliver a defibrillatory shock.</AbstractText> |
7,759 | Aortic valve replacement for low-flow/low-gradient aortic stenosis operative risk stratification and long-term outcome: a European multicenter study. | We evaluated a large multicenter series of patients operated on for low-flow/low-gradient aortic stenosis (LF/LGAS) to stratify the operative risk, assess whether perioperative mortality has decreased over recent years, and analyze the post-operative outcome.</AbstractText>Although LF/LGAS is classically associated with a high operative risk, few data are available concerning the results of surgery in this setting.</AbstractText>A total of 217 consecutive patients (168 men, 77%) with severe aortic stenosis (area <1 cm(2)), low ejection fraction (EF) (<or=35%), and low mean gradient (MG) (<or=30 mm Hg) who underwent aortic valve replacement (AVR) between 1990 and 2005 were included.</AbstractText>Perioperative mortality was 16% and decreased dramatically from 20% in the 1990 to 1999 period to 10% in the 2000 to 2005 period. Higher European System for Cardiac Operative Risk Evaluation score (EuroSCORE), very low MG and EF, New York Heart Association functional class III or IV, history of congestive heart failure, and multivessel coronary artery disease (MVD) were associated with perioperative mortality. On multivariate analysis, very low pre-operative MG and MVD were predictors of excess perioperative mortality. In the subgroup of patients with dobutamine stress echocardiography, the absence of contractile reserve was a strong predictor of perioperative mortality. Overall 5-year survival rate was 49 +/- 4%. Lower MG, higher EuroSCORE, prior atrial fibrillation, and MVD were identified as independent predictors of overall long-term mortality.</AbstractText>In view of the very poor prognosis of unoperated patients, the current operative risk, and the long-term outcome after surgery, AVR is the treatment of choice in the majority of cases of LF/LGAS.</AbstractText> |
7,760 | A randomized comparison of triple-site versus dual-site ventricular stimulation in patients with congestive heart failure. | We compared the effects of triple-site versus dual-site biventricular stimulation in candidates for cardiac resynchronization therapy.</AbstractText>Conventional biventricular stimulation with a single right ventricular (RV) and a single left ventricular (LV) lead is associated with persistence of cardiac dyssynchrony in up to 30% of patients.</AbstractText>This multicenter, single-blind, crossover study enrolled 40 patients (mean age 70 +/- 9 years) with moderate-to-severe heart failure despite optimal drug treatment, a mean LV ejection fraction of 26 +/- 11%, and permanent atrial fibrillation requiring cardiac pacing for slow ventricular rate. A cardiac resynchronization therapy device connected to 1 RV and 2 LV leads, inserted in 2 separate coronary sinus tributaries, was successfully implanted in 34 patients. After 3 months of biventricular stimulation, the patients were randomly assigned to stimulation for 3 months with either 1 RV and 2 LV leads (3-V) or to conventional stimulation with 1 RV and 1 LV lead (2-V), then crossed over for 3 months to the alternate configuration. The primary study end point was quality of ventricular resynchronization (Z ratio). Secondary end points included reverse LV remodeling, quality of life, distance covered during 6-min hall walk, and procedure-related morbidity and mortality. Data from the 6- and 9-month visits were combined to compare end points associated with 2-V versus 3-V.</AbstractText>Data eligible for protocol-defined analyses were available in 26 patients. No significant difference in Z ratio, quality of life, and 6-min hall walk was observed between 2-V and 3-V. However, a significantly higher LV ejection fraction (27 +/- 11% vs. 35 +/- 11%; p = 0.001) and smaller LV end-systolic volume (157 +/- 69 cm(3) vs. 134 +/- 75 cm(3); p = 0.02) and diameter (57 +/- 12 mm vs. 54 +/- 10 mm; p = 0.02) were observed with 3-V than with 2-V. There was a single minor procedure-related complication.</AbstractText>Cardiac resynchronization therapy with 1 RV and 2 LV leads was safe and associated with significantly more LV reverse remodeling than conventional biventricular stimulation.</AbstractText> |
7,761 | Right ventricular endomyocardial fibrosis. | Endomyocardial fibrosis (EMF) is a neglected tropical cardiomyopathy of unknown etiology and pathogenesis that is common in certain tropical areas of Africa, Asia, and South America. It affects predominantly children and young adults. Endocardial fibrosis is the hallmark of this restrictive cardiomyopathy leading to restriction to diastolic filling of the ventricles with severe atrial dilatation. Endomyocardial fibrosis carries a poor prognosis, due to the late presentation of patients. The salient features of this condition are present in the case presented here of a 14-year-old boy who died from progressive heart failure due to right ventricular EMF. These pathological findings of advanced disease highlight the need for early diagnosis and better understanding of the pathogenesis in order to improve prognosis of this debilitating and fatal disease. |
7,762 | Association of echocardiographic atrial size and atrial fibrosis in a sequential model of congestive heart failure and atrial fibrillation. | Cardioversion (CV) success of atrial fibrillation (AF) inversely correlates to the size of the left atrium (LA). Atrial fibrillation and its most important risk factor, congestive heart failure (CHF), both induce atrial structural enlargement and fibrosis. To investigate the effect of AF and CHF on atrial dilatation and fibrosis, and to estimate whether echocardiographically determined atrial size may be used as a marker for atrial fibrosis.</AbstractText>In six dogs, pacemakers were implanted followed by HIS bundle ablation. After 4 weeks of rapid ventricular stimulation (185 bpm) for CHF induction, additional rapid atrial stimulation (500 bpm) was maintained for 7 weeks to induce AF. Serial determinations of echocardiographic atrial size were performed. Seven dogs with sinus rhythm served as histological controls. Postmortem tissue was obtained to determine the degree and composition of atrial fibrosis.</AbstractText>While the ejection fraction of the AF/CHF dogs decreased significantly from 57+/-5% to 19+/-7% (P<.01), an increased degree of atrial fibrosis was found (right atrium [RA], 4.9+/-2.0% to 19.9+/-5.4%; LA, 4.4+/-1.6% to 22.2+/-3.2%; P<.01), accompanied by a significant increase of atrial volumes (LA: 21+/-4 to 44+/-4 mm3; P<.01; RA: 10+/-3 to 18+/-6 mm3; P<.05) and LA diameters (34+/-4 to 43+/-2 mm, P<.05). Atrial fibrosis and size significantly correlated.</AbstractText>Atrial fibrillation/CHF leads to a significant atrial fibrosis and dilation. The increased echocardiographic size correlates to the degree of atrial fibrosis and may be used as clinical marker for atrial fibrosis. The fibrosis accompanying atrial dilatation may also explain why LA size, as determined by echocardiography, is a strong predictor of CV success.</AbstractText> |
7,763 | [Ventricular repolarisation disorders and long QT syndrome: clinical and genetic study in 10 paediatric cases]. | We report 10 paediatric cases of ventricular repolarisation disorders and long QT syndrome, which differed in their mode of revelation, from asymptomatic forms to syncope events or heart arrest. Diagnosis is based on electrophysiological explorations and exhaustive genetic investigation. It allows a well-codified preventive and therapeutic action according to the genotype. |
7,764 | Identification of a novel KCNQ1 mutation associated with both Jervell and Lange-Nielsen and Romano-Ward forms of long QT syndrome in a Chinese family. | Long QT syndrome (LQTS) is a cardiac disorder characterized by prolonged QT intervals on electrocardiograms (ECG), ventricular arrhythmias, and sudden death. Clinically, two inherited forms of LQTS have been defined: autosomal dominant LQTS or Romano-Ward syndrome (RWS) not associated with deafness and autosomal recessive LQTS or Jervell and Lange-Nielsen syndrome (JLNS) associated with deafness.</AbstractText>A Chinese family with both RWS and JLNS was identified. Family members were diagnosed based on the presence of a prolonged QT interval as seen on a 12-lead ECG and a medical history of syncope, palpitation, and deafness. Mutational studies in the KCNQ1 potassium channel gene were performed using direct DNA sequence analysis and restriction length polymorphism analysis.</AbstractText>The proband in the Chinese family and her brother had previously been diagnosed with JLNS, and two other members were affected with RWS. The proband was also affected with atrial fibrillation. A single nucleotide substitution of C to T at nucleotide 965 of KCNQ1 was identified, and the mutation resulted in the substitution of a threonine residue at codon 322 by a methionine residue (T322M). The novel heterozygous T322M mutation was identified in two patients with RWS, one member with borderline QTc, and two normal family members. The two JLNS patients in the family carried the homozygous T322M mutation. The T322M mutation was not found in 200 Chinese normal controls.</AbstractText>Our results suggest that T322M is a novel mutation that caused RWS with high intrafamilial variability in the heterozygous carriers and typical JLNS in the homozygous carriers within this Chinese family. The T322M mutation is the first mutation identified for JLNS in the Chinese population.</AbstractText> |
7,765 | Inducibility of atrial and ventricular arrhythmias along the ligament of marshall: role of autonomic factors. | The mechanism(s) underlying atrial fibrillation (AF) initiation along the ligament of Marshall (LOM) remains controversial.</AbstractText>We sought to examine the role of the autonomic nervous system in arrhythmogenesis along the LOM.</AbstractText>In 31 anesthetized dogs, a left thoracotomy exposed the LOM. During atrial pacing, high-frequency stimulation (HFS: 200 Hz, 0.1 ms pulse width, 40 ms duration, 0.6-12 V) was delivered during atrial refractoriness to different sites of LOM (LOM(CS)= near coronary sinus; LOM(LIPV)= near left inferior pulmonary vein; LOM(LS-LIPV)= between LIPV and left superior pulmonary vein (LSPV); LOM(LSPV)= near LSPV). HFS was repeated after intravenous administration of esmolol (1 mg/kg; n = 9) or atropine (2 mg; n = 12). Norepinephrine (10(-7) M, 0.4 cc) was injected into LOM(LSPV) (n = 5).</AbstractText>The median voltages for HFS to induce AF were 3.2 V, 3.2 V, 8.0 V*(,double dagger), and 12 V*(,double dagger) at LOM(CS), LOM(LIPV), LOM(LS-LIPV), and LOM(LSPV), respectively (*P < 0.01, compared with LOM(CS) and double dagger P < 0.01, compared with LOM(LIPV)). Esmolol or atropine markedly increased the threshold for AF induction. Ventricular tachycardias (VT) and accelerated junctional rhythm were induced in 8 of 12 and 6 of 12 dogs after atropine administration, respectively. Sustained VT occurred within minutes in 5 of 5 dogs receiving norepinephrine injection into the LOM(LSPV.)</AbstractText>HFS induced AF along LOM with a gradient of stimulation thresholds from LOM(CS) (lowest) toward LOM(LSPV) (highest). This response was inhibited by esmolol or atropine. These data suggest an autonomic basis for AF initiation in LOM, and both sympathetic and parasympathetic neural elements play an important role in AF initiation. Hyperactivity of the sympathetic neural elements in LOM may be crucial in the initiation of ventricular tachyarrhythmias.</AbstractText> |
7,766 | Effect of cardiac resynchronization therapy in isolated ventricular noncompaction in adults: follow-up of four cases. | An isolated ventricular noncompaction (IVNC) is an unclassified cardiomyopathy and, despite the increasing awareness of and interest in this disorder, the role of cardiac resynchronization therapy (CRT) remains obscure.</AbstractText>The purpose of this study was to clarify the long-term effect of CRT on IVNC in adult patients.</AbstractText>Four cases of IVNC were included in this study. Before the CRT device was implanted, all four patients (54 +/- 16-year-old, 4 males) presented with symptomatic congestive heart failure. Echocardiography revealed their systolic dysfunction and their left ventricular ejection fraction (LVEF) was 21 +/- 8%. There was also mechanical dyssynchrony observed between the LV septum and free wall area. The QRS duration was "narrow" (112 and 120 ms) in two patients. One patient had been resuscitated from ventricular fibrillation (VF) and two had nonsustained ventricular tachycardia (VT). A CRT defibrillator (CRT-D) was implanted in three patients with VT/VF and a CRT pacemaker (CRT-P) in a patient without VT/VF. The LV lead was positioned in a lateral branch of the coronary sinus where a thickened noncompacted wall existed.</AbstractText>During the follow-up period (28 +/- 23 months), their congestive heart failure had improved in terms of the cardiothoracic ratio on the chest X-ray, B-type natriuretic peptide level, LV systolic dimension, and LVEF. No episodes of defibrillation shocks were observed.</AbstractText>CRT may improve the prognosis and quality-of-life in patients with an IVNC with mechanical dyssynchrony.</AbstractText> |
7,767 | Downregulation of the calcium current in human right atrial myocytes from patients in sinus rhythm but with a high risk of atrial fibrillation. | A decrease in L-type calcium current (ICaL) is an important mechanism favouring atrial fibrillation (AF). Here, we aimed to identify pathogenic factors associated with ICaL downregulation.</AbstractText>Atrial myocytes were isolated from right atrial appendages obtained from 86 adult patients in sinus rhythm with coronary artery disease, aortic valve disease, or mitral valve disease (MVD). Current was recorded in isolated myocytes using the whole-cell patch-clamp technique. The ICaL recorded in the 172 myocytes studied showed a marked variability of peak density ranging from 0.1 to 9.0 pA/pF. The ICaL peak density did not correlate with membrane capacitance or changes in current biophysical properties. The ICaL peak density was homogeneous for a given sample. Small ICaL values were recorded in patients with MVD or with a low left ventricular ejection fraction (<45%). Small ICaL values were more sensitive to the beta-adrenergic agonist, isoproterenol (1 microM), and to the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine (10 microM).</AbstractText>In human atrial myocytes, the variability of ICaL is related to the clinical history of the donors. The downregulation of ICaL is already observed in patients in sinus rhythm with a high risk of AF and is associated with the greatest response to beta-adrenergic agonist.</AbstractText> |
7,768 | Cardiac involvement in adults with Pompe disease. | Glycogen storage disease type II or Pompe disease is a neuromuscular disorder caused by deficiency of lysosomal acid alpha- glucosidase. Classic infantile Pompe disease results in massive left ventricular (LV) hypertrophy and failure. Although Pompe disease is often included in the differential diagnosis of LV hypertrophy the true frequency of cardiac involvement in adults with Pompe disease is not known.</AbstractText>Forty-six consecutive adult patients (mean age 48 +/- 12, 22 men) with Pompe disease were included. Each patient underwent a clinical examination, electrocardiography, and rest and low-dose dobutamine (in 20 patients) two-dimensional echocardiography including contrast and tissue Doppler imaging.</AbstractText>All patients had limited exercise tolerance; a rollator walking aid was used in seven patients (15%), a wheelchair in 13 patients (28%), and assisted ventilation in 14 patients (30%). Prior to this study, one patient was known with permanent atrial fibrillation, His-bundle ablation and a VVI pacemaker and another patient was known with fluid retention. The first patient had increased LV end-diastolic diameter, impaired LV ejection fraction, low systolic mitral annular velocities and diastolic dysfunction grade II. The patient with fluid retention was wheelchair bound and dependent on 24-h assisted ventilation and showed right ventricular and LV hypertrophy (septum 16 mm, posterior wall 15 mm). LV hypertrophy was not seen in any of the other patients. One woman of advanced age had isolated low systolic mitral annular velocities. Mean global systolic LV function, including contractile reserve, was not decreased in patients with Pompe disease. Eight patients (17%) had mild diastolic dysfunction grade I, related to hypertension in four and advanced age in seven.</AbstractText>In adult patients with Pompe disease without objective signs of cardiac affection by 12-leads electrocardiography or physical examination, echocardiographic screening for LV hypertrophy seems not effective.</AbstractText> |
7,769 | Phantom shocks in patients with an implantable cardioverter defibrillator. | Phantom shock is the sensation of shock in the absence of an actual implantable cardioverter-defibrillator (ICD) discharge. The ICD is now the first-line therapy for patients with ventricular tachycardia and fibrillation. There has been a significant increase in the number of patients with an ICD and patients presenting to the Emergency Department (ED) after a shock for evaluation and device interrogation. Phantom shock is more likely to be nocturnal in the first 6 months after implantation, and patients are more likely to be clinically depressed and have higher levels of anxiety. There is no specific treatment. We report 3 patients who presented to the ED with the sensation of ICD discharges, however, on device interrogation had no shocks and no dysrhythmias. |
7,770 | ICD patients with elevated defibrillation threshold: clinical behavior and therapeutic alternatives. | The ideal programming of the implantable cardioverter defibrillator (ICD) shock energy should be at least 10J above the defibrillation threshold (DFT), requiring alternative techniques when the DFT is elevated.</AbstractText>To assess the clinical behavior of ICD patients with DFT>25J and the efficacy of the chosen therapy.</AbstractText>Patients who had undergone ICD implantation between Jan/00 and Aug/04 (prospective database) and presented intraoperative DFT>25J were selected. The analyzed variables were: clinical characteristics, LVEF, rescue of arrhythmic events from ICD and causes of deaths.</AbstractText>among 476 patients, 16 (3.36%) presented DFT>25J. The mean age was 56.5 years, and 13 patients (81%) were men. According to the baseline cardiomyopathy, 09 patients had Chagas' disease, 04 had ischemic cardiomyopathy and 03 had idiopathic cardiomyopathy. Mean LVEF was 0.37 and amiodarone was used by 94% of the patients. Mean follow-up (FU) period was 25.3 months. DFT was higher than maximum energy shock (MES) in 2 patients and it was necessary to implant an additional shock electrode (array). It was programmed MES in ventricular fibrillation zone of ICD therapy in the other patients. In the FU, 03 patients had 67 successful appropriate shock therapies (AST). There were 05 noncardiac and 02 heart failure deaths. The patients who died showed higher DFT levels (p=0.044) without correlation with death because there wasn't unsuccessful AST.</AbstractText>In this cohort of ICD patients, the occurrence of elevated DFT (>25J) was low, leading to alternative therapies. There was an association with severe ventricular dysfunction, although without correlation to the causes of death.</AbstractText> |
7,771 | Arterial stiffness is associated with left atrial size in hypertensive patients. | Arterial stiffness is a strong predictor of cardiovascular events and particularly of stroke. A likely explanation is the development of atherosclerotic lesions at the carotid level, favored by increased local stiffness. Another possibility involves cardiac consequences of aortic stiffness and particularly left atrial dilatation with its subsequent risk of atrial fibrillation (AF) and cerebral embolism.</AbstractText>The present study investigated the link between arterial stiffness, pulse pressure and left atrial size, a determinant of AF risk.</AbstractText>Arterial stiffness was determined from pulse wave velocity (PWV) and pulse pressure (PP). Left atrial size was also measured. Several potential confounders were taken into account including indices of ventricular remodeling and diastolic function (estimated by NT-Pro brain natriuretic peptide (NT-proBNP) levels).</AbstractText>Three-hundred and ten hypertensive patients, aged 53 +/- 13 years, were included. Mean 24-h blood pressure (BP) was 154 +/- 20 over 93 +/- 13 mmHg. Significant relationships were found between left atrial diameter (LAD) and PWV (r=0.27, P<0.001) and between LAD and 24-h PP (r=0.32, P<0.001). LAD was also correlated significantly, although not always tightly, with left ventricular dimensions, geometry and NT-proBNP. In two different multivariate models, LAD remained significantly correlated with PWV or with 24-h PP, independently of classical determinants like age, gender, body mass index, ventricular remodeling (i.e. dimensions and geometry) and filling pressure.</AbstractText>These results led us to propose AF as a new possible pathophysiological link between arterial stiffness and stroke. These results also emphasize the cardiac consequences of arterial stiffness which can fuel a new approach to AF prevention.</AbstractText> |
7,772 | Death without prior appropriate implantable cardioverter-defibrillator therapy: a competing risk study. | Implantable cardioverter-defibrillators (ICDs) improve survival in selected patients with left ventricular systolic dysfunction in randomized trials. Competing death without prior appropriate ICD therapy might preclude benefit from ICD implantation in a less selected routine-care population.</AbstractText>We selected all patients with ischemic or dilated cardiomyopathy with an ICD implanted for primary or secondary prevention from a single-center prospective registry between 1994 and 2006. The end point was time to first appropriate ICD therapy/confirmed ventricular fibrillation or death without prior appropriate ICD therapy. We analyzed cumulative incidence functions and used competing risk regression to study predictors of appropriate ICD therapy or prior death. In 442 patients, 73 deaths occurred during a median follow-up of 3.6 years (maximum, 12.7 years). The cumulative incidence of first appropriate ICD therapy until year 7 was 52%, whereas 11% died without prior ICD therapy. The cumulative incidence of appropriate ICD therapy for ventricular fibrillation was 13%, whereas 23% died without prior therapy for ventricular fibrillation. Appropriate ICD therapy was twice as likely in secondary prevention compared with primary prevention, whereas death rates before ICD therapy were similar in both groups. Diuretic use for heart failure compared with nonuse predicted a 4-fold-increased risk of death prior to ICD therapy, although the incidence of appropriate ICD therapy was similar in both groups.</AbstractText>In a contemporary ICD population, the risk of death without prior appropriate ICD therapy is substantial, especially in patients with advanced heart failure.</AbstractText> |
7,773 | Atrial fibrillation and isolated systolic hypertension: the systolic hypertension in the elderly program and systolic hypertension in the elderly program-extension study. | We performed a post hoc analysis of the Systolic Hypertension in the Elderly Program database to assess the incidence of atrial fibrillation in the elderly hypertensive population, its influence on cardiovascular events, and whether antihypertensive treatment can prevent its onset. The Systolic Hypertension in the Elderly Program was a double-blind placebo-controlled trial in 4736 subjects with isolated systolic hypertension aged >or=60 years. Atrial fibrillation was an exclusion criterion from the trial. Participants were randomly assigned to stepped care treatment with chlorthalidone and atenolol (n=2365) or placebo (n=2371). The occurrence of atrial fibrillation and cardiovascular events over 4.7 years as well as the determination of cause of death at 4.7 and 14.3 years were followed. Ninety-eight subjects (2.06%) developed atrial fibrillation over 4.7 years mean follow-up, without significant difference between treated and placebo groups. Atrial fibrillation increased the risk for: total cardiovascular events (RR 1.69; 95% CI 1.21 to 2.36), rapid death (RR 3.29; 95% CI 1.08 to 10.00), total (RR 5.10; 95% CI 3.12 to 8.37) and nonfatal left ventricular failure (RR 5.31; 95% CI 3.09 to 9.13). All-cause and total cardiovascular death were significantly increased in the atrial fibrillation group at 4.7 years (HR 3.44; 95% CI 2.18 to 5.42; HR 2.39; 95% CI 1.05 to 5.43) and 14.3 years follow-up (HR 2.33; 95% CI 1.83 to 2.98; HR 2.21; 95% CI 1.54 to 3.17). Atrial fibrillation increased the risk for total cardiovascular events, rapid death, and left ventricular failure. All-cause mortality and total cardiovascular mortality were significantly increased in hypertensives with atrial fibrillation at 4.7 and 14.3 years follow-up. |
7,774 | Long-term survival in patients undergoing cardiac resynchronization therapy: the importance of performing atrio-ventricular junction ablation in patients with permanent atrial fibrillation. | To investigate the effects of cardiac resynchronization therapy (CRT) on survival in heart failure (HF) patients with permanent atrial fibrillation (AF) and the role of atrio-ventricular junction (AVJ) ablation in these patients.</AbstractText>Data from 1285 consecutive patients implanted with CRT devices are presented: 1042 patients were in sinus rhythm (SR) and 243 (19%) in AF. Rate control in AF was achieved by either ablating the AVJ in 118 patients (AVJ-abl) or prescribing negative chronotropic drugs (AF-Drugs). Compared with SR, patients with AF were significantly older, more likely to be non-ischaemic, with higher ejection fraction, shorter QRS duration, and less often received ICD back-up. During a median follow-up of 34 months, 170/1042 patients in SR and 39/243 in AF died (mortality: 8.4 and 8.9 per 100 person-year, respectively). Adjusted hazard ratios were similar for all-cause and cardiac mortality [0.9 (0.57-1.42), P = 0.64 and 1.00 (0.60-1.66) P = 0.99, respectively]. Among AF patients, only 11/118 AVJ-abl patients died vs. 28/125 AF-Drugs patients (mortality: 4.3 and 15.2 per 100 person-year, respectively, P < 0.001). Adjusted hazard ratios of AVJ-abl vs. AF-Drugs was 0.26 [95% confidence interval (CI) 0.09-0.73, P = 0.010] for all-cause mortality, 0.31 (95% CI 0.10-0.99, P = 0.048) for cardiac mortality, and 0.15 (95% CI 0.03-0.70, P = 0.016) for HF mortality.</AbstractText>Patients with HF and AF treated with CRT have similar mortality compared with patients in SR. In AF, AVJ ablation in addition to CRT significantly improves overall survival compared with CRT alone, primarily by reducing HF death.</AbstractText> |
7,775 | Incidence and prognosis of sustained arrhythmias in critically ill patients. | Sustained arrhythmias are common in postoperative and cardiac intensive care units (ICUs), but their incidence and prognosis in general ICUs have never been reported.</AbstractText>To estimate the incidence and prognosis of sustained arrhythmias in a general ICU population.</AbstractText>Prospective, multicenter, 1-month inception cohort study.</AbstractText>A total of 1,341 patients were included: 12% (163/1,341) had sustained arrhythmias, including 8% (113/1,341) and 2% (30/1,341) with supraventricular and ventricular arrhythmias, respectively, and 2% (30/1,341) with conduction abnormalities. In-hospital death rates were 17% (205/1,178) in patients without arrhythmia and 29% (33/113) in patients with supraventricular arrhythmias (odds ratio [OR], 1.95; 95% confidence interval [CI], 1.27-3.01), 73% (22/30) in patients with ventricular arrhythmias (OR, 13.20; 95% CI, 5.79-30.10), and 60% (18/30) in patients with conduction abnormalities (OR, 7.46; 95% CI, 3.52-15.82). Neurological sequel rates were 6% (55/973) in arrhythmia-free survivors and 15% (12/80) in survivors with supraventricular arrhythmias (OR, 2.92; 95% CI, 1.45-5.89), 38% (3/8) in survivors with ventricular arrhythmias (OR, 7.53; 95% CI, 1.60-35.50), and 17% (2/12) in survivors with conduction abnormalities (OR, 8.77; 95% CI, 1.65-46.57). After adjusting for prognosis factors and propensity scores, ventricular arrhythmias still increased mortality (OR, 3.53; 95% CI, 1.19-10.42) but supraventricular arrhythmias and conduction abnormalities did not.</AbstractText>Sustained arrhythmias are observed in 12% of patients admitted to general ICUs. Ventricular arrhythmias increase the risk of death.</AbstractText> |
7,776 | Impact of percutaneous transluminal septal myocardial ablation on refractory paroxysmal atrial fibrillation in patients with hypertrophic obstructive cardiomyopathy. | Atrial fibrillation is commonly observed in patients with hypertrophic obstructive cardiomyopathy. Episodes of paroxysmal atrial fibrillation are often torturous and limit the quality of life by causing congestive heart failure, transient hypotension, or bradycardia. Control of paroxysmal atrial fibrillation in patients with hypertrophic obstructive cardiomyopathy is considered to be important for symptomatic improvement and prevention of the development to chronic atrial fibrillation. The authors report on 3 patients with hypertrophic obstructive cardiomyopathy who suffered from paroxysmal atrial fibrillation despite receiving medical treatment using antiarrhythmic agents. However, after undergoing percutaneous transluminal septal myocardial ablation, the incidence of episodes became significantly less frequent. Percutaneous transluminal septal myocardial ablation is normally performed for attenuating left ventricular obstruction by reducing the systolic anterior motion of the mitral leaflet. However, in these patients, this procedure was also effective in preventing supraventricular arrhythmia, probably by improving left ventricular diastolic dysfunction, smooth blood inflow into the left ventricular, and decreasing the pressure stress against the left atrial wall. |
7,777 | Coronary collateral circulation: any effect on P-wave dispersion? | Coronary collateral circulation determines the severity of ischemic myocardial damage. Increased P-wave dispersion is an independent predictor for atrial fibrillation. Consistent evidence is little about the relation between coronary collateral circulation and arrhythmia risk. In this article, the effect of coronary collateral circulation on P-wave dispersion was evaluated. Collateral grade and P-wave dispersion were ascertained in 100 patients with >or=85% diameter stenoses in left anterior descending or right coronary arteries. Left ventricular function score was also determined in all patients. Coronary collateral circulation was absent in 32 patients, whereas 68 patients had coronary collateral circulation. Patients with collateral grade >or=1 had greater left ventricular function score than did patients with collateral grade 0 (P = .048). However, there was no significant difference between P-wave dispersion of patients with and without coronary collateral circulation (P = .45). The presence of coronary collateral circulation failed to exert a beneficial decreasing effect on P-wave dispersion. |
7,778 | Chemical preconditioning effect of 3-nitropropionic acid in anesthetized rat heart. | Short ischemic episodes increase tolerance against subsequent severe ischemia in the heart. Nitropropionate (3-NP), an irreversible inhibitor of succinic dehydrogenase of the mitochondrial complex II, was shown to induce protective effect against ischemic brain injury. The aim of this study was to investigate the possible protective effect of 3-NP on regional ischemia in preconditioned rat heart in vivo. Hearts were assigned into three groups: first, in order to induce ischemic preconditioning (IP) 5 min ischemia separated by 10 min reperfusion protocol was used; second, non-preconditioned group was used as control; and third, 3-NP (20 mg/kg, i.p.) was injected 3 h before the surgical procedure in order to induce chemical preconditioning. In all these groups, 30 min regional ischemia was followed by 60 min reperfusion. Infarct size, bax expression, number of ventricular ectopic beats (VEB), duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) were significantly decreased in ischemic preconditioning and 3-NP pretreatment groups, whereas bcl-2 values were not markedly changed in these groups during occlusion period. These results showed that in the anesthetized rat heart 3-NP induced chemical preconditioning by decreasing infarct size, number of VEB, duration of VT and VF. Protective effect is associated with via decreased production of bax protein expression. |
7,779 | Ataxia caused by amiodarone in older people. | Amiodarone is recommended for the cardioversion of atrial fibrillation and prevention of paroxysmal atrial fibrillation in patients with structural heart disease, coronary artery disease or left ventricular dysfunction. It has well-recognised side-effects on the skin, lungs, liver, thyroid and eyes. Neurological side-effects, including ataxia and neuropathy, also occur, and may be more prevalent in older patients. These side-effects are reversible after cessation of amiodarone. Monitoring of amiodarone therapy should include assessment of the central and peripheral nervous system especially in older patients. |
7,780 | Catheter ablation of paroxysmal atrial fibrillation improves cardiac function: a prospective study on the impact of atrial fibrillation ablation on left ventricular function assessed by magnetic resonance imaging. | Beneficial effects of atrial fibrillation (AF) ablation have been demonstrated in patients with congestive heart failure (CHF) and significantly impaired left ventricular ejection fraction (LVEF). However, the impact of pulmonary vein isolation (PVI) on cardiac function in patients with paroxysmal AF and impaired LVEF remains under discussion. This study aimed to evaluate the impact of PVI for paroxysmal AF on cardiac function in patients with impaired LVEF using cardiac magnetic resonance imaging (CMRI).</AbstractText>A total number of 70 patients with paroxysmal AF and episodes < or = 24 h were scanned on a 1.5-T-CMRI before and 6 months after PVI during sinus rhythm. End-diastolic volume, end-systolic volume, and LVEF were determined by epicardial and endocardial measurements. Patients were categorized into two groups regarding cardiac function as assessed by CMRI: group 1 patients (n = 18) with an LVEF < 50% and patients with an LVEF > 50% (group 2, n = 52). Group 1 patients demonstrated a significant lower success rate than patients of group 2 after a follow-up of 152 +/- 40 days (50 vs. 73%, P < 0.05). Cardiac magnetic resonance imaging in group 1 patients demonstrated a significant improvement in cardiac function after AF ablation (41 +/- 6 vs. 51 +/- 12%, P = 0.004), whereas group 2 patients did not show significant differences (60 +/- 6 vs. 59 +/- 9%, P = 0.22) after a 6 months follow-up.</AbstractText>Pulmonary vein isolation improves cardiac function in patients with paroxysmal AF and impaired LVEF. These data suggest that an impaired LV function can be partially attributed to AF with short-lasting paroxysms.</AbstractText> |
7,781 | Paced ventricular electrogram fractionation predicts sudden cardiac death in hypertrophic cardiomyopathy. | Paced electrogram fractionation analysis (PEFA) has been assessed for the prediction of sudden cardiac death (SCD) in a large-scale, prospective study of patients with hypertrophic cardiomyopathy (HCM).</AbstractText>We determined the positive predictive value (PPV) of PEFA in relation to other risk factors for SCD and outcomes in 179 patients with HCM and no prior history of cardiac arrest. Patients were followed over a mean 4.3 years (range: 1.1-6.3 years). Thirteen patients had SCD-equivalent events: four of these patients died suddenly, three were resuscitated from ventricular fibrillation (VF), and six had implantable cardioverter-defibrillator (ICD) discharges in response to VF. PEFA identified nine of these patients and another 14 non-VF patients yielding a censored PPV of between 0.19 and 0.59 that was greater than the PPV that was the formal stopping point of the trial (0.18). Eighty per cent of patients were followed for 4 years or more. The PPV for the identification of SCD in this group was 0.38 (0.17-0.59). The use of two or more conventional markers to predict SCD identified five patients with SCD-equivalent events in the 4-year follow-up group and 42 other patients without events yielding a PPV of 0.106 (confidence limits 0.02-0.15).</AbstractText>PEFA identifies HCM patients at risk of SCD with greater accuracy than non-invasive techniques and may have an important role in determining indications for ICD prescription.</AbstractText> |
7,782 | Implantable defibrillators and prevention of sudden death in hypertrophic cardiomyopathy. | Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people, including trained athletes. The implantable cardioverter-defibrillator (ICD), although initially designed as a treatment for older patients with coronary artery disease, has more recently proved to be a safe and effective therapeutic intervention in young patients with HCM, both for primary or secondary prevention of sudden death. The largest such report of >500 patients showed that the ICD intervened appropriately to abort ventricular tachycardia/fibrillation (VT/VF) in 20% of patients over an average follow-up period of only 3.7 years, at a rate of about 4% per year in those patients implanted prophylactically, and often with considerable delays of up to 10 years. Extensive experience with high-risk HCM patients showed that appropriate device discharges for VT/VF occur with similar frequency in patients with 1, 2, or > or = 3 noninvasive risk markers. Despite the extreme morphology characteristic of HCM, often with massive degrees of left ventricular (LV) hypertrophy and/or LV outflow tract obstruction, ICDs performed in a highly effective fashion, with failure to convert life-threatening arrhythmias extraordinarily rare. In conclusion, in a large high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients with only one risk factor. Therefore, a single marker of high risk may represent sufficient evidence to justify the recommendation for a prophylactic ICD in selected patients with HCM. |
7,783 | [Highlights 2007 in hospital-based internal medicine: the point of view from the chief residents]. | In 2007, several international studies brought useful information for the daily work of internists in hospital settings. This summary is of course subjective but reflects the interests and questions of the chief residents of the Department of internal medicine who wrote this article like an original trip in medical literature. This trip will allow you to review some aspects of important fields such as heart failure, diabetes, endocarditis, COPD, and quality of care. Besides the growing diversity of the fields covered by internal medicine, these various topics underline also the uncertainty internists have to face in a practice directed towards evidence. |
7,784 | Electrocardiographic evaluation of cardiovascular status. | The electrocardiogram (ECG) is indispensable for the diagnosis and management of patients with a wide variety of cardiac and noncardiac diseases. The purpose of this paper is focused on recent research that used ECG, specifically the long-QT interval and microvolt T wave alternans, for the evaluation of life-threatening ventricular arrhythmias. Although remaining to be validated, QT prolongation along with other emerging electrocardiographic indices such as T wave morphology, T peak-to-T end time, or beat-to-beat QT variability may be sensitive indicators of malignant polymorphic ventricular tachyarrhythmia, torsade de pointes. Microvolt T wave alternans may provide important information in identifying a low-risk group with left ventricular dysfunction who is unlikely to benefit from unnecessary prophylactic implantable cardioverter defibrillator therapy. These ECG markers have the potential to aid in the safe administration of individualized medications, avoidance of sudden cardiac death, and provision of a noninvasive strategy to identify patients who are most and least likely to benefit from expensive prophylactic implantable cardioverter defibrillator placement. |
7,785 | Clinical and molecular genetics of the short QT syndrome. | Sudden cardiac death in patients without structural heart disease remains a challenge in diagnostics and risk stratification. Genetically determined arrhythmias are a potential cause for a primary electrical disease. A recently discovered primary electrical disease is discussed.</AbstractText>The inherited short QT syndrome is a recently recognized genetic condition, which is associated with atrial fibrillation, syncope and/or sudden cardiac death. Attention has been focused on diagnostic ECG features, the identification of underlying mutations and mechanisms of arrhythmogenesis.</AbstractText>The short QT syndrome is clinically associated with atrial fibrillation, syncope and sudden cardiac death. A shortened QT interval (QTc <360 ms) and reduced ventricular refractory period together with an increased dispersion of repolarization constitute the potential substrate for reentry and life-threatening ventricular tachyarrhythmia. To date, gain-of-function mutations in KCNH2, KCNQ1, KCNJ2, encoding potassium channels and loss-of-function mutations in CACNA1C and CACNB2b, encoding L-type calcium channel subunits have been identified. The therapy of choice is the implantable cardioverter defibrillator in symptomatic patients. Quinidine has been shown to prolong the QT interval and to normalize the effective refractory periods of the atrium and ventricle in patients with short QT-1 syndrome.</AbstractText> |
7,786 | Simultaneous right atrioventricular pacing: a novel model to study atrial remodeling and fibrillation in the setting of heart failure. | Atrial fibrillation (AF) is a common arrhythmia which contributes to morbidity and mortality in patients with heart failure (HF). Atrial remodeling is a key substrate for the development of AF in HF. However, experimental models that study AF in the setting of HF have important limitations. We evaluated a new dog model of atrial remodeling and AF.</AbstractText>Twenty-two mongrel dogs were randomized into 2 groups: 14 dogs with simultaneous atrioventricular pacing (SAVP) for 2 weeks (220 beats/min, no AV delay) and 8 control dogs with no pacing. SAVP for 2 weeks induced marked changes in atrial mechanical function and conduction. Left atrial area fractional shortening decreased 61 +/- 17%, whereas left ventricular area fractional shortening decreased by 38 +/- 18% from baseline (both P < .05). Conduction slowed and conduction heterogeneity increased. AF was induced in 83% of SAVP dogs, lasting a median of 1600 seconds, versus no dogs with induced AF in the controls. SAVP significantly increased nonfibrillar collagen in the mid-myocardium of both atrial appendages and matrix metalloproteinase-9 activity.</AbstractText>SAVP in dogs induces structural and electrical remodelling that form the substrate for reproducibly inducible AF. This novel model may be useful for studies of the pathophysiology and treatment of AF in heart failure.</AbstractText> |
7,787 | The prediction of ICD therapy in multicenter automatic defibrillator implantation trial (MADIT) II like patients: a retrospective analysis. | MADIT II like patients have not been compared to patients without an electrophysiological study, patients in whom ventricular tachycardia or fibrillation were induced in an electrophysiological study (EPS) and patients without an inducibility in EPS in one study.</AbstractText>The multicenter automatic defibrillator implantation trial (MADIT) II showed a benefit of ICD implantation in patients with ischemic heart disease.</AbstractText>We performed a retrospective analysis in 93 patients with an ischemic heart disease and an ejection fraction </=30% who had an ICD implanted with a follow-up at least an 18 months. Patients were divided into 3 groups according to the primary indication for ICD implantation: without EPS (group I), patients in whom ventricular tachycardia or fibrillation were inducible in EPS (group II) or patients without an inducibility in EPS (group III).</AbstractText>During the mean follow-up of 32.9 +/- 16.1 months 289 appropriate ICD therapies and 10 deaths occurred. The incidence of appropriate ICD therapies did not differ significantly between the groups (group I 40%, group II 54% and group III 48% of patients). We found in group II a higher risk of appropriate ICD therapies with occurrence of a specific constellation of EPS values. These patients showed a 15-fold risk (P = 0.005) of an appropriate ICD therapy. Furthermore a brain natriuretic peptide value of 265 pg/ml also predicted an appropriate ICD therapy with a 3.5-fold risk (P = 0.017).</AbstractText>In the present retrospective study the results of MADIT II were affirmed in the case of incidence of ventricular arrhythmias in patients with an EF < 30% and coronary heart disease. The prediction of an appropriate ICD therapy with EPS was only achieved in patients with inducibility in the EPS.</AbstractText> |
7,788 | Cardiac arrests in hemodialysis patients: An ongoing challenge. | Hemodialysis patients have significant cardiac-related mortality. Sudden cardiac arrests in the dialysis unit are infrequent events but carry a poor prognosis. The predominant rhythm is ventricular tachycardia/fibrillation. Although the exact etiologies are not clear, several studies have confirmed an increased incidence on the first day after the weekend interval. Use of cardioprotective drugs and possibly an implantable cardioverter defibrillator may improve the prognosis of survivors after a cardiac arrest. More research is needed in this field. |
7,789 | Successful outcome utilizing hypothermia after cardiac arrest in pregnancy: a case report. | To date, pregnancy has been considered a contraindication to the use of therapeutic hypothermia after cardiac arrest.</AbstractText>We present the case of a 35-yr-old woman, 13 wks pregnant, who had a witnessed out-of-hospital ventricular fibrillation cardiac arrest. She was resuscitated by prehospital personnel yet remained comatose at arrival to the hospital. Therapeutic cooling (33 degrees C) was initiated for 24 hrs, and she was discharged home with mild neurologic deficit (Cerebral Performance Category 2) on hospital day 6. The infant was delivered via cesarean section at 39 wks' gestation. Apgar scores were 8 and 9, and neurodevelopmental testing was appropriate for age at birth and at 2 months.</AbstractText>This is the first case of therapeutic hypothermia applied to postarrest care of a pregnant woman followed by a successful delivery. This therapy should be considered in pregnant patients with cardiac arrest.</AbstractText> |
7,790 | Ventricular fibrillation during colonoscopy: a case report--colonoscopy in high-risk patients should be performed with ECG monitoring. | While ventricular premature contractions have been noted during colonoscopy (CS), ventricular fibrillation (VF) is rare. We recently had a patient who developed VF during CS and recovered without any sequelae despite severe complications after cardiopulmonary resuscitation (CPR). If electrocardiogram (ECG) monitoring had been done during CS, a direct current shock defibrillation could have been accomplished and prevented complications. CS in high-risk patients should be done with ECG monitoring. |
7,791 | Subcutaneous array with active can implantable cardioverter defibrillator configuration: a follow-up study. | Novel nontransvenous implantable cardioverter defibrillator (ICD) configurations are sometimes required for small children and children with complex congenital heart disease at risk for sudden death. Mid- to long-term follow-up of these nontraditional implant techniques is not well known. We assessed the mid-term performance of a subcutaneous lead technique used in our practice.</AbstractText>Between July 2002 and November 2003, 4 patients (age 2.1-8.5 years, weight 13-33.3 kg, height 90-126.7 cm) received an ICD with a single-finger (n = 3) or 2-finger (n = 1) subcutaneous array with an active abdominal can and epicardial pace/sense lead. The subcutaneous tunnel was created via a subxiphoid incision using a tunneling tool within a sheath along the seventh intercostal space and extended posterior to the spine. Diagnoses included long QT syndrome (n = 2), idiopathic ventricular fibrillation (n = 1), and idiopathic dilated cardiomyopathy (n = 1). Implantable cardioverter defibrillator indications included syncope (n = 2) and cardiac arrest (n = 2).</AbstractText>Mean follow-up was 22.3 +/- 13.9 months. During follow-up, 1 patient underwent heart transplantation and the other 3 patients underwent generator replacement secondary to a manufacturer's advisory. There was 1 appropriate and successful shock for ventricular fibrillation. This patient experienced a second episode of ventricular fibrillation that the ICD discharge failed to terminate. The arrhythmia spontaneously resolved. There were no inappropriate shocks. There was 1 instance of false detection of ventricular fibrillation because of intermittent T wave oversensing but therapy was not administered. There were no infections, lead fractures, or other complications during follow-up.</AbstractText>This novel nontransvenous ICD configuration can be used safely in a select group of pediatric patients and allows for the applicability of this life-saving technology to small children at high risk for sudden cardiac death.</AbstractText> |
7,792 | Atrial-selective sodium channel block as a strategy for suppression of atrial fibrillation. | Antiarrhythmic drug therapy remains the principal approach for suppression of atrial fibrillation (AF) and flutter (AFl) and prevention of their recurrence. Among the current strategies for suppression of AF/AFl is the development of antiarrhythmic agents that preferentially affect atrial, rather than ventricular electrical parameters. Inhibition of the ultrarapid delayed rectifier potassium current (IKur), present in the atria, but not in the ventricles, is an example of an atrial-selective approach. Our recent study examined the hypothesis that sodium channel characteristics differ between atrial and ventricular cells and that atrial-selective sodium channel block is another effective strategy for the management of AF. We have demonstrated very significant differences in the inactivation characteristics of atrial versus ventricular sodium channels and a striking atrial selectivity for the action of ranolazine, an inactivated-state sodium channel blocker, to produce use-dependent block of the sodium channels, leading to depression of excitability, development of post-repolarization refractoriness (PRR), and suppression of AF. Lidocaine and chronic amiodarone, both predominantly inactivated-state sodium channel blockers, also produced a preferential depression of sodium channel-dependent parameters (VMax conduction velocity, diastolic threshold of excitation, and PRR) in the atria. Propafenone, a predominantly open-state sodium channel blocker, produced similar changes of electrophysiological parameters, which were was not atrial-selective. The ability of ranolazine, chronic amiodarone, and propafenone to prolong the atrial action potential potentiated their ability to suppress AF in coronary-perfused canine atrial preparations.</AbstractText>Our data demonstrate important differences in the inactivation characteristics of atrial versus ventricular sodium channels and a striking atrial selectivity for the action of agents like ranolazine to produce use-dependent block of sodium channels leading to suppression of AF. Our findings suggest that atrial-selective sodium channel block may be a valuable strategy to combat AF.</AbstractText> |
7,793 | Anesthetic preconditioning decreases arrhythmias and improves regional conduction in isolated hearts. | Anesthetic preconditioning (APC) is known to protect the heart against necrosis and contractile dysfunction, but protection against arrhythmias has not been well characterized. The authors hypothesized that APC alters the dispersion of electrophysiologic parameters to reduce arrhythmias after global (G) or regional (R) ischemia.</AbstractText>Prospective vehicle-controlled study.</AbstractText>A university research laboratory.</AbstractText>Langendorff rat hearts (n = 66).</AbstractText>The authors examined the occurrence of arrhythmias, their mean duration, and the magnitude-squared coherence (MSC) of spectral components that provide a quantitative measure of rhythm organization at multiple sites in the heart, expressed as a function of time. Six groups received 0.5 minimum alveolar concentration (MAC) (APC-G, 0.5; APC-R, 0.5, respectively; 0.17 +/- 0.01 mmol/L and 0.18 +/- 0.05 mmol/L) or 1 MAC of isoflurane (APC-G 1.0; APC-R 1.0, respectively, 0.28 +/- 0.02 mmol/L and 0.31 +/- 0.05 mmol/L) before 30 minutes of global (ISC-G) or regional ischemia (ISC-R). Another group (SHAM) was neither subjected to ischemia nor isoflurane.</AbstractText>Electrodes were placed on the right atrium, the base, and the apex of the right ventricle. The incidence of ventricular fibrillation (VF) was as follows: ISC-G, 100%; APC-G 0.5, 50%; APC-G 1.0, 40%; ISC-R, 100%; APC-R 0.5, 50%; APC-R 1.0, 50% compared with SHAM 0%. Isoflurane-treated hearts showed delayed onset and decreased duration of arrhythmias on reperfusion. Untreated hearts showed low levels of MSC during reperfusion. In contrast, the isoflurane-treated hearts exhibited moderate-to-high levels of MSC during reperfusion.</AbstractText>APC reduces the incidence of arrhythmia after global and regional ischemia. In addition, the temporal synchrony of conduction is increased, suggesting a more organized pattern of excitation.</AbstractText> |
7,794 | The role of mechanoelectric feedback in vulnerability to electric shock. | Experimental and clinical studies have shown that ventricular dilatation is associated with increased arrhythmogenesis and elevated defibrillation threshold; however, the underlying mechanisms remain poorly understood. The goal of the present study was to test the hypothesis that (1) stretch-activated channel (SAC) recruitment and (2) geometrical deformations in organ shape and fiber architecture lead to increased arrhythmogenesis by electric shocks following acute ventricular dilatation. To elucidate the contribution of these two factors, the study employed, for the first time, a combined electro-mechanical simulation approach. Acute dilatation was simulated in a model of rabbit ventricular mechanics by raising the LV end-diastolic pressure from 0.6 (control) to 4.2 kPa (dilated). The output of the mechanics model was used in the electrophysiological model. Vulnerability to shocks was examined in the control, the dilated ventricles, and in the dilated ventricles that also incorporated currents through SAC as a function of local strain, by constructing vulnerability grids. Results showed that dilatation-induced deformation alone decreased upper limit of vulnerability (ULV) slightly and did not result in increased vulnerability. With SAC recruitment in the dilated ventricles, the number of shock-induced arrhythmia episodes increased by 37% (from 41 to 56) and the lower limit of vulnerability (LLV) decreased from 9 to 7 V/cm, while ULV did not change. The heterogeneous activation of SAC caused by the heterogeneous fiber strain in the ventricular walls was the main reason for increased vulnerability to electric shocks since it caused dispersion of electrophysiological properties in the tissue, resulting in postshock unidirectional block and establishment of reentry. |
7,795 | Cardiac effects of electrical stun guns: does position of barbs contact make a difference? | The use of electrical stun guns has been rising among law enforcement authorities for subduing violent subjects. Multiple reports have raised concerns over their safety. The cardiovascular safety profile of these devices in relationship to the position of delivery on the torso has not been well studied.</AbstractText>We tested 13 adult pigs using a custom device built to deliver neuromuscular incapacitating (NMI) discharge of increasing intensity that matched the waveform of a commercially available stun gun (TASER(R) X-26, TASER International, Scottsdale, AZ, USA). Discharges with increasing multiples of output capacitances were applied in a step-up and step-down fashion, using two-tethered barbs at five locations: (1) Sternal notch to cardiac apex (position-1), (2) sternal notch to supraumbilical area (position-2), (3) sternal notch to infraumbilical area (position-3), (4) side to side on the chest (position-4), and (5) upper to lower mid-posterior torso (position-5). Endpoints included determination of maximum safe multiple (MaxSM), ventricular fibrillation threshold (VFT), and minimum ventricular fibrillation induction multiple (MinVFIM).</AbstractText>Standard TASER discharges repeated three times did not cause ventricular fibrillation (VF) at any of the five locations. When the barbs were applied in the axis of the heart (position-1), MaxSM and MinVFIM were significantly lower than when applied away from the heart, on the dorsum (position-5) (4.31 +/- 1.11 vs 40.77 +/- 9.54, P< 0.001 and 8.31 +/- 2.69 vs 50.77 +/- 9.54, P< 0.001, respectively). The values of these endpoints at position-2, position-3, and position-4 were progressively higher and ranged in between those of position-1 and position-5. Presence of ventricular capture at a 2:1 ratio to the delivered TASER impulses correlated with induction of VF. No significant metabolic changes were seen after standard NMI TASER discharge. There was no evidence of myocardial damage based on serum cardiac markers, electrocardiography, echocardiography, and histopathologic findings confirming the absence of significant cardiac effects.</AbstractText>Standard TASER discharges did not cause VF at any of the positions. Induction of VF at higher output multiples appear to be sensitive to electrode distance from the heart, giving highest ventricular fibrillation safety margin when the electrodes are placed on the dorsum. Rapid ventricular capture appears to be a likely mechanism of VF induction by higher output TASER discharges.</AbstractText> |
7,796 | Evaluation of a novel ventricular support device with defibrillation capabilities in canine and porcine animal models. | Sudden death is prevalent in heart failure patients. We tested an implantable ventricular support device consisting of a wireform harness with one or two pairs of integrated defibrillation electrode coils.</AbstractText>The device was implanted into six pigs (36-44 kg) through a subxiphoid incision. Peak voltage (V) defibrillation thresholds (DFT) were determined for five test configurations compared with a control transvenous lead (RV to CanPect). Defibrillator can location (abdominal or pectoral) and common coil separation on the implant (0 degrees or 60 degrees ) were studied.(.) The DFT for RV60 to LV60 + CanPect was significantly less than control (348 +/- 57 vs 473 +/- 27 V, P < 0.05). The DFTs for other vectors were similar to control except for RV0 to LV0 + CanAbd (608 +/- 159 V). The device was implanted into 12 adult dogs for 42, 90, or 180 days with DFT and pathological examination performed at the terminal study. Cardiac pressures were determined at baseline, after implantation, and at the terminal study. The DFT was also determined in a separate group of four dogs at 42 days following implantation of the support device with one pair of defibrillation electrodes. The DFTs at implant and explant in dogs with one pair (8 +/- 1.5 Joules [J] and 6 +/- 1.9 J) or two pairs (8 +/- 3.4 J and 7 +/- 1.9 J) of defibrillation electrodes were not significantly different from each other but significantly less than control measured at the terminal study (18 +/- 3.4 J). Left-sided pressures were significantly decreased at explant but within expected normal ranges. Right-sided pressures were not different except for RV systolic. Histopathology indicated mild to moderate epicardial inflammation and fibrosis, consistent with a foreign body healing response.</AbstractText>This defibrillation-enabled ventricular support system maintained mechanical functionality for up to 6 months while inducing typical chronic healing responses. The DFT was equal to or lower than a standard transvenous vector.</AbstractText> |
7,797 | Implications of obstructive sleep apnea for atrial fibrillation and sudden cardiac death. | Obstructive sleep apnea (OSA) is a sleep-related breathing disorder with important cardiovascular consequences, including arrhythmogenesis. The unique pathophysiology of OSA results in multiple intermediate mechanisms that may promote atrial fibrillation, ventricular arrhythmias, and sudden cardiac death. These mechanisms may act acutely to trigger nocturnal dysrhythmias, or chronically by affecting the electrical and myocardial substrates. Burgeoning epidemiological data have identified an increased risk for atrial fibrillation and sudden cardiac death related to OSA. Currently, few data exist to support the efficacy of OSA therapy, namely continuous positive airway pressure, as an adjunct for arrhythmia prevention or management. |
7,798 | Preoperative alterations in correlation properties and complexity of R-R interval dynamics predict the risk of atrial fibrillation after coronary artery bypass grafting in patients with preserved left ventricular function. | We evaluated whether there are constant preoperative alterations in nonlinear R-R interval dynamics that associate with the risk of postoperative atrial fibrillation in patients with preserved left ventricular function.</AbstractText>We analyzed mean normal-to-normal R-R intervals, short-term scaling exponent of detrended fluctuation analysis (DFA alpha(1)), approximate entropy and entropy of symbolic dynamics (SymDyn En) from 10-minute ECG recordings during rest, paced breathing, and passive tilt performed 1 day before surgery in 67 elective coronary artery bypass grafting patients.</AbstractText>Nineteen patients developed postoperative atrial fibrillation. The preoperative DFA alpha(1) was constantly lower in patients developing postoperative atrial fibrillation than in patients remaining in sinus rhythm (P = 0.016); during spontaneous breathing, the DFA alpha(1) was 0.93 +/- 0.33 in patients with atrial fibrillation and 1.13 +/- 0.24 in patients with sinus rhythm. The entropy of symbolic dynamics was higher during the spontaneous breathing in patients with atrial fibrillation than in patients with sinus rhythm (4.72 +/- 0.51 vs 4.36 +/- 0.51, P = 0.012). Higher short-term scaling exponent of detrended fluctuation analysis during the spontaneous breathing period reduced the risk of postoperative atrial fibrillation (OR 0.31 for an interquartile increase in DFA alpha(1), 95% CI 0.13-0.78), while higher entropy of symbolic dynamics increased it (OR 3.16 for an interquartile increase in SymDyn En, 95% CI 1.23-8.10), independently of age and clinical risk factors.</AbstractText>The preoperatively altered nonlinear R-R interval dynamics were independent predictors of postoperative atrial fibrillation and might become a useful tool for the risk assessment of atrial fibrillation.</AbstractText> |
7,799 | Myocardial gap junctions: targets for novel approaches in the prevention of life-threatening cardiac arrhythmias. | Direct cell-to-cell communication in the heart is maintained via gap junction channels composed of proteins termed connexins. Connexin channels ensure molecular and electrical signals propagation and hence are crucial in myocardial synchronization and heart function. Disease-induced gap junctions remodeling and/or an impairment or even block of intercellular communication due to acute pathological conditions results in derangements of myocardial conduction and synchronization. This is critical in the development of both ventricular fibrillation, which is a major cause of sudden cardiac death and persistent atrial fibrillation, most common arrhythmia in clinical practice often resulting in stroke. Many studies suggest that alterations in topology (remodeling), expression, phosphorylation and particularly function of connexin channels due to age or disease are implicated in the development of these life-threatening arrhythmias. It seems therefore challenging to examine whether compounds that could prevent or attenuate gap junctions remodeling and connexin channels dysfunction can protect the heart against arrhythmias that cause sudden death in humans. This assumption is supported by very recent findings showing that an increase of gap junctional conductance by specific peptides can prevents atrial conduction slowing or re-entrant ventricular tachycardia in ischemic heart. Suppression of ischemia-induced dephosphorylation of connexin seems to be one of the mechanisms involved. Another approach for identifying novel treatments is based on the hypothesis that even non-antiarrhythmic drugs with antiarrhythmic ability can modulate gap junctional communication and hence attenuate arrhythmogenic substrates. |
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