Atrial fibrillation and sudden death related to occupational solvent exposure

Two cases of atrial fibrillation and one case of sudden death occurred in workers exposed to trifluorotrichloroethane (CFC 113) as a solvent/degreasing agent. This agent and related halogenated hydrocarbons are widely used in industry as solvents and degreasing agents, and have been previously linked to ventricular arrhythmias and cardiac sudden death when inhaled in excessive concentrations. We suggest that occupational overexposure to halogenated hydrocarbons should be considered a potential precipitant for atrial as well as ventricular arrhythmias. © 1994 Wiley-Liss, Inc.     

Sexual activity as a trigger for ventricular tachycardia in a patient with implantable cardioverter defibrillator

Occurrence of life threatening arrhythmias and sudden death during or following sexual activity is infrequent. We describe a patient with an implantable cardioverter defibrillator who developed increased ventricular ectopic activity followed by sustained ventricular tachycardia during extramarital coitus. A review of literature and management is discussed.     

原发性高血压的QT离散度分析

目的：研究原发性高血压左室重量（ＬＶＭ）对ＱＴ间期离散度（ＱＴｄ）的影响及ＱＴｄ对室性心律失常的预测作用。方法：检测１５０例患者的ＱＴ、ＪＴ、ＱＴｃ、ＪＴｃ离散度和超声心动图,其中６８例行２４小时动态心电图监测。结果：原发性高血压的复极离散度大小与左室重量呈正相关,伴左室肥厚者（ＬＶＨ组）的ＱＴｄ大于无左室肥厚者（对照组）（Ｐ＜０．０１）,有持续性室速发生者（ＳＶＴ组）的复极离散度大于无室性心律失常者（对照组）（Ｐ＜０．０１）,仅有室性期前收缩者（ＶＰＣ组）的ＱＴｄ与对照组无明显差异（Ｐ＞０．０５）。结论：复极离散度的大小主要与左室重量有关,伴左室肥厚者的心性猝死率增加可能与ＱＴｄ的增大有关,ＱＴｄ的变化可作为原发性高血压恶性室性心律失常的预测指标。     

Beta-Blocker Heart Attack Trial: impact of propranolol therapy on ventricular arrhythmias

The natural history of and the effect of propranolol on ventricular arrhythmias post-myocardial infarction were analyzed using data from the Beta-Blocker Heart Attack Trial (BHAT). The Beta-Blocker Heart Attack Trial was a multicenter, randomized, double-blind, placebo-controlled trial among 3,837 patients entered from 5 to 21 days after hospitalization for acute myocardial infarction. At baseline, prior to randomization, 3,290 (85.7%) patients underwent 24-hr ambulatory ECG monitoring which was repeated in approximately 25% of a randomly selected subset of the study population at 6 weeks. Ventricular arrhythmias were divided into eight different categories which defined the prevalence of ventricular arrhythmias in terms of frequency and/or complexity. Ventricular arrhythmias at baseline were associated with age, past history of myocardial infarction, and use of diuretics and digitalis. Paired data (baseline and 6-week) were available for 428 patients on propranolol and 412 on placebo. Propranolol markedly blunted the two- to threefold increase in ventricular arrhythmias that occurred from baseline to 6 weeks in the placebo group. Propranolol decreased the proportion of patients having ventricular arrhythmias during waking hours compared with sleep. These data show that propranolol has an antiarrhythmic effect and suggest that an antiarrhythmic mechanism may in part be responsible for the observed reduction in sudden cardiac death mortality in BHAT.     

Aborted sudden cardiac death as a presentation of isolated non-compaction cardiomyopathy

Left ventricular non-compaction cardiomyopathy (LVNC) is a rare disorder characterized by a thick myocardial wall with two distinct layers consisting of compacted and noncompacted myocardium. The major clinical manifestations of LVNC have been described as heart failure, cardiac arrhythmias, and cardioembolic events. In this report we present a case of a young woman with LVNC who presented with aborted sudden cardiac death. This is the second case of LVNC reported in Puerto Rico, but the first presenting with this complication. Recent advances in the field of cardiology allow the identification and diagnosis of this disease; thus, preventive and treatment strategies could be established for this potentially life-threatening condition. LVNC has to be considered in young patients presenting with sudden cardiac death.     

Natural History of Mucus in the Bronchial Tree

Aerosol “sniffing,” a variant of glue “sniffing,” involves the deliberate inhalation of aerosol products and propellants. Approximately 65 deaths have been attributed to this practice. They have been predominantly sudden and generally lack conclusive autopsy findings. The cause of death has not been defined in most cases; however, various mechanisms have been postulated. The evidence suggests acute cardiac arrest as a frequent cause. It could result from the sudden onset of ventricular fibrillation due to sensitization of the heart to epinephrine by inhalation of high concentrations of aerosol contents. Experimental investigation revealed that the commonly used aerosol propellants, in high concentrations, are capable of sensitizing the heart to epinephrine resulting in serious cardiac arrhythmias. Therefore, it is concluded that cardiac sensitization is a likely mechanism of death in many of the aerosol-sniffing fatalities.     

Fish fatty acids and cardiovascular diseases--an update

Epidemiologic observational research shows that higher intake of fish fatty acids is associated with a lower risk of fatal heart disease and sudden death, but this effect is not observed with non-fatal heart disease. Currently available trials with clinical endpoints provide no convincing evidence that supplementation with fish oil prevents cardiovascular disease. The theory that fish fatty acids can prevent cardiac arrhythmias is not supported by the trials performed in patients with life-threatening cardiac arrhythmias. For the specific group of patients who have previously experienced a ventricular tachycardia and who have not been prescribed an anti-arrhythmia medication for this, there are indications that the intake of fish oil might even lead to a slightly increased risk ofsevere cardiac arrhythmias. However, other subgroups of patients, such as patients with a recent myocardial infarction may benefit from taking fish oil to prevent cardiac arrhythmias. The advice of the Health Council of the Netherlands to eat fish twice per week, of which fatty fish once per week, or to take 450 mg of the combination eicosapentaenic acid (EPA) and docosahexaenic acid (DHA) per day remains justifiable until the results from current studies become available. However, patients with a ventricular arrhythmia who do not receive specific anti-arrhythmic medication should be careful about taking fish oil capsules.     

Right bundle branch block and ST-segment elevation in right precordial leads: a marker for sudden cardiac death

The authors present a patient with a specific ECG pattern and a history of syncope and malignant ventricular arrhythmias. Patients without demonstrable structural heart disease and an ECG pattern of RBBB and ST segment elevation in leads V1 through V3 are at risk for sudden cardiac death. They demonstrate the role of cardiac electrophysiology study including programmed ventricular stimulation and pharmacological testing in evaluation of patients with possible Brugada syndrome. The authors emphasize the role of implantable cardioverter defibrillator (ICD) therapy in treatment of patients with Brugada syndrome.     

The clinical utility of QT interval assessment in diabetes

A prolonged (QT) interval is considered an indicator of an increased risk of malignant ventricular arrhythmias and/or sudden death. It has been proposed that autonomic neuropathy in diabetes is related to QT interval prolongation and higher mortality rates. More recently, the interlead difference in QT interval duration has been referred to as QT interval dispersion, which has proven to be predictive of ventricular arrhythmias and mortality in different groups of patients. QT interval duration and dispersion are significantly related, but are not concordant in a substantial number of cases in identifying patients at risk. The prevalence of QT prolongation in Type 1 and Type 2 diabetic (T1 and T2DM) patients is higher than 20%. Several studies in T1 and T2DM patients have confirmed the independent relation between prolonged QT interval duration and increased QT interval dispersion and chronic ischemic heart disease. It has been consistently shown that autonomic neuropathy is related to QT interval duration, while more controversies exist on the association with QT interval dispersion. In recent years 5 studies have been published which confirm the value of QT interval as a predictor of total mortality in diabetic as well as in non-diabetic subjects. Surprisingly, no data exist on the relation between the risk of sudden death and QT interval prolongation in diabetic patients. As corrected QT interval is significantly related to mortality, it could be used to stratify the death risk in diabetic patients, particularly those who are candidates for surgery or kidney and/or pancreas transplantation. We still do not know why QT interval is prolonged and how this abnormality leads to death: however, a simple, low-cost measurement, which is easily obtainable without the need of the patient's compliance, could help select patients who need second level diagnostic procedures and strict observation.     

Clinical effectiveness and cost-effectiveness of implantable cardioverter defibrillators for arrhythmias: a systematic review and economic evaluation

OBJECTIVES: The clinical effectiveness and cost-effectiveness of implantable cardioverter defibrillators (ICD) for arrhythmias was assessed. METHODS: A systematic review of the literature of systematic reviews and randomized controlled trials that reported mortality outcomes associated with implantable cardioverter defibrillators compared with antiarrhythmic drug therapy in people at risk of sudden cardiac death due to arrhythmias was undertaken. Economic evaluations were also sought. Inclusion criteria, data extraction, and quality assessment were undertaken by standard methodology. A decision analytic model was constructed using best available evidence to determine cost-effectiveness in a UK setting. RESULTS: Eight randomized controlled trials, two systematic reviews, and a meta-analysis met the inclusion criteria and were of variable quality. Evidence suggests that ICDs reduce mortality in both secondary and primary prevention, although the magnitude of benefit depends on baseline risk for sudden cardiac death. Incremental cost per quality-adjusted life year ranged from 52,000 UK pounds ($98,000) to over 200,000 UK pounds ($379,000), depending on mortality risk and assumptions made. CONCLUSIONS: Evidence suggests that ICDs reduce total mortality but may be cost-effective only in some subgroups of patients at high risk of ventricular arrhythmias. Further research is needed on risk stratification of patients in whom ICDs are most likely to be clinically and cost-effective.     

Mitral valve prolapse in eating and panic disorder: A pilot study

The prevalence of echocardiographic mitral valve prolapse (MVP) and arrhythmias was studied in controls (n = 23) and patients with panic disorder (n = 14), bulimia nervosa (n = 14), and anorexia nervosa (n = 21). There was approximately twice the rate of MVP in patient groups compared to controls, a statistically insignificant difference. Importantly, the presence of prolapse was not associated with measures of weight or depression but there was a trend for MVP to be associated with anxiety disorder in bulimic patients. There were no significant arrhythmias found. These results raise the possibility that MVP may not be a state weight-related phenomenon as has been proported, but rather a trait phenomenon reflecting comorbidity with anxiety disorder.     

New perspectives in long QT syndrome

Long QT Syndrome (LQTS) is a cardiac channelopathy characterized by prolonged ventricular repolarization and increased risk to sudden death secondary to ventricular dysrrhythmias. Was the first cardiac channelopathy described and is probably the best understood. After a decade of the sentinel identification of ion channel mutation in LQTS, genotype-phenotype correlations have been developed along with important improvement in risk stratification and genetic guided-treatment. Genetic screening has shown that LQTS is more frequent than expected and interestingly, ethnic specific polymorphism conferring increased susceptibility to drug induced QT prolongation and torsades de pointes have been identified. A better understanding of ventricular arrhythmias as an adverse effect of ion channel binding drugs, allow the development of more safety formulas and better control of this public health problem. Progress in understanding the molecular basis of LQTS has been remarkable; eight different genes have been identified, however still 25% of patients remain genotype-negative. This article is an overview of the main LQTS knowledge developed during the last years.     

Recent advances in implantable cardioverter defibrillator systems

The usefulness of the implantable cardioverter defibrillator (ICD) for the prevention of sudden cardiac death caused by ventricular tachyarrhythmias has been proven by several international randomized multi-center clinical trials. Recent advances in medical technologies, such as size reduction and the functional improvements of the device, have resulted in relatively easy implantation. As a result, the number of ICD recipients has been rapidly increasing and the indications for ICD implantation have been expanding. Dual chamber ICDs offer improved tachyarrhythmia detection algorithms such as discrimination of supraventricular arrhythmias. In Europe and the United States, biventricular ICDs are now available for the treatment of congestive heart failure associated with ventricular tachyarrhythmias. Although the incidence of inappropriate shock by ICDs is decreasing, inappropriate discharges of ICDs and a declining quality of life are still problems.     

Omega-3 fatty acids and cardiovascular disease

PURPOSE OF REVIEW: In the last 2 years in the cardiovascular field eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been investigated in terms of their epidemiology and vascular biology, and in large-scale intervention trials, and incorporated into the guidelines of cardiac societies. EPA and DHA have advanced from scientific research into everyday practice, a development reviewed here. RECENT FINDINGS: EPA and DHA are antiarrhythmic on the supraventricular and ventricular levels, besides having an anti-atherosclerotic effect. Fish rich in EPA and DHA, contaminated with methyl-mercury, appears less protective. Large-scale clinical trials demonstrated that morbidity can be reduced with EPA even in a population already consuming large amounts of EPA and DHA. Therapy with EPA and DHA can be monitored with the omega-3 index, a risk factor for sudden cardiac death. EPA and DHA appear to be cost-saving in the USA, and, as Omacor, are cost-effective in several European countries. SUMMARY: European and American Cardiac Societies incorporated EPA and DHA into recent treatment guidelines for myocardial infarction, prevention of cardiovascular disease, treatment of ventricular arrhythmias and prevention of sudden cardiac death. Physicians need to reduce the burden of cardiovascular disease by advocating EPA and DHA to all patients likely to benefit.     

Trans fatty acids and coronary heart disease.

Epidemiologic evidence has linked trans fatty acids (TFAs) in the diet to coronary heart disease in human populations. It has been estimated that dietary TFAs from partially hydrogenated oils may be responsible for between 30,000 and 100,000 premature coronary deaths per year in the United States. Although it is known that TFAs increase low-density lipoprotein (LDL) cholesterol levels and decrease high-density lipoprotein (HDL) cholesterol levels (markers of coronary heart disease), there is little known about the mechanisms by which TFAs actually function at the cellular level. It is unknown what levels of TFAs are clinically significant and it is unclear how TFAs are associated with cardiac arrhythmias or sudden cardiac death. We hypothesize that TFAs affect membrane structure, thus altering enzymatic pathways that may subsequently induce cardiac arrhythmias and sudden death.     

Mitral valve prolapse in a family practice setting

Mitral valve prolapse (MVP) syndrome is a relatively new clinical entity and fairly commonly encountered in clinical practice. The symptoms are often so vague that it is frequently not diagnosed or misdiagnosed for completely unrelated conditions. The recognition of MVP is important since the symptoms as well as the arrhythmias produced may be responsive to propranolol and the incidence of bacterial endocarditis is known to be increased. This paper reports on 25 patients with MVP in a family practice setting and compares this experience to recent literature on this problem.     

Integrative medicine and arrhythmias

Abnormalities of cardiac arrhythmias and conduction can be lethal (sudden cardiac death and stroke) or symptomatic (dizziness or palpitations). This article reviews the role of nutrients in the treatment of arrhythmias.     

MicroRNA在心律失常研究中的进展及其应用前景

心律失常与多种心血管疾病的发生发展有关,并与心源性猝死密切相关。研究心律失常的分子机制及其可能的治疗手段具有重要意义。microRNA与心脏多种离子通道蛋白表达以及心律失常的发生有紧密关系。同时,microRNA干扰技术的发展和应用为心律失常的生物或基因治疗奠定了基础。     

A novel algorithm for ventricular arrhythmia classification using a fuzzy logic approach

In the present study, it has been shown that an unnecessary implantable cardioverter-defibrillator (ICD) shock is often delivered to patients with an ambiguous ECG rhythm in the overlap zone between ventricular tachycardia (VT) and ventricular fibrillation (VF); these shocks significantly increase mortality. Therefore, accurate classification of the arrhythmia into VT, organized VF (OVF) or disorganized VF (DVF) is crucial to assist ICDs to deliver appropriate therapy. A classification algorithm using a fuzzy logic classifier was developed for accurately classifying the arrhythmias into VT, OVF or DVF. Compared with other studies, our method aims to combine ten ECG detectors that are calculated in the time domain and the frequency domain in addition to different levels of complexity for detecting subtle structure differences between VT, OVF and DVF. The classification in the overlap zone between VT and VF is refined by this study to avoid ambiguous identification. The present method was trained and tested using public ECG signal databases. A two-level classification was performed to first detect VT with an accuracy of 92.6 %, and then the discrimination between OVF and DVF was detected with an accuracy of 84.5 %. The validation results indicate that the proposed method has superior performance in identifying the organization level between the three types of arrhythmias (VT, OVF and DVF) and is promising for improving the appropriate therapy choice and decreasing the possibility of sudden cardiac death.     

Sudden cardiac death of rhythmic origin in athletes: literature review

The sudden death in athletes is, in the vast majority of cases, related to ventricular fibrillation, often in a subject with unknown cardiovascular abnormality; this dramatic event has a significant impact on society and the medical profession. We conducted through a literature review an analysis of data on sudden cardiac death of rhythmic origin in athletes; sudden death may be cardiovascular in 95.3% of cases and related to ventricular arrhythmia in 88% cases. The main causes are: hypertrophic cardiomyopathy, congenital anomalies of coronary arteries, and arhythmogenic right ventricular dysplasia for athletes under 35 years, and atherosclerosis beyond 35 years. Prevention is based on three main areas: the medical assessment and screening for cardiovascular disease; the chain of survival; the education of the athlete and the public. All these measures should improve significantly the survival prognosis of patients suffering from these accidents.