恶性快速性室性心律失常致心脏骤停的临床观察

目的探讨恶性快速性室性心律失常致心脏骤停的原因与高危心电表现。方法分析45例在入院时或入院后至少发生1次心脏骤停患者的原因及其发作时与发作前后的常规12导联心电图或持续心电监视心电图形。结果45例恶性快速性心律失常致心脏骤停最常见的基本原因为冠心病急性或陈旧性心肌梗死,次为特发性及继发性巨大异常J波、扩张型心肌病;低钾血症是最常见的诱因;最常见的恶性快速性室性心律失常类型是心室颤动。其高危心电图表现:①复杂性室性早搏;②异常J波;③继发性长Q-T间期综合征;④Brugada综合征;⑤广泛前壁心肌梗死伴墓碑样ST段抬高。上述各种原因心脏骤停者有各自不同的临床及心电学特征。结论恶性快速性室性心律失常所致心脏骤停存在多种原因及高危心电图表现。     

Prevalence of supraventricular tachycardia and tachyarrhythmias in resuscitated cardiac arrest

Supraventricular arrhythmias are considered to be benign when the ventricular rate is slowed and treated by anticoagulants. The aim of this study was to determine the possible influence of these arrhythmias in resuscitated cardiac arrest. Between 1980 and 2002, 151 patients were admitted after a cardiac arrest. Supraventricular arrhythrmias were identified as a possible cause of the cardiac arrest in 21 patients. They underwent echocardiography, exercise stress test, Holter ECG monitoring , coronary angiography and electrophysiological investigation. After these investigations, three patients had a malignant form of the Wolff-Parkinson-White syndrome, two were asymptomatic and, in the third patient, ventricular fibrillation was induced by treatment with diltiazem. In 8 patients, a rapid supraventricular arrhythmia was considered to be the cause of cardiac arrest by cardiogenic shock; 2 patients had hypertrophic cardiomyopathy, 5 had severe dilated cardiomyopathy which regressed in one patient. In ten patients, cardiac arrest due to ventricular tachycardia or fibrillation was provoked by a rapid (> 220 beats/min) supraventricular arrhythmia; two patients had no apparent underlying cardiac pathology. In the others, myocardial ischaemia or acute cardiac failure were considered to be the cause of the cardiac arrest. The authors conclude that rapid supraventricular arrhythmias may cause cardiac arrest either by cardiogenic shock or degenerescence to ventricular tachycardia or fibrillation. Usually, this event occurs in patients with severe cardiac disease but it may occur in subjects without cardiac disease or by an arrhythmia-induced cardiomyopathy.     

Genetic aspects of the etiology of arrhythmia

Cardiac arrhythmias are common causes of morbidity and mortality in clinical medicine. Much has been learned about cellular mechanisms of arrhythmogenesis in the past but genetic components have only recently been recognized for some heritable forms of arrhythmias. The long QT syndrome and the Brugada syndrome are both caused by molecular defects in ion channel proteins. Cardiac arrhythmias can also be associated with structural heart diseases. For example, sinus node dysfunction or AV-block can precede some forms of inherited dilated cardiomyopathy. A distinct genetic form of hypertrophic cardiomyopathy is associated with the Wolff-Parkinson-White syndrome and maps to chromosome 7q35. Arrhythmogenic right ventricular cardiomyopathy has a strong genetic basis and often manifests with ventricular tachycardia. Atrial fibrillation can also occur as familial disease and may be allelic with dilated cardiomyopathy as both diseases can be closely linked to chromosome 10q2.     

Voraussetzungen der ICD-Implantation

An electrophysiological study (EPS) and a programmed ventricular stimulation (PVS) are strongly recommended and clearly indicated before the implantation of a cardioverter defibrillator (ICD), if patients present with a cardiac arrest and no structural heart disease or a hypertrophic cardiomyopathy. In these patients the prevalence of a curable cause of the cardiac arrest, such as accessory pathways or an idiopathic ventricular tachycardia (VT), is high and the ICD implantation may be avoided. The same is true for patients who present with a cardiac arrest and a short PQ interval or a delta wave. If patients present with wide-complex tachycardias and the diagnosis of VT is unclear, an EPS and PVS are also clearly indicated. If patients have syncope or nonsustained VTs and a structural heart disease, PVS may be used for risk stratification. However, EPS and PVS may be of little use in patients with a structural heart disease and an impaired left ventricular function after a survived cardiac arrest or an unstable VT, which makes them candidates for ICD implantation anyway.     

The Clinical Significance of Nonsustained Ventricular Tachycardia

Nonsustained Ventricular Tachycardia. Nonsustained ventricular tachycardia (NSVT) is an arrhythmia not often associated with symptoms; however, its occurrence in patients with structural heart disease is a prognostic indicator of an increased risk of mortality and sudden death. The management of asymptomatic patients with NSVT should first attempt to identify which patients are at highest risk for cardiac arrest, and second, devise a treatment that can reduce the incidence and/or mortality of cardiac arrest in this group. In patients with chronic coronary artery disease (CAD) and NSVT, programmed electrical stimulation identifies both a low and high risk group with respect to occurrence of ventricular arrhythmias. The negative predictive value of programmed electrical stimulation in patients with CAD and NSVT has been well established; however, uncertainty remains as to the optimal therapy for CAD patients with inducible ventricular arrhythmias. A number of reports suggest that patients whose inducible ventricular arrhythmias are rendered noninducible with antiarrhythmic drugs have a much lower risk of sudden death. It is yet to be resolved whether arrhythmias rendered noninducible identify a subgroup at low risk for cardiac arrest, independent of treatment. There is some evidence to suggest that the frequency of NSVT in patients with nonischemic dilated cardiomyopathy identifies a group at higher risk of sudden death. Programmed electrical stimulation adds little in helping to identify which of these patients are most likely to have cardiac arrest. The presence of NSVT in asymptomatic patients with hypertrophic cardiomyopathy may identify a group at higher risk for cardiac arrest. Further clinical studies are needed to define the best management strategy for NSVT in different types of structural heart disease.     

Mavacamten,a novel revolutionizing therapy in hypertrophic obstructive cardiomyopathy: A literature review

Hypertrophic cardiomyopathy (HCM) is one of the most common inherited cardiac diseases, defined as a left ventricular wall thickness of ≥15 mm, in the absence of other causes of abnormal ventricular loading. A major hallmark of this disease is the presence of left ventricular outflow tract obstruction, which develops in up to three quarters of patients, referred to as obstructive hypertrophic cardiomyopathy. Current treatment is offered to symptomatic patients, based on the presence of documented left ventricular obstruction, aimed at reducing symptoms and disease progression. This is achieved through pharmacological empirical therapy, surgery, alcohol ablation and/or pacing. Mavacamten is a first-in-class allosteric inhibitor of cardiac myosin that promises to provide clinicians with targeted therapy for these patients. The aim of this review is to provide a general overview of the modern approach to the diagnosis and management of HCM, as well as to integrate all the current knowledge on mavacamten, in anticipation of a future change in the treatment algorithm of patients with HCM.     

Sudden cardiac death in the young: a strategy for prevention by targeted evaluation

The annual incidence of sudden cardiac death (SCD) in the general population is estimated as 1 in a 1,000. Since survival rates from out-of-hospital cardiac arrests are poor, primary prevention is key to reducing the burden of SCD in the community. Prominent causes of SCD include ischaemic heart disease, anomalous coronary arteries, and the primary myocardial diseases: hypertrophic cardiomyopathy, dilated cardiomyopathy, and ar rhythmogenic right ventricular cardiomyopathy (ARVC). In 4% of sudden deaths in the 16-64 age group, post-mortem examination fails to identify a cause, yielding a default diagnosis of sudden arrhythmic death syndrome (SADS). The inherited arrhythmia syndromes (long QT, short QT, and Brugada syndromes, and familial catecholaminergic polymorphic ventricular tachycardia) may be implicated in SADS, owing to their propensity for producing ventricular tachyarrhythmia in the structurally normal heart. Monogenic disorders therefore predominate as causes of SCD in the young. The advent of effective therapies for these diseases, particularly implantable cardioverter defibrillators, has prompted calls for universal screening to enable timely diagnosis of occult cardiac disease. Since prospective cardiac assessment of the general population is not feasible, the solution may be to target high-risk subgroups, namely, patients with cardiac symptoms, relatives of SCD victims, and competitive athletes. The recommended preliminary work-up includes a 12-lead ECG, signal-averaged ECG, transthoracic echocardiogram, exercise test, and ambulatory ECG monitoring. Cardiovascular magnetic resonance is a useful adjunct in patients with suspected ARVC or anomalous coronary arteries. Provocative challenge with a sodium challenge blocker may be of value in unmasking the Brugada syndrome. Identification of disease-causing mutations in affected individuals facilitates cascade screening of families.     

Young adult survivors of sudden cardiac arrest: analysis of invasive evaluation of 22 subjects

Twenty-two young adult (mean age 27.8 +/- 5.3 years) survivors of sudden cardiac arrest underwent invasive cardiac assessment. Initial evaluation by cardiac catheterization, coronary angiography, and hemodynamic studies identified two groups of young survivors. The first consisted of 13 (60%) subjects who had definable structural cardiac or lung disease accountable for a cardiac arrest event. Dilated cardiomyopathy dominated this group. Mitral valve prolapse, hypertrophic cardiomyopathy, left ventricular hypertrophy, anomalous origin of the right coronary artery, and tetralogy of Fallot were also encountered. The second group included nine subjects (40%) with normal cardiac structure and normal hemodynamic parameters. Electrophysiologic testing demonstrated in three of these patients the presence of Wolff-Parkinson-White syndrome. The electrophysiologic studies had a higher yield in reproduction of life-threatening arrhythmias among the subjects in the second group as opposed to the first group. The observation that 10 subjects (45%) from both groups had preceding symptoms varying from palpitations and chest pain to syncope and recurrent cardiac arrest events, is in contradiction to previous findings in the literature and raises a question of appropriate evaluation of young adults with cardiac symptoms.     

Sudden cardiac death in Long QT syndrome (LQTS), Brugada syndrome,and catecholaminergic polymorphic ventricular tachycardia (CPVT)

Sudden cardiac death (SCD) accounts for 230,000 to 350,000 deaths per year in the United States. While many who suffer SCD possess underlying structural heart disease, inherited arrhythmia syndromes are also important contributors to SCD. In patients without structural heart disease, inherited arrhythmia syndromes are identified in >50% of the remaining patients. In this review, we will focus on the presentation and management of three major inherited syndromes that lead to SCD in patients without structural heart disease: long QT syndrome (LQTS), Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT). All these syndromes can present in patients who are asymptomatic or, at the other extreme, with syncope and even SCD. LQTS syndrome and Brugada are the most common inherited arrhythmogenic syndromes, while CPVT is much rarer. Determining which patients need pharmacologic treatment and those who would benefit from more aggressive treatment such as sympathectomies and implantable defibrillators is not always clear.     

ECG Features that suggest a potentially life-threatening arrhythmia as the cause for syncope

Syncope is a risk factor for sudden cardiac death (SCD) in many conditions associated with structural heart disease as well as inherited heart disease. The ECG in patients with syncope should be examined carefully for signs of structural heart disease, such as myocardial infarction or cardiomyopathy; signs of conduction system disease, such as bundle branch block or atrioventricular block; and signs of primary electrical disease. Important forms of cardiomyopathy accompanied by ECG changes include hypertrophic cardiomyopathy (HCM), and arrhythmogenic right ventricular dysplasia (ARVD/C). Common ECG findings in HCM include left ventricular hypertrophy by voltage, repolarization abnormalities, QRS widening, pseudoinfarction patterns, and slurred QRS upstroke mimicking delta waves. Classical ECG findings of ARVD/C include T-wave inversions and epsilon waves in the right precordial leads (V₁–V₃). Important forms of primary electrical disease which may result in syncope include Wolff–Parkinson–White syndrome, long QT syndrome, and Brugada syndrome, which is characterized by coved ST-segments in the right precordial leads, associated with a history of syncope, ventricular arrhythmia, or sudden cardiac death in probands or family member. There are three Brugada ECG patterns; however, only type I (spontaneous or induced) is considered diagnostic. Recently, studies have suggested that patients with J-point elevation or early repolarization pattern on ECG are at elevated risk of SCD. The clinical significance of finding early repolarization in a patient with syncope is unknown and should be a subject of future research.     

Predicting Sudden Cardiac Death in Genetic Heart Disease

Genetic heart diseases are common causes of sudden cardiac death (SCD) in the young and are typically divided into inherited cardiomyopathies and primary electrical heart diseases. Cardiomyopathies associated with risk of SCD include hypertrophic cardiomyopathy (HCM) and arrhythmogenic cardiomyopathy (ACM). The latter includes arrhythmogenic right ventricular cardiomyopathy (ARVC) as well as ACM primarily affecting the left ventricle, such as lamin cardiomyopathy. Primary electrical diseases more commonly seen in clinical practice include Brugada syndrome (BrS) and long QT syndrome (LQTS). Risk stratification of SCD is a central component of the management of patients with these genetic heart diseases. Numerous risk factors have been identified with variable degrees of scientific evidence. More recently, risk prediction models have been developed to estimate the absolute risk of sustained arrhythmias and SCD, to support clinicians and patients in decision making regarding prophylactic implantable cardioverter-defibrillators (ICDs). This paper provides a practical review of the current literature on risk stratification in ARVC and other ACMs, HCM, BrS, and LQTS, and summarises current recommendations for ICD use.     

Loperamide Toxicity Revealing Apical Hypertrophic Cardiomyopathy

Loperamide, a μ-opioid receptor agonist, can cause cardiotoxicity by inhibiting the potassium ion channel and slowing cardiomyocyte repolarization. This, in turn, can lead to frequent early afterdepolarizations, the most common mechanism of drug-induced long QT syndrome and torsades de pointes. Apical hypertrophic cardiomyopathy (AHCM) is a nonobstructive hypertrophic cardiomyopathy rarely associated with malignant arrhythmias. We present a case of loperamide-induced malignant ventricular arrhythmia revealing underlying AHCM in a 25-year-old woman with a history of sudden cardiac arrest (SCA) and opioid use.It is important to evaluate for structural heart disease in all patients presenting with SCA, regardless of presumed etiology such as drug-induced cardiotoxicity, to prevent missed opportunities for adequate treatment. Furthermore, the diagnosis of AHCM in SCA warrants further genetic evaluation for variances with a predilection for malignant arrhythmias.     

Cardiac Abnormalities in Acromegaly

Cardiovascular disease is claimed to be one of the most severe complications of acromegaly, contributing significantly to mortality in this disease. In fact, an excess of growth hormone (GH) and insulin-like growth factor 1 (IGF-I) causes a specific derangement of cardiomyocytes, leading to abnormalities in cardiac muscle structure and function, inducing a specific cardiomyopathy. In the early phase of acromegaly the excess of GH and IGF-I induces a hyperkinetic syndrome, characterized by increased heart rate and increased systolic output. Concentric hypertrophy is the most common feature of cardiac involvement in acromegaly, found in more than two thirds of patients at diagnosis. This abnormality is commonly associated with diastolic dysfunction and eventually with impaired systolic function ending in heart failure, if the GH/IGF-I excess is left untreated. In addition, abnormalities of cardiac rhythm and of heart valves have also been described in acromegaly. The coexistence of other complications, such as arterial hypertension and diabetes mellitus, aggravates acromegalic cardiomyopathy. Successful control of acromegaly induces a decrease in left ventricular mass and an improvement in diastolic function, while the effects of GH/IGF-I suppression on systolic function are more variable. However, since cardiovascular alterations in young patients with short disease duration are milder than in those with longer disease duration, it is likely to be easier to reverse and/or arrest acromegalic cardiomyopathy in young patients with early-onset disease. In conclusion, careful assessments of cardiac function, morphology, and activity are required in patients with acromegaly. An early diagnosis and prompt effective treatment are important in order to reverse acromegalic cardiomyopathy.     

Sodium Channel Variants in Heart Disease: Expanding Horizons

Inherited arrhythmia syndromes have advanced our understanding of cardiac sodium (Na) channel function in health and disease. Long QT syndrome (LQT3) is consistently caused by increased net Na current secondary to inactivation defects, which give rise to persistent Na current. Conversely, various gating changes that ultimately result in reduced Na current may elicit Brugada syndrome, conduction disease, atrial standstill, and sinus node disease. Emerging insights now also link these gating defects to enhanced arrhythmia susceptibility in common, acquired, disease. For instance, action potential prolongation in congestive heart failure may be explained by increased persistent Na current. Of note, recent studies have also linked Na current reduction to structural cardiac defects, notably cardiac fibrosis, dilated cardiomyopathy and, possibly, arrhythmogenic right ventricular cardiomyopathy. These structural changes may also be conducive to (reentrant) arrhythmias. Clearly, these observations highlight the cardiac Na channel as an interesting target for novel therapy strategies.     

Clinical features and prognosis of patients with out of hospital cardiac arrest and a normal electrophysiologic study

Nineteen patients survived a cardiac arrest not associated with an acute myocardial infarction, and had a normal electrophysiologic study with no inducible ventricular tachycardia despite programmed stimulation with one to three extrastimuli at two or more ventricular sites. Among 14 patients who had obstructive coronary artery disease, cardiac arrest occurred during exertion or an episode of angina pectoris in 11; 24 hour ambulatory electrocardiographic recordings demonstrated infrequent or no premature ventricular complexes in 10 and an ischemic response occurred during stage I or II (Bruce protocol) in 6 of 9 patients who underwent exercise testing. Treatment of these patients consisted of myocardial revascularization (eight patients) or antianginal medications (six patients). Only three patients were also treated with an antiarrhythmic drug. Over a follow-up period of 26 +/- 15 months (mean +/- standard deviation), only one patient died suddenly. Two patients who had coronary artery spasm were treated with coronary vasodilator medications and had no recurrence of cardiac arrest over 7 and 36 months of follow-up, respectively. Three patients who had cardiomyopathy or no identifiable structural heart disease were treated with nadolol or amiodarone and had no recurrence of cardiac arrest over 3 to 27 months of follow-up. Among patients who survive a cardiac arrest and have a normal electrophysiologic study, those with obstructive coronary artery disease or coronary artery spasm generally have an excellent prognosis with treatment directed primarily at the underlying heart disease. The clinical features of these patients suggest that cardiac arrest was related to ischemia rather than a primary arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetics and arrhythmias: diagnostic and prognostic applications

This review article discusses the genetic bases of cardiac arrest with a specific focus on cardiac channelopathies and right ventricular cardiomyopathy. We review the appropriate use of genetic testing in those patients suspected to have inherited cardiac arrhythmias, highlighting the importance of most genotype-phenotype correlations for risk stratification. The article also presents the most recent views on diagnostic criteria and flowcharts for treatment of patients with inherited arrhythmogenic diseases.     

Sudden death and ion channel disease: pathophysiology and implications for management

The underlying aetiology of sudden arrhythmic death syndrome is predominantly inherited cardiac disease, and 'channelopathies' (cardiac ion channel disease) are the most common detectable cause of death. This heterogeneous group includes Brugada syndrome, long QT syndrome and catecholaminergic polymorphic ventricular tachycardia. Common features include variable penetrance, sudden death due to ventricular arrhythmias, and the absence of structural heart disease. The understanding of cardiac ion channel disease has been revolutionised by genetics. At present, genotype contributes to risk stratification in Brugada syndrome, long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, and the future promises management tailored to the genetic diagnosis.     

Genomics and cardiac arrhythmias

Sudden cardiac death in patients younger than 35 years of age is primarily due to genetic causes. Familial hypertrophic cardiomyopathy accounting for 30% to 40% is associated with structural heart disease while the Brugada syndrome and the long QT syndrome (LQTS) are associated with normal cardiac function. This is a review of the genetics of supraventricular and ventricular arrhythmias. Atrial fibrillation is mapped to nine chromosomal loci and four genes are identified. AMP-activated protein kinase is one gene responsible for Wolff-Parkinson-White syndrome. The LQTS and the Brugada syndromes are due to defects primarily in cardiac sodium and potassium ion channels. The role of single nucleotide polymorphisms in predisposing to arrhythmias in acquired disorders such as hypertrophy is discussed.     

Genomics and cardiac arrhythmias.

Sudden cardiac death in patients younger than 35 years of age is primarily due to genetic causes. Familial hypertrophic cardiomyopathy accounting for 30% to 40% is associated with structural heart disease while the Brugada syndrome and the long QT syndrome (LQTS) are associated with normal cardiac function. This is a review of the genetics of supraventricular and ventricular arrhythmias. Atrial fibrillation is mapped to nine chromosomal loci and four genes are identified. AMP-activated protein kinase is one gene responsible for Wolff-Parkinson-White syndrome. The LQTS and the Brugada syndromes are due to defects primarily in cardiac sodium and potassium ion channels. The role of single nucleotide polymorphisms in predisposing to arrhythmias in acquired disorders such as hypertrophy is discussed.     

Current management of syncope: Treatment alternatives

Opinion statement Syncope, defined as a transient loss of consciousness and postural tone with spontaneous recovery and no neurologic sequelae, is among one of the most common causes of consultation with a physician. The diagnostic workup is complex but can be simplified if focused on the underlying condition. Prognosis is highly dependent on the presence or absence of structural heart disease, primarily the presence of cardiomyopathy regardless of etiology, particularly if the left ventricular (LV) function is less than 35%. The diagnostic approach to the patient with recurrent syncope and no structural heart disease is targeted to rule out neurally mediated causes. This approach usually includes a tilt table test (ie, head-up tilt), carotid sinus massage in patients older than 55 years, and an adenosine challenge test in patients who remain with unexplained syncope. Unexplained syncope in patients with reduced LV function (< 35%) may be potentially life-threatening. Infrequent causes of syncope should be sought in younger patients with a family history of sudden cardiac death. Channelopathies such as the long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia are among this variety. Therapy should address the potential mechanism of syncope. In neurally mediated causes, restoration of orthostatic tolerance, primarily by increasing volume during orthostatic stress, is recommended. Physiologic countermaneuvers and increase in salt and water intake are usually the initial therapy. With syncope in patients with an LV dysfunction (< 35%), an ICD is frequently recommended after ruling out common causes of syncope. Syncope in the elderly is usually multifactorial and therapy should include reassessment of multiple medications, which can promote neurally mediated syncope as well as searching for bradycardic causes. Empiric pacing may be used in this complex group of patients.