心动过速性心肌病的研究进展

心动过速性心肌病是一种可逆的扩张型心肌病,室性或室上性心动过速均可诱发,相关心动过速被终止后,患者心功能多可恢复正常。近几年随着导管消融技术的发展,大部分快速性心律失常可以得到根治,因此,明确诊断心动过速性心肌病更加重要。现虽然有很多文献报道心动过速性心肌病,我们对此病的认识仍很肤浅,仍有很多问题有待解决。本文就心动过速性心肌病相关研究已取得的进展及仍需解决的问题进行概述。     

The response of patients with complex ventricular arrhythmias secondary to dilated cardiomyopathy to programmed electrical stimulation

A prospective study was undertaken to assess the response of patients with idiopathic dilated cardiomyopathy to programmed electrical stimulation (PES). Fifteen patients undergoing evaluation of congestive heart failure were studied. All patients underwent cardiac catheterization and coronary angiography as well as endomyocardial biopsy to exclude known causes of heart fallure. No patient had a history of syncope or sustained ventricular arrhythmias. All patients were found to have severe left ventricular dysfunction (mean ejection fraction 17%), as well as nonsustained ventricular tachycardia on ambulatory monitoring or exercise testing. A protocol using up to two premature stimuli and burst pacing, from two right ventricular sites, induced up to four repetitive ventricular responses but failed to induce a sustained ventricular arrhythmia in any patient. Patients with dilated cardiomyopathy, advanced ventricular arrhythmias, and depressed left ventricular function respond differently than do patients with coronary artery disease, advanced ventricular arrhythmias, and depressed left ventricular function, to PES. PES appears to have limited value in the evaluation of patients with dilated cardiomyopathy and nonsustained ventricular arrhythmias.     

牛磺酸镁对抗哇巴因诱发心律失常的实验研究

目的　观察新型配合物牛磺酸镁 (TMC)的整体抗心律失常作用。方法　对豚鼠颈静脉分别缓慢推注剂量为10 m g· kg- 1 、2 0 mg· kg- 1 和 4 0 mg· kg- 1 的 TMC,5 min后以 7.5 μg· 0 .2 5 ml· m in- 1 速度持续滴注 0 .0 0 3%哇巴因 ,观察不同剂量 TMC对哇巴因诱发的室性早博、室性心动过速、心室颤动和死亡时间以及相应的哇巴因累积用量的影响 ,并与 3mg· kg- 1 利多卡因进行比较。结果　 TMC 2 0 mg· kg- 1 可减慢正常豚鼠心率 ,其作用与 3m g·kg- 1 利多卡因相当。 2 0 m g· kg- 1 、4 0 mg· kg- 1 的 TMC和 3mg· kg- 1 利多卡因可推迟哇巴因诱发的豚鼠室性心律失常的发生时间和延长哇巴因致死时间 ,哇巴因累积用量增加 ,以 2 0 mg· kg- 1 组作用最为显著。结论　 TMC具有防治哇巴因诱发心律失常的作用。     

Arrhythmias in Patients with Heart Failure

Opinion statement Both atrial and ventricular arrhythmias are very common in patients with congestive heart failure, and their presence is associated with symptoms, significant morbidity, and mortality. Studies have attempted to determine the prognostic significance of atrial and ventricular arrhythmias in patients with heart failure. Whether atrial fibrillation is an independent risk factor of mortality remains controversial. The presence of ventricular arrhythmias in patients with ischemic cardiomyopathy identifies patients at high risk for sudden death. However, in patients with nonischemic cardiomyopathy there is not a strong correlation between ventricular arrhythmias and increased risk for sudden death. Multiple trials using antiarrhythmic drugs, pharmacologic therapy, and implantable cardioverter defibrillators have been performed in an attempt to improve survival in patients 1) post-myocardial infarction; 2) with congestive heart failure, with and without nonsustained ventricular tachycardia; and 3) with sustained ventricular tachycardia and those who have survived an out-of-hospital cardiac arrest. The purpose of this article is to present an overview of arrhythmias in patients with heart failure and discuss the prevalence, prognostic significance, complications, mechanisms, and trials that have formed the current therapies presently used.     

Genesis of arrhythmias in the failing heart and therapeutic implications

Between 50 and 70% of patients with heart failure die suddenly and unexpectedly before they have deteriorated to New York Heart Association class IV symptoms. It has long been known that ventricular ectopy predicts sudden cardiac death in coronary heart disease, and this has also been shown in dilated cardiomyopathy. It is less certain whether antiarrhythmic drugs reduce this risk and improve prognosis. Supraventricular arrhythmias frequently develop in heart failure of all causes. They nearly always cause symptoms, and the establishment of atrial fibrillation may mark a permanent deterioration. Except for sustained ventricular tachycardia, ventricular arrhythmias are often occult. Hypokalemia and digitalis toxicity may have been precipitated by diuretics or interaction with antiarrhythmic drugs. In coronary heart failure, arrhythmias may be related to scar tissue or ischemia, which may also be responsible in dilated cardiomyopathy. Use of inotropes and inodilators may precipitate arrhythmias, whereas drugs that conserve energy or potassium, such as beta blockers and angiotensin-converting enzyme inhibitors, may prevent them. Since suppression of ventricular arrhythmias has not been shown to prevent sudden death or prolong life in patients with heart failure, it may be that such arrhythmias do not directly presage ventricular fibrillation except in so far as they are markers of a poor prognosis with a risk of sudden death. If so, such arrhythmias are most likely to be suppressed by agents that result in improvement of left ventricular function and, through that, prolongation of life.     

Sudden cardiac death in patients with nonischemic cardiomyopathy

Sudden cardiac death (SCD) is an important cause of mortality worldwide. Although SCD is most often associated with coronary heart disease, the risk of SCD in patients without ischemic heart disease is well-established. Nonischemic cardiomyopathies, including idiopathic dilated cardiomyopathy, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy represent three unique disease entities that have been shown to be highly associated with SCD and ventricular arrhythmias. A variety of risk stratification tools have been investigated, although the optimal strategy remains unknown. Identification of the arrhythmogenic substrate and treatment of ventricular arrhythmias in these subgroups can be challenging. Herein, we aim to discuss the current understanding of the anatomic and electrophysiologic substrate underlying ventricular arrhythmias and highlight features that may be associated with a higher risk of SCD in these 3 conditions.     

Ambulatory ECG in cardiomyopathies

DILATED CARDIOMYOPATHY - Conduction and rhythm disturbances are frequent findings in dilated cardiomyopathy. 65 patients with dilated cardiomyopathy underwent 24-hour electrocardiographic monitoring: 95.4% showed ventricular arrhythmias, 80% complex ventricular arrhythmias and 44% runs of non-sustained ventricular tachycardia. Over 1000 ventricular extrasystoles in 24 hours were present in 44% of cases. Ventricular tachycardia and multiform and paired ventricular extrasystoles correlated significantly with the severity of cardiac dysfunction and with a worse prognosis. Patients undergoing antiarrhythmic therapy (amiodarone) showed a significant reduction in the number of ventricular extrasystoles and in the incidence of complex ventricular arrhythmias. HYPERTROPHIC CARDIOMYOPATHY - The high incidence of arrhythmias, particularly ventricular arrhythmias (approx. 70% of cases) in hypertrophic cardiomyopathy is well recognized: episodes of ventricular tachycardia are present in 20% of cases and are related to an elevated risk of sudden death. Antiarrhythmic treatment with amiodarone significantly reduces the number of ventricular extrasystoles and the episodes of ventricular tachycardia, may prevent sudden death and improve survival. RESTRICTIVE CARDIOMYOPATHY - Very little information is present in literature concerning this extremely rare form, in which every type of rhythm and conduction disturbance has been observed. CONCLUSIONS - Electrocardiographic monitoring is nowadays a very important tool in the management of cardiomyopathy patients, to identify possible patients at risk and to monitor the antiarrhythmic treatment.     

Ventricular tachycardia and sudden death in myotonic dystrophy: clinical, electrophysiologic and pathologic features

A 37 year old man who presented with a cardiomyopathy, conduction defects and atrial and ventricular arrhythmias was found to have the neuromuscular manifestations of myotonic dystrophy. Despite implantation of a permanent cardiac pacemaker, antiarrhythmic drug therapy and antiarrhythmic surgery, sudden death occurred. The results of electrophysiologic studies, coronary arteriography and pathologic findings are described. This case confirms previous observations that ventricular arrhythmias, in addition to atrial arrhythmias and conduction disturbances, are cardiac manifestations of myotonic dystrophy and can lead to sudden death.     

Sudden death related cardiomyopathies – Arrhythmogenic right ventricular cardiomyopathy,arrhythmogenic cardiomyopathy,and exercise-induced cardiomyopathy

Sudden cardiac death (SCD) is a devastating possible outcome of all cardiomyopathies. The risk of SCD is increased in patients with structural heart disease and continues to increase as ventricular dysfunction worsens. There is, however, a subset of cardiomyopathy, so-called “arrhythmogenic cardiomyopathy” (ACM), that carries an inherent propensity for arrhythmia in all stages of the disease, even preceding ventricular dysfunction. The aim of this review is to identify cardiomyopathies, other than ischemic and dilated cardiomyopathies, that are associated with ventricular arrhythmias (VAs) and SCD. We discuss prevalence, diagnosis, natural history and management of arrhythmogenic right ventricular dysplasia/cardiomyopathy, ACM, and exercise-induced cardiomyopathy, with emphasis on the morbidity and mortality of VAs associated with these cardiomyopathies and how they can be mitigated through lifestyle modification, medical management, and implantation of cardioverter defibrillators.     

室性期前收缩对无器质性心脏病患者心功能的影响

室性期前收缩是最常见的室性心律失常,不伴有器质性心脏病的室性期前收缩,通常被认为是良性的,但近10年的研究发现,频发室性期前收缩在某些条件下可导致左室重构,甚至诱发心力衰竭症状.这些条件包括患者年龄、病程长短、室性期前收缩负荷及室性期前收缩的起源部位和室性期前收缩QRS波的宽度.诱发心力衰竭的机制可能与室性期前收缩时左右心室失同步、心肌细胞能量储备耗竭、心内膜下至心外膜下血流比失调导致心肌缺血、钙平衡失调、氧自由基损伤,以及β受体密度下调、反应性下降等多种病理生理因素有关.近来有学者提出“室性期前收缩诱发的心肌病”的概念,和心动过速性心肌病一样,也可能成为一种独立的未分类心肌病.     

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.     

Arrhythmogenic right ventricular cardiomyopathy

Arrythmogenic right ventricular (RV) cardiomyopathy (ARVC) is a cardiomyopathy characterized pathologically by fibrofatty replacement primarily of the RV and clinically by life-threatening ventricular arrhythmias in apparently healthy young people. The prevalence of the disease has been estimated at 1 in 5,000 individuals, although this estimate will likely increase as awareness of the condition increases among physicians. Arrythmogenic RV cardiomyopathy is recognized as a cause of sudden death during athletic activity because of its association with ventricular arrhythmias that are provoked by exercise-induced catecholamine discharge. Diagnosis may be difficult because many of the electrocardiographic abnormalities mimic patterns seen in normal children, and the disease often involves only patchy areas of the RV. For this reason, international diagnostic criteria for ARVC were proposed by an expert consensus panel in 1996. Treatment is directed to preventing life-threatening cardiac arrhythmias with medications and the use of implantable defibrillators. This article will present in detail the etiology, clinical presentation, diagnosis and management of this condition.     

Isolated noncompaction cardiomyopathy presenting with paroxysmal supraventricular tachycardia--case report and literature review

Isolated noncompaction cardiomyopathy is an exceedingly rare congenital cardiomyopathy. A case of isolated noncompaction cardiomyopathy is reported and the literature on the subject collected through a comprehensive literature search is reviewed. Fewer than 100 cases of this condition have been reported. Isolated noncompaction cardiomyopathy is caused by a defect in cardiac morphogenesis resulting in an arrest of compaction of loose interwoven meshwork of myocardial fibers during intrauterine life, which results in severe systolic dysfunction as well as undue hypertrophy of the involved walls of the ventricles. Although the most frequent sites involved are left ventricular apex and inferior wall, involvement of other left ventricular walls and right ventricle has also been reported. Etiology of the isolated noncompaction of myocardium is not clear. Familial cases have been reported and the mode of inheritance is heterogeneous. In X-linked form of the disease, a locus has been found on Xq28, and mutations have been reported in G4.5 gene. The age of onset of symptoms ranges from infancy to the geriatric age. Patients with isolated noncompaction cardiomyopathy have a high incidence of heart failure, arrhythmias, and thromboembolism. The most common presentation is congestive heart failure. Arrhythmias include atrial arrhythmias, ventricular tachycardia, and sudden cardiac death. The patient reported in this article presented with paroxysmal supraventricular tachycardia. Echocardiography is the procedure of choice to establish diagnosis. Due to the lack of associated cardiac anomalies, antenatal detection is difficult. The treatment is that for congestive heart failure, arrhythmias, and thromboembolism. The end-stage congestive heart failure is managed with heart transplantation and potential life-threatening ventricular tachyarrhythmias with an implantable cardioverter defibrillator. Prognosis is poor and the common causes of death are intractable heart failure and sudden cardiac death.     

Arrhythmias in tako-tsubo syndrome—Benign or malignant?

Tako-tsubo syndrome appears to be an apparently reversible form of the cardiomyopathy, but little is known about the long term risk even with normalization of ventricular function. The incidence of ventricular arrhythmias after resolution of cardiomyopathy is not known. We present a unique case of tako-tsubo syndrome in a 71-year-old woman who developed symptomatic ventricular arrhythmias after complete resolution of cardiomyopathy.     

Management of arrhythmias in heart failure

The literature for coronary artery disease as well as ischemic and dilated cardiomyopathy suggests that ventricular arrhythmias and left ventricular dysfunction are independent risk factors for sudden death, but that the presence of organic heart disease provides the substrate for potentially lethal arrhythmias. Patients with a cardiomyopathy and ventricular tachycardia are at a high risk for sudden death as a group. The general risk, then, is high for the group with CHF and arrhythmias. The prognostic indices for hypertrophic cardiomyopathy are imprecise, but the risk for sudden death for the group is high in the young and remains high even among the adult survivors. Many conditions associated with CHF and its treatment may lead to arrhythmias and are potentially reversible. Most studies suggest that EPS and exercise provocation have limited power in predicting the risk to the individual patient. Therapeutically, reversible causes of arrhythmias should be sought and corrected. In general, antiarrhythmic drug therapy has been disappointing with adequate control being achieved in only about 30 per cent of patients and uncertainties about the effectiveness of such therapy in altering long-term prognosis. This is due to various causes including the inability to find an effective drug, problems with patient compliance, the failure of physicians to properly monitor drug levels, and changes in the anatomical and physiologic substrate due to disease and therapy. Surgical ablation or resection of arrhythmogenic foci is effective in selected patients. The AICD will become first-line therapy in patients at high risk for sudden death due to ventricular arrhythmias, with antiarrhythmic drugs and other approaches being used to minimize the frequency of the arrhythmias.     

Dilated cardiomyopathy: functional status, hemodynamics, arrhythmias, and prognosis

The natural history of dilated cardiomyopathy is variable, and the prognosis difficult to predict. Several clinical and hemodynamic parameters have been proposed as prognostic indicators. Reports on the relationship between ventricular arrhythmias, degree of hemodynamic impairment, and sudden death are controversial. To define accurately the prognosis in dilated cardiomyopathy, 55 patients with this clinical syndrome underwent clinical evaluation, radionuclide ventriculography, echocardiography, 12-lead electrocardiography, and 24 hr ambulatory monitoring, and the data thus obtained were evaluated based on predictive value. Over a follow-up period of 14.1 +/- 7.9 months, 11 patients (20%) died, all suddenly. Univariate analysis revealed that patients with more severe functional impairment (P = 0.0449), lower cardiac index (P = 0.0226), lower ejection fraction (P = 0.0426), and higher pulmonary artery wedge pressure (P = 0.0314) had greater mortality risk. Age, duration of symptoms, 12-lead electrocardiographic abnormalities, and atrial arrhythmias were not predictive of higher mortality. The number of PVCs per hr, the occurrence of couplets, the degree of PVCs prematurity, and the presence, frequency, rate, and duration of ventricular tachycardia did not have prognostic significance. A stepwise discriminant analysis identified functional class, cardiac index, and presence or absence of multiform PVCs as the group of variables that together could more accurately predict outcome in our dilated cardiomyopathy patients. Using a formula derived from the results of this analysis, the outcomes of 36 of 49 patients (74%) was correctly predicted, with a specificity of 100% and a sensitivity of 70%.     

Peculiaridade dos Pacientes com Arritmias Hereditárias na Pandemia pela COVID-19

Since December 2019 we have observed the rapid advance of the severe acute respiratory syndrome caused by the new coronavirus (SARS-CoV-2). The impact of the clinical course of a respiratory infection is little known in patients with hereditary arrhythmias, due to the low prevalence of these diseases. Patients who present with infectious conditions may exacerbate hidden or well-controlled primary arrhythmias, due to several factors, such as fever, electrolyte disturbances, drug interactions, adrenergic stress and, eventually, the septic patient’s own myocardial damage. The aim of this review is to highlight the main challenges we may encounter during the Covid 19 pandemic, specifically in patients with hereditary arrhythmias, with emphasis on the congenital long QT syndrome (LQTS), Brugada syndrome (SBr), ventricular tachycardia polymorphic catecholaminergic (CPVT) and arrhythmogenic right ventricular cardiomyopathy.     

Difficult cases in heart failure: Left ventricular assist device implantation for the treatment of recurrent ventricular tachycardia in end stage heart failure

The authors describe the surgical implantation of a left ventricular assist device (LVAD) in a patient with ischemic cardiomyopathy and recurring episodes of ventricular tachycardia with associated sudden death, as a therapeutic intervention for the recurrent ventricular arrhythmias. The clinical inference of this report demonstrates that these devices are useful as a bridge to heart transplantation, not only improving the symptoms of heart failure but also suppressing malignant ventricular arrhythmias. (c) 1999 by CHF, Inc.     

Heart rate variability and chemoreflex sensitivity. Proved and new methods in risk prediction of malignant arrhythmias

For the analysis of a disturbed autonomic function as a risk predictor for ventricular tachyarrhythmias, tonic and phasic procedures are available. The heart rate variability as a tonic procedure shows significant differences between patients with an increased risk of malignant arrhythmias and patients without increased risk. This can be demonstrated in patients with survived myocardial infarction, dilated cardiomyopathy and congestive heart failure. But the positive predictive value amounts only to about 50%. The chemoreflex sensitivity as a new phasic method represents a new possibility for the evaluation of a dysfunction of autonomic reflex arches. It is reduced due to a decreased left ventricular function and increasing age. Furthermore, it shows significant differences between patients with ventricular arrhythmias and patients without. The predictive accuracy concerning malignant ventricular arrhythmias in a population of 60 patients in the chronic postinfarction stadium amounts to 55%, the relative risk to 7.6. Thus, this method shows a high predictive power, but more investigations in larger patient cohorts are necessary to corroborate these results.     

Endocardial catheter mapping in patients in sinus rhythm: relationship to underlying heart disease and ventricular arrhythmias

Catheter mapping during sinus rhythm was performed in 132 patients with coronary artery disease and 26 patients with congestive noncoronary cardiomyopathy. Each of the patients had a clinical history of one of the following: no ventricular arrhythmia, nonsustained ventricular tachycardia, cardiac arrest, or sustained ventricular tachycardia. The characteristics of the endocardial electrogram and other measured indexes of slow endocardial conduction were compared between patients with different types of disease and in different arrhythmia groups to determine if differences existed. The cardiomyopathic group had a higher percent of normal endocardial electrograms than the coronary artery disease group, with no evidence of slow endocardial conduction. The sustained ventricular tachycardia group exhibited a greater percent of abnormal endocardial electrograms and more evidence of slow endocardial conduction, distinguishing this group from the three other arrhythmia groups. We conclude the following: The underlying electrophysiologic substrate varies in patients with different ventricular arrhythmias. It is therefore inappropriate to analyze all patients with ventricular arrhythmias as a single group. Patients with congestive noncoronary cardiomyopathy, regardless of the type of their arrhythmia, have a relatively normal endocardium. Those patients with serious ventricular arrhythmias should not be considered candidates for surgery directed at removing abnormal endocardium.