心脏再同步治疗:双心室起搏还是希氏-浦肯野系统起搏?

希氏-浦肯野系统(希浦系统)起搏是近年出现的除传统双心室同步起搏外同样能达到心脏再同步治疗(CRT)的新方法。本文阐述了2种方法达到CRT的途径、机制、临床证据及各自的利弊,并对现阶段CRT方式的选择提出了建议。     

Cardiac resynchronization therapy for heart failure: biventricular pacing and beyond

In the early 1990s, attempts at treating patients with dilated cardiomyopathy and end-stage heart failure by using right-sided, dual-chamber pacing met with equivocal results. Although initially discouraging, this work did provide further insight into the electromechanical consequences of advanced heart failure and suggested that atrial-synchronized biventricular pacing, or cardiac resynchronization therapy, might provide better and more consistent symptomatic and hemodynamic improvement. Several studies have recently validated the safety and efficacy of cardiac resynchronization therapy in advanced heart failure. Data from these studies have shown statistically significant improvements in left ventricular ejection fraction, New York Heart Association class, exercise tolerance, and quality of life. Observed reductions in morbidity and mortality await confirmation from ongoing large-scale outcomes studies. This article reviews the evolution of pacing in heart failure and discusses the underlying mechanisms that are potentially responsible for the improvement seen in patients receiving cardiac resynchronization therapy. In addition, the results of recently completed clinical trials, as well as the status of ongoing clinical trials, are reviewed.     

对心脏再同步治疗的思考

国际上自90年代开展起搏治疗技术以来,心脏再同步治疗（cardiacresynchronization thera-py,CRT）以其卓越的疗效逐渐成为治疗心力衰竭的最有效方法之一。我国自引进CRT技术10余年来,确实在慢性充血性心力衰竭的治疗方面,迈上一个新的台阶。随着CRT被我国医生逐步认知、被患者接受,从而其置入例数在中国几何级数地增长后,CRT的疗效也逐步显现。     

Cardiac resynchronization therapy

Despite advances in medical therapy for patients with congestive heart failure, morbidity and mortality remain high. Conventional atrioventricular pacing with a short atrioventricular delay was first introduced as a non-pharmacologic treatment for patients with severe heart failure. Further development of this new therapeutic approach led to biventricular pacing, also known as cardiac resynchronization therapy. Many studies have been published and many are still ongoing. This review summarizes the results reported in randomized trials and focuses on questions that have not yet been answered.     

Cardiac resynchronization therapy

Left ventricular (LV) dysynchrony, generally defined as the effect of intraventricular conduction defects or bundle branch block to produce nonsynchronous ventricular activation, places the failing heart at a further mechanical disadvantage. The deleterious effects of ventricular dysynchrony include suboptimal ventricular filling, paradoxical septal wall motion, reduced LV contractility, increased mitral regurgitation, and poor clinical outcomes (eg, increased hospitalization and mortality). The clinical and mechanical manifestations of ventricular dysynchrony can be treated by simultaneously pacing both the right and left ventricles usually in association with right atrial sensing, resulting in atrial-synchronized biventricular pacing or cardiac resynchronization therapy (CRT). The weight of evidence supporting the routine use of CRT in patients with heart failure with ventricular dysynchrony is now quite substantial. More than 4000 patients have been evaluated in randomized controlled trials of CRT, and several thousand additional patients have been assessed in observational studies and in registries. Data from these studies have consistently demonstrated the safety and efficacy of CRT in patients with New York Heart Association class III and IV heart failure. Cardiac resynchronization therapy has been shown to significantly improve LV structure and function, New York Heart Association functional class, exercise tolerance, quality of life, and morbidity and mortality.     

Cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) addresses abnormal left ventricular (LV) activation that produces detrimental effects on cardiac systolic and diastolic function. CRT improves symptoms and ventricular performance, promotes reverse remodeling, and decreases mortality and hospitalization in patients with congestive heart failure (CHF). Atrial-synchronized biventricular stimulation reverses many of the temporal delays in mechanical activation associated with LV dysfunction and conduction system disease. The therapy evolved from anecdotal application through surgical implantation of LV pacing leads to transvenous delivery of LV pacing leads for use with dedicated CRT devices. The controlled clinical trials included specific patient groups, and provided data leading to widely adopted indications for the therapy. Current indications exclude the use of CRT in patients with permanent atrial fibrillation, although small series suggest a benefit of the therapy in these patients. The role of cardiac imaging with echocardiography to detect cardiac dyssynchrony promises to improve patient selection by not only excluding likely nonresponders, but also extending the therapy to those with dyssynchrony in the absence of QRS prolongation. Expanded indications under evaluation include the role of CRT in patients with mildly symptomatic CHF, mild to moderate LV dysfunction, dyssynchrony in the absence of QRS prolongation, and dyssynchrony induced by right ventricular pacing.     

Cardiac resynchronization therapy

Opinion statement  It is now well established that electrical and mechanical dyssynchrony are not clinically synonymous; however, at present no individual noninvasive method can reliably and consistently identify the criteria for mechanical dysfunction correctable through device therapy. The results of the PROSPECT (Predictors of Response to CRT) trial not only highlight the complicated nature of this dilemma, but also emphasize the importance of broadening our approach to this topic. Not only do the capabilities of real-time three-dimensional echocardiography and cardiac magnetic resonance imaging need to be maximized, but the strengths and weaknesses of each modality need to be more selectively matched to the heterogeneity of this particular patient population and subsequently studied in a robust clinical fashion.     

Pediatric cardiac resynchronization pacing therapy

PURPOSE OF REVIEW: Advances in pacemaker lead designs, permitting precise lead implantation at sites other than the ventricular apex, have provoked interest in the utilization of ventricular pacing beyond maintenance of heart rate. Select older adult patients with various cardiomyopathies may improve clinically following alternative site, biventricular and cardiac resynchronization pacing. This report reviews recent applications and directions of these pacing technologies to younger patients with congenital heart defects. RECENT FINDINGS: Acutely, following congenital heart surgery or chronically, studies now indicate that select younger patients may demonstrate physiologic benefits from pacing preselected single ventricular or combined right and left ventricular sites. This may prevent eventual paced myocardial deterioration as well as support and even reverse existing myocardial dysfunction, deferring the need for heart transplantation. SUMMARY: There are limited worldwide pediatric experiences, and, to date, no randomized multicenter studies. It is becoming more evident, however, that as these pacing techniques are used in younger patients, clinical improvements, comparable to older adult patients, even delaying heart transplant, may be anticipated. Since these newer techniques are more complicated and costly than simple pacemaker implantation, future directions will be for multi-institutional pediatric studies with clear definition of which pre-implant variables will define physiologic improvement.     

Cardiac resynchronization therapy in China

Congestive heart failure (HF) is a major and growing public health problem. The therapeutic approach includes non-pharmacological measures, pharmacological therapy,mechanical devices, and surgery. Despite the benefits of optimal pharmacologic therapy, the prognosis is still not ideal. At this time, cardiac resynchronization therapy (CRT)has gained wide acceptance as an alternative treatment for HF patients with conduction delay.1……     

Cardiac resynchronization as therapy for congestive cardiac failure in children dependent on chronic cardiac pacing

Three patients with heart failure after chronic right ventricular apical pacing were treated with resynchronization. Biventricular pacing was used for two patients, and the other was treated with left univentricular pacing. In all patients, we observed a dramatic improvement of left ventricular dimension, function, and clinical state. We conclude that biventricular or left ventricular pacing is superior to right ventricular apical pacing in children who are pacemaker-dependent.     

Cardiac resynchronization therapy for heart failure

Opinion statement Cardiac resynchronization therapy has been established as important adjuvant therapy in the treatment of severe heart failure. As lead delivery systems have improved and the number of experienced implanters has increased, more patients have access to transvenous left ventricular lead implantation, outside of clinical trials at large medical centers. Ongoing research continues to perfect implantation techniques to optimize patient outcomes, as well as develop hardware and software technology used in implanted devices. Resynchronization therapy typically results in a decreased burden of emergency room visits and hospitalizations for decompensated heart failure. In addition, diagnostic tools available in resynchronization devices allow clinicians to not only predict heart failure decompensation and adjust medical therapies accordingly, but they also allow for the diagnosis of asymptomatic arrhythmias that may predict adverse outcomes, as well as allow for the diagnosis of symptomatic arrhythmias without the need for additional costly workup. This suggests that in the long term, biventricular device implantation may actually provide cost savings to the health care system. On a macroeconomic scale, there are significant concerns about the cost burden to society of increased implantation of resynchronization therapy devices, along the same lines as concerns raised regarding the expanding indications for implantable cardioverter-defibrillator implantation. As future research broadens indications for implanting implantable cardioverter-defibrillators, as well as resynchronization systems, we may see cardiac resynchronization therapy become a secondary prevention tool yielding long-term patient benefits by postponing or preventing a decline in heart failure status.