右室双部位起搏的临床应用

右室双部位起搏是一种阃接的双室起搏技术，操作简单，不增加安置术的风险，同时可以使心室再同步变为可能，增加心肌收缩力，改善心功能，具有较好的临床应用价值。     

The BRIGHT study: bifocal right ventricular resynchronization therapy: a randomized study.

AIMS: The BRIGHT study evaluated bifocal right ventricular (RV) (apex and outflow tract) pacing in a single, blind, randomized crossover study in patients eligible for cardiac resynchronization therapy (CRT). Forty-two patients were enrolled with the following characteristics: chronic drug refractory heart failure New York Heart Association (NYHA) class III-IV; ejection fraction (EF)<35%; QRS width >or= 120 ms; and a left bundle branch block. The aim of the study was to assess an improvement in left ventricular (LV) EF, 6 min walk test, Minnesota quality-of-life score, and NYHA classification. Methods and result Patients were randomized to receive either bifocal pacing or the control mode, each for a period of 3 months. Parameters were measured prior to randomization and after 3 months of control or bifocal pacing. Eight patients failed to make the 7 month follow-up, three patients died (one prior to randomization at the first month), five patients dropped out, and three patients refused further participation. One patient had a persistent lead problem, which was subsequently replaced with an LV lead, and one patient suffered with persistent atrial fibrillation. Compared with baseline, bifocal pacing improved EF from 26 +/- 12% to 36 +/- 11% (P < 0.0008), NYHA classification decreased from 2.8 +/- 0.4 to 2.3 +/- 0.7 (P < 0.007). Furthermore, the 6 min walk test improved from 372 +/- 129 m to 453 +/- 122 m (P < 0.05), and the Minnesota Living with Heart Failure scores decreased from 33 +/- 20 to 24 +/- 21 (P < 0.006). In the control group, no significant changes in any parameters were observed. Eight patients did not tolerate reprogramming from DDD BRIGHT to control pacing, with symptoms disappearing in all patients after reprogramming to bifocal pacing. CONCLUSION: Bifocal RV pacing in patients with a classic indication for CRT shows improvement in all parameters.     

心脏再同步化治疗的总结及分析

目的对心脏再同步化治疗(CRT)围手术期的处理进行探讨。方法对104例符合CRT植入指证的患者行CRT/心脏再同步化除颤器(CRTD)治疗和随访,并对围手术期的注意事项进行总结和分析。结果共成功植入CRT73例,CRTD28例。总手术成功率为97%(101/104),经心内膜成功率为93%(97/104),3例手术失败(2例术中发生急性肺水肿,1例术中发生心室颤动),另外4例因未找到冠状静脉窦开口或心脏静脉成角畸形明显或固定不可靠而分别改为右室双部位和心外膜电极。随访92%(93/101)有效,7例死亡,其中4例死于终末期心力衰竭,2例为心源性猝死,1例死于脑出血。结论 CRT手术安全、疗效可靠,应重视围手术期的管理。     

心脏再同步化治疗术中所遇问题及并发症的处理

目的介绍心脏再同步化治疗(CRT)手术中所遇的问题及并发症处理。方法回顾分析单中心CRT植入过程中所遇问题及并发症的发生与相应处理。结果共有4例患者出现问题或并发症,其中男3例、女1例。例1冠状静脉窦难以寻找,而改为右室双部位起搏;例2术中发生冠状静脉窦静脉夹层;例3术中突发急性左心衰竭,左室电极导线难以固定而留置经皮冠状动脉腔内成形术(PTCA)钢丝;例4左室电极导线置于心中静脉,在右房、右室电极植入时反复出现空气栓塞。结论 CRT术前应充分抗心力衰竭治疗,术中避免静脉夹层及空气栓塞,必要时右室双部位起搏,难以固定时留置PTCA钢丝于靶静脉内是可行的。     

Ventricular dyssynchrony in dilated cardiomyopathy: the role of biventricular pacing in the treatment of congestive heart failure

Despite advances in pharmacologic therapy, the prognosis of patients with advanced congestive heart failure (CHF) remains poor. Many of these patients have cardiac conduction abnormalities, such as left bundle-branch block or interventricular conduction delays, that can lead to ventricular dyssynchrony (abnormal ventricular activation that results in decreased ventricular filling and abnormal ventricular wall motion). Biventricular pacing is an alternative, nonpharmacologic therapy under active investigation for the treatment of CHF. Resynchronization devices with transvenous leads in the right atrium, right ventricle, and left ventricle (via the coronary sinus) have been implanted in patients to provide atrial triggered biventricular pacing. The use of such devices has been associated with improvement in ejection fraction, dP/dt, stroke work, and functional class. The proposed mechanisms involved in improving ventricular function with biventricular pacing include improved septal contribution to ventricular ejection, increased diastolic filling times, and reduced mitral regurgitation. This article reviews the pathophysiology of ventricular dyssynchrony and examine insights from clinical trials that are evaluating cardiac resynchronization therapy for CHF.     

Cardiac resynchronization: a novel therapy for heart failure

Despite advances in medical therapy for patients with congestive heart failure, morbidity and mortality remain high. Conduction abnormalities, such as left bundle branch block, right bundle branch block, and nonspecific conduction delay, are observed commonly in patients with dilated cardiomyopathy. In patients with heart failure, the presence of intraventricular conduction delay is associated with more severe mitral regurgitation and worsened left ventricular systolic and diastolic function, and is an independent risk factor for increased mortality. Conventional dual-chamber (right atrial and right ventricular) pacing with a short atrioventricular delay was initially introduced as therapy for patients with advanced congestive heart failure to improve diastolic dysfunction and reduce mitral regurgitation. The acute beneficial hemodynamic effects observed in early, uncontrolled studies were not confirmed in subsequent randomized, controlled studies with longer follow-up. Cardiac resynchronization with novel biventricular (left and right ventricular) pacing systems has resulted in hemodynamic and functional benefits in patients with congestive heart failure and an underlying intraventricular conduction delay. Improvements in cardiac index, systolic blood pressure, and functional class have been reported with biventricular pacing, both acutely and at more than 1 year of follow-up. These encouraging preliminary results with biventricular pacing in patients with congestive heart failure will be validated in two prospective, randomized, controlled trials, Multicenter InSync Randomized Clinical Evaluation (MIRACLE) and Comparison of Medical Therapy, Pacing, and Defibrillation in Chronic Heart Failure (COMPANION). These studies are designed to evaluate the long-term efficacy of biventricular pacing in improving exercise capacity and in reducing morbidity and mortality in patients with advanced, symptomatic congestive heart failure. (c)2001 by CHF, Inc.     

双心室起搏的初步临床经验

目的 探讨缺血性或扩张型心肌病合并充血性心力衰竭行永久性双心室起搏治疗的临床效果。方法 对５例缺血性或扩张型心肌病合并难治性心力衰竭和左束支阻滞患者常规植入右心室起搏导线的同时植入冠状静脉窦导线于心大静脉或心中静脉，分别行右心室心尖部起搏及双心室起搏，应用Ｓｗａｎ－Ｇａｎｚ导管或超声心动图测定不同起搏地心功能的影响。结果 在充血性心力衰竭合并左束支阻滞患者植入冠状静脉窦导经至心大静脉或心中静脉行以     

Cardiac resynchronization pacing therapy

Approximately one third of patients with congestive heart failure and systolic dysfunction have an intraventricular conduction delay that is manifested as a QRS duration >120 ms. An intraventricular conduction delay adversely affects ventricular performance by causing dyssynchrony in ventricular activation. When ventricular dyssynchrony is present, simultaneous left and right ventricular pacing or cardiac resynchronization therapy can improve ventricular synchrony. This can lead to an improvement in hemodynamics, ventricular remodeling, mitral regurgitation, exercise capacity and quality of life. Candidates for cardiac resynchronization therapy include patients with advanced congestive heart failure that is refractory to medical therapy, a QRS duration >130 ms, left ventricular ejection fraction <0.35 and sinus rhythm. Because patients who are candidates for biventricular pacing are at high risk of sudden death, they should be considered for implantation of a biventricular pacing device that also provides defibrillation therapy. This paper reviews biventricular pacing for congestive heart failure, including results of acute hemodynamic studies and randomized clinical trials, patient and device selection, and procedural issues.     

Biventricular pacing using two pacemakers and triggered VVT mode in patients with atrial fibrillation and congestive heart failure: a case report

A 76-year-old female had undergone implantation of a single chamber pacemaker for sick sinus syndrome 20 years previously. She developed chronic atrial fibrillation and required repeated admission due to congestive heart failure. She had significant mitral and tricuspid regurgitation. Paradoxical movement of the intraventricular septum was severe. Due to right ventricular apical pacing, significant interventricular conduction delay was present with a paced QRS duration of 189 msec. The left ventricular pacing lead was positioned via the coronary sinus. The mode of the previously implanted pacemaker was set at VVT. Biventricular pacing could be achieved even in intrinsic beats by VVT mode. The battery life time was improved. This method is useful in patients with conventional pacemakers.     

Effects of Multisite Ventricular Pacing on Cardiac Function in Normal Dogs and Dogs with Heart Failure

INTRODUCTION: We studied the effects on cardiac function of pacing two right and two left ventricular sites in normal and failing hearts with a normal QRS duration. METHODS AND RESULTS: Hemodynamic parameters were studied in isoflurane-anesthetized dogs with normal hearts and dogs with heart failure induced by rapid ventricular pacing. Unipolar intramyocardial electrodes were placed at the high right atrium and the apex (A) and base (B) of the left (L) and right (R) ventricles (V). Data were collected after pacing for 5 to 20 minutes. In normal dogs, without bundle branch block (BBB), pacing at either the apex or the base of the left ventricle increased cardiac output by approximately 10% compared with right ventricular apex (RVA) pacing with an AV delay of 0 msec. Positive dP/dt increased approximately 10% during four-site left and right ventricular apex and base (LRVAB) pacing compared with RVA pacing. In dogs with heart failure but without BBB, cardiac output increased by 8.5% (P < 0.01) during four-site ventricular pacing with AV delays of 0 and 60 msec compared with RVA pacing. Positive dp/dt increased by 23.5% (P < 0.001) with an AV delay of 0 msec and 9.6% (P < 0.001) with an AV delay of 60 msec during LRVAB pacing compared with RVA pacing. His-bundle pacing was associated with increased cardiac output compared with RVA pacing. CONCLUSIONS: We conclude that pacing simultaneously at two right and two left ventricular sites significantly improves cardiac function compared with single RVA pacing, with or without sequential AV synchrony, in dogs with rapid ventricular pacing-induced heart failure and no BBB.     

双心室起搏的临床疗效观察

目的　探讨缺血性或扩张型心肌病合并充血性心力衰竭行永久性双心室起搏治疗的临床效果。方法　对 1 0例缺血性或扩张型心肌病合并难治性心力衰竭和左束支阻滞患者 ,常规植入右心室起搏导线的同时植入冠状静脉窦电极导线于左室侧静脉、心大或心中静脉 ,行双心室同步起搏 (其中 2例为四腔起搏 )。通过临床观察、超声心动图测定及 6分钟平地行走评定对心功能的影响。结果　在充血性心力衰竭合并左束支阻滞患者植入冠状静脉窦电极导线行双心室起搏 ,产生较窄 QRS波 ,临床心功能从 ～ 级提高至 ～ 级 ( NYHA) ,同时使二尖瓣返流减少 ,射血分数提高 ,左室舒张末期内径缩小 ,6分钟平地行走距离比术前明显提高。结论　双心室起搏对难治性心力衰竭可能有辅助治疗作用。     

Pacemaker-induced mitral regurgitation as a cause of refractory congestive heart failure during pacing therapy in a patient with hypertrophic obstructive cardiomyopathy

This report describes a woman with hypertrophic obstructive cardiomyopathy in whom initial hemodynamic improvement by dual chamber (DDD) pacing with short atrioventricular delay was excellent, but severe mitral regurgitation developed during the subsequent follow-up period, resulting in refractory congestive heart failure. There were two possible explanations for the origin of the complicating mitral regurgitation in this patient: pacing-induced semiclosure of the mitral valve, or left ventricular asynchrony caused by right ventricular pacing. Heart failure in patients with hypertrophic obstructive cardiomyopathy who undergo placement of a DDD pacemaker to improve not only mitral regurgitation but also heart failure symptoms can be associated with systolic mitral regurgitation as the cause of failure in DDD pacing therapy.     

Focal origin of atrial tachycardia in dogs with rapid ventricular pacing-induced heart failure

Mapping and Ablation of Atrial Tachycardia in Heart Failure. INTRODUCTION: Dogs with rapid ventricular pacing-induced congestive heart failure (CHF) have inducible atrial tachycardia (AT), with a mechanism consistent with delayed afterdepolarization-mediated triggered activity. We assessed the hypothesis that AT has a focal origin. METHODS AND RESULTS: Twenty-one CHF dogs undergoing 3 to 4 weeks of ventricular pacing at 235 beats/min were studied. Biatrial epicardial mapping of 20 sustained AT episodes (cycle length [CL], 175 +/- 53 msec) in 5 dogs revealed an area of earliest activation in the right atrial (RA) free wall (13 episodes), RA appendage (4 episodes), or between the pulmonary veins (3 episodes). Total epicardial activation time during AT (73 +/- 19 msec) was similar to that during sinus rhythm (72 +/- 13 msec) and on average was <50% of the AT CL. Higher-density mapping of the RA free wall during 30 sustained AT episodes (163 +/- 55 msec) in 9 dogs identified a site of earliest activation along the sulcus terminalis most frequently as a stable, focal activation pattern from a single site. Endocardial mapping of 49 sustained AT episodes (156 +/- 27 msec) in 10 dogs revealed multiple sites of AT origin arising along the crista terminalis and pulmonary veins. Right and left ATs were terminated with discrete radiofrequency ablation, but other ATs remained inducible. A rapid, left AT generating an ECG pattern of atrial fibrillation was ablated inside the pulmonary vein. CONCLUSION: AT induced in this CHF model after 3 to 4 weeks of rapid ventricular pacing has an activation pattern consistent with a focal origin. Sites of earliest activation are distributed predominately along the crista terminalis and within or near the pulmonary veins.     

Cardiac resynchronization therapy: from creation to evolution--an evidence-based review

In the past decade, cardiac resynchronization therapy (CRT), achieved by simultaneous left and right ventricular pacing, has emerged as a potent therapeutic option for patients with congestive heart failure. Electrical dyssynchrony, most often manifested by left bundle branch block on the surface 12-lead electrocardiogram, results in mechanical dyssynchrony of the left ventricular septum and free wall, which decreases cardiac efficiency. In patients with ejection fractions <30%, New York Heart Association (NYHA) class III or IV, and QRS width >120 ms, CRT improves clinical parameters such as 6-minute walk distances, quality-of-life scores, and NYHA functional class. Long-term reverse remodeling of the failing ventricle results in reductions in congestive heart failure hospitalizations and mortality independent of defibrillator therapy. While most patients show significant improvement, a small proportion fail to respond. Appropriately identifying patients who will benefit most from CRT and timing the initiation of resynchronization therapy remain areas of intense investigation.     

Biventricular pacing as a treatment for advanced heart failure. Preliminary experience in a series of 22 consecutive patients

BACKGROUND AND OBJECTIVES: Recent data suggest that biventricular pacing may play an important role in treating advanced heart failure in the presence of a significant interventricular and/or intraventricular conduction disorder by correcting cardiac dysynchrony. In this article, we review the initial technical and clinical experience with cardiac resynchronization therapy in an electrophysiology laboratory. METHODS: The first 22 consecutive patients with severe congestive heart failure, ejection fraction < 0.35, NYHA functional class III or IV, and QRS duration > 120 ms who were implanted biventricular pacemakers were studied. Clinical, electrocardiographic, and echocardiographic evaluations were made before and three months after pacemaker implantation. Acute functional capacity testing with peak oxygen uptake was measured during biventricular pacing and during intrinsic rhythm or right ventricular pacing three months after the implantation procedure. RESULTS: The success rate of pacemaker implantation was 95%. Pre-discharge left ventricular pacing was achieved in 91%, with an average pacing threshold of 1.53 (1.04) volts. NYHA functional class improved (p = 0.039) from 3.4 (0.7) to 2.3 (0.78). The rate of hospitalization for heart failure decreased from an average of 3.12 (0.58) three months before the procedure to 1.38 (0.34) three months after the procedure. Peak oxygen uptake was significantly greater (p = 0.028) during biventricular pacing: 14.89 (2.1) ml/min/kg, than during intrinsic rhythm or right ventricular pacing: 12.65 (2.3) ml/min/kg. CONCLUSIONS: Cardiac resynchronization therapy can be performed safely and with a high success rate in the electrophysiology laboratory. Biventricular pacing seems to improve the symptoms of congestive heart failure in patients with evidence of atrioventricular and/or interventricular/intraventricular dysynchrony. An acute benefit in peak oxygen uptake was associated with biventricular pacing after the implantation procedure.     

Potential proarrhythmic effects of biventricular pacing.

Resynchronization therapy involving right ventricular endocardial and left ventricular epicardial pacing improves cardiac output, quality of life, and New York Heart Association functional class in patients with congestive heart failure. Although a great deal of attention has been directed at showing the mechanical benefits and in fine-tuning the biventricular pacing configuration and protocol, little attention has been focused on the consequences of reversing the direction of activation of the left ventricular wall. Recent basic science and clinical studies have shown a proarrhythmic effect of reversing the direction of activation of the left ventricular wall. Reversal of the normal activation sequence prolongs the QT interval and increases the existing transmural dispersion of repolarization, creating the substrate and trigger for re-entrant arrhythmias under long QT conditions. A number of case reports of R-on-T extrasystoles and ventricular tachyarrhythmia induction as a result of biventricular pacing support this observation, and raise concern that biventricular pacing may be proarrhythmic in select cases, particularly when associated with a prolonged QT interval. Our focus in this review is on current understanding of transmural heterogeneity of repolarization that exists across the left ventricular wall, how this dispersion of repolarization is amplified as a consequence of reversal of the normal activation sequence, and how these basic experimental findings may apply to patients receiving cardiac resynchronization therapy.     

Potential proarrhythmic effects of biventricular pacing

Resynchronization therapy involving right ventricular endocardial and left ventricular epicardial pacing improves cardiac output, quality of life, and New York Heart Association functional class in patients with congestive heart failure. Although a great deal of attention has been directed at showing the mechanical benefits and in fine-tuning the biventricular pacing configuration and protocol, little attention has been focused on the consequences of reversing the direction of activation of the left ventricular wall. Recent basic science and clinical studies have shown a proarrhythmic effect of reversing the direction of activation of the left ventricular wall. Reversal of the normal activation sequence prolongs the QT interval and increases the existing transmural dispersion of repolarization, creating the substrate and trigger for re-entrant arrhythmias under long QT conditions. A number of case reports of R-on-T extrasystoles and ventricular tachyarrhythmia induction as a result of biventricular pacing support this observation, and raise concern that biventricular pacing may be proarrhythmic in select cases, particularly when associated with a prolonged QT interval. Our focus in this review is on current understanding of transmural heterogeneity of repolarization that exists across the left ventricular wall, how this dispersion of repolarization is amplified as a consequence of reversal of the normal activation sequence, and how these basic experimental findings may apply to patients receiving cardiac resynchronization therapy.     

Cardiac resynchronisation therapy versus dual site right ventricular pacing in a patient with permanent pacemaker and congestive heart failure.

A 46-year-old male patient who had long-term right ventricular (RV) pacing for symptomatic complete heart block, initially by an epicardial, later with an endocardial pacing lead at the RV apex, developed congestive heart failure (CHF) and chronic atrial fibrillation 7 years following the pacemaker implantation and was medically treated. During follow-up, his pacemaker was upgraded to a cardiac resynchronisation therapy (CRT) device, because of uncontrolled CHF symptoms, New York Heart Association (NYHA) functional class IV, while on drugs. The patient's symptomatic status improved to NYHA functional class II with CRT. After 17 months of CRT, the battery became depleted, because of the high capture threshold of the left ventricular lead. The patient was then given dual site RV pacing (RV outflow tract+RV apex) in place of CRT, which showed similar efficacy at 12 weeks follow-up.     

Coronary venoplasty during the implantation of the cardiac resynchronisation device--a case report

We describe a case of a 76-year-old patient with advanced block in the His-Purkjnie system, who underwent implantation of a cardioverter-defibrillator with cardiac resynchronisation therapy. Complete heart block occurred during the insertion of the coronary sinus cathether. The implantation of the left ventricular (LV) lead was impossible due to difficult anatomy of the coronary venous system. The right ventricular pacing caused the further prolongation of the QRS duration and exacerbation of heart failure symptoms. Thus, the LV lead was successfully implanted during the second procedure after the balloon venoplasty of the lateral cardiac vein. The biventricular pacing was successful during 4 months follow-up.     

InSync 8040起搏器在充血性心力衰竭治疗中的初步应用

观察InSync 80 40起搏器治疗扩张型心肌病 (DCM)伴充血性心力衰竭 (CHF)的疗效。 8例DCM伴CHF患者 ,男 7例、女 1例。其中伴完全性左束支阻滞 6例 ,左前分支阻滞、右室起搏后宽QRS波 (>0 .2 0s)各 1例。通过冠状静脉窦置入 2 187电极起搏左室 ,右房电极和左、右室电极分别与InSync 80 40起搏器A、V1、V2 孔相连接。术后起搏阈值 3.75± 0 .6 (3.0～ 5 .0 )V。患者CHF的症状明显改善 ,术后左室舒张末径、左室射血分数、左室短轴缩短率、心胸比例较术前均有改善 (分别为 6 6 .1± 6 .93mmvs 72 .5± 8.1mm、0 .374± 0 .0 31vs 0 .2 81± 0 .0 5 3、19.8%± 2 .2 %vs12 .2 %± 2 .7%、0 .5 9± 0 .4vs 0 .6 4± 0 .2 0 ;P均 <0 .0 5 )。结论 :初步临床应用表明 ,以InSync 80 40起搏器行双心室同步起搏治疗CHF疗效肯定