The role of echocardiography in cardiac resynchronization therapy

Echocardiography is the most important imaging tool for managing heart failure patients. With the advent of cardiac resynchronization therapy (CRT), its role has been broadened by data pertaining to patient selection, optimization of device settings, and outcome assessment. Beyond ejection fraction determination, echocardiographic methods that measure tissue velocity and strain may have the capability to determine degree of mechanical dyssynchrony and possibly predict likelihood of benefit with CRT. After implantation (as the ventricles are fully paced, adjusting the atrioventricular delay [atrioventricular optimization]), the timing of the right ventricular and left ventricular lead stimulation (ventricular-ventricular optimization) to achieve maximal cardiac filling or ejection may be clinically important. Atrioventricular and ventricular-ventricular optimization rely on echocardiography to determine optimal values. In long-term follow-up, serial measurement of left ventricular volume has significant correlation with mortality and is a reasonable measure of successful CRT; echocardiography is uniquely suited for this purpose.     

Exercise stress echocardiography is superior to rest echocardiography in predicting left ventricular reverse remodelling and functional improvement after cardiac resynchronization therapy

Aims: Cardiac resynchronization therapy (CRT) improves functionalcapacity and survival in heart failure. However, one-third ofpatients fail to respond to CRT. Resting left ventricular (LV)dyssynchrony assessed by echocardiography (ECHO) showed discordantresults in identifying CRT responders. LV dyssynchrony can totallychange during exercise. Aim of this study was to evaluate whetherexercise dyssynchrony could select responders to CRT. Methods and results: Sixty-four patients scheduled for CRT implantation performedbicycle exercise ECHO in semi-supine position on an exercisetilting table before and 6 months after CRT implantation. TissueDoppler imaging (TDI) was acquired both at rest and during exerciseto detect LV mechanical dyssynchrony. Predictive values forCRT response were 70% for rest TDI and 89% for exercise TDI(P = 0.01). Exercise LV dyssynchrony was the only parameterindependently associated with follow-up improvement of restejection fraction and LV volume during multivariable analysis(P < 0.001). Functional improvement at 6-min walking testwas statistically higher in patients with exercise dyssynchrony(P = 0.005), and not different considering rest dyssynchrony(P = 0.30). Conclusion: Exercise intraventricular dyssynchrony assessed by exerciseTDI ECHO is a strong independent predictor of CRT response.It could be used to select candidates for CRT, thus reducingineffective implantations of biventricular pacemakers.     

Myocardial tissue Doppler echocardiography and cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is a promising technique for patients with end-stage, drug-refractory heart failure. Still 20-30% of the patients treated with CRT do not respond. Accordingly, the current selection criteria need to be refined, and it appears that demonstration of left ventricular dyssynchrony may be mandatory for response to CRT. Novel echocardiographic methods are currently investigated to detect left ventricular dyssynchrony and thereby improve the selection of candidates for CRT. In this brief review, these techniques will be discussed.     

Electromechanical effects of cardiac resynchronization therapy during rest and stress in patients with heart failure

BACKGROUND: Haemodynamic and functional effects of cardiac resynchronization therapy (CRT) have been studied mostly at rest. CRT effects on left ventricular (LV) dyssynchrony and function during stress have not been evaluated in detail. AIMS: We studied the electromechanical effects of CRT at rest and during Dobutamine stress echocardiography (DSE), during active and withheld CRT. METHODS: Twenty-one responders to CRT (62+/-12 yr) were assessed by walking test, quality of life, and BNP with active CRT ("on") and 2 weeks after pacing withdrawal ("off"). DSE (10 microg/kg/min) was performed both at "on" and "off" to evaluate dyssynchrony parameters, systolic and diastolic function. RESULTS: At rest, CRT withdrawal was associated with an increased interventricular mechanical delay (IVMD, from 21+/-18 ms to 49+/-24 ms, p<0.001) and impaired intraventricular synchrony. There was a significant decrease in LV systolic function and LV filling time. Dobutamine infusion had no impact on inter- and intraventricular synchrony. During stress, there was an improvement in LV performance both at "on" and "off". However, LV dp/dt, aortic VTI, cardiac output, mean systolic peak velocities and LV filling time during dobutamine stress were significantly greater with CRT "on". CONCLUSION: In long-term responders, CRT improves LV performance both at rest and during dobutamine stress. This is attributable to an improvement in LV synchrony, which is maintained during stress.     

Three-dimensional echocardiography for optimization of cardiac resynchronization therapy

We read with great interest the nice review by Stanton et al.¹concerning techniques for optimization of cardiac resynchronizationtherapy (CRT). In addition to the methods discussed by     

Prospective validation of stress echocardiography as an identifier of cardiac resynchronization therapy responders.

BACKGROUND: Cardiac resynchronization therapy (CRT) provides benefit for congestive heart failure (CHF), but predictors of the clinical response are debated. OBJECTIVE: The aim of this prospective study was to assess the predictive role of dobutamine stress echocardiography (DSE) in identifying a suitable candidate for CRT. METHODS: From March 2001 to December 2003, 71 CHF patients were prospectively enrolled on the basis of four criteria: New York Heart Association (NYHA) class III and IV; QRS > or =150 ms with a left bundle branch block pattern, and left ventricular ejection fraction (LVEF) < or =35% under optimal medical treatment. The combined endpoints were hospital readmission for class IV CHF, heart transplant (HT), and CHF-related death. RESULTS: The 67 patients completing the study presented with the following characteristics: age (70 +/- 10 years; 11 women); etiology (idiopathic in 44, ischemic in 23); NYHA class (40 in class III and 27 in class IV); LVEF 26% (+/-5%); QRS duration (190 +/- 28 ms); 6-minute walk test 330 m (+/-108); peak oxygen uptake 10.7 (+/-3.3 mL/kg/min); mitral insufficiency in 42 (> or =III grade); interventricular (IV) delay (62 +/- 21 ms); and intraventricular dyssynchrony in 30 patients. Over the follow-up period of 12.1 +/- 8.7 months, 20 (29.9%) of 67 patients presented with at least one hemodynamic event: hospitalization for CHF in 19 (28%) of 67, HT in 2 (3%) of 67, and CHF death in 7 (10%) 67. Univariate analysis identified NYHA class (P = .03), LVEF (P = .015), IV dyssynchrony before (P = .038) and after CRT (P = .0035), IV delay after CRT (P = .002), 6-minute walk distance (P = .01), and DSE Res+ (P = .008) as significant predictors of clinical events. A receiver operating curve established a cut-off value of 1.25 for the DSE responders (Res+: 34 patients at 10 microg/kg/min infusion rates), and the improvement at the 10 microg/kg/min level was 41% +/- 7% in Res+ and 29% +/- 8% in nonresponders (P<.0001). With a cut-off value of 1.25-fold the LVEF increase, the DSE test exhibits 70% sensitivity, 61.7% specificity, 43.8% positive predictive value, and 82.9% negative predictive value. Cox analysis identified IV dyssynchrony before CRT (P = .01) and DSE Res+ (P = .003) as independent predictive factors. CONCLUSIONS: Independent predictive factors of severe hemodynamic clinical outcome in patients with CRT are IV dyssynchrony and DSE.     

超声心动图在心脏再同步化治疗优化中的应用研究

目的:探讨超声心动图评价和优化心脏再同步化治疗(CRT)的价值,总结超声心动图应用于CRT优化的关键指标及方法学.方法:CRT治疗1～3年患者23例,优化组(17例)设定房室间期(AVD)在80～180ms,以20 ms逐次增减,比较不同AVD下超声心动图指标的即刻差异;6例未优化患者作为对照组.对优化组和对照组优化即刻/首次检查与随访6个月时各项指标进行比较.结果:优化组最佳AVD间期分布在100～140ms,取值跨度为80～160 ms,个体差异明显;优化后获得即刻血流动力学改善:左心室舒张充盈时间(LVFT)、二尖瓣流速时间积分(VTI-MV)、左心室收缩期压力上升速率(dp/dt)增加,二尖瓣反流口面积(MV-EROA)、心功能指数(Tei指数)降低(均P＜0.05).优化组优化后6个月血流动力学和临床指标进一步改善:Tei指数和纽约心功能分级(NYHA)分级降低,dp/dt和6min步行试验增加,与优化即刻比较,均P＜0.05,对照组6个月后仅Tei指数优于首次检查(P＜0.05),其他指标均差异无统计学意义(P＞0.05).结论:超声心动图指导CRT优化可使CRT患者获得即刻和长期的血流动力学和临床状态改善,该方法有可能成为改进CRT疗法的重要手段,有良好应用前景.     

Role of echocardiography to determine candidacy for cardiac resynchronization therapy

PURPOSE OF REVIEW: Cardiac resynchronization therapy is a great benefit to many patients with severe symptomatic heart failure, wide QRS duration, and depressed left ventricular ejection fraction. Although the widened QRS is a surrogate for delayed mechanical activation, known as dyssynchrony, imaging techniques have identified a subset of patients with widened QRS who do not have dyssynchrony and accordingly do not respond to cardiac resynchronization therapy. RECENT FINDINGS: Many echocardiographic techniques have emerged to quantify regional dyssynchrony, in hopes of improving patient selection and response rate to cardiac resynchronization therapy. Principal methods include M-mode septal to posterior wall motion delay, pulsed Doppler measures of left ventricular ejection in relation to right ventricular ejection, diastolic filling time as a ratio of cycle length, and several tissue Doppler imaging techniques to assess intraventricular opposing wall delay or dispersion of time to peak velocities. Although the simple and straightforward methods are easy to reproduce, they are modest in predictive value. In contrast, tissue Doppler imaging and other more recent techniques have higher predictive value, but are technically much more complex and require training and experience. SUMMARY: This field continues to evolve and further data are needed to precisely define the appropriate role of echocardiographic dyssynchrony information in patient selection for cardiac resynchronization therapy.     

Optimal use of echocardiography in cardiac resynchronisation therapy

Echocardiography has several roles in patients with cardiac resynchronisation therapy (CRT). First, it can optimise selection of CRT candidates by demonstration of left ventricular (LV) dyssynchrony. Second, it can be used to assess immediate response to CRT, including detection of acute LV resynchronisation. Echocardiography is also useful to evaluate long-term benefit from CRT. Finally, echocardiography is important in optimisation of pacemaker settings, including AV and VV optimisation.     

The role of cardiac resynchronization therapy in heart failure

The worldwide prevalence of heart failure is increasing in part due to an ageing population. In the developed world, heart failure affects 1-2% of the general population, accounting for 5% of adult hospital admissions. There is now convincing evidence supporting the beneficial effects of cardiac resynchronization therapy for the treatment of heart failure. Numerous observational studies, as well as a series of randomised controlled trials, have demonstrated the safety, efficacy, and long-term benefits for patients with chronic systolic heart failure who have broad QRS complexes and refractory symptoms despite optimal medical therapy. These studies have consistently demonstrated statistically significant improvements in quality of life, NYHA functional class, exercise tolerance, and left ventricular reverse remodeling. Recent evidence suggests that the benefit may at least in part be due to a reduction in mechanical dyssynchrony.     

超声心动图预测心脏再同步治疗反应性的研究进展

慢性心力衰竭的治疗一直是心脏科医生每天面对的难题,尽管目前药物治疗已经取得了很大进展,仍然有相当多的患者疗效不佳.在这种情况下心脏再同步治疗(cardiac resynchronization therapy,CRT)即左右心室同步起搏,由于其卓越的疗效得到了欧洲和美国心力衰竭治疗指南的一致推荐.     

超声新技术在心脏再同步治疗中的应用

慢性充血性心力衰竭是临床上常见的综合征,相当一部分患者合并房室传导或室内传导延迟,导致室壁运动的不同步,引起心功能的进一步恶化。从上一世纪90年代初,心脏再同步治疗(cardiac resynchronization therapy,CRT)开始用于治疗药物难治性心力衰竭,它通过起搏系统刺激左、右心室, 可改善心室的不同步收缩。超声新技术如组织速度显像、组织追踪显像、应变率显像、组织同步化显像可以直接测量心室机械同步性,识别理想的入选者,预测治疗效果,以及识别室壁运动最延迟的部位。这篇综述回顾了CRT的机制和超声新技术在CRT中的应用进展。     

超声心动图预测心脏再同步治疗反应性的研究进展

慢性心力衰竭的治疗一直是心脏科医生每天面对的难题,尽管目前药物治疗已经取得了很大进展,仍然有相当多的患者疗效不佳。在这种情况下心脏再同步治疗（cardiacresynch ronizationtherapy,CRT）即左右心室同步起搏,由于其卓越的疗效得到了欧洲和美国心力衰竭治疗指南的一致推荐。     

多巴酚丁胺药物负荷在心脏缺血及再同步化诊疗中的应用

药物负荷超声心动图可提高静息状态下无缺血症状患者冠心病(ＣＡＤ)诊断的准确性,可床边操作,已成为美国和欧洲心血管病诊疗指南推荐的主要非创伤性诊断方法之一[1]。出现新的室壁运动异常或原有运动异常加重是负荷试验的主要观察指标,其主观性强,需要检查者临床经验的积累,不同研究者分析的结果差异较大。药物与组织多普勒速度成像(ＴＤＩ)相结合的分析技术,为定量研究提供了可行的检查手段,显著降低了人为的影响,但易受心脏转位、相邻组织牵拉影响和超声束角度依赖影响,限制其在临床中应用[2]。