Real time three-dimensional echocardiography in assessment of left ventricular dyssynchrony and cardiac resynchronization therapy

Left ventricular (LV) mechanical dyssynchrony is an important prognostic marker for higher morbidity and mortality in patients with symptomatic heart failure. However, the response rate to resynchronization varies among patients meeting current guidelines for Cardiac resynchronization therapy (CRT). Two-dimensional echocardiography and Doppler-based techniques have shown variable results in the assessment of LV dyssynchrony. There is an obvious need for a noninvasive tool that can reliably measure LV dyssynchrony. Accurate prediction of response to CRT will improve patient selection for such therapy. Real time three-dimensional echocardiography (RT3DE) is a novel noninvasive imaging modality that has been recently used in quantitative evaluation of global and regional LV function. A number of published studies have described the use of RT3DE in the measurement of LV dyssynchrony in patients with normal or reduced LV function. The systolic dyssynchrony index derived from RT3DE has been used to quantify LV dysynchrony and to evaluate and predict the response to CRT. This review will discuss the recently published data regarding the role of RT3DE in CRT.     

Preferred left ventricular lead position for upgrade from right ventricular pacing to cardiac resynchronization therapy

Introduction

Cardiac resynchronization therapy (CRT) is well-established for treating symptomatic heart failure with electrical dyssynchrony. The left ventricular (LV) lead position is recommended at LV posterolateral to lateral sites in patients with left bundle branch block; however, its preferred region remains unclear in patients being upgraded from right ventricular (RV) apical pacing to CRT. This study aimed to identify the preferred LV lead position for upgrading conventional RV apical pacing to CRT.

Methods

We used electrode catheters positioned at the RV apex and LV anterolateral and posterolateral sites via the coronary sinus (CS) branches to measure the ratio of activation time to QRS duration from the RV apex to the LV anterolateral and posterolateral sites during RV apical pacing. Simultaneous biventricular pacing was performed at the RV apex and each LV site, and the differences in QRS duration and LV dP/dt_max from those of RV apical pacing were measured.

Results

Thirty-seven patients with anterolateral and posterolateral LV CS branches were included. During RV apical pacing, the average ratio of activation time to QRS duration was higher at the LV anterolateral site than at the LV posterolateral site (0.90 ± 0.06 vs. 0.71 ± 0.11, p < .001). The decreasing ratio of QRS duration and the increasing ratio of LV dP/dt_max were higher at the LV anterolateral site than at the posterolateral site (45.7 ± 18.0% vs. 32.0 ± 17.6%, p < .001; 12.7 ± 2.9% vs. 3.7 ± 8.2%, p < .001, respectively) during biventricular pacing compared with RV apical pacing.

Conclusion

The LV anterolateral site is the preferred LV lead position in patients being upgraded from conventional RV apical pacing to CRT.     

左心室心肌做功预测心脏再同步化治疗的效果

目的 利用二维斑点追踪成像(2D-STI)技术新参数左心室心肌做功预测心脏再同步化治疗(CRT)的效果.方法 选取2017年12月至2019年10月在苏北人民医院接受CRT治疗的75例心力衰竭患者为研究对象,于CRT术前及术后6个月测量常规超声心动图参数以及利用2D-STI技术分析整体心肌做功参数.将术后左心室收缩末期...     

Effect of cardiac resynchronization therapy on longitudinal and circumferential left ventricular mechanics by velocity vector imaging: description and initial clinical application of a novel method using high-frame rate B-mode echocardiographic images

Cardiac resynchronization therapy (CRT) has emerged as an important method to treat patient with symptomatic heart failure with evidence of intraventricular dyssynchrony. Tissue Doppler imaging by echocardiography has been shown to be an excellent tool for the assessment of mechanical left ventricular dyssynchrony and the selection of patients for CRT. However, there are some patients who do not show symptomatic improvement following CRT. One possible explanation for this is the need to optimize not only longitudinal synchrony, but also improve the circumferential and radial dynamics of the left ventricle. Doppler imaging does not allow reliable assessment of the latter because of the angle-dependency of the technique. Velocity Vector Imaging (VVI) is a newer technique which is angle-independent and thus provides an avenue to evaluate short-axis mechanics of the left ventricle. We describe a case in which VVI was used to assess the left ventricular dynamics in a patient with heart failure who did not respond to CRT.     

Real-time three-dimensional echocardiography permits quantification of left ventricular mechanical dyssynchrony and predicts acute response to cardiac resynchronization therapy

Objective: To evaluate the value of real-time three-dimensional echocardiography (RT3DE) to predict acute response to cardiac resynchronization therapy (CRT).
Methods: Sixty consecutive heart failure patients scheduled for CRT were included. RT3DE was performed before and within 48 hours after pacemaker implantation to calculate both left ventricular (LV) volumes and LV dyssynchrony. LV dyssynchrony was defined as the standard deviation of the time taken to reach the minimum systolic volume for 16 LV segments (referred to as the systolic dyssynchrony index, SDI). Patients were subsequently divided into acute responders or nonresponders, based on a reduction ≥ 15% in LV end-systolic volume immediately after CRT.
Results: Four patients (7%) were excluded from further analysis because of either suboptimal apical acquisitions or significant translation artifacts. Out of the remaining 56 patients, 35 patients (63%) were classified as acute responders. Baseline characteristics were similar between responders and nonresponders, except for the SDI, which was larger in responders. Moreover, responders demonstrated a significant reduction of SDI immediately after CRT (from 9.7 ± 4.1% to 3.6 ± 1.8%, P < 0.0001), whereas SDI did not change in nonresponders (3.4 ± 1.8% vs 3.1 ± 1.1%, NS). ROC curve analysis revealed that a cut-off value for SDI of 5.6% yielded a sensitivity of 88% with a specificity of 86% to predict acute echocardiographic response to CRT (AUC 0.96).
Conclusion: RT3DE is highly predictive for acute response to CRT (sensitivity 88% and specificity 86%). In addition, RT3DE allows assessment of changes in LV volumes and LV ejection fraction before and after CRT implantation.     

左室电极起搏位置与心脏再同步化治疗的疗效

目的探讨左室电极在左室游离壁不同位置起搏对慢性心力衰竭(简称心衰)心脏再同步化治疗(CRT)患者远期疗效的影响。方法 110例扩张型心肌病或高血压病合并慢性左心衰患者均符合CRT植入指征而接受CRT术,术后根据后前位和左前斜位的胸部X线影像,左室电极导线植入部位分为前壁、侧壁、后壁和后基底部。术后12个月,分别查心脏超声、心电图等,分析心功能、心电图QRS波时限和左室射血分数(LVEF)及左室容积变化。以心功能(NYHA)分级至少改善1级或LVEF升高25%以上定义为有效。结果由于患者心脏静脉变异和组织超声多普勒检查结果,左室电极导线分别被植入前壁4例、侧壁68例和后壁37例、后基底部1例。术后3例因心功能恶化死亡,2例发生猝死,1例术后第9天因肺部感染死亡。术后12个月,104例生存者中,有效91例,无效13例,总有效率87.5%。左室电极位于侧壁组的有效率(92.4%)明显高于后壁组(85.7%)(P<0.05)。前壁或后基底部的5例均无效。结论 CRT对慢性心衰患者有效,其疗效与左室电极起搏位置密切相关,左室侧壁或后壁是左室电极导线的理想起搏部位。     

Hemodynamic changes during cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is a new method for the correction of inter- and/or intraventricular conduction delays of patients with heart failure. The long-term impact of CRT on central hemodynamics is not fully characterized. We performed complete right heart catheterization studies in 31 patients receiving a CRT device pre and 6 months after implantation. Most of the patients improved in their NYHA stage, their LVEF, and in parallel showed reduced right atrial (RA) pulmonary artery (PA) and pulmonary capillary wedge (PCW) pressures and pulmonary vascular resistance both at rest and at 25 watts. In addition, we found a reduction in heart rate accompanied by an increased mean arterial pressure both at rest and at 25 watts. Accordingly, brain natriuretic peptide levels (BNP) were lowered. It was concluded that, besides other well-known effects on ventricular coordination, central hemodynamics after 6 months were improved during CRT.     

Avoidance of right ventricular pacing in cardiac resynchronization therapy improves right ventricular hemodynamics in heart failure patients

Background: Cardiac resynchronization therapy (CRT) applied by pacing the left and right ventricles (BiV) has been shown to provide synchronous left ventricular (LV) contraction in heart failure patients. CRT may also be accomplished through synchronization of a properly timed LV pacing impulse with intrinsically conducted activation wave fronts. Elimination of right ventricular (RV) pacing may provide a more physiological RV contraction pattern and reduce device current drain. We evaluated the effects of LV and BiV pacing over a range of atrioventricular intervals on the performance of both ventricles.
Methods: Acute LV and RV hemodynamic data from 17 patients with heart failure (EF = 30 ± 1%) and a wide QRS (138 ± 25 msec) or mechanical dyssynchrony were acquired during intrinsic rhythm, BiV, and LV pacing.
Results: The highest LV dP/dt_max was achieved during LV pre- (LV paced prior to an RV sense) and BiV pacing, followed by that obtained during LV post-pacing (LV paced after an RV sense) and the lowest LV dP/dt_max was recorded during intrinsic rhythm. Compared with BiV pacing, LV pre-pacing significantly improved RV dP/dt_max (378 ± 136 mmHg/second vs 397 ± 136 mmHg/second, P < 0.05) and preserved RV cycle efficiency (61.6 ± 14.6% vs 68.6 ± 11.4%, P < 0.05) and stroke volume (6.6 ± 4.4 mL vs 9.0 ± 6.3 mL, P < 0.05). Based on LV dP/dt_max, the optimal atrioventricular interval could be estimated by subtracting 30 msec from the intrinsic atrial to sensed RV interval.
Conclusions: Synchronized LV pacing produces acute LV and systemic hemodynamic benefits similar to BiV pacing. LV pacing at an appropriate atrioventricular interval prior to the RV sensed impulse provides superior RV hemodynamics compared with BiV pacing.     

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.     

超声心动图定量组织速度成像技术对心脏再同步治疗后右心室功能的判定价值

目的 应用超声心动图定量组织速度成像技术(QTVI)评价慢性心力衰竭(CHF)患者应用心脏再同步治疗(CRT)后右心功能及同步性变化.方法 接受CRT患者22例,在CRT术前、术后1周及6个月用常规超声心动图测量左心室功能、右心室功能及同步性参数,通过QTVI技术测量右心室游离壁的三尖瓣环处的右心室等容舒张时间(RVIRT)、等容收缩时间(RVICT)及射血时间(RVET),并计算右心室心肌功能指数(RV-MPI).结果 ①术后6个月右心室舒张末期面积(RVEDA)、右心室收缩末期面积(RVESA)较术前明显减小(P＜0.05);右心室面积变化率(RVFAC)及左心室射血分数(LVEF)在术后1周及6个月均不同程度提高(P＜0.05);②术后1周室间机械延迟时间(IVMD)明显减低(P＜0.05),表明术后1周左、右心室间同步性即明显改善;③术后1周及6个月右心室的RVICT、右心室等容舒张时间(RVIRT)明显缩短(P＜0.05),RVET明显延长(P＜0.01),RV-MPI明显改善(P＜0.01).结论 QTVI可应用于心力衰竭患者右心室功能评测,CRT可改善慢性心力衰竭患者的心室同步性及右心室功能.     

Association between left ventricular lead position and intrinsic QRS morphology with regard to clinical outcome in cardiac resynchronization therapy for heart failure

Background

Left ventricular (LV) lead position may be an important factor for delivering effective cardiac resynchronization therapy (CRT). We therefore aimed to evaluate the effects of LV lead position, stratified by native QRS morphology, regarding the clinical outcome.

Methods

A total of 1295 CRT-implanted patients were retrospectively evaluated. LV lead position was classified as lateral, anterior, inferior, or apical, and was determined using the left and right anterior oblique X-ray views. Kaplan Meier and Cox regression were performed to evaluate the effects on all-cause mortality and heart failure hospitalization, and the potential interaction between LV lead position and native ECG morphologies.

Results

A total of 1295 patients were included. Patients were aged 69 ± 7 years, 20% were female, 46% received a CRT-Pacemaker (vs. CRT-Defibrillator), mean LVEF was 25% ± 7%, and median follow-up was 3.3 years [IQR 1.6–5–7 years]. Eight hundred and eighty-two patients (68%) had a lateral LV lead location, 207 (16%) anterior, 155 (12%) apical, and 51 (4%) inferior. Patients with lateral LV lead position had larger QRS reduction (−13 ± 27 ms vs. −3 ± 24 ms, p < .001). Non-lateral lead location was associated with a higher risk for all-cause mortality (HR 1.34 [1.09–1.67], p = .007) and heart failure hospitalization (HR 1.25 [1.03–1.52], p = .03). This association was strongest for patients with native left or right bundle branch block, and not significant for patients with prior paced QRS or nonspecific intraventricular conduction delay.

Conclusions

In patients treated with CRT, non-lateral LV lead positions (including apical, anterior, and inferior positions) were associated with worse clinical outcome and less reduction of QRS duration. This association was strongest for patients with native LBBB or RBBB.     

Left ventricular lead proximity to an akinetic segment and impact on outcome of cardiac resynchronization therapy

BACKGROUND: Previous studies report that the optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricular (LV) lateral and postero-lateral (PL) wall. However, little is known regarding whether pacing over an akinetic site impacts the contractile response and long-term outcome from CRT. METHODS AND RESULTS: A total of 38 patients with ischemic cardiomyopathy were studied for their acute hemodynamic and 12-month clinical response to CRT. The intraindividual percentage change in dP/dt (%DeltadP/dt), over baseline, was derived from the mitral regurgitation (MR) Doppler profile with CRT on versus off. Two-dimensional echocardiography was used for myocardial segmentation and determinination of akinetic sites. LV lead implant site was determined using angiographic and radiographic data and categorized as being "on" (group 1) or "off" (group 2) an akinetic site. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to primary endpoint was estimated by the Kaplan-Meier method. Clinical characteristics and acute hemodynamic response was similar in both (group 1 [n = 14]; %DeltadP/dt 48.8 +/- 67.4% vs group 2 [n = 24]; %DeltadP/dt 32.2 +/- 40.1%, P = 0.92). No difference in long-term outcome was observed (P = 0.59). In contrast, lead placement in PL or mid-lateral (ML) positions was associated with a better acute hemodynamic response when compared to antero-lateral (AL) positions (PL, %DeltadP/dt 45.7 +/- 50.7% and ML, %DeltadP/dt 45.1 +/- 58.8% vs AL, %DeltadP/dt 2.9 +/- 30.9%, respectively, P = 0.014). CONCLUSION: LV lead proximity to an akinetic segment does not impact acute hemodynamic or 12-month clinical response to CRT.     

无冠状静脉窦长鞘技术植入左室导线在心脏再同步化治疗中的应用

目的 探讨无冠状静脉窦（CS）长鞘（无鞘）技术植入左室导线的可行性及适合人群心脏静脉形态特点。方法 51例拟行心脏再同步化治疗（CRT）的患者,CRT前常规行冠状动脉造影顺行心脏静脉显影。随机分为无鞘组（n=26）和常规组（n=25）,前者先采用无鞘技术植入左室导线,失败者（未成功亚组）继改为常规有鞘方法植入;后者通过常规有鞘方法植入左室导线。 观察无鞘组植入左室导线的成功率,比较两组导线植入时间、曝光时间、相关并发症、导线参数,并分析无鞘组成功亚组心脏静脉形态与临床资料。 结果 无鞘组8例成功（成功亚组）,另18例未成功（未成功亚组）,无鞘组植入成功率30. 8% ;常规组植入成功率96% ,显著高于无鞘组（P〈0. 001）。 但无鞘组成功亚组导线植入时间、曝光时间均显著短于常规组[（24.1±5.1）min vs （45.6±10.1）min,（9.1±2.5）min vs（13.3±2.4）min, P均〈0. 001]。 常规组2例（8% ）出现心脏静脉夹层、撕裂,3例（12% ）在退出CS长鞘即刻发生导线脱位;无鞘组成功亚组无1例出现上述并发症。 无鞘组未成功亚组手术时间、曝光时间同常规组相比并未延长,围术期并发症也未增加（P均〉0. 05）。 成功亚组管状CS比例显著高于未成功亚组（87. 5% vs 33. 3% ,P〈0.05）,同时与未成功组亚组相比,CS、靶血管直径更粗[（15.7±2.7）mm vs （13.3±2.0）mm,（4.0±0.8）mm vs （3.3±0. 5）mm,P均〈0. 05],靶血管与CS近端成角更大[（117.9±12.7）° vs （97.1±10.4）°,P〈0. 01]。 结论 无鞘技术为植入左室导线提供了一种简化、安全、经济的方法,但成功率有限,更适用于管状 CS、靶血管直径粗大、呈钝角走形的患者。     

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.     

Assessment of left ventricular wall motion in diabetic rats using velocity vector imaging combined with stress echocardiography

Objective: The aim of this study was to investigate whether velocity vector imaging (VVI) combined with stress echocardiography could detect potential diffused myocardial impairment of the left ventricle (LV) in diabetic rats. Methods: Thirty-five male SD rats were randomly divided into either the control group or the diabetes mellitus (DM) group (induced with STZ). VVI was performed both at rest and after dipyridamole stress in all rats 12 weeks later. Segmental peak systolic velocity (V_s), diastolic velocity (V_d), radial strain (ɛ_r), circumferential strain (ɛ_c), systolic and diastolic radial strain rate (SR_r), and circumferential strain rate (SR_c) were measured from six segments at the mid-level of the LV. Results: At rest, systolic and diastolic SR_c in the DM group were significantly lower than those in the control group. After dipyridamole stress, all VVI parameters in the DM group were significantly lower than those in the control group, although all values increased significantly after dipyridamole stress compared to those at rest in both groups. Conclusions: The VVI-derived V_s, V_d, ɛ_r, ɛ_c, systolic and diastolic SR_r and SR_c, combined with dipyridamole stress are all effective parameters in evaluating potential myocardial impairment due to ultrastructural alterations of cardiocytes and microcirculation disturbances in DM rats. Systolic and diastolic SR_c may be more sensitive indices that could be useful in detecting myocardial impairment at rest.