AV junctional ablation allowing more effective delivery of cardiac resynchronization therapy in patients with intra- and interatrial conduction delay

We report two patients with cardiac resynchronization therapy (CRT) devices and evidence of refractory heart failure in whom impaired intraatrial conduction in one patient, and interatrial conduction in the other, prohibited optimization of the atrioventricular (AV) timing sequence. The patient with intraatrial conduction delay exhibited late right atrial sensing and latency during right atrial pacing that required programming of a short-sensed AV delay and long-paced AV delay (wide differential AV delay). In both patients AV junctional ablation and echocardiography-guided device optimization significantly improved heart failure.     

Rate-dependent aberrancy and cardiac resynchronization therapy

Left bundle branch block (LBBB) can result in significant dyssynchrony in left ventricular (LV) contraction, ultimately leading to cardiac remodeling. LBBB can be rate dependent and may appear with LV systolic dysfunction. Cardiac resynchronization therapy (CRT) has been demonstrated to improve hemodynamics as well as clinical symptoms in patients with LBBB. We describe the case of a 57-year-old man who underwent CRT implantation due to exertional dyspnea, rate-dependent LBBB, and impaired left LV systolic function.     

Relationship of baseline electrocardiographic characteristics with the response to cardiac resynchronization therapy for heart failure

Prospective identification of patients most and least likely to respond to cardiac resynchronization therapy (CRT) for congestive heart failure (CHF) will allow clinicians to target this intervention most efficiently. The authors hypothesized that ECG variables including RBBB and indicators of RV dysfunction and extensive prior myocardial infarction would correlate with diminished response to CRT. This study analyzed preimplantation ECGs in 110 patients with ICD indications and CHF due to left ventricular systolic dysfunction randomized to active biventricular pacing in the MIRACLE ICD trial. Clinical and ECG variables on the outcome of change in peak oxygen consumption from baseline to 6 months (Delta-VO2 ) were evaluated. For this cohort, average peak VO2 improved from 13.4 to 14.3 mL/kg per minute. Among clinical variables, the strongest predictors of increasing Delta-VO2 were reduced exercise time and peak VO2 at baseline. A dominant R wave in lead a VR, RBBB, and evidence of prior anterior infarction were each associated with significantly smaller average improvements in Delta-VO2 than their absence in univariate analysis. Alternative ECG criteria, including QRS duration, had no relationship with the outcome. In a multivariate model, only baseline VO2 (beta=-0.3, P=0.001) and ECG evidence of prior anterior infarction (beta=-1.3, P=0.03) were associated with the outcome. ECG markers of anterior infarction and RV dilation may help identify CHF patients unlikely to benefit from biventricular pacing. Further assessment is needed of these and other predictors of therapeutic response to CRT.     

心脏再同步化治疗适应证的变迁

心脏再同步化治疗(CRT)慢性心力衰竭已走过20个春秋,其疗效已得到充分的肯定.随着系列临床研究结果的揭晓,其适应证也不断发生改变.从1998年最早的Ⅱb(C)类适应证,逐步发展到Ⅰ(A)类适应证;从纽约心脏病协会(NYHA)心功能Ⅲ或Ⅳ级拓展到Ⅰ～Ⅱ级;从窦性心律患者发展到心房颤动患者.对起搏依赖的心力衰竭患者其适应证变化也很大,从Ⅱb类适应证进展到Ⅰ(B)适应证,并且对左心室射血分数(LVEF)降低没有严格限制,其目的是为了防止大量右心室起搏给心力衰竭患者带来的危害,使患者达到最大获益.然而在QRS时限及形态的掌握上更加严格.目前认为,对QRS时限≥150 ms及完全性左束支传导阻滞(LBBB)患者,CRT治疗的获益最大,已经否定了对窄QRS时限(＜120 ms)的疗效.我们相信随着循证医学证据的积累,CRT治疗的目标人群会更加明确和具体,CRT应答率会进一步提高.     

超声心动图评价心脏再同步化治疗疗效

目的探讨超声心动图在慢性充血性心力衰竭患者心脏再同步化治疗疗效评价中的应用价值。方法 27例接受心脏再同步化治疗的慢性充血性心力衰竭患者,分别于术前及术后6个月应用超声心动图测量左心室大小、左心室容积、左心室射血分数、二尖瓣反流面积、房室间、心室间及左心室内同步性。结果术后6个月患者左心室收缩末内径、左心室舒张末内径、左心室收缩末容积、左心室舒张末容积小于术前（P〈0.05或P〈0.01）,房室间、心室间、左心室内收缩同步性改善（P〈0.05或P〈0.01）。结论超声心动图可通过多项参数综合评价心脏再同步化治疗的效果。     

心脏再同步化治疗充血性心力衰竭并发症的观察及护理

目的观察心脏再同步化治疗（CRT）充血性心力衰竭（CHF）患者并发症的疗效及护理。方法对12例CHF患者进行CRT,观察手术期并发症,并给予一定护理措施。结果12例患者中, 10例无并发症发生,2例并发冠状窦静脉夹层瘤。结论正确指导配合科学护理可有效减少CHF患者手术期并发症,是CRT植入手术成功的重要保障。     

Cardiac resynchronization therapy: predictors of failure and strategies to overcome

Evaluation of: Macias A, Garcia-Bolao I, Diaz-Infante E et al. Cardiac resynchronization therapy: predictive factors of unsuccessful left ventricular lead implant. Eur. Heart J. 28, 450–456 (2007).

Congestive heart failure (CHF) is a leading cause of morbidity, mortality and hospitalization in the elderly of industrialized nations. In CHF patients with moderate-to-severe left ventricular systolic dysfunction and significant dyssynchrony, cardiac resynchronization therapy (CRT) has been shown to improve functional status and decrease heart failure mortality and hospitalizations. Inability to transvenously implant a lead within a desired branch of the coronary sinus for CRT occurs in 5–10% of cases. The article under evaluation identifies two independent predictors of failed transvenous left ventricular lead implantation – the presence of permanent atrial fibrillation and an increased anteroposterior left atrial diameter.     

超声指导下参数优化提高心脏再同步化治疗疗效的应用价值

目的 探讨超声引导下参数优化提高心脏再同步化治疗(CRT)疗效的价值.方法 对17例慢性心力衰竭的患者,CRT术后在超声心动图指导下优化AV间期、VV间期.结果 17例患者CRT优化后心功能均得到不同程度改善,心功能NYHA分级从Ⅲ～Ⅳ级改善为Ⅱ～Ⅲ级,心房起搏AV间期/心房自身感知AV间期优化至130～180 ms/100～150 ms,使得左室充盈时间从(354±147)ms升至(420±112)ms,二尖瓣反流由(9.33±4.69)cm2减少至(5.44±4.62)cm2;VV间期优化至4～40 ms,使得左室内各室壁收缩期达峰时间标准差从(48.4±17.9)ms减少至(30.2±18.6)ms,左室流出道速度时间积分由(21.6±9.3) cm/s上升至(26.3±3.4)cm/s.3个月后左室收缩末容积减少(15±6)%.结论 CRT术后行超声指导下个体化参数优化可以提高CRT疗效.

Abstract：

Objective To investigate the effects of echocardiography-guided pacemaker parameters optimization in order to enhance the efficacy of cardiac resynchronization therapy(CRT).Methods Seventeen patients with chronic heart failure received biventricular resynchronous pacing therapy.A-V delay and V-V delay was optimized under the guiding of spectral Doppler echocardiography and tissue Doppler imaging.Results The indices of heart function in all patients were significantly improved after the treatment.The NYHA class of the patients was improved from class Ⅲ～Ⅳ to class Ⅱ～Ⅲ.Since PAV/SAV was optimized to 130-180/100-150 ms,left ventricular filling time(LVFT) was increased from (354±147)ms to (420±112)ms,mitral reflux (MR) was decreased from (8.41±4.55)cm2 to (5.36±4.71)cm2.After VV delay was optimized to 4-40ms,standard deviation of time to regional peak systolic velocity (Ts-SD-12) was decreased from (48.4±17.9)ms to (30.2±18.6)ms,left ventricular outflow tract velocity time integral(VTI LVOT) was increased from (20.6±9.0)cm/s to (26.1±3.1)cm/s.Conclusions Echocardiography-guided optimization of the pacemaker parameters is necessary in order to enhance the efficacy of CRT.     

Gender disparity in the use of cardiac resynchronization therapy in the United States

Background: Although several studies have shown the effectiveness of cardiac resynchronization therapy (CRT) for advanced congestive heart failure (CHF), gender differences in utilization of CRT are not known.
Methods: We used the Healthcare Cost and Utilization Project (HCUP) to study national rates for admissions due to CHF along with procedures for initial CRT implantation, including both CRT-defibrillator (CRT-D) and CRT-pacemakers (CRT-P) during the years of 2002–2004. Chi-square tests were used for comparison between number of women and men. A P < 0.05 was considered significant.
Result: Women had consistently higher rates of admission for CHF during each year (574,037 (54%) vs 482,005 (46%), 2002; 601,181 (54%) vs 517,202 (46%), 2003; and 580,913 (53%) vs 521,280 (47%), 2004). The number of initial CRT device implantations (both CRT-D and CRT-P) was significantly lower during each year for women compared to men (659 (25%) vs 1,931 (75%), 2002; 6,928 (26%) vs 19,646 (74%), 2003; and 11,286 (27%) vs 42,196 (73%), 2004; P < 0.01 for all). Both CRT-P and CRT-D were used less frequently in women compared to men; however, this difference was consistently less prominent during each year with CRT-P compared to CRT-D (301 (41%) CRT-P vs 358 (19%) CRT-D, 2002; 659 (39%) CRT-P vs 2,530 (28%) CRT-D, 2003; and 2,891 (39%) CRT-P vs 8,395 (24%) CRT-D, 2004; P < 0.05).
Conclusion: Our data clearly demonstrate a significant gender disparity in utilization of CRT devices. Further studies are needed to find possible reasons behind this disparity.     

Comparison of hemodynamic versus dyssynchrony assessment for interventricular delay optimization with echocardiography in cardiac resynchronization therapy

Background: Best practice for cardiac resynchronization therapy (CRT) device optimization is not established. This study compared Tissue Doppler Imaging (TDI) to study left ventricular (LV) synchrony and left ventricular outflow tract velocity‐time integral (LVOT VTI) to assess hemodynamic performance. Methods: LVOT VTI and LV synchrony were tested in 50 patients at three interventricular (VV) delays (LV preactivation at ?30 ms, simultaneous biventricular pacing, and right ventricular preactivation at +30 ms), selecting the highest VTI and the greatest degree of superposition of the displacement curves, respectively, as the optimum VV delay. Results: In 39 patients (81%), both techniques agreed (Kappa = 0.65, p < 0.0001) on the optimum VV delay. LV preactivation (VV ? 30) was the interval most frequently chosen. Conclusions: Both TDI and LVOT VTI are useful CRT programming methods for VV optimization. The best hemodynamic response correlates with the best synchrony. In most patients, the optimum VV interval is LV preactivation. (PACE 2011; 34:984–990)     

Pacemaker optimization in nonresponders to cardiac resynchronization therapy: left ventricular pacing as an available option

Background: Echocardiographic (ECHO)‐guided pacemaker optimization (PMO) in cardiac resynchronization therapy (CRT) nonresponders acutely improves left ventricular (LV) function. However, the chronic results of LV pacing in this group are less understood. Methods: We retrospectively studied 28 CRT nonresponders optimized based on ECHO to LV pacing and compared them to 28 age‐ and gender‐matched patients optimized to biventricular (BiV) pacing. ECHOs with tissue Doppler imaging assessed LV hemodynamics before, immediately after, and 29 ± 16 months after PMO. Also, 56 age‐ and gender‐matched CRT responders were included for comparison of clinical outcomes. Results: PMO resulted in acute improvements in longitudinal LV systolic function and several measures of dyssynchrony, with greater improvements in the LV paced group. Chronic improvements in ejection fraction (EF) (3.2 ± 7.7%), and left ventricle end‐systolic volume (LVESV) (?11 ± 36 mL) and one dyssynchrony measure were seen in the combined group. Chronically, both LV and BiV paced patients improved some measures of systolic function and dyssynchrony although response varied between the groups. Survival at 3.5 years was similar (P = 0.973) between the PMO (58%) and nonoptimized groups (58%) but survival free of cardiovascular hospitalization was significantly (P = 0.037) better in the nonoptimized group. Conclusions : CRT nonresponders undergoing PMO to either LV or BiV pacing have acute improvements in longitudinal systolic function and some measures of dyssynchrony. Some benefits are sustained chronically, with improvements in EF, LVESV, and dyssynchrony. A strategy of ECHO‐guided PMO results in survival for CRT nonresponders similar to that of CRT patients not referred for PMO. (PACE 2012; 35:685–694))     

Double wire technique to catheterize sharply angulated coronary sinus branches in cardiac resynchronization therapy

Placing a pacing lead for left ventricular pacing through the coronary sinus can be hampered by anatomic obstacles. In this case report we describe a technique that can overcome the problem of sharply angulated coronary sinus branches by using simultaneously two guidewires in the target vessel.     

Changes in heart rate variability, quality of life, and activity in cardiac resynchronization therapy patients: results of the HF-HRV registry

BACKGROUND: Cardiac resynchronization therapy (CRT) is a viable therapy in the treatment of heart failure (HF). Heart rate variability (HRV) is a prognostic marker of HF and mortality and is a sign of autonomic dysfunction. Acute improvements in measures of HRV have been demonstrated after CRT in small clinical studies. The purpose of the present study was to evaluate changes in HRV and patient outcomes over time and the relationship between these changes in a large generalized sample of patients who received CRT with defibrillator (CRT-D). METHODS: The Heart Failure-Heart Rate Variability (HF-HRV) registry enrolled 1,421 patients who received a CRT-D device capable of measuring HRV. Patients were followed for a 1-year period. Device diagnostics, including HRV footprint; standard deviation of averaged normal R to R intervals (SDANN); and mean, minimum, and maximum heart rate were measured at each visit, in addition to activity log, New York Heart Association (NYHA) class, and quality of life (QOL) data. RESULTS: This large sample of HF patients showed an overall improvement in SDANN (69.2 +/- 25.5, 78.5 +/- 27.8, 79.4 +/- 27.2, 80.7 +/- 28.2) and HRV footprint (31.5 +/- 11.8, 33.4 +/- 12.3, 34.2 +/- 12.2, 34.5 +/- 12.3) at the 2 week, 3 month, 6 month, and 12 month visits, respectively (both P < 0.001). There were also significant changes over time in clinical status (improved QOL, increased activity, and improved NYHA, all P < 0.0001), with the greatest changes occurring between the 2 week and 3 month visits. CONCLUSION: In conclusion, these study results demonstrate that device measured HRV parameters and patient outcomes significantly improve after receipt of CRT.     

Mood disorders and outcome in patients receiving cardiac resynchronization therapy

Background: Mood disorders (MD) have been demonstrated to influence outcome in cardiac disease in general and specifically in chronic heart failure (HF). Little is known about their possible effect on response to cardiac resynchronization therapy (CRT). Objective: To evaluate the influence of MD on CRT response. Methods: We conducted a retrospective chart review of all cardiac CRT‐D (CRT defibrillator) recipients (N = 153) at the Veterans Affairs Pittsburgh Healthcare System from beginning of 2004 through end of 2006. All‐cause death and HF‐related hospitalizations (HFH), individually and combined, were sought through 2009. Results: During a mean follow‐up time of 31.4 ± 14.7 months, there were 48 (31.4%) deaths and 55 (35.9%) HFHs in HF patients having New York Heart Association class of 2.9 ± 0.3, left ventricular ejection fraction (LVEF) of 25.8 ± 9.1%, left ventricular end‐diastolic diameter (LVEDD) of 61.6 ± 11.6 mm, and QRS of 152 ± 30.5 ms . A total of 65 (42.5%) patients had MD (depression, anxiety, or posttraumatic stress disorder). Compared to others, patients in the MD group were at a significantly higher risk of HFH alone (47.7% vs 27.3%, P = 0.009) or when combined with death (58.5% vs 39.8%, P = 0.022) but not death alone (35.4% vs 28.4%, P = 0.36). The significant predictive effect of MD on HFH alone and when combined with death shown in univariate analysis was not attenuated after adjustment for age, ejection fraction, etiology of cardiomyopathy, cumulative number of any shocks, smoking, and evidence of postimplantation echocardiographic improvement. Conclusions: MD in patients with advanced but stable HF receiving CRT‐D therapy was a predictor of HFH alone or when combined with death but not mortality alone. (PACE 2011;1–9)     

Optimization of device programming for cardiac resynchronization therapy

Cardiac resynchronization therapy may lead to remarkable improvement in clinical status in selected patients with heart failure. However, approximately 20-30% of patients may not respond to this treatment. One of the reasons for this may be suboptimal programming of the device, which has particular considerations as compared to standard pacemakers. Hemodynamic response to pacing may be affected by timing of the atrioventricular (AV) interval, affecting synchronicity of atrial and ventricular contraction. In addition current biventricular devices have separate right and left ventricular channels that allow programming of an interventricular (VV) interval with right or left ventricular preexcitation. This article focuses on the parameters that may be optimized for biventricular pacing, and reviews the different techniques currently available for this application, with special emphasis paid to echocardiography.     

Changes in global longitudinal strain during rest and exercise in patients treated with cardiac resynchronization therapy

Relatively few data have been reported on prospective changes in global longitudinal strain (GLS) following cardiac resynchronization therapy (CRT), and none are available on GLS during physical exercise. We investigated the effects of CRT on GLS, assessed by speckle tracking two-dimensional (2D) echocardiography, at rest and during exercise after a mid-term follow-up. Twenty consecutive CRT patients (45% ischaemic) were assessed prospectively by speckle tracking 2D echocardiography before implant (at rest) and at mid-term follow-up (during rest and bicycle exercise). GLS, septum and lateral wall longitudinal strain, left ventricular ejection fraction (LVEF), and conventional functional variables were evaluated at baseline and follow-up. All patients completed the study protocol at rest. Exercise images were available in 90% of the patients. At follow-up, GLS improved at rest from -7.1 ± 2.6% to -9.1 ± 4.5% (P<0.01), with a further increase to -11 ± 5.1% during exercise (P<0.001). Longitudinal strain increased at rest both in the septum and in the lateral wall, with an additional increase during exercise in the lateral wall (P<0.05). GLS correlated with LVEF both at rest (r= -0.55 and r= -0.91 at baseline and 3 months, respectively; P<0.05) and during exercise (r= -0.89, P<0.05). Improvement in GLS during rest and exercise can be observed in CRT patients at mid-term follow-up and seems to correlate with changes in LVEF. GLS may be a valuable method to assess left ventricular function during rest and exercise.     

Interatrial conduction correlates with optimal atrioventricular timing in cardiac resynchronization therapy devices

Background: Echocardiographic optimization of the atrioventricular delay (AV) may result in improvement in cardiac resynchronization therapy (CRT) outcome. Optimal AV has been shown to correlate with interatrial conduction time (IACT) during right atrial pacing. This study aimed to prospectively validate the correlation at different paced heart rates and examine it during sinus rhythm (Sinus). Methods: An electrophysiology catheter was placed in the coronary sinus (CS) during CRT implant (n = 33). IACT was measured during Sinus and atrial pacing at 5 beats per minute (bpm) and 20 bpm above the sinus rate as the interval from atrial sensing or pacing to the beginning of the left atrial activation in the CS electrogram. P‐wave duration (PWd) was measured from 12‐lead surface electrocardiogram, and the interval from the right atrial to intrinsic right ventricular activation (RA‐RV) was measured from device electrograms. Within 3 weeks after the implant patients underwent echocardiographic optimization of the sensed and paced AVs by the mitral inflow method. Results: Optimal sensed and paced AVs were 129 ± 19 ms and 175 ± 24 ms, respectively, and correlated with IACT during Sinus (R = 0.76, P < 0.0001) and atrial pacing (R = 0.75, P < 0.0001), respectively. They also moderately correlated with PWd (R = 0.60, P = 0.0003 during Sinus and R = 0.66, P < 0.0001 during atrial pacing) and RA‐RV interval (R = 0.47, P = 0.009 during Sinus and R = 0.66, P < 0.0001 during atrial pacing). The electrical intervals were prolonged by the increased atrial pacing rate. Conclusion: IACT is a critical determinant of the optimal AV for CRT programming. Heart rate‐dependent AV shortening may not be appropriate for CRT patients during atrial pacing. (PACE 2011; 34:443–449)