Biventricular pacing preserves left ventricular performance in patients with high-grade atrio-ventricular block: a randomized comparison with DDD(R) pacing in 50 consecutive patients

Aims: We aimed to investigate whether biventricular (BiV) pacing minimizesleft ventricular (LV) dyssynchrony and preserves LV ejectionfraction (LVEF) as compared with standard dual-chamber DDD(R)pacing in consecutive patients with high-grade atrio-ventricular(AV) block. Methods and results: Fifty patients were randomized to DDD(R) pacing or BiV pacing.LVEF was measured using three-dimensional echocardiography.Tissue-Doppler imaging was used to quantify LV dyssynchronyin terms of number of segments with delayed longitudinal contraction(DLC). LVEF was not different between groups after 12 months(P = 0.18). In the DDD(R) group LVEF decreased significantlyfrom 59.7(57.4–61.4)% at baseline to 57.2(52.1–60.6)%at 12 months of follow-up (P = 0.03), whereas LVEF remainedunchanged in the BiV group [58.9(47.1–61.7)% at baselinevs. 60.1(55.2–63.3)% after 12 months (P = 0.15)]. Dyssynchronywas more prominent in the DDD(R) group than in the BiV groupat baseline (2.2 ± 2.2 vs. 1.4 ± 1.3 segmentswith DLC per patient, P = 0.10); and at 12 month follow-up (1.8± 1.9 vs. 0.8 ± 0.9 segments with DLC per patient,P = 0.02). NT-proBNP was unchanged in the DDD(R) group duringfollow-up (122 ± 178 pmol/L vs. 91 ± 166 pmol/L,NS) but decreased significantly in the BiV-group (from 198 ±505 pmol/L to 86 ± 95 pmol/L after 12 months, P = 0.02). Conclusion: BiV pacing minimizes LV dyssynchrony, preserves LV function,and reduces NT-proBNP in contrast to DDD(R) pacing in patientswith high-grade AV block.     

Regional myocardial blood flow in patients with sick sinus syndrome randomized to long-term single chamber atrial or dual chamber pacing--effect of pacing mode and rate

OBJECTIVES: This study aimed to evaluate regional myocardial blood flow (MBF) and global left ventricular ejection fraction (LVEF) during chronic pacing in patients with sick sinus syndrome (SSS) randomized to either single chamber atrial (AAI) or dual chamber (DDD) pacing. BACKGROUND: Experimental studies indicate that chronic pacing in the right ventricular apex changes regional MBF, thereby compromising left ventricular function. METHODS: Thirty patients (age 74 +/- 10 years) were randomized to AAI (n = 15) or DDD (n = 15) pacemakers. After 22 +/- 7 months of pacing, MBF was quantified with 13N-labeled ammonia positron emission tomography scanning at 60 beats per min and 90 beats per min. Patients in the DDD group furthermore underwent MBF measurement at temporary AAI pacing, 60 beats per min. Myocardial blood flow was assessed in the anterior, lateral, inferior and septal regions, and the global mean MBF was calculated. Left ventricular ejection fraction was determined by echocardiography at pacemaker implantation and at the time of MBF measurements. RESULTS: Myocardial blood flow at rates 60 and 90 beats per min did not differ between the AAI and DDD groups. During temporary AAI pacing in the DDD group, MBF was significantly higher than during DDD pacing in both the inferior (p = 0.001) and septal (p = 0.004) regions and also globally (0.61 +/- 0.15 vs. 0.53 +/- 0.13 mL x g(-1) x min(-1), p = 0.005). In the DDD group, LVEF decreased from pacemaker implantation to time of MBF measurements (0.61 +/- 0.09 vs. 0.56 +/- 0.07, p = 0.013). Left ventricular ejection fraction during temporary AAI pacing at time of MBF measurements was not different from LVEF at pacemaker implantation. CONCLUSIONS: In patients with SSS, chronic DDD pacing reduced inferior, septal and global mean MBF as well as LVEF, as compared with temporary AAI pacing. The LVEF reversed to baseline level during temporary AAI pacing despite 22 months of permanent ventricular pacing preceding it. Augmenting pace rate to 90 beats per min increased MBF equally in the two treatment groups.     

A randomized comparison of atrial and dual-chamber pacing in 177 consecutive patients with sick sinus syndrome: echocardiographic and clinical outcome

OBJECTIVES: A randomized trial was done to compare single-chamber atrial (AAI) and dual-chamber (DDD) pacing in patients with sick sinus syndrome (SSS). Primary end points were changes in left atrial (LA) size and left ventricular (LV) size and function as measured by M-mode echocardiography. BACKGROUND: In patients with SSS and normal atrioventricular conduction, it is still not clear whether the optimal pacing mode is AAI or DDD pacing. METHODS: A total of 177 consecutive patients (mean age 74 +/- 9 years, 73 men) were randomized to treatment with one of three rate-adaptive (R) pacemakers: AAIR (n = 54), DDDR with a short atrioventricular delay (n = 60) (DDDR-s), or DDDR with a fixed long atrioventricular delay (n = 63) (DDDR-l). Before pacemaker implantation and at each follow-up, M-mode echocardiography was done to measure LA and LV diameters. Left ventricular fractional shortening (LVFS) was calculated. Analysis was on an intention-to-treat basis. RESULTS: Mean follow-up was 2.9 +/- 1.1 years. In the AAIR group, no significant changes were observed in LA or LV diameters or LVFS from baseline to last follow-up. In both DDDR groups, LA diameter increased significantly (p < 0.05), and in the DDDR-s group, LVFS decreased significantly (p < 0.01). Atrial fibrillation was significantly less common in the AAIR group, 7.4% versus 23.3% in the DDDR-s group versus 17.5% in the DDDR-l group (p = 0.03, log-rank test). Mortality, thromboembolism, and congestive heart failure did not differ between groups. CONCLUSIONS: During a mean follow-up of 2.9 +/- 1.1 years, DDDR pacing causes increased LA diameter, and DDDR pacing with a short atrioventricular delay also causes decreased LVFS. No changes occur in LA or LV diameters or LVFS during AAIR pacing. Atrial fibrillation is significantly less common during AAIR pacing.     

AAI与DDD起搏对病窦综合征患者的影响

目的比较AAI与DDD起搏方式对有正常房室传导功能的病窦综合征患者预后的长期影响。方法104例因病窦综合征置入起搏器的患者,按不同起搏方式分为两组:AAI组36例,DDD组68例。术后随访内容包括起搏器程控,患者的症状、体征,心电图和/或动态心电图,超声心动图及心功能分级(NYHA)。主要终点为心房颤动(简称房颤)的发生率,次要终点为脑卒中的发生率,心功能分级及超声心动图检查指标。结果随访43.2±15.7(21～79)个月,①DDD组房颤发生率明显高于AAI组(20.6%vs5.6%,P<0.05),而脑卒中发生率无差异(7.4%vs2.8%,P>0.05);②左房内径、左室舒张末期内径和左室射血分数在AAI组置入前后无差异,而DDD组术后左房内径、左室舒张末期内径增大,左室射血分数下降(P均<0.05);③AAI组与DDD组比较,对心功能影响较小。结论对于房室传导功能正常的病窦综合征患者,与DDD起搏比较,AAI起搏房颤发生率较低,对心功能影响较小,更符合生理性。     

起搏方式对病态窦房结综合征患者的随访研究

目的 比较AAI起搏器与DDD起搏器不同的起搏方式对病态窦房结综合征(SSS)患者预后的长期影响.方法 86例因SSS植入起搏器的患者,按不同起搏方式分为两组,AAI起搏组32例,DDD起搏组54例.植入术后随访内容包括起搏器程控,患者的症状、体征,心电图或动态心电图,超声心动图及心功能.研究终点(1)心房颤动的发生率;(2)脑卒中的发生率;(3)心功能分级及超声心动图检查指标.结果 随访20～80(42.1±15.7)个月,(1)DDD组心房颤动(房颤)发生率明显高于AAI组(P＜0.05);(2)脑卒中发生率差异无统计学意义(P＞0.05);(3)左心房内径、左心室舒张末期内径和左心室射血分数在AAI组植入前后差异无统计学意义(P＞0.05),而DDD组术后左心房内径、左心室舒张末期内径增大,左心室射血分数下降(P＜0.05);(4)AAI组与DDD组比较,对心功能影响较小.结论 与DDD起搏方式比较,AAI起搏方式房颤发生率低,对心功能影响小.     

Multicenter, prospective, randomized safety and efficacy study of a new atrial-based managed ventricular pacing mode (MVP) in dual chamber ICDs

BACKGROUND: Ventricular desynchronization caused by right ventricular pacing may impair ventricular function and increase risk of heart failure (CHF), atrial fibrillation (AF), and death. Conventional DDD/R mode often results in high cumulative percentage ventricular pacing (Cum%VP). We hypothesized that a new managed ventricular pacing mode (MVP) would safely provide AAI/R pacing with ventricular monitoring and DDD/R during AV block (AVB) and reduce Cum%VP compared to DDD/R. METHODS: MVP RAMware was downloaded in 181 patients with Marquis DR ICDs. Patients were initially randomized to either MVP or DDD/R for 1 month, then crossed over to the opposite mode for 1 month. ICD diagnostics were analyzed for cumulative percentage atrial pacing (Cum%AP), Cum%VP, and duration of DDD/R pacing for spontaneous AVB. RESULTS: Baseline characteristics included age 66 +/- 12 years, EF 36 +/- 14%, and NYHA Class II-III 36%. Baseline PR interval was 190 +/- 53 msec and programmed AV intervals (DDD/R) were 216 +/- 50 (paced)/189 +/- 53 (sensed) msec. Mean Cum%VP was significantly lower in MVP versus DDD/R (4.1 +/- 16.3 vs 73.8 +/- 32.5, P < 0.0001). The median absolute and relative reductions in Cum%VP during MVP were 85.0 and 99.9, respectively. Mean Cum%AP was not different between MVP versus DDD/R (48.7 +/- 38.5 vs 47.3 +/- 38.4, P = 0.83). During MVP overall time spent in AAI/R was 89.6% (intrinsic conduction), DDD/R 6.7% (intermittent AVB), and DDI/R 3.7% (AF). No adverse events were attributed to MVP. CONCLUSIONS: MVP safely achieves functional atrial pacing by limiting ventricular pacing to periods of intermittent AVB and AF in ICD patients, significantly reducing Cum%VP compared to DDD/R. MVP is a universal pacing mode that adapts to AVB and AF, providing both atrial pacing and ventricular pacing support when needed.     

不同起搏模式对病态窦房结综合征患者心功能长期影响的探讨

目的前瞻性观察不同起搏模式对心功能长期的影响并探讨可能机制。方法 185例病态窦房结综合征（SSS）患者均采用常规方法经锁骨下静脉途径成功置入永久双腔心脏起搏器,术后即刻程控起搏器,根据SAS软件的PROC程序产生一组随机序列分为AAI（92例）及DDD（93例）起搏组。采用心脏超声观察术前,术后1、2、5年左室舒张末容积（LVEDV）、左室收缩末容积（LVESV）及左室射血分数（LVEF）的变化,比较两种起搏模式对左心功能的影响;术后1、2及5年进行随访结合起搏器程控记录房颤发生并记录DDD起搏组右室起搏百分比（VP%）,探讨VP%与心功能变化及房颤发生的关系。结果 AAI起搏组术前,术后1、2、5年随访LVEDV,LVESV及LVEF比较差异无统计学意义（P〉0.05）,DDD起搏组术前、术后1、2、5年LVEDV差异无统计学意义（P〉0.05）,术后5年LVESV（60.33±13.28）ml较术后1、2年增加,差异有统计学意义（F=2.7388,P〈0.05）,术后5年LVEF（41.75±8.74）%较术前、术后1、2年明显降低,差异有统计学意义（F=33.4393,P〈0.05）;AAI组与DDD组房颤的发生差异有统计学意义（P〈0.05）。术后5年DDD组中〈50%VP%,组中出现房颤患者为3例,≥50%VP%组中出现房颤患者为15例,两组之间房颤的发生率差异有统计学意义（P〈0.05）。结论在DDD起搏模式下,高的VP%可对患者的左心功能造成损害并增加房颤的发生。对于不合并房室传导阻滞的SSS患者,AAI起搏较DDD起搏能使患者更受益。     

Relative importance of activation sequence compared to atrioventricular synchrony in left ventricular function

This study evaluated the relative hemodynamic importance of a normal left ventricular (LV) activation sequence compared to atrioventricular (AV) synchrony with respect to systolic and diastolic function. Twelve patients with intact AV conduction and AV sequential pacemakers underwent radionuclide studies at rest and Doppler echocardiographic studies at rest and during submaximal exercise, comparing atrial demand pacing (AAI) to sequential AV sensing pacing (DDD) and ventricular demand pacing (VVI). Studies at rest were performed at a constant heart rate between pacing modes, and the exercise study was performed at a constant heart rate and work load. Cardiac output was higher during AAI than during both DDD and VVI (6.2 +/- 1 vs 5.6 +/- 1 and 5.3 +/- 1 liters/min, p less than 0.05). LV ejection fraction was likewise higher during AAI (55 +/- 12 vs 49 +/- 11 vs 51 +/- 13, p less than 0.05). VVI with or without AV synchrony was associated with a paradoxical septal motion pattern, resulting in a 25% impairment of regional septal ejection fraction. In addition, LV contraction duration was more homogenous during AAI. Peak filling rate during AAI and VVI was higher than during DDD (2.86 +/- 1 and 2.95 +/- 1 vs 2.25 +/- 1 end-diastolic volume/s; p less than 0.05). During VVI, the time to peak filling was significantly shorter than during both AAI and DDD (165 +/- 34 vs 239 +/- 99 and 224 +/- 99 ms; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Right atrial pacing impairs cardiac function during resynchronization therapy: acute effects of DDD pacing compared to VDD pacing

OBJECTIVES: We aimed to compare the hemodynamic effects of right-atrial-paced (DDD) and right-atrial-sensed (VDD) biventricular paced rhythm on cardiac resynchronization therapy (CRT). BACKGROUND: Cardiac resynchronization therapy improves hemodynamics in patients with severe heart failure and left ventricular (LV) dyssynchrony. However, the impact of active right atrial pacing on resynchronization therapy is unknown. METHODS: Seventeen CRT patients were studied 10 months (range: 1 to 46 months) after implantation. At baseline, the programmed atrioventricular delay was optimized by timing LV contraction properly at the end of atrial contraction. In both modes the acute hemodynamic effects were assessed by multiple Doppler echocardiographic parameters. RESULTS: Compared to DDD pacing, VDD pacing resulted in much better improvement of intraventricular dyssynchrony assessed by the septal-to-posterior wall motion delay (VDD 106 +/- 83 ms vs. DDD 145 +/- 95 ms; p = 0.001), whereas the interventricular mechanical delay (difference between onset of pulmonary and aortic outflow) did not differ (VDD 20 +/- 21 ms vs. DDD 18 +/- 17 ms; p = NS). Furthermore, VDD pacing significantly prolonged the rate-corrected LV filling period (VDD 458 +/- 123 ms vs. DDD 371 +/- 94 ms; p = 0.0001) and improved the myocardial performance index (VDD 0.60 +/- 0.18 vs. DDD 0.71 +/- 0.23; p < 0.01). CONCLUSIONS: Our findings suggest that avoidance of right atrial pacing results in a higher degree of LV resynchronization, in a substantial prolongation of the LV filling period, and in an improved myocardial performance. Thus, the VDD mode seems to be superior to the DDD mode in CRT patients.     

Randomized pilot study of a new atrial-based minimal ventricular pacing mode in dual-chamber implantable cardioverter-defibrillators

OBJECTIVE: We hypothesized that a new minimal ventricular pacing mode (MVP) that provides AAI/R pacing with ventricular monitoring and back-up DDD/R pacing as needed during AV block (AVB) would significantly reduce cumulative percent ventricular pacing compared to DDD/R. BACKGROUND: Conventional DDD/R mode often results in high cumulative percent ventricular pacing that may adversely affect ventricular function and increase risk of heart failure and atrial fibrillation. METHODS: MVP was made operational in 30 patients with DDD/R implantable cardioverter-defibrillators (ICDs) and no history of AVB. Patients were randomized to one week each in DDD/R and MVP. Holter monitor recordings (ECG, intracardiac electrograms, and event markers) and device diagnostics were analyzed for cumulative % atrial paced (Cum%AP), cumulative percent ventricular pacing, and frequency and duration of DDD/R pacing back-up. Diaries were used to report symptoms. RESULTS: Age of the study population was 61 years +/- 12 years and 83% were male. Baseline PR interval was 204 ms +/- 32 ms and programmed AV intervals (DDD/R) were 200 ms +/- 50 ms (paced)/167 ms +/- 54 ms (sensed). Cum%AP was similar between MVP and DDD/R (47.9 +/- 37 vs 46.3 +/- 36). Cumulative percent ventricular pacing was significantly lower in MVP vs DDD/R (3.79 +/- 16.3 vs 80.6 +/- 33.8, P < .0001). Back-up DDD/R pacing during MVP operation due to transient AVB occurred in 10% of patients (9.3 +/- 7.4 [range 1-15] episodes/patient-day, duration 39.7 minutes +/- 156 minutes). Fifteen percent of AV intervals during MVP operation exceeded 300 ms. No significant symptoms were reported during MVP operation. CONCLUSIONS: MVP dramatically reduced cumulative percent ventricular pacing compared to DDD/R while maintaining AV synchrony and providing sensor-modulated atrial pacing support. Intermittent oscillations between MVP and DDD/R during transient AV block appeared safe and well tolerated.     

Hemodynamic effects of atrial septal pacing in cardiac resynchronization therapy patients

INTRODUCTION: Spontaneous or pacing-induced interatrial conduction delay may affect the outcome of heart failure patients treated with cardiac resynchronization therapy (CRT). The objective of this study was to evaluate the impact of the atrial pacing site (right atrial appendage, RAA; and low interatrial septum, LIS) during biventricular (BV) pacing on the left ventricular (LV) systolic function in candidates for CRT. METHODS AND RESULTS: Fifteen heart failure patients with left bundle branch block and LV ejection fraction < or =35% were enrolled. Electrodes were placed at the RAA, LIS, right ventricular apex, and LV free wall. A DDD protocol was tested, which consisted of 50 beats in AAI mode from the RAA followed by 50 beats in BV DDD mode with atrial pacing at the RAA (DDD_RAA) or at the LIS (DDD_LIS) at four AV delays. The average (+/-SD)%LV+dP/dtmax increase during DDD_RAA and DDD_LIS pacing with respect to baseline was 24 +/- 16% and 21 +/- 15%, respectively (P < 0.01), and average percentage change in aortic pulse pressure during DDD_RAA and DDD_LIS with respect to baseline (%PP) was 13 +/- 8% and 13 +/- 7% (ns). CONCLUSIONS: Our results show a significant hemodynamic improvement with both DDD_RAA and DDD_LIS biventricular pacing compared to AAI pacing. However DDD_LIS pacing was not superior to DDD_RAA pacing in acute hemodynamic responses.     

Realisierbarkeit und Sicherheit einer alleinigen AAI(R)-Schrittmacherbehandlung beim isolierten symptomatischen Sinusknotensyndrom

Recent investigations prove that AAI(R) pacing is the "ideal" stimulation mode in isolated sick sinus syndrome. Nevertheless, in Germany this bradycardia is treated by AAI(R) pacemakers in less than 4% of cases compared to 25% in other countries. In our institution treatment of patients with isolated sick sinus syndrome is uniform and corresponds to the actual guidelines since the early 1990s; therefore the aim of our study was to analyze feasibility and safety of AAI(R) pacing in a retrospective study.Between 1998 and 2000, 52 of 165 patients (31.5%) with isolated sick sinus syndrome were treated by an AAI(R) pacemaker. The median follow-up duration was 51.5 months (minimal: 36 months). 6 patients died, in all cases unrelated to the stimulation mode. Three patients required reoperations, however, in only one case due to second degree AV block with the need for upgrading to DDD stimulation. Thus, the yearly incidence of this specific complication in the AAI(R) cohort is 0.64%.In conclusion, permanent atrial stimulation in isolated sick sinus syndrome is feasible in a quarter of all cases. It is safe if performed corresponding to actual guidelines. Additionally, single lead AAI(R) pacing is a cost-effective therapy and the only stimulation mode which, today, reliably prevents unnecessary right ventricular stimulation. If, on the other hand, algorithms providing automatic mode switching from AAI to DDD and vice versa are implemented reliably into all dual chamber pacemakers, single chamber atrial pacing will no longer be a subject for discussion.     

Effect of triangle ventricular pacing on haemodynamics and dyssynchrony in patients with advanced heart failure: a comparison study with conventional bi-ventricular pacing therapy.

AIMS: This study examined the impact of cardiac resynchronization therapy (CRT) by triangle ventricular pacing (Tri-V) on left ventricular (LV) function and dyssynchrony. METHODS AND RESULTS: Twenty-one patients with NYHA class III or IV heart failure were studied. For Tri-V, two right ventricular (RV) leads were connected to the CRT device via a Y-connector with one lead anchored at the RV apex and the other at the RV outflow tract. The LV lead was positioned in the posterolateral or lateral cardiac vein. CRT with standard bi-ventricular pacing (Bi-V) was performed with the RV apical and LV leads. LV function was assessed by the measurement of LV positive dp/dt (dP/dt(max)) and cardiac output (CO). LV dyssynchrony was assessed using the standard deviation of the time to peak myocardial velocity during the systolic phase in 12 LV segments (Ts-SD) derived from tissue Doppler images. In comparison to Bi-V, Tri-V increased dP/dt(max) (baseline, 746 +/- 165; Bi-V, 909 +/- 186; Tri-V, 959 +/- 195 mmHg/s, P = 0.04) and CO (baseline, 3.1 +/- 1.0; Bi-V, 3.4 +/- 1.1; Tri-V, 3.8 +/- 1.2 L/min, P < 0.001), decreased Ts-SD (baseline, 54.0 +/- 35.0; Bi-V, 33.6 +/- 15.3; Tri-V, 22.4 +/- 8.1 ms, P = 0.02). CONCLUSION: The acute beneficial effects of Tri-V on LV function and dyssynchrony were greater than those of Bi-V.     

实时三维超声心动图评价永久起搏患者左心室收缩同步性和心功能

目的 探讨应用实时三维超声心动图(RT-3DE)评价永久起搏患者左心室收缩同步性和心功能.方法 15例病态窦房结综合征置入双腔起搏器患者,分别将起搏模式程控为心房抑制型按需起搏(AAI)、房室按需型起搏(DDD)、心室抑制型按需起搏(VVI),每种起搏模式稳定5 min后,在RT-3DE下取左心室全容积图像.应用Qlab4.2脱机分析软件,获得左心室整体与17节段容积-时间曲线和比较左心室16、12、6节段心电图QRS波起点至左心室最小容积点时间的标准差和最大时间差(即Tmsv16-s、Tmsv12-s、Tmsv6-s、Tmsv16-dif、Tmsv12-dif、Tmsv6-dif)、左心室舒张末期容积、左心室收缩末期容积、左心室射血分数、左心室舒张早期峰值充盈率、左心室17节段的舒张末期容积、收缩末期容积和节段射血分数.结果 心室同步性指标容积-时间曲线和Tmsv16-s、Tmsv12-s、Tmsv6-s、Tmsv16-dif、Tmsv12-dif、Tmsv6-dif在AAI模式明显优于DDD、VVI模式(P<0.05),心功能指标左心室射血分数、左心室舒张早期峰值充盈率在AAI模式下显著高于DDD和VVI模式(P<0.05);DDD和VVI模式的上述指标差异无统计学意义(P>0.05);DDD与VVI模式时左心室前间隔、下壁和后壁基底段、心尖段节段射血分数较AAI模式明显降低(P<0.05).结论 采用RT-3DE可客观准确地评价永久起搏患者左心室收缩同步性和心功能.     

Speckle-tracking radial strain reveals left ventricular dyssynchrony in patients with permanent right ventricular pacing.

OBJECTIVES: Speckle-tracking strain analysis was used to assess the effects of permanent right ventricular (RV) pacing on the heterogeneity in timing of regional wall strain and left ventricular (LV) dyssynchrony. BACKGROUND: Recent studies have shown detrimental effects of RV pacing, possibly related to the induction of LV dyssynchrony. METHODS: Fifty-eight patients treated with His bundle ablation and pacemaker implantation were studied. To assess the effect of RV pacing on time-to-peak radial strain of different LV segments, we applied speckle-tracking analysis to standard LV short-axis images. In addition, New York Heart Association (NYHA) functional class, LV volumes, and systolic function were assessed at baseline and after long-term RV pacing. RESULTS: At baseline, similar time-to-peak strain for the 6 segments was observed (mean 371 +/- 114 ms). In contrast, after a mean of 3.8 +/- 2.0 years of RV pacing, there was a marked heterogeneity in time-to-peak strain of the 6 segments. In 33 patients (57%), LV dyssynchrony, represented by a time difference > or =130 ms between the time-to-peak strain of the (antero)septal and the posterolateral segments, was present. In these patients, a deterioration of LV systolic function and NYHA functional class was observed. In 11 patients, an "upgrade" of the conventional pacemaker to a biventricular pacemaker resulted in partial reversal of the detrimental effects of RV pacing. CONCLUSIONS: Speckle-tracking analysis revealed that permanent RV pacing induced heterogeneity in time-to-peak strain, resulting in LV dyssynchrony in 57% of patients, associated with deterioration of LV systolic function and NYHA functional class. Biventricular pacing may reverse these adverse effects of RV pacing.     

Impact of right atrial-left ventricular dual-chamber permanent pacing in patients with severely symptomatic hypertrophic obstructive cardiomyopathy.

BACKGROUND: Effective alternatives to surgical myectomy for patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM) remain unestablished. Dual-chamber (DDD) pacing was evaluated in these patients using right atrial (RA) and epicardial left ventricular (LV) leads. METHODS AND RESULTS: In 6 patients with HOCM refractory to medical therapy and conventional RA-right ventricular (RV) DDD pacing, we implanted DDD pacemakers using RA and epicardial LV leads. The baseline intraventricular pressure gradient before pacemaker implantation was 103+/-44 mmHg. The pressure gradient decreased significantly to 8+/-16 mmHg by temporary RA-LV DDD pacing (p=0.006), while it decreased only to 68+/-25 mmHg by temporary RA-RV pacing (NS). It was nearly eliminated to 1+/-2 mmHg (p=0.027) 3 months after RA-LV DDD pacemaker implantation. LV end-diastolic pressure, cardiac index and systolic aortic pressure did not change significantly. New York Heart Association class improved in all patients (p=0.023). Brain and atrial natriuretic peptide concentrations, respectively 516+/-286 and 143+/-34 pg/ml at baseline, decreased significantly to 230+/-151 and 93+/-44 pg/ml 3 months after implantation (p=0.027 and 0.028). CONCLUSION: RA-LV DDD pacemaker implantation is a useful option for patients with symptomatic HOCM.     

Altered cardiac hemodynamic and electrical state in normal sinus rhythm after chronic dual-chamber pacing for relief of left ventricular outflow obstruction in hypertrophic cardiomyopathy.

Dual-chamber (DDD) pacing relieves left ventricular (LV) outflow tract obstruction in patients with hypertrophic cardiomyopathy. The reduction in LV outflow gradient persists in some patients after cessation of pacing. Twelve-lead and signal-averaged electrocardiograms were obtained before and after 12 weeks of DDD pacing in 18 patients with obstructive hypertrophic cardiomyopathy to determine whether the altered hemodynamic state after chronic pacing is accompanied by electrical changes. Hemodynamic studies were performed at baseline and at follow-up. Signal-averaged electro-cardiograms were obtained using a Corazonix Predictor and bidirectional filters at 25 Hz to a noise level of less than 0.5 microV. At follow-up, LV outflow tract gradients were reduced significantly during DDD pacing and with cessation of pacing in sinus rhythm by 56 +/- 10 and 47 +/- 10 mm Hg, respectively (p less than 0.001). There was no simple relation between changes in LV outflow tract gradient and in the electrocardiogram. For example, amplitude of the R wave in V5,6 was reduced by greater than or equal to 0.5 mv in 4 patients, unchanged in 12 and increased in 2. Similarly, the S wave in leads V1,2 was reduced in 7 patients, unchanged in 7 and increased in 4. The T wave became more negative (greater than or equal to 0.1 mv) in leads II, III, aVF and V5,6 in 13 patients and more positive in leads I and aVL in 12.(ABSTRACT TRUNCATED AT 250 WORDS)     

Asynchronism and right ventricular pacing

In patients with congenital heart block (CHB), dual-chamber pacing restores physiological heart rate and atrio-ventricular synchronization. However, patients with narrow QRS junctional escape rhythm may be deleteriously affected by long-term, permanent, apical ventricular pacing. We assessed the impact of apical ventricular pacing on echocardiographic ventricular dyssynchrony and hemodynamic parameters. METHODS: Fourteen CHB adults (23 +/- years, 58% male), with a DDD transvenous pacemaker and a junctional escape rhythm (QRS<120 ms) before implantation, were studied. Echocardiography coupled with tissue Doppler imaging (TDI) and Strain rate was performed in spontaneous rhythm (VVI mode 30/mn) and during atrio-synchronized ventricular pacing. RESULTS: The heart rate (43 +/- 09 vs 68 +/- 07: p<0.01), cardiac output (2.9 +/- 0.7 vs 3.7 +/- 0.6 L/min) and left ventricular filling time (325 +/- 38 vs 412 +/- 51 ms; p<0.01) were significantly less in the escape spontaneous rhythm compared with atrio-ventricular synchronized apical pacing. However, interventricular dyssynchrony (28 +/- 12 vs 59 +/- 25 ms, p<0.05), intra-left ventricular dyssynchrony (36 +/- 11 vs 57 +/- 29 ms; p<0.05), extent of left ventricular myocardium displaying delayed longitudinal contraction (26 +/- 10 vs 39 +/- 17%: p<0.05) were significantly less in the escape rhythm compared with paced rhythm. CONCLUSION: Once implanted with a DDD pacemaker, CHB patients present with increased cardiac output secondary to the restoration of physiological heart rate and improved diastolic function. However, the apical site is not optimal, as it creates detrimental ventricular dyssynchrony in patients with previous nearly physiological ventricular activation. Alternative pacing sites should be investigated.     

Cardiac resynchronization therapy improves left ventricular remodeling and function compared with right ventricular pacing in patients with atrioventricular block

Right ventricular pacing (RVP) exerts a detrimental effect on left ventricular (LV) remodeling. In patients with atrioventricular block (AVB) that require ventricular pacing, the effect of biventricular pacing (BiVP) versus RVP on LV remodeling and function has not been comprehensively assessed in a meta-analysis. Electric databases MEDLINE and Cochrane Library were retrieved for randomized controlled trials (RCT) comparing RVP and BiVP in patients with AVB. Data on left ventricular ejection fraction (LVEF) and LV volumes were analyzed, stratified by different time points. Eleven RCTs were included in the final analysis. There was a significant reduction of LV end-systolic volume in BiVP compared with RVP, at 3, 6, 12, and 24 months follow-up (P?<?0.05 for all). BiVP was associated with a decreased LV end-diastolic volume in comparison to RVP at 3, 6, and 12 months. Compared with RVP, BiVP had a higher LVEF at all follow-up visits, with mean difference of 5.91, 3.29, 3.9, 6.66, and 8.69% at 3, 6, 12, 24, and beyond 24 months follow-up, respectively. The results were not significantly changed in sensitivity analysis after removal of studies with mean baseline LVEF <?50% or excluding studies with ablation-induced AVB. In patients with AVB and bradycardia that require ventricular pacing, BiVP is superior to RVP in improving LV remodeling and function.     

Left ventricular dyssynchrony predicts right ventricular remodeling after cardiac resynchronization therapy.

OBJECTIVES: The purpose of this research was to evaluate right ventricular (RV) remodeling after six months of cardiac resynchronization therapy (CRT). BACKGROUND: Cardiac resynchronization therapy is beneficial in patients with end-stage heart failure. The effect of CRT on RV size is currently unknown. Accordingly, the effects of CRT on RV size, severity of tricuspid regurgitation, and pulmonary artery pressure were evaluated. METHODS: Fifty-six consecutive patients with end-stage heart failure (52% ischemic cardiomyopathy), left ventricular (LV) ejection fraction (EF) < or =35%, QRS duration >120 ms, and left bundle branch block were included. Clinical parameters, LV volumes, LVEF, LV dyssynchrony, and RV chamber size were assessed at baseline and after six months of CRT; LV dyssynchrony was assessed using tissue Doppler imaging. RESULTS: Clinical parameters improved significantly; LV dyssynchrony was acutely reduced after CRT and remained unchanged at six-month follow-up. Left ventricular EF improved significantly from 19 +/- 6% to 26 +/- 8% (p < 0.001), and LV end-diastolic volume decreased from 257 +/- 98 ml to 227 +/- 86 ml (p < 0.001). Right ventricular annulus decreased significantly from 37 +/- 9 mm to 32 +/- 10 mm, RV short-axis from 29 +/- 11 mm to 26 +/- 7 mm, and RV long-axis from 89 +/- 11 mm to 82 +/- 10 mm (all p < 0.001). Left ventricular and RV reverse remodeling were only observed in patients with substantial LV dyssynchrony at baseline. Finally, significant reductions in severity of tricuspid regurgitation and pulmonary artery pressure were observed. CONCLUSIONS: Cardiac resynchronization therapy results in significant reverse LV and RV remodeling after six months of CRT in patients with LV dyssynchrony. Moreover, CRT leads to a reduction of the severity of tricuspid regurgitation and a decrease in pulmonary artery pressure.