右室间隔部起搏与右室心尖部起搏对患者心功能的影响

目的探讨右室间隔部起搏(right ventricular septum pacing,RVS)与右室心尖部起搏(right ventricular apex pa-cing,RVA)对心功能的影响。方法 45例Ⅲ度或高度房室传导阻滞或病态窦房结综合征行永久起搏器置入患者分为RVA组(24例)与RVS组(21例)。随访术后不同时期超声心动图,监测左室射血分数(LVEF)、左室舒张末期内径(LVDd)、左室Tei指数变化。结果 RVA组术后LVEF与术前比较呈逐渐降低趋势,LVDd呈持续增大趋势,差异有统计学意义(P<0.05)。RVS组术后LVEF、LVDd与术前比较均无明显变化,差异无统计学意义(P>0.05)。两组Tei指数在术后均持续增大,术后1天、12月与24月组间比较差异有统计学意义(P<0.05)。结论右室间隔部起搏较右室心尖部起搏对左心功能影响更小。     

右室心尖部起搏对完全性房室传导阻滞高龄患者心功能的影响

目的探讨心脏永久起搏器在心功能基本正常的高龄患者中的应用,评价右室心尖部(RVA)起搏对高龄患者心功能的影响。方法43例年龄≥75岁的完全性房室传导阻滞患者分为两组,VVI型起搏器23例,DDD型起搏器20例,心房电极置于右心耳,心室电极置于右室心尖部。术后平均随访12个月,了解患者自觉症状、运动耐量(6min步行距离试验)、起搏器功能情况及左室射血分数(LVEF)和脑利尿钠肽(BNP)水平。结果所有患者随访期间起搏器功能正常,新发生心房颤动5例;与术前相比,术后6分钟步行距离有改善[(368.58±65.74)mvs(377.47±57.72)m,P<0.01],LVEF无改变[(52.05±4.71)%vs(51.86±4.77)%,P>0.05],血浆BNP升高[(234.93±151.86)ng/Lvs(262.07±122.53)ng/L,P<0.05];术后随访期间,6分钟步行距离、LVEF和全血BNP,VVI组和DDD组相比无差别。结论高龄患者完全RVA起搏改善症状,未观察到加重心功能损害状况。     

右室心尖部起搏和右室流出道起搏最佳房室延迟的比较

目的:对右室流出道(RVOT)起搏的房室延迟(AVD)优化进行探讨,并对RVOT起搏与右室心尖部(RVA)起搏患者的最佳AVD进行比较。方法:入选因高度或Ⅲ度房室传导阻滞植入DDD起搏器的患者50例,其中RVA起搏组25例,RVOT起搏组25例。通过心脏超声测得主动脉血流速度时间积分(AVTI)及左室充盈时间(LVFT),以产生最大的AVTI及最长的LVFT对应的AVD为最佳的AVD。结果:以AVTI优化AVD后,RVA起搏组[(22.57±5.00)cmvs(25.05±4.45)cm,P<0.001]及RVOT组[(21.99±4.78)cmvs(25.18±4.37)cm,P<0.001]的AVTI均增加,两组的AVTI增加量差异无显著性[(2.50±1.86)cmvs(3.14±1.45)cm,P>0.05]。以LVFT优化AVD后,RVA起搏组[(22.57±5.00)cmvs(24.34±4.12)cm,P<0.001]及RVOT组[(21.99±4.78)cmvs(24.88±3.84)cm,P<0.001]的AVTI也均增加,两组的AVTI增加量差异也无统计学意义[(1.89±1.74)cmvs(2.03±1.58)cm,P>0.05]。直线相关分析显示,AVTI优化的AVD与LVFT优化的AVD显著相关(R=0.79,P<0.0001),但AVTI优化的AVD比LVFT优化的AVD明显长[(134.63±34.46)msvs(114.30±31.28)ms,P<0.001]。RVA起搏组及RVOT起搏组AVTI优化的AVD差异无显著性[(136.47±39.36)msvs(132.78±29.64)ms,P>0.05],LVFT优化的AVD也无统计学差异[(119.23±35.03)msvs(109.36±27.35)ms,P>0.05]。结论:AVD优化能使RVA起搏和RVOT起搏患者均获益,RVOT起搏与RVA起搏相比最佳的AVD差异无显著性。     

右心室间隔部起搏与心尖部起搏对起搏依赖患者心功能的长期影响

目的:通过超声心动图评价右心室间隔部起搏与右心室心尖部起搏对起搏依赖患者心功能的长期影响.方法:56例行DDD永久起搏器植入的Ⅲ度房室传导阻滞患者,根据右心室电极植入部位随机分为右心室间隔部起搏组29例(RVS组),心尖部起搏组27例(RVA组).平均随访(22.64±4.29)个月,通过超声心动图比较术前和随访时的左室舒张末内径(LVEDD)、射血分数(LVEF)、短轴缩短率(FS)、每搏输出量(SV)的变化.结果:术前基线RVS组与RVA组年龄、LVEDD、EF、FS、SV无差别;RVS组术前与随访时比较LVEDD、EF、FS、SV无差别,RVA组术前与随访时LVEDD、EF、FS、无差别.SV降低(P<0.05);随访时两组间各指标之间无明显差异(P均>0.05).结论:对于完全依赖右心室起搏的患者,在左室收缩功能方面,右心室间隔部起搏并不优于传统的心尖部起搏.     

右室流出道间隔部起搏与右室心尖部起搏对心室同步化的影响

目的:探讨右室流出道间隔部起搏(RVSP)与右室心尖部起搏(RVAP)对心室电、机械同步化影响的差异.方法:收集我院Ⅲ度房室传导阻滞患者共15例,均因心动过缓在入院后行临时右室心尖部起搏.术后24～48 h行右室流出道间隔部永久起搏.分别在两次术后观察心室起搏状态下心电图QRS时限,左右心室延迟时间(IVMD),室间隔与左心室后壁间的收缩延迟时间(SPWMD),QRS波起点距左心室12节段收缩速度峰值的时间标准差(Ts12SD).通过上述指标来评估RVSP与RVAP对心室电机械同步性影响的差异.结果:与RVAP相比较,RVSP组心电图QRs时限更短(P=0.007),心室收缩同步化指标IVMD,SPWMD,Ts12SD明显优于RVAP(P=0.000 9,P=0.000 5,P=0.000 4).结论:RVsP较RVAP更有利于保证心室电、机械同步化.     

右心室心尖部起搏与右心室流出道间隔部起搏对心室高频事件及室性早搏的影响

目的 观察右心室不同起搏比例及不同起搏部位,包括心尖部（RVA）起搏与右心室流出道间隔部（RVOT）起搏对心室高频事件（VHR）和室性早搏（PVC）影响.方法 选取2008年1月至2011年2月因病态窦房结综合征或房室传导阻滞在南京鼓楼医院植入双腔起搏器的患者.依据心室电极植入部位分为RVOT组及RVA组.起搏器植入12个月时进行随访,收集起搏器记录的心律失常数据及心室起搏比例.结果 共入组了96例患者,RVA组及RVOT组各48例.术前两组患者间心功能及24h动态心电图记录的PVC比较无差异.术后12个月随访,依据心室起搏比例,将患者分为三组,VP＜ 10％组、VP 11％～89％组及VP ＞90％组.在RVOT组及RVA组的组内比较结果显示,随着心室起搏比例的增加,VHR及PVC均逐渐减少.组间比较结果,RVA组及RVOT组的VHR无统计学差异（VP＜ 10％组,P=0.2;VP 11％～89％组,P=0.3;VP ＞90％组,P=0.2）,但RVA组的PVC在各起搏比例组的发生均明显高于RVOT组（VP＜ 10％组,P=0.01;VP 11％ ～89％组,P=0.04;VP ＞90％组,P=0.02）,其差异有统计学意义.结论 随着心室起搏比例的增加,PVC及VHR发生率减少,RVA组PVC的发生率高于RVOT组.     

右心室流出道间隔部起搏和右心室心尖部起搏对血流动力学的影响

自上世纪60年代心室单腔起搏器在临床使用,经过数十年的发展,目前起搏器的常规起搏部位仍为右心室心尖部。由于该部位电极导线固定容易而得到广泛应用,但严重的缺点是改变了正常的心室激动顺序。来源于动物与人群的基础研究表明,长期的右心室心尖部(RVA)起搏可以损害左心室收缩     

不同右心室心尖部起搏百分比对心功能的影响

目的 探讨在不同心室起搏百分比(CUM%VP,即起搏心室率占总心室率的百分比)时长期右心室心尖部起搏(RVA)对基础心功能正常患者心室结构和心功能的影响.方法 选取安装起搏器时基础心功能正常、因行起搏器更换和门诊复诊起搏器的患者为研究对象,CUM%VP≥85%组78例,CUM%VP≤40%组63例.以新发心力衰竭、死亡及左心室重构、功能受损为终点,比较2组之间的发生率;同时观察左心室舒张末期内径(LVEDD)、左心室射血分数(LVEF)、室间隔厚度(IVS)从基线至随访结束时的改变(ALVEDD、△LVEF、△IVS).结果 两次评估相隔的平均时间CUM%VP≥85%组为7.4年,CUM%VP≤40%组为7.7年.起搏前2组患者年龄、性别、总起搏时间、起搏模式、基础疾病及心脏超声指标等情况基本相似,差异无统计学意义(P均＞0.05);随访结束时,CUM%VP≥85%组与CUM%VP≤40%组△LVEDD分别为(3.8±0.5)、(1.4±0.4)mm(t=4.540,P＜0.01),△LVEF分别为(-6.5±1.2)%、(-3.3±1.0)%(t=2.578,P=0.011),而△IVS比较差异无统计学意义;随访结束时2组均无死亡,CUM%VP≥85%组和CUM%VP≤40%组左心室重构、功能受损发生率分别为25.6%(20/78)、6.3%(4/36),差异有统计学意义(x2=9.183,P=0.002);新发心力衰竭发生率分别为10.3%(8/78)、1.6%(1/36),2组比较差异有统计学意义(x2=4.383,P=0.036).结论 基础心功能正常患者长期右心室心尖部起搏(RVA)存在发生心室重构、功能受损和心力衰竭的可能,起搏时间越长、CUM%VP越高其发生风险越大.

Abstract：

Objective To evaluate the effect of permanent right ventricular apical (RVA) pacing in different cumulative percent of right ventricular pacing( CUM% VP) on the heart function and cardiac ventricle structure in subjects with normal basic heart function. Methods Patients who had implanted pacemaker when heart function was still normal were recruited in the study while they revisited for replacement or examinations of implanted pacemaker at outpatient. According to different CUM% VP, patients were divided into group A ( CUM% VP≥85% ,n =78) and group B( CUM% VP≤40% ,n =63) . The primary composite endpoint was defined as new-onset heart failure, death, left ventricular ( LV ) dysfunction and remodeling. The occurrence of endpoints were compared between the two groups. The left ventricular end-diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF) and interventricular septum(IVS) were measured through baseline and follow-up, their absolute alterations ( △ LVEF, △ LVEDD and △ IVS ) were observed. Results The mean duration of two assessment was 7.4 years in group A and 7.7 years in group B, respectively. Before pacemaker implantation,there were no differences in age, sex, basic diseases, cardiac function and constituent ratio of pacemakers between the two groups. By comparing the outcomes of group A with those of group B at the end of follow up, we found that: △ LVEDD in group A was significantly larger than that in group B ( [3. 8 ± 0. 5] mm vs [1.4 ± 0. 4] mm,t = 4. 540,P ＜ 0. 01 ), △ LVEF was ( - 6.5 ± 1.2) % and ( - 3.3 ± 1.0) % in group A and B, respectively,with significant difference between the two groups(t = 2. 578 ,P ＜0. 01 ). There were no significant difference in AIVS between the two groups. No death occurred in both group at the end of follow up. The incidence of LV dysfunction and remodeling was 25.6% (20/78) in group A,which was significantly higher than that of 6.3% (4/63) in group B( x2 =9. 183 ,P =0. 002). and the incidence of new-onset heart failure was 10. 3% (8/78)in group A,which was significantly higher than that of 1.6% (1/63) in group B (x2 =4.383,P =0.036).Conclusion Among patients with normal basic LV function who underwent permanent RVA pacing,there are potential risk in developing LV remodel, function damage and heart failure. The risk increases with the pacing time getting longer and CUM% VP getting higher.     

右心室流入道间隔部和右心室心尖部起搏神经内分泌激素和心功能的变化

目的探讨右心室流入道间隔部(RVIS)和右心室心尖部(RVA)起搏治疗缓慢性心律失常神经内分泌激素和心功能的变化。方法房室全能型起搏器(DDD)治疗患者106例,男86例,女20例,年龄45～86岁,平均(76.4±9.5)岁,随机分为右心室流入道间隔部起搏组(RVIS起搏组)56例,右心室心尖部起搏组(RVA起搏组)50例。两组心房电极均植入右心耳梳状肌内,RVIS起搏组心室电极植入右心室流入道间隔部、RVA起搏组心室电极植入右心室心尖部。分别观察两组在起搏器植入时、起搏3个月和6个月不同时期,血浆肾素活性(PRA)、血管紧张素Ⅱ(AngⅡ)、醛固酮(ALD)、心钠肽(BNP)和去甲肾上腺素(NE)等神经内分泌激素的含量;应用彩色多普勒超声心动图测定:心排血量(CO)、每搏输出量(SV)、射血分数(EF)和左心室舒张末内径(LVDd)。结果 RVA起搏组治疗后,血浆PRA、AngⅡ、ALD、BNP和NE含量增加,而RVIS起搏组则明显下降;RVIS起搏组心功能改善明显:CO、SV和EF值明显增加,LVDd值缩小,RVA起搏组SV、EF值下降,LVDd增加,CO虽然有所增加,但不如RVIS起搏组明显,差异均有统计学意义(P<0.05)。结论 RVIS起搏优于RVA起搏,可明显改善心功能,纠正神经内分泌激素失调,值得临床推广。     

右室间隔部与心尖部起搏影响心功能的对比分析

目的对比分析右室间隔部起搏和心尖部起搏对患者心功能的长期影响。方法连续选取高度以上房室传导阻滞患者分别行右室间隔部起搏和心尖部起搏,随访观察两组手术情况、电极参数变化、心电图、并发症、超声心动图改变。结果两组在手术时间、感知阈值、起搏阈值、QRS波宽度改变上差异有统计学意义,在电极阻抗方面差异无统计学意义;长期随访右室心尖部起搏组LVEDD、LVESD均较间隔部起搏者增加,LVEF减低。结论长期右室间隔部起搏较心尖部起搏对心功能影响更小。     

Thresholds and Complications with Right Ventricular Septal Pacing Compared to Apical Pacing

Background: Right ventricular septal pacing has been proposed as an alternative to apical pacing. However, data concerning thresholds and requirement for lead repositioning with this technique are scant.
Methods: We reviewed data at implantation and follow-up of 362 consecutive recipients of the same model of active fixation lead (Medtronic 5076-58, Minneapolis, MN, USA) to avoid differences due to lead characteristics. Patients were divided into two groups according to whether the lead was positioned on the interventricular septum (n = 157) or at the right ventricular apex (n = 205). Thresholds, lead impedance, and requirement for lead repositioning were compared between groups at implantation and follow-up.
Results: There were no differences between the septal and apical groups in sensing and pacing thresholds or lead impedance, either at implantation or during a 24-month follow-up. In the septal group, the lead had to be repositioned in four patients (2.5%) due to lead dislodgement in two patients, acute threshold rise in one patient, and pericardial effusion in another patient (the lead had unintentionally been positioned on the anterior free wall in these last two patients). In the apical group, the lead had to be repositioned in eight patients (3.9%, P = 0.56) due to lead dislodgement in three patients and acute threshold rise in five patients.
Conclusions: Acute and chronic thresholds associated with septal pacing are similar to those observed with apical pacing, and risk of lead dislodgement is low. However, multiple radioscopic views must be used to avoid inadvertent positioning of the lead on the anterior free wall .     

右室双部位起搏对犬心电图及血流动力学的影响

[目的]研究右室双部位起搏对犬QRS波时限(QRSd)及血流动力学的影响.[方法]12只犬,每只犬随机行右室心尖部(RVA)、右室流出道(RVOT)、右室双部位(RV-Bi)、双心室(Bi-V)起搏,起搏频率为150次/分,起搏稳定15 min后测定QRSd、平均肺动脉压(mPAP)、肺毛细血管楔压(PCWP)、心输出量(CO).[结果]①同RVA相比,RVOT、RV-Bi、Bi-V起搏时均有QRSd减小,CO增加,差异有显著性;②RV-Bi起搏时:与RVA和RVOT)相比,QRSd、mPAP、PCWP减小,CO增加,差异有显著性;与RV-Bi起搏相比,上述指标间无显著差异.[结论]RV-Bi起搏的心电及血流动力学效果明显优于RVA和RVOT起搏,基本等同于Bi-V起搏.     

心室起搏对老年房颤患者超声心动图指标的影响

【目的】采用超声心动图来评价老年高龄房颤患者安置心脏起搏器前后各项心功能指标的变化。【方法】128例慢性房颤患者分为两组,对照组不安装心脏起搏器,起搏组予装·心脏起搏器,入选时及三年后所有患者均行超声心动图检查,记录并比较左室每搏量（SV）、心输出量（CO）、左室射血分数（LVEF）、左室舒张末期内径（LVEDD）、心脏指数（CI）及心率（HR）等指标。【结果】起搏组CO、CI及HR较对照组升高,且差异有统计学意义（P〈0．05）;SV、LVEF较对照组降低,LVEDD较对照组升高,但差异无统计学意义（P〉0．05）。两组患者治疗前后心脏结构指标无显著性改变（P〉0．05）。【结论】老年高龄的房颤患者安装心脏起搏器后CO和CI显著增加,费用并不昂贵,且在心脏起搏器使用年限内患者的生活质量得到了提高。     

右室双部位及双室起搏对心衰犬急性心功能及心室同步的影响

【目的】探讨右室5X部位及双室起搏心衰模型犬急性心功能及心室同步的影响。【方法】选取12只左束支传导阻滞的心衰模型犬,采用自身对照方法随机行右心房一右室双部位（或双室）起搏,起搏频率180次／分钟,每种方式起搏前及起搏稳定15min后行彩色多普勒超声心动图检查,测定左心室舒张末期内径（LVEDd）、左室射血分数（LVEF）、室间机械延迟（IVMD）、室间隔与左室后壁运动延迟（SPWMD）、左心室12个节段达峰时间的标准差（Ts—SD）。【结果】右室双部位起搏：与起搏前相比,LVEDd、IvMD、SPWMD、Ts—SD减小,LVEF增加,差异有显著性（P〈O．05）;与双室起搏相比,SPWMD、Ts—SD增加,差异有显著性（P〈0．05）,LVEDd、IVMD、LVEF差异无显著性（P〉0．05）。【结论】在改善室间不同步及心功能方面,右室双部位与双室起搏有近似效果,但改善左室内不同步前者不及后者。     

Altered Cardiac Histology Following Apical Right Ventricular Pacing in Patients with Congenital Atrioventricular Block

Previous studies have demonstrated that right ventricular apical pacing inherently alters ventricular contraction, regional blood flow, wall stress, and predisposes to diminished function. However, histological consequences of chronic apical pacing potentially contributing to the observed ventricular dysfunction remain conjectural. Previous canine studies have demonstrated histopathological cellular abnormalities with apically initiated ventricular pacing that may result in the observed diminished ventricular function. To determine if comparable adverse changes also occur in the clinical setting, 16 endomyocardial biopsies were obtained from 14 age-matched patients with congenital complete atrioventricular block (CCAVB) and otherwise normal anatomy, divided into two groups: eight biopsies (median patient age 15.5 years) from patients prior to pacemaker implant and another eight biopsies (median patient age 16 years) from patients following 3-12 years (median 5.5) of chronic ventricular pacing. In one patient, biopsy samples were obtained before and after pacing. Results demonstrated a significant (P<0.05) increase in histopathological alterations among the patient biopsy samples following pacing, consisting of myofiber size variation, fibrosis, fat deposition, sclerosis, and mitochondrial morphological changes. These findings indicate that chronic apical right heart ventricular pacing may adversely alter myocellular growth, especially among the young, on the cellular and subcellular level, potentially contributing to the diminished function observed clinically.     

A Comparison of Ventricular Function During High Right Ventricular Septal and Apical Pacing after His-Bundle Ablation for Refractory Atrial Fibrillation

This study compares LV performance during high right ventricular septal (RVS) and apical (RVA) pacing in patients with LV dysfunction who underwent His-bundle ablation for chronic AF. We inserted a passive fixation pacing electrode into the RVA and an active fixation electrode in the RVS. A dual chamber, rate responsive pulse generator stimulated the RVA through the ventricular port and the RVS via the atrial port. Patients were randomized to initial RVA (VVIR) or RVS (AAIR) pacing for 2 months. The pacing site was reversed during the next 2 months. At the 2 and 4 month follow-up visit, each patient underwent a transthoracic echocardiographical study and a rest/exercise first pass radionuclide ventriculogram. We studied nine men and three women (mean age of 68 +/- 7 years) with congestive heart failure functional Class (NYHA Classification): I (3 patients), II (7 patients), and III (2 patients). The QRS duration was shorter during RVS stimulation (158 +/- 10 vs 170 +/- 11 ms, P < 0.001). Chronic capture threshold and lead impedance did not significantly differ. LV fractional shortening improved during RVS pacing (0.31 +/- 0.05 vs 0.26 +/- 0.07, P < 0.01). RVS activation increased the resting first pass LV ejection fraction (0.51 +/- 0.14 vs 0.43 +/- 0.10, P < 0.01). No significant difference was observed during RVS and RVA pacing in the exercise time (5.6 +/- 3.2 vs 5.4 +/- 3.1, P = 0.6) or the exercise first pass LV ejection fraction (0.58 +/- 0.15 vs 0.55 +/- 0.16, P = 0.2). The relative changes in QRS duration and LV ejection fraction at both pacing sites showed a significant correlation (P < 0.01). We conclude that RVS pacing produces shorter QRS duration and better chronic LV function than RVA pacing in patients with mild to moderate LV dysfunction and chronic AF after His-bundle ablation.     

Effect of Right Ventricular Apical Pacing in Survivors of Myocardial Infarction

Background: Much information is available regarding the possible negative effects of long-term right ventricular (RV) apical pacing, which may cause worsening of heart failure. However, very limited data are available regarding the effects of RV pacing in patients with a previous myocardial infarction (MI).
Methods and Results: We screened 115 consecutive post-MI patients and matched a group of 29 pacemaker (PM) recipients with a group of 49 unpaced patients, for age, left ventricular (LV) ejection fraction, and site of MI. During a median follow-up of 54 months, echocardiograms showed a decrease in LV ejection fraction in the paced group, from 51 ± 10 to 39 ± 11 (P < 0.01), and a minimal change in the unpaced group, from 57 ± 8 to 56 ± 7 (P = 0.98). Similar change was observed in systolic and diastolic diameters and volumes.
Conclusions: The study showed that, in post-MI patients, RV apical pacing was associated with a worsening of LV function, suggesting that, among MI survivors, the need for a PM is a marker of worse outcome .     

右心室不同部位起搏对心脏结构和左心功能的影响

[目的]对比研究右心室不同部位起搏对患者心脏结构和左心功能的影响.[方法]90例Ⅲ度或高度房室传导阻滞患者, 随机分为三组, A组行右室流入道（RVIS）间隔部起搏,B组行右室流出道（RVOT）间隔部起搏,C组行右心室心尖部（RVA）起搏. 观察三组手术中情况,监测术中血流动力学变化及手术曝光时间,比较三组术后随访的起搏器工作情况,心电图QRS波宽度,左心功能及血浆中B型钠尿肽（BNP）的差异.[结果]术中监测血流动力学,A组及B组明显优于C组.术后随访观察,A组及B组心电图QRS波宽度明显窄于C组,A组及B组具有更好的心脏功能.[结论]右心室间隔部起搏无论右室流出道起搏还是右室流入道间隔部起搏都是安全,有效的,比右室心尖部起搏更有利于双心室电激动的同步性,且长期对心脏结构及心功能影响也较少.     

Long‐Term Nonoutflow Septal Versus Apical Right Ventricular Pacing: Relation to Left Ventricular Dyssynchrony

Background: Right ventricular (RV) apical pacing deteriorates left ventricular (LV) function. RV nonoutflow (low) septal pacing may better preserve ventricular performance, but this has not been systematically tested. Our aim was to assess (1) whether long‐term RV lower septal pacing is superior to RV apical pacing regarding LV volumes and ejection fraction (EF), and (2) if the changes in LV dyssynchrony imposed by pacing are related to the long‐term changes in LV volumes and EF. Methods: In thirty‐six patients with atrioventricular (AV) block, a dual‐chamber pacemaker was implanted. The ventricular electrode was placed either at the apex or at the lower septum, in a randomized sequence. Twenty‐four to 48 hours following implantation, we measured LV volumes, EF, and LV dyssynchrony (by tissue Doppler imaging), both with and without pacing. Patients were reassessed echocardiographically after 12 months. Results: Lower septal pacing induced a more synchronized pattern of LV contraction changes (P < 0.05). Following 12 months, differences were observed between groups regarding LV volumes and EF. EF increased within the septal group (from 52 ± 3.3% to 59 ± 3.0%, P < 0.05). A significant inverse relation was documented between changes in LV dyssynchrony and changes in EF (r =?0.64, P < 0.05). Conclusions: In patients with AV block, RV nonoutflow septal pacing represents an attractive alternative, since it preserves better and may even improve LV volumes and EF. Late changes in EF are associated with the changes in LV dyssynchrony imposed by pacing.