右心室心尖部与高位间隔部起搏对心功能长期影响

目的比较右心室心尖部(RVA)起搏与右室高位间隔部(RHIVS)起搏对心功能的长期影响。方法选取因Ⅲ度房室传导阻滞植入双腔起搏器且无器质性心脏病患者,根据右室电极部位分为右心室心尖部(RVA组)和高位间隔部(RHIVS组),同时选取同期因病态窦房结综合征植入双腔起搏器的患者作为对照组。比较三组患者术后4年氨基末端脑钠肽前体(NT-proBNP),左心室射血分数(LVEF),舒张期早期二尖瓣血流速度与二尖瓣瓣环运动速度比值(E/E'),Tei指数,左心房容积及指数(LAV、LAVI)等超声心动图指标。结果共入选48例患者,其中RVA起搏组16例,RHIVS起搏组16例,对照组16例。三组患者术前年龄、纽约心功能分级、合并症、伴随用药、LVEF、LAD、E/E'、Tei指数等无统计学意义。随访4年时,RVA起搏组的NT-proBNP、E/E'、LAV和LAVI高于对照组(P0.05),RHIVS起搏组的上述指标与对照组比较,差异无统计学意义(P0.05),三组的LVEF无统计学意义。结论长期RVA起搏导致左心室舒张功能下降,但对LVEF的影响不显著;与RVA起搏相比,RHIVS起搏对左心室舒张功能有保护作用。     

DDD起搏器治疗肥厚型梗阻性心肌病的临床应用

目的:评价DDD起搏治疗肥厚型梗阻性心肌病(HOCM)的疗效。方法:5例HOCM患者植入DDD起搏器;用超声心动图观察术后即刻以及随后2年室间隔厚度(IVST),左室后壁厚度(LVPWT),左室舒张末内径(LVEDD),左室收缩末内径(LVESD),左房径(LAD),跨左室流出道压力阶差(LVOTG),心输出量(CO)及二尖瓣前向运动程度(SAM)的变化,以及DDD起搏器不同房室(AV)间期时LVOTG,CO的变化。结果:起搏即刻及其后随访中,不同的AV间期(保证心室起搏状态下)均显示LVOTG下降显著(P<0.01),CO升高明显(P<0.05)但以AV间期100ms时效果最佳,SAM运动明显改善(P<0.05),其他指标无显著变化。结论:DDD起搏治疗HOCM临床效果初步满意。     

不同房室间期对双腔起搏左室收缩功能的影响

为探讨双腔起搏不同房室间期对左室收缩功能的影响及最佳房室间期 ,选择 18例置入DDD起搏器的病窦综合征患者 ,在DOO起搏方式下随机将房室 (AV)间期程控为 10 0 ,130 ,15 0 ,170 ,2 0 0ms,在超声心动图下观察左室收缩功能指标 ,每次测量间隔 5min以上。结果 :AV间期为 15 0ms时左室收缩功能最好 ,与AV间期为 10 0ms时相比 ,左室收缩功能明显改善。以心输出量 (CO)为标准 ,18例中有 9例AV间期在 15 0ms时CO最佳 ,5例在 2 0 0ms时CO最佳 ,3例在 170ms时CO最佳 ,1例在 130ms时CO最佳 ;以CO为标准 ,DOO起搏方式最佳AV间期为 16 6±2 4ms。结论 :双腔起搏的AV间期对左室收缩功能有重要的影响 ,以CO为标准 ,个体化地选择双腔起搏的最佳AV间期对改善患者的心脏功能有重要的意义。     

病窦综合征患者行右心耳起搏对左室舒张功能影响的临床观察

目的观察植入双腔起搏器的病窦综合征(均无房室传导阻滞)患者行右心耳起搏时对左室舒张功能的影响。方法入选36例植入双腔起搏器的病窦综合征患者,分别在窦性心律和右心耳起搏情况下用彩色超声多普勒测定二尖瓣口快速充盈期峰值血流速度(Ep)、二尖瓣口左房收缩期峰值血流速度(Ap)、二尖瓣环后壁处收缩期峰值血流速度平均值(Vs)、二尖瓣环后壁处舒张早期峰值血流速度平均值(Ve)、二尖瓣环后壁处舒张晚期峰值血流速度平均值(Va)、等容舒张时间(IVRT)、左室射血分数(LVEF)、左室短轴缩短率(LVFS)各参数,通过Ep/Ap、Ve/Va、IVRT评价左室舒张功能,Vs、LVEF、LVFS评价左室收缩功能。结果在心房激动完全经房室结下传激动心室的情况下,两组间Ep/Ap、Ve/Va、IVRT均有显著差异[1.35±0.65vs 0.96±0.53;1.06±0.45vs 0.88±0.53;(0.55±0.05)ms vs(0.56±0.05)ms;P均0.01],Vs、LVEF、LVFS差异无显著性。结论右心耳起搏可导致左室舒张功能下降,短期内对收缩功能无明显影响。     

房室间期优化对三度房室传导阻滞患者房室顺序起搏心功能的影响

目的:探讨不同房室间期(AVD)对三度房室传导阻滞(Ⅲ°AVB)患者房室顺序起搏(DDD)后心功能的影响。方法:接受DDD起搏治疗的Ⅲ°AVB患者16例,其中男女比例3∶1,平均年龄(64.50±15.96)岁。起搏器术后调整不同的AVD,应用左心导管检查测量左心室内压力上升/下降的速率(±dP/dT),评价不同AVD对Ⅲ°AVB患者DDD起搏后心功能的影响。结果:个体间最佳AVD的离散度较大(120～260 ms);不同AVD时,±dP/dT组内差异有统计学意义(P0.05),最佳AVD在160～220 ms区间的分布较集中;在160～220 ms区间的+dP/dT水平与其他区间的+dP/dT水平比较差异有统计学意义(P0.05);+dP/dT组最佳AVD与-dP/dT组最佳AVD比较差异无统计学意义(P0.05)。结论:不同的AVD对Ⅲ°AVB患者DDD起搏后心脏的收缩及舒张功能均有影响,最佳AVD能使其心脏的收缩及舒张功能达到最佳状态。     

脉冲波组织多普勒超声心动图检测肥胖患者心脏结构和心功能

目的:应用脉冲波组织多普勒超声心动图检测超重和单纯肥胖患者的心脏结构和心功能,以探讨单纯肥胖患者早期心脏功能的改变。方法:根据体重指数将143例无其他心血管疾病者分为正常体重组(体重指数18.5～23.9kg/m2,n=57),超重组(体重指数24.0～27.9kg/m2,n=53),肥胖组(体重指数≥28.0kg/m2,n=33),比较各组间左心房内径(LAD)、室间隔(IVS)厚度、左心室后壁(PW)厚度、左心室舒张末期内径(LVEDD)、左心室收缩末期内径(LVESD)、左心室重量(LVM)、左心室射血分数(LVEF)、二尖瓣舒张早期血流速度峰值(E)和二尖瓣舒张晚期血流速度峰值(A);脉冲波组织多普勒超声心动图测量二尖瓣环侧壁收缩期运动峰速度(Sm)及二尖瓣环侧壁舒张早期运动峰速度(Em),E/A,E/Em的差异,并分析这些指标与体重指数的相关性。结果:与正常体重组比较,超重组左心房内径增大、室间隔增厚,差异有统计学意义(P0.05)。与正常体重组比较,肥胖组左心房内径、舒张末期室间隔厚度、左心室后壁厚度、左心室舒张末期内径、左心室收缩末期内径、左心室重量均增加,二尖瓣环侧壁收缩期运动峰速度、二尖瓣环侧壁舒张早期运动峰速度下降,而E/Em增加,差异均有统计学意义(P0.05)。心脏结构和心功能变化与体重指数的相关性:左心房内径,舒张末期室间隔厚度,左心室后壁厚度,左心室舒张末期内径、左心室收缩末期内径、左心室重量与体重指数呈正相关,传统的表示左心室收缩功能和舒张功能的超声参数左心室射血分数、E/A与体重指数均无相关性,而脉冲波组织多普勒超声心动图参数二尖瓣环侧壁收缩期运动峰速度、二尖瓣环侧壁舒张早期运动峰速度与体重指数呈负相关,E/Em与体重指数呈正相关。结论:单纯肥胖可导致左心房内径、左心室壁厚度、左心室内径增加,而脉冲波组织多普勒超声心动图能够早期检测出肥胖所致的亚临床收缩及舒张功能的改变。     

房室延迟对舒张功能不良患者左心房功能的影响

目的 探讨双腔起搏器不同房室延迟(AV间期)起搏对单纯舒张功能不良患者左心房功能的影响.方法 选择植入双腔起搏器的患者76例,分为单纯舒张功能不良组(38例)和心功能正常组(38例),应用超声心动图及应变率成像测算在不同AV间期时的心排出量(CO)、左心房射血分数(LAEF)；收缩期、舒张早期和舒张晚期的左心房心肌平均峰值应变率(SR-s、SR-e和SR-a).结果 单纯舒张功能不良组:①AV间期自80 ms开始增至200 ms时,SR-a、LAEF和CO随AV间期的延长相应增大,在AV间期200 ms时达到最大,达峰值后逐渐下降,SR-a、LAEF和CO在AV间期＜150 ms及＞200 ms时较AV间期150 ～ 200 ms时降低(P＜0.05)；②AV间期为80 ms时SR-s较AV间期为200 ms时增加明显(P＜0.05).心功能正常组:①随着AV间期变化,评价左心房功能的各指标无显著变化(P＞0.05)；②CO在AV间期为150 ms时达到最大,在AV间期＜150 ms及＞200 ms时较AV间期为150～200 ms时降低(P＜0.05).结论 双腔起搏器不同AV间期可影响单纯舒张功能不良患者左心房的收缩功能,适当延长AV间期在生理上更有利于左心房功能的改善.     

双腔起搏器治疗扩张型心肌病(并充血性心力衰竭)的A-V间期与血流动力学改变的关系

目的探讨不同A-V间期时双腔起搏治疗扩张型心肌病对心脏血流动力学的影响,寻找设置最佳A-V间期的方法。方法选择3例扩张型心肌病并充血性心力衰竭置入双腔起搏器的患者,于术后6个月时设置不同的A-V间期,在超声心动图下记录舒张期二尖瓣反流情况、心脏收缩、舒张功能指标。用Swan-Ganz导管测量相关血流动力学参数。结果3例扩张型心肌病并充血性心力衰竭置入双腔起搏器患者在A-V间期为100~120ms时射血分数(EF)、心排血量(CO)达到最大,心脏收缩、舒张功能指标,相关血流动力学参数得到明显改善。结论100~120ms的生理性起搏可改善扩张型心肌病并充血性心力衰竭患者血流动力学状况。     

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.     

Ⅲ度房室传导阻滞患者高位右室间隔部起搏VAT与DDD模式对左心功能的影响

目的通过研究Ⅲ度房室传导阻滞患者高位右室间隔部起搏(HRVS)时,VAT与DDD模式对心功能的影响,探讨心房的生理收缩和舒张对左心功能的作用。方法 32例Ⅲ度房室传导阻滞患者,在HRVS时,分别给予DDD模式或VAT模式工作,于调控即刻通过超声心动图测定二尖瓣口快速充盈期峰值血流速度(Ep),二尖瓣口左房收缩期峰值血流速度(Ap),二尖瓣环后壁处收缩期脉冲组织多普勒峰值速度平均值(Vs),二尖瓣环后壁处舒张早期脉冲组织多普勒峰值速度平均值(Ve),二尖瓣环后壁处舒张晚期脉冲组织多普勒峰值速度平均值(Va),二尖瓣血流频谱等容舒张时间(IVRT),通过Ep/Ap,Ve/Va,Ep/Ve和IVRT评价左室舒张功能,通过Vs,LVEF和LVFS评价收缩功能。结果 HRVS时DDD较VAT模式Ep/Ap、Ve/Va、Ep/Ve,IVRT差异有显著性(0.97±0.11 vs 1.01±0.11,0.89±0.09 vs 0.97±0.07,6.00±0.45 vs 6.24±0.36,100.4±14.32 vs 89.99±7.94;P均<0.01),Vs、左室射血分数和左室短轴缩短率无显著性差异。结论Ⅲ度房室传导阻滞时,HRVS起搏时,DDD模式较VAT模式使左室舒张功能下降,收缩功能无影响,表明了心房生理性起搏的重要性。     

双腔起搏房室延迟优化对心功能及神经内分泌因子的影响

观察双腔起搏不同房室延迟(AVD)对即刻心功能的影响,并探讨以优化的AVD起搏对心功能及神经内分泌因子的影响。用SwanGanz导管和彩色多谱勒心脏超声仪分别测定20例心功能ⅡⅢ级患者不同AVD起搏时心功能参数的变化,将心排血量(CO)最大的和/或平均肺毛细血管楔嵌压(MPCWP)下降最明显的AVD定为优化AVD。其后,所有患者分别进行8周常规AVD及8周优化AVD起搏,分别在8周结束时对患者进行心脏B超测试及测定血浆内皮素(ET)、心钠素(ANP)、肾素活性(PRA)、血管紧张素Ⅱ(AngⅡ)、醛固酮(ALD)。结果:根据心导管及心脏B超测量的优化AVD分别为134±13ms及131±12ms。优化AVD组较常规AVD组对左室收缩功能指标有改善,但未达有统计学显著性差异。左室舒张功能指标在优化AVD组较常规AVD组明显改善。神经内分泌因子在优化AVD组较常规AVD组明显减低。结论:优化AVD起搏对心力衰竭患者远期心功能有改善作用,能明显降低有关神经内分泌因子。     

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.     

双腔起搏器不同房室间期起搏对心功能影响的研究

探讨双腔起搏器不同房室间期 (AVD)起搏对即时心功能的影响 ,并观察根据即时心功能调定的最佳房室间期对CHF患者长期疗效的影响。用M型和B型超声心动图比较了 6例无心力衰竭DDD起搏者和 14例CHFDDD起搏患者 (其中 13例存在缓慢型心律失常 )不同AVD起搏时心功能参数的变化。 14例CHFDDD起搏患者常规起搏 3个月后随机分为常规起搏组 (7组 )和最佳房室间期起搏组 (7例 ) ,起搏 3个月后随访心功能 (NYHA分级 )和心室腔径的改变。结果 :CHF组和无心力衰竭组不同AVD起搏时各项心功能指标变化均无差异 (P >0 .0 5 ) ;常规起搏组和最佳AVD起搏组起搏 3个月后NYHA分级和心室腔径无显著变化 (P >0 .0 5 )。结论 :经调定的短AVDDDD起搏不能改善CHF患者的心功能和心室重构。不宜将双腔起搏器最佳AVD起搏作为CHF患者的常规非药物疗法 ,对因纠治心脏电学异常而安装DDD起搏器的CHF患者 ,在无其他证据之前仍宜采用常规AVD起搏     

双腔起搏器不同房室延迟对左心房功能的影响

目的：探讨双腔起搏器不同房室延迟（AVD）起搏时对左心房功能的影响。方法：选择植入双腔起搏器的40例患者,分为舒张功能正常组（20例）和舒张功能不全组（20例）。应用实时三平面应变率成像分别测算两组患者在不同AVD时左心房心肌在收缩期、舒张早期和舒张晚期平均峰值应变率（SRs、SRe和SRa）。结果：在舒张功能正常组,不同AVD起搏对左心房功能的影响不显著（P〉0．05）。在舒张功能不全组：①AVD自80ms开始增至250ms时,SRa随AVD的延长相应增大,在AVD为200ms时达到最大,达峰值后又逐渐下降,AVD为150ms、200ms时SRa和LAEF较AVD为80ms、100ms、250ms时明显升高[SRa：（-2．87±0．50）S-1、（-3．14±0．44）S-1,比（-2．35±0．53）S-1、（-2．55±0．52）S、（-2．55±0．49）S-1,LAEF：（46．00±3．67）％、（51．22±3．33）％比（37．99±3．56）％、（39．64±3．08）％、（43．78±3．83）％,P〈0．05];②当AVD为80ms、250ms时,SRs增大,SRe减小;AVD为200ms时SRs明显低于AVD为80ms时[（3．02±0．56）S。比（3．27±0．62）S-1,P〈0．05]。结论：不同房室延迟对舒张功能正常患者左心房功能的影响不明显,但对于单纯舒张功能不全的患者,适当延长房室延迟更有利于左心房的功能,改善血流动力学。     

Similar pattern of diastolic function adaptation of both ventricles to programmed atrioventricular interval modification in patients with DDD pacing.

OBJECTIVE: To evaluate both left ventricular (LV) and right ventricular (RV) diastolic performance adaptation to variable atrioventricular interval (AVI), in patients with DDD pacing for complete heart block and to investigate a possible interaction between LV and RV in this specific cohort of patients. METHODS: We studied 22 consecutive patients (mean age 65.2 +/- 14.3 years) who underwent DDD pacemaker implantation following admission for complete heart block. One day following implantation, patients were paced at 3 different pacing modes, under the same programmed heart rate and a different AVI (100, 150 and 200 ms respectively). Standard Doppler echocardiography of mitral and tricuspid valve inflow was performed to evaluate LV and RV diastolic function, during each pacing mode. RESULTS: Left ventricular and RV diastolic performance adaptation to variable AVI modifications was similar, showing a progressive increase of late diastolic filling velocities and a subsequent decrease of E/A wave ratios following AVI prolongation. A short AVI of 100 or 150 ms was associated with improved LV and RV diastolic filling dynamics. CONCLUSIONS: In elderly patients with complete heart block and unimpaired systolic function undergoing DDD pacemaker implantation, both ventricles share a similar pattern of diastolic function adaptation to AVI modifications and that might be the reflection of ventricular interaction under this specific pacing mode.     

Effect of dual-chamber pacing on systolic and diastolic function in patients with hypertrophic cardiomyopathy Acute doppler echocardiographic and catheterization hemodynamic study

Objectives. This study sought to evaluate prospectively the acute hemodynamic effect of dual-chamber pacing by using a combined hemodynamic approach of high fidelity pressure and Doppler velocity measurements.Background. Dual-chamber pacing has been proposed recently as an alternative in the symptomatic treatment of patients with hypertrophic obstructive cardiomyopathy. Although early reports documented a decrease in left ventricular outflow tract gradient and symptomatic improvement, questions remain about the hemodynamic effects of dual-chamber pacing on systolic and diastolic function.Methods. Twenty-nine patients with hypertrophic cardiomyopathy underwent a combined cardiac catheterization and Doppler echocardiographic study during normal sinus rhythm and P-synchronous pacing at various atrioventricular (AV) intervals. High fidelity pressure measurements of left ventricular inflow and left atrial pressures, ascending aortic pressure, thermodilution cardiac output and Doppler mitral flow velocity curves were obtained to evaluate both systolic and diastolic left ventricular function.Results. During AV pacing at the shortest delay of 60 ms, there was a significant decrease in cardiac output (p < 0.05) and peak positive dP/dt (p < 0.05), an increase in mean left atrial pressure (p < 0.05) and a prolongation of τ, the time constant of relaxation (p < 0.05), compared with that during normal sinus rhythm. During pacing at the optimal AV delay (longest AV interval with pre-excitation), there was a similar trend, with deterioration in both systolic and diastolic function variables but of lesser magnitude than that during pacing at the shortest AV intervals. The deterioration in both systolic and diastolic function was present in 21 patients with and 8 without left ventricular outflow obstruction. There was a modest decrease in left ventricular outflow tract gradient from 73.3 ± 45.0 (mean ± SD) to 61.3 ± 40.5 mm Hg (p = 0.03) during dual-chamber pacing at the optimal AV delay compared with that during normal sinus rhythm.Conclusions. The acute effect of pacing the right atrium and ventricle may be detrimental to both systolic and diastolic function of the left ventricle, particularly at the short AV intervals. Further studies of the long-term effects of dual-chamber pacing in carefully performed randomized studies are needed.     

The effect of different atrioventricular delays on left atrium and left atrial appendage function in patients with DDD pacemaker

Background: Although it has been known that optimization of atrioventricular delay (AVD) has favorable effect on the left ventricular functions in patients with DDD pacemaker, the effect of different AVDs on left atrium (LA) and left atrial appendage (LAA) functions has not been exactly evaluated. The aim of the present study was to assess the effect of different AVDs on LA and LAA functions in DDD pacemaker implanted patients with atrioventricular block. Methods: Forty‐eight patients with DDD pacemaker were enrolled into the study. Patients were divided into two groups according to the echocardiographic diastolic function: Group I (normal diastolic function) and Group II (diastolic dysfunction). LAA emptying velocity on pulsed wave Doppler and LAA late systolic wave velocity by using tissue Doppler were recorded. Patients were paced for five successive continuous pacing periods of 10 minutes duration using five selective AVDs (80–250 ms). Results: Significant effect on LA and LAA functions has not been observed by the setting of AVD in Group I. However, when the AVD was gradually shortened form 150 ms to 80 ms, LA and LAA functions gradually decreased in Group II patients. When AVD increased to 200 ms, LA and LAA functions were improved. Further increase in AVD resulted in decreased LA and LAA functions. Conclusion: Setting of AVD has not significant effect on the LA and LAA functions in patients with normal diastolic function, but moderate prolongation of AVD in physiological limits improved LA and LAA functions in DDD pacemaker implanted patients with diastolic dysfunction. (Echocardiography 2011;28:626‐632)     

Pacing-related acute pulmonary edema and mechanical asynchrony illustrated by three-dimensional echocardiography.

Sick sinus syndrome with symptomatic bradycardia is an indication for a permanent pacemaker. Either a single (AAIR) or dual-chamber (DDDR) pacemaker can be implanted in these patients with normal atrioventricular nodal function. This report presents a 92-year-old male with right ventricular apical pacing related recurrent acute pulmonary edema and mechanical asynchrony demonstrated by three-dimensional echocardiogram. Although three-dimensional echocardiography has been available for many years, it has seldom been applied to evaluate pacing-related intraventricular asynchrony. The systolic asynchrony index for this patient was 6.7% during AAIR pacing mode and 22% during DDDR pacing mode.     

Acute pacing-induced dyssynchronous activation of the left ventricle creates systolic dyssynchrony with preserved diastolic synchrony

Introduction: Patients with heart block have conventionally received a pacemaker that stimulates the right ventricular apex (RVA) to restore heart rate control. While RVA pacing has been shown to create systolic dyssynchrony acutely, dyssynchrony can also occur in diastole. The effects of acute RVA pacing on diastolic synchrony have not been investigated. RVA pacing acutely impairs diastolic function by increasing the time constant of relaxation, decreasing the peak lengthening rate and decreasing peak negative dP/dt. We therefore hypothesized that acute RVA pacing would cause diastolic dyssynchrony in addition to creating systolic dyssynchrony.
Methods and Results: Fourteen patients (13 ± 4 years old) with non-preexcited supraventricular tachycardia underwent ablation therapy with subsequent testing to confirm elimination of the tachycardia substrate. Normal cardiac structure and function were then documented on two-dimensional echocardiography and 12-lead electrocardiography prior to enrollment. Tissue Doppler images were collected during normal sinus rhythm (NSR), right atrial appendage pacing (AAI), and VVI-RVA pacing during the postablation waiting interval. Systolic and diastolic dyssynchrony were quantified using cross-correlation analysis of tissue Doppler velocity curves. Systolic dyssynchrony increased 81% during RVA pacing relative to AAI and NSR (P < 0.01). Diastolic synchrony was not affected by the different pacing modes (P = 0.375).
Conclusion: Acute dyssynchronous activation of the LV created by RVA pacing resulted in systolic dyssynchrony with preserved diastolic synchrony in pediatric patients following catheter ablation for treatment of supraventricular tachycardia. Our results suggest that systolic and diastolic dyssynchrony are not tightly coupled and may develop through separate mechanisms.