动态优化AV/VV间期心脏再同步化治疗慢性心力衰竭的中远期疗效

目的 观察动态优化AV/VV间期心脏再同步化治疗（CRT）慢性心力衰竭的中远期疗效。方法 19例心衰晚期患者接受CRT治疗,分别于植入前、植入术后1周、3、6及12个月在心脏彩超指导下优化AV/VV间期治疗,同时观察心腔结构、二尖瓣返流、主动脉瓣射血速度时间积分（AVTI）、心电图以及测定血浆脑钠肽（BNP）水平等,评价其血流动力学改变。结果 动态优化下最佳优化AV间期120～180 ms （158.33±19.46 ms）之间和VV间期4～28 ms （15.83±7.12 ms）之间临床症状改善,6分钟步行距离由255.71±21.58 m增加至397.37±11.35 m（P0.001）,QRS时限由138.79±16.06 ms降至105.53±8.80 ms（P<0.05）。植入后左心室舒张期末内径（LVEDD）较植入前明显缩小（73.53±9.41 mm比54.11±3.41;P<0.05）,左心室射血分数（LVEF）较植入前明显提高（31%±3%比58%±6%;P<0.01）;AVTI由14.69±1.48优化后增加至20.52±1.18（P<0.05）,血浆BNP水平由植入前的1069.02±501.85 ng/L降至81.26±31.51 ng/L（P<0.05）。结论 动态优化AV/VV间期可以改善患者的血流动力学,提高CRT对慢性心力衰竭患者中远期疗效。     

右室阳极夺获影响QuickOpt VV间期优化一例

患者女,76岁,因扩张型心肌病,心功能Ⅲ级,窦性心律,QRS波时限>120 ms,植入心脏再同步化起搏/除颤器进行治疗。植入后应用QuickOpt进行AV、VV间期优化。初始左室电极采用左室头端—右室环的起搏设置,因有右室环阳极夺获的存在,致使VV间期优化时,左室电极起搏到右室电极感知的时间参数错误测定,结果优化为右室优先35 ms;将左室电极改为双极起搏,消除了右室阳极夺获后,重新进行QuickOpt优化,结果为左室优先25 ms,体表心电图明显变窄。     

超声心动图引导下心脏再同步化治疗的优化调节

目的 应用超声心动图技术优化调节心脏再同步化治疗(CRT)的疗效.方法 接受CRT的慢性心力衰竭患者30例,在超声心动图引导下进行优化AV间期和VV间期.结果 30例患者CRT优化后心功能得到改善,左室充盈时间较优化前增加,二尖瓣返流减少;左室内各室壁收缩期达峰时间标准差减少,左室流出道速度时间积分上升,左室收缩末容积减少.结论 超声引导下AV间期和VV间期优化能够提高CRT临床疗效.     

心脏再同步化治疗慢性心力衰竭的疗效观察

目的观察心脏再同步化治疗(CRT)慢性心力衰竭(CHF)的临床疗效。方法26例CHF患者行CRT,全部患者均经冠状静脉窦置入左室导线1根至心脏静脉,术后随访13.8±10.4个月,观察心功能,患者活动度及夜间心率、QRS波时限,左室射血分数(LVEF)及相关心功能超声指标。结果24例治疗后心功能改善,2例猝死,有效率92.3%,心功能NYHA分级,从Ⅲ～Ⅳ级改善为Ⅱ～Ⅲ级,患者活动度从0.17±0.24小时/天增加至2.98±0.46小时/天,夜间心率由80.8±12.0次/分降低至61.3±2.5次/分,QRS波时限从158.60±31.86ms缩短至130.95±23.44ms,P<0.05。LVEF从0.21±0.05提高至0.35±0.05,P<0.05,其他相关超声指标较CRT之前明显改善(P均<0.05)。结论CRT是治疗CHF的有效方法。     

动态优化AV/VV间期心脏再同步治疗慢性心力衰竭的临床观察

目的: 观察动态优化AV/VV间期心脏再同步治疗（cardiac resynchronization therapy,CRT）治疗慢性心力衰竭（CHF）的短中期疗效。方法: 12例CHF晚期患者接受CRT治疗,分别于植入前、植入术后3、6个月在超声心动图指导下优化房室（AV）间期和室室（VV）间期,同时观察心腔结构、二尖瓣返流及心电图、脑钠尿肽（BNP）检查等,评价CRT临床疗效。结果: 最佳优化AV间期120～180（158±19）ms和VV间期4～28（16±7）ms,临床症状改善,六分钟步行距离由(257±23)m增加至(344±21)m,QRS时限由（136±17）ms降至(109±12)ms(P<0.01,P<0.05)。植入后左室舒张末内径（LVEDD）较植入前明显缩小［(71±10) mm vs. (54±4),P<0.05］; 左室射血分数（LVEF）提高［(0.308±0.022) vs. (0.531±0.085),P<0.01］;血浆BNP值由植入前（876±415）ng/L降至(70±28)ng/L(P<0.05)。结论: 动态程控AV/VV间期可以提高CRT对CHF患者短、中期疗效。     

心电图与超声心动图优化VV间期的对比研究

目的 评价心电图在心脏再同步治疗（CRT）患者VV间期优化中的作用.方法 入选30例心功能Ⅲ～Ⅳ级（NYHA分级）CRT患者（男27例,女3例）,年龄42 ～79（63.3±10.6）岁.植入1个月后,分别程控为单独右心室起搏和单独左心室起搏,记录体表心电图.左心室起搏时,记录胸前导联从起搏信号到QRS波起始部假δ波结束之间的间期（T1）;右心室起搏时,记录胸前导联从起搏信号到QRS波开始改变之间的间期（T2）.T1 -T2的值为从心室侧壁与间隔部同步除极左心室所需的时间延迟,为最佳左-右心室激动的间期（Optimal VV间期）.同时采用超声扫描测定不同VV间期时的主动脉速度时间积分（VTI）,产生最大VTI间期为最佳VV间期,对比两种方法结果.结果 超声优化最佳VV间期在左心室领先起搏-30 ms、-70 ms时分别有20例、5例;左、右心室同步起搏（0 ～5 ms）时有3例;右心室领先起搏＋30 ms时有2例.心电图优化最佳VV间期在左心室领先起搏-30 ms、-70 ms时分别有19例和5例;左、右心室同步起搏时有4例;右心室领先起搏＋30 ms时有2例.两种方法相关性良好.结论 采用心电图可计算出CRT患者最佳VV间期,与超声心动图相关性良好.     

电生理标测冠状静脉窦分支最延迟电激动处植入左室导线行心脏再同步化治疗

目的探讨电生理标测冠状静脉窦(CS)分支最延迟电激动处植入左室导线行心脏再同步治疗(CRT)。方法 10例中重度心力衰竭患者,均满足NYHA心功能Ⅲ～Ⅳ级,左室射血分数(LVEF)<0.35且QRS波时限≥120 ms。CRT术中在可植入左室导线的CS分支内进行电生理标测,将标测的最延迟心室电激动处作为左室导线的植入部位,观察该方法的可行性及临床疗效。结果 10例中,扩张型心肌病7例,缺血性心脏病3例;7例为窦性心律,3例为心房颤动;9例ECG表现为左束支传导阻滞,1例为室内传导阻滞。对10例的28个可作为左室导线植入部位的CS分支进行了电生理标测,10例均成功将左室导线植入在标测的最延迟电激动处,该处局部电位较体表ECG的QRS波起始延迟116±28 ms。术后即刻QRS波时限为121±17 ms,比术前153±30 ms明显缩短,P<0.01。8例CRT术后随访时间超过3个月,均有CRT应答(8/8,100%),其中3例超应答(3/8,37.5%),另外1例缺血性心肌病患者CRT术后2个月死于急性前壁心肌梗死;8例CRT应答患者NYHA心功能分级、6 min步行距离、LVEF值、左室收缩末容积、二尖瓣返流速度均较术前明显改善(1.6±0.5级vs 3.3±0.5级;405±92 m vs 307±82m;0.42±0.06 vs 0.30±0.04;121±38 ml vs 153±44 ml;3.9±1.2 m/s vs 4.5±1.5 m/s,P均<0.01)。结论电生理标测指引CS分支最延迟电激动处植入左室导线的CRT方法可行且短期疗效明显。     

心脏超声与起搏器程控最佳AV及VV间期长期疗效对比研究

目的本研究旨在对比QuickOpt TM与心脏超声程控最佳AV及VV间期的相关性,并观察两组的长期临床疗效。方法 2007年2月～2009年5月住院病人44例,男29例,年龄平均60.34±13.16岁。Ⅰ组(QuickOpt TM)20例,在术后1周内同时分别用心脏超声及QuickOpt TM优化AV及VV间期,取二者方法中最大主动脉血流速度(VTI)时的AV及VV间期为最佳时间进行程控;术后6个月时用QuickOpt TM方法优化AV及VV间期。Ⅱ组(心脏超声)24例,在术后1周内及6个月均用心脏超声方法优化AV及VV间期。两组治疗前的基础状况无统计学差异。持续性房颤、高度房室传导阻滞及术前QRS间期<120ms的CRT患者为排除病例,随访1年。结果 (1)心脏超声及QuickOpt TM优化AV及VV间期的相关性Ⅰ组每位患者同时用两种方法AV及VV间期均有极好的相关性(r=0.89～0.95,P<0.01),两组之间的耗时亦明显不同,QuickOptTM优化费时为(1.45±0.39)min,而心脏超声优化AV或VV间期费时为(27.15±11.82)～(36.50±12.73)min,全部优化结束为(63.65±16.24)min(P<0.01)。(2)Ⅰ组和Ⅱ组术后临床及心脏超声指标的比较两组患者术后NYHA心功能、6MWT及LVEF均较术前明显改善(P<0.01),而在同期两组间比较无明显差异(P>0.05)。Ⅰ组术后可见LVEDD明显减小,随着时间的延长减小更明显(P<0.05～0.01),在术后12个月时Ⅰ组与Ⅱ组比较LVEDD有明显差异(P<0.05)。结论 QuickOpt TM优化的最佳AV及VV间期与心脏超声对比具有良好的相关性,且用QuickOpt TM优化后患者远期的临床及心功能指标有明显的改善,并能很好的逆转左心室重构。     

心脏再同步化治疗慢性心力衰竭临床观察

目的观察心脏再同步化治疗(CRT)慢性心力衰竭(CHF)的疗效。方法 11例慢性心力衰竭患者行CRT,术后随访12个月,观察心功能、QRS时限、左室射血分数(LVEF)及相关心功能超声指标。结果 9例患者治疗后心功能均有明显改善,心功能NYHA分级从(3.5±0.4)级改善为(2.3±0.4)级,QRS时限从(157.0±21.4)ms缩短至(131.0±23.6)ms,LVEF从(26.7±5.2)%提高至(39.7±7.9)%;以上观察指标治疗前后比较差异均有统计学意义(P<0.05)。2例分别在植入起搏器后2个月及7个月死亡。结论 CRT通过改善心脏收缩同步性,提高左室射血分数,从而改善心功能,提高生活质量和运动能力。     

动态优化AV／VV间期的心脏再同步治疗对慢性心力衰竭的疗效评价

目的评价AV／VV间期动态优化的心脏再同步治疗（CRT）对慢性心力衰竭的疗效。方法26例因心力衰竭接受CRT的患者分别于植入术后1周,6个月以及12～18个月在超声指导下行AV／VV间期优化。同时行超声心动图以及组织多普勒、心电图、6min步行距离试验（6MHW）、血浆脑钠肽（BNP）值以及x线胸片（心胸比）检查。结果本文最佳优化AV间期在100～140（120．77±8．91）ms之间,最佳优化VV间期在4～24（12．92±5．34）ms之间。CRT植入后最佳AV间期在±10ms之间波动,最佳VV间期在±4ms之间波动。植入后1周同植入前相比左心室射血分数（LVEF）由0．30±0．04增加至0．31±0．03,舒张期二尖瓣反流速度时间积分（VTImr）由（18．97±3．81）cm降至（16．04±3．64）cm;间隔对后壁的运动延迟（SPWMD）由植入前（125．06±7．47）ms降至（105．06±12．06）ms;QRS时限由植入前（144．35±10．76）ms降歪（129．00±6．65）ms;6MHW由植入前（278．46±12．55）m增加至（324．62±25．49）m;血浆BNP值由植入前（672．79±98．36）pg／ml降至（484．03±106．02）pg／ml。12～18个月AV／VV间期优化后同优化前相比：LVEF值由0．32±0．03增至0．40±0．03,VTImr由（16．04±3．64）cm降至（8．67±1．18）cm;SPWMD由（105．06±12．06）ms降至（101．00±7．56）ms;QRS时限无明显变化;6MHW由（324．62±25．49）m增加至（347．12±15．24）m;血浆BNP值由（484．03±106．02）pg／ml降至（98．41±8．57）pg／ml。左心室舒张末期内径（LVEDD）由（71．73±7．07）mm降至（64．46±4．95）mm;心胸比由（71±5）％降至（63±4）％。结论动态程控AV／VV间期可以提高CRT对慢性心力衰竭的短、中、远期疗效。     

Determination of the optimal atrioventricular and interventricular delays in cardiac resynchronization therapy

Objective In order to provide the maximum benefit of cardiac resynchronization therapy (CRT), we tried to use an echocardiography method to optimize the atrioventricular and interventricular delay. Methods The study included 6 patients who underwent implantation of biventricular pacemakers for drug-resistant heart failure. Two-dimensional echocardiography and tissue Doppler imaging were carried out before and after the pacemaker implantation. The optimal AV delay was defined as the AV delay resulting in maximum time-velocity integral (TVI) of transmitral filling flow, the longest left ventricular filling time (LVFT) and the minimum mitral regurgitation (MR). The optimal VV delay was defined as the VV delay producing the maximum LV synchrony and the largest aortic TVI. Results CRT was successfully performed in all patients. After pacemaker implantation, an acute improvement in left ventricular ejection fraction (LVEF) was observed from 26.5% to 35%. Meanwhile, the QRS duration decreased from 170ms to 150ms. The optimal AV delay was programmed at 130, 120, 120, 120, 150 and 110ms respectively with heart rate corrected, LVFT significantly lengthened and TVI of MR decreased (non-optimal vs optimal AV delay: LVFT: 469ms vs 523ms; TVI of MR: 16.43cm vs 13.06cm, P<0.05). The optimal VV delay was programmed at 4, 4, 4, 8, 12 and 8ms with LV preactivation respectively. Programming the optimal VV delay increased the aortic TVI from 17.33cm up to 21.42cm (P<0.05). In the septal and lateral wall, peak systolic velocities improved from 2.70cm/s to 3.02cm/s (P>0.05) and froml.31cm/s to 2.50cm/s (P<0.05) respectively. The septal-to-lateral delay in peak velocity improved from 56.4ms to 13.3ms after CRT (P<0.01). Conclusions Optimization of AV and VV delays may further enhance the efficacy of CRT. However, there was interindividual variability of optimal values, warranting individual patient examination.     

Cardiac resynchronization therapy: variations in echo-guided optimized atrioventricular and interventricular delays during follow-up

BACKGROUND: Relatively few data are available on long-term echocardiographic optimization of atrioventricular (AV) and interventricular (VV) delay programming in cardiac resynchronization therapy (CRT). We assessed variations in optimized AV and VV delays during long-term follow-up. METHODS: Thirty-seven consecutive heart failure patients received Doppler echocardiographic optimization of AV and VV delay within 48 hours from CRT device implantation, at 6 months and at 12 months (the last for the first enrolled 14 patients). RESULTS: After implantation, median optimized AV delay was 100 ms (range, 45 ms); VV optimization led to simultaneous biventricular activation in 4 patients, left ventricular preactivation in 17 patients and right ventricular preactivation in 16 patients. At 12 months median AV delay decreased to 85 ms (23 ms) (P < 0.05 vs. baseline). With respect to previous assessment, VV delay variations > or =40 ms were observed in 41% of the patients at 6 months and in 57% of the tested patients at 12 months. A nonconcordance (by Kappa test) of optimized VV delays was found between each new assessment and the previous one. VV delay optimization was associated with significant (P < 0.001) increases in aortic velocity time integral both at baseline and during follow-up. CONCLUSIONS: Echocardiographic optimization of AV and VV delay is associated with broad intraindividual variability during follow-up. A new assessment of optimized VV delays during long-term follow-up reveals a nonconcordance with previous values and provides increases in forward stroke volume.     

心脏再同步治疗术后房室延迟和室间延迟参数的优化

目的 超声心动图指导下优化房室延迟和室问延迟参数。方法 8例因心力衰竭接受心脏再同步治疗的患者于植入术前、术后分别行二维超声及组织多普勒检查。结果 心脏再同步治疗后，左心室射血分数从0、26提高至0．36，QRS时限由163ms缩短至146ms。8例患者的最佳房室延迟和室间延迟分别程控为：130、4ms；120、4ms；120、4ms；120、8ms；150、12ms；110、8ms；130、20ms；和120、20ms，其中室间延迟均为左心室提前激动。优化房室延迟可以延长左心室充盈时间、减少二尖瓣返流（充盈时间：463ms对537ms；二尖瓣返流速度时间积分：15．98cm对12．77cm，P〈0．05）。优化室间延迟可以增加心排出量，达到更大程度的同步化。具体表现为左心室流出道前向血流速度时间积分由16．98cm增至22．07cm（P〈0．05），间隔侧壁达峰时差由54．3ms降至15．6ms（P〈0．01）。结论CRT术后进行个体化的参数优化可以进一步提高CRT疗效。     

Cardiac resynchronization therapy with sequential biventricular pacing: impact of echocardiography guided VV delay optimization on acute results.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves left ventricular synchrony as evaluated by tissue Doppler imaging (TDI), leading to improved left ventricular performance and reverse remodeling. New CRT devices enable programming of left and right VV delay. The aim of this study was to determine whether sequential biventricular (BiV) pacing by echo-guided programming of VV delay would enhance the response to CRT. METHODS: 15 consecutive patients with severe heart failure and left bundle branch block underwent CRT by BiV device implantation. They were studied with conventional and TDI echo the day before implantation. Left ventricular ejection fraction (LVEF) was determined, and the electromechanical delay (QS), defined as the time interval from the beginning of the QRS to the S wave in pulsed TDI, was assessed in each of the four left ventricular basal segments. The dyssynchrony index was calculated as the difference between the longest and shortest electromechanical delay (QS(max-min)). The parameters were re-evaluated the day after implantation during simultaneous BiV pacing and with seven different VV delays. The optimal VV delay was determined by finding the VV interval corresponding to the maximum aortic velocity time interval (VTI). RESULTS: QS(max-min) decreased from 85.3 +/- 27.0 msec to 46.7 +/- 23.0 msec (p = 0.0002), LVEF increased from 21.7 +/- 7.3% to 30.0 +/- 7.7% (p = 0.0001) and aortic VTI increased from 12.7 +/- 3.6 cm to 15.2 +/- 4.0 cm (p < 0.0001), with simultaneous BiV pacing. The VV intervals were programmed as follows: LV pre-excitation by 10 msec in five patients, 20 msec in three, 30 msec in two, and 40 msec in three; and RV pre-excitation by 10 msec in one and by 20 msec in one. The maximal aortic VTI obtained with VV delay programming increased from 15.2 +/- 4.0 cm to 17.7 +/- 4.0 cm (p = 0.0005). During optimized sequential BiV pacing, QS(max-min) further decreased from 46.7 +/- 23.0 msec to 30.6 +/- 21.0 msec (p = 0.02) and LVEF further increased from 30.0 +/- 7.7% to 35.0 +/- 7.7% (p = 0.0003). CONCLUSIONS: Sequential BiV pacing with VV delay optimized by evaluation of aortic VTI enhanced the response to CRT with additional improvements in left ventricular synchrony and left ventricular function compared to simultaneous CRT.     

Prospective comparison of echocardiographic atrioventricular delay optimization methods for cardiac resynchronization therapy

BACKGROUND: Atrioventricular (AV) delay optimization can be an important determinant of the response to cardiac resynchronization therapy (CRT) in patients with medically refractory heart failure and a ventricular conduction delay. OBJECTIVES: The purpose of this study was to compare two Doppler echocardiographic methods of AV delay optimization after CRT. METHODS: Forty consecutive patients (age 59 +/- 12 years) with severe heart failure, New York Heart Association class 3.1 +/- 0.4, QRS duration 177 +/- 23 ms, and left ventricular ejection fraction 26% +/- 6% referred for CRT were studied using two-dimensional Doppler echocardiography. In each patient, the acute improvement in stroke volume with CRT in response to two methods of AV delay optimization was compared. In the first method, the AV delay that produced the largest increase in the aortic velocity time integral (VTI) derived from continuous-wave Doppler (aortic VTI method) was measured. In the second method, the AV delay that optimized the timing of mitral valve closure to occur simultaneously with the onset of left ventricular systole was calculated from pulsed Doppler mitral waveforms at a short and long AV delay interval (mitral inflow method). RESULTS: The optimized AV delay determined by the aortic VTI method resulted in an increase in aortic VTI of 19% +/- 13% compared with an increase of 12% +/- 12% by the mitral inflow method (P <.001). The optimized AV delay by the aortic VTI method was significantly longer than the optimized AV delay calculated from the mitral inflow method (119 +/- 34 ms vs 95 +/- 24 ms, P <.001). There was no correlation in the AV delay determined by the two methods (r = 0.03). CONCLUSION: AV delay optimization by Doppler echocardiography for patients with severe heart failure treated with a CRT device yields a greater systolic improvement when guided by the aortic VTI method compared with the mitral inflow method.     

Improved response to cardiac resynchronization therapy through optimization of atrioventricular and interventricular delays using acoustic cardiography: a pilot study

BackgroundThe purpose of this pilot study was to determine the utility of acoustic cardiography for the optimization of atrioventricular (AV) and interventricular (VV) delays in cardiac resynchronization therapy (CRT).Methods and ResultsWe evaluated 14 patients (86% male, mean age 64 ± 9 years, mean time since implant 15 ± 18 months). Subjects were enrolled >10 weeks after CRT implant. Spiroergometry and 2-dimensional/3-dimensional echocardiography were used to assess cardiac performance for “out-of-the-box” settings (baseline settings: AV 120 ms, VV 0 ms) versus optimal settings (determined by acoustic cardiography). Cardiac performance measurements were performed 6 weeks after settings were modified. Optimal AV/VV settings were determined based on the lowest electromechanical activation time (EMAT, the time from the onset of QRS to the mitral valve component of the first heart sound). Statistical analysis was performed using a paired 2-tailed Student's t-test. In comparison to “out-of-the-box” settings, AV/VV delay optimization with acoustic cardiography improved cardiac performance as indicated by significant changes in work capacity, maximum oxygen uptake, oxygen pulse, ejection fraction, end-systolic volume, and velocity-time integral in left ventricular outflow tract.ConclusionsAV and VV optimization by acoustic cardiography produces significant improvements in objective clinical and hemodynamic parameters in comparison to typical “out-of-the-box” settings.     

Transvenous versus open chest lead placement for resynchronization therapy in patients with heart failure: comparison of ventricular electromechanical synchronicity

Background Transvenous lead placement is the standard approach for left ventricular (LV) pacing in cardiac resynchronization therapy (CRT), while the open chest access epicardial lead placement is currently the most frequently used second choice. Our study aimed to compare the ventricular electromechanical synchronicity in patients with heart failure after CRT with these two different LV pacing techniques. Methods We enrolled 33 consecutive patients with refractory heart failure secondly to dilated cardiomyopathy who were eligible for CRT in this study. Nineteen patients received transvenous (TV group) while 14 received open chest (OP group) LV lead pacing. Intra- and inter-ventricular electromechanical synchronicity was assessed by tissue Doppler imaging (TDI) before and one year after CRT procedure. Results Before CRT procedure, the mean QRS-duration, maximum time difference to systolic peak velocity among 12 left ventricle segments (LV Ts-12), standard deviation of time difference to systolic peak velocity of 12 left ventricle segments (LV Ts-SD), and inter-ventricular mechanical delay (IVMD) in OP and TV group were 166 ± 17 ms and 170 ± 21 ms, 391 ± 42 ms and 397 ± 36 ms, 144 ± 30 ms and 148 ± 22 ms, 58 ± 25 ms and 60 ± 36 ms, respectively (all P > 0.05). At one year after the CRT, the mean QRS-duration, LV Ts-12, LV Ts-SD, and IVMD in TV and OP group were 128 ± 14 ms and 141 ± 22 ms (P = 0.031), 136 ± 37 ms and 294 ± 119 ms (P = 0.023), 50 ± 22 ms and 96 ± 34 ms (P = 0.015), 27 ± 11 ms and 27 ± 26 ms (P = 0.86), respectively. The LV lead implantation procedure time was 53.4 ± 16.3 min for OP group and 136 ± 35.1 min for TV group (P = 0.016). The mean LV pacing threshold increased significantly from 1.7 ± 0.6 V/0.5 ms to 2.3 ± 1.6 V/0.5 ms (P < 0.05) in TV group while it remained stable in the OP group. Conclusions Compared to conventional endovascular approach, open chest access of LV pacing for CRT leads to better improvement of the intraventricular synchronization.