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。     

DDD起搏最佳房室延迟的设置及血流动力学评价

目的 对不同房室延迟DDD起搏患者进行血流动力学评价,探讨DDD起搏最佳房室延迟的设置方法。方法 应用超声心动图研究17例植入DDD起搏器患者不同AV间期时心排出量（CO）、舒张期二尖瓣返流（DMRD）、A波结束至二尖瓣完全关闭时间间期及同步心电图QT间期等的变化。结果（1）当 AV延迟调至（16.9±19.9）ms时,A波结束与二尖瓣关闭同时出现,此时将AV延迟分别延长20ms、40ms、60ms、80ms,A波结束至二尖瓣完全关闭的间期分别延长（13.9±3.7）ms、（31.5±5.1）ms、（52.8±4.1）ms、（72.4±4.0）ms,而且在此间期可发现舒张期二尖瓣返流;（2）CO最大时的AV延迟（即最佳房室延迟）与预测的最佳 AV延迟呈明显正相关（r=0.893,P<0.05）;（3）临界AV间期与最佳AV间期有显著正相关（r=0.884,P<0.05）,临界AV间期较最佳AV间期长;（4）临界AV间期及其后不同AV间期预测的最佳AV间期之间差异均无显著性（P>0.05）。结论 （1）临界AV间期可代表最佳AV间期的上限,可用临界AV间期减去A波结束至二尖瓣完全关闭的时间间期来预测最佳AV间期;（2）最佳AV延迟可按以下公式预测:先设置一个较长的AV间期,然后于超声心动图下测量A波结束至二尖瓣完全关闭的时间间期,则最佳AV间期等于此较长的AV间期减去A波结束至二尖瓣完全关闭的     

DDD起搏器不同房室延迟对血流动力学的影响

笔者对 15例Ⅲ度房室阻滞置入DDD起搏器的患者 ,观察不同的AV间期时超声心动图左室射血分数 (EF)与心输出量 (CO)、血浆心钠素水平及平板运动试验参数的变化 ,以评价不同AV间期对血流动力学的影响。结果显示不同的AV间期将产生不同的左室EF与CO及血浆心钠素水平 ,当AV间期最佳时 (15 3 .67± 18.75ms)将产生最佳左室EF与CO ,血浆心钠素水平最低。结论 :对置入DDD起搏器的病人应加强随访 ,调整AV间期可使起搏器发挥最大效能。     

较长I度房室阻滞置人心脏永久起搏器一例

患者女，78岁，因高血压病史10多年，胸闷、呼吸困难2个月，ECG示较长PR间期（0．46s）入院，彩色多普勒超声：心脏各腔室不大，左室舒张径35mm，经二尖瓣多普勒血流示：E峰和A峰融合，舒张期二尖瓣返流明显，冠状动脉造影检查正常。给患者安装DDD型心脏永久起搏器，调整适当AV间期后，临床心力衰竭症状明显改善。结论：对较长PR间期I度房室阻滞、且伴心力衰竭的患者，安装DDD型心脏永久起搏器，似可给患者带来明显的血流动力学益处。     

体表心电图在双腔起搏器房室传导间期最佳化中的价值

目的:探讨置入了双腔起搏器的患者,在随访时,根据体表心电图P波宽度调节房室传导间期(AV间期)对血流动力学的影响。方法:因高度或Ⅲ度房室传导阻滞而安装美墩力SD303双腔起搏器的患者31例。测量患者体表心电图自身P波宽度,和(或)心房起搏脉冲至起搏的P波末端的宽度,在此测量值上加100ms,分别设定双腔起搏器的感知AV间期和起搏AV间期。使用多普勒超声仪,分别在出厂常规设置的AV间期和根据体表心电图优化的AV间期设定值,进行超声检查。结果:经体表心电图调整AV间期后的左室每搏量、左室舒张末期容量和左室射血分数、左室充盈时间、二尖瓣血流速度时间积分,均高于常规出厂设置的AV间期,前三者差异显著(P<0.05)。结论:根据体表心电图中P波宽度的变化来调节AV间期,不但能获得良好的血流动力学效果,且由于其简单易行,而具有广泛的临床实用价值。     

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。     

病窦综合征患者起搏器术后房室传导方式对血浆BNP水平的影响

目的评估固定的长AV间期下的DDD起搏模式对SSS患者在减少心室起搏方面的效果;比较应用固定的长AV间期保留自身房室传导与最适AV间期下房室顺序起搏两种模式的优劣性,为临床选择具有最佳血流动力学效应的起搏参数设置提供依据。方法选取因SSS而安置双腔心脏永久起搏器进行治疗的45例患者,分3次随访进行,每次随访时间间隔为2个月,将起搏器程控与血液生化指标测量相结合,进行两种不同AV间期下房室顺序起搏模式的血流动力学效应评估与对比。结果与临床经验性AV间期相比,固定的长AV间期(350 ms)下的房室顺序起搏使心室起搏百分比由31.8%降低至1.18%(P=0.000);由最适AV间期下转为固定的长AV间期下的房室顺序起搏模式后,血浆BNP浓度明显降低(P=0.02)。结论固定的长AV间期(350 ms)下的房室顺序起搏能够有效减少心室起搏,且在血流动力学方面优于最适AV间期下的房室顺序起搏。     

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。     

较长Ⅰ度房室阻滞置入心脏永久起搏器一例

患者女,78岁,因高血压病史10多年,胸闷、呼吸困难2个月,ECG示较长PR间期(0.46s)入院,彩色多普勒超声:心脏各腔室不大,左室舒张径35mm,经二尖瓣多普勒血流示:E峰和A峰融合,舒张期二尖瓣返流明显,冠状动脉造影检查正常。给患者安装DDD型心脏永久起搏器,调整适当AV间期后,临床心力衰竭症状明显改善。结论:对较长PR间期I度房室阻滞、且伴心力衰竭的患者,安装DDD型心脏永久起搏器,似可给患者带来明显的血流动力学益处。     

双腔起搏治疗肥厚型梗阻性心肌病的临床应用及血液动力学评价

目的对１０例肥厚型梗阻性心肌病（ＨＯＣＭ）患者行双腔（ＤＤＤ）起搏器治疗,探讨不同ＡＶ间期的血液动力学效应,并对其长期疗效进行评价。方法经锁骨下静脉植入ＤＤＤ起搏器,并同时植入Ｓｗａｎ－Ｇａｎｚ导管及猪尾导管,测量不同ＡＶ间期的血液动力学指标,二维超声心动图测量超声形态学指标,并于起搏器植入后二年随访上述指标。结果所有患者临床症状及心功能明显改善,急性起搏时不同ＡＶ间期的血液动力学均有改善,而以ＡＶ间期为１００ｍｓ、１２０ｍｓ时最明显,左室流出道内径（ＬＶＯＴＤ）增宽,收缩期二尖瓣前向运动程度（ＳＡＭ）明显改善,而起搏后１年、２年随访与起搏后即刻相比,上述指标均无显著变化。结论ＤＤＤ起搏可做为药物难治性ＨＯＣＭ的一种有效方法。     

Reevaluation of the role of atrial systole to cardiac hemodynamics: Evidence for pulmonary venous regurgitation during abnormal atrioventricular sequencing

Twenty open-chest dogs with experimental AV heart block were evaluated hemodynamically, angiographically, and by M-mode echocardiography to further elucidate mechanisms whereby abnormal AV sequencing results in decreased cardiac hemodynamics. During fixed-rate AV pacing, there was a consistent decrease in cardiac output, left ventricular and aortic pressures, and left ventricular dimensions with an increase in left atrial pressure as the AV interval was decreased from 100 to 0 msec, and there were further changes when the AV interval was set at ?50 and ?100 msec. The hemodynamic consequences of atrial fibrillation with regular ventricular rhythms were similar to the effects of an AV interval of 0 msec. It is important to note that retrograde blood flow into the pulmonary venous system (pulmonary venous regurgitation) was demonstrated by left atrial angiography at AV intervals of both ?50 and ?100 msec. However, left ventricular angiography failed to reveal mitral regurgitation during fixed-rate pacing at any AV interval or during atrial fibrillation with regular ventricular rates. Thus, during tachyarrhythmias characterized by abnormal AV sequencing, not only is there the loss of active atrial contribution to ventricular filling but there is also evidence for a retrograde or “negative atrial kick” further compromising cardiac hemodynamics.     

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     

Role of echo-doppler in programming of sequential pacemakers. Evaluation of optimal atrioventricular delay in patients with normal or hypertrophic left ventricle]

2D-echocardiography, together with simultaneous measurement of systolic blood pressure and pulsed doppler examination of the transmitral flow were used to assess the left ventricular (LV) systolic and diastolic function during sequential pacing at 4 different atrioventricular (AV) intervals (50, 100, 150, 200 msec), and VVI pacing under the same rate of 90 beats/min in 13 patients (pts), mean age 61.25 +/- 8.26 years with DDD pacemakers implanted for complete AV block. The pts were divided into 2 groups: group I was comprised of 7 subjects showing no clinical abnormalities and normal echocardiograms, and group II of 6 hypertensive subjects with LV hypertrophy and normal systolic function on echocardiography. There was no change in LV diastolic dimension, but a depression in LV systolic function and contractility were shown by the conversion from DDD to VVI pacing in all pts, particularly in group II VVI pacing caused mitral regurgitation with LV filling pattern changing from beat to beat. By changing the AV interval during DDD pacing, the LV filling pattern was modified in all pts. Systolic performance showed little change in group I, whereas in group II more evident modifications were seen. An optimal AV delay, defined as the delay with maximal stroke volume, was identified in all subjects as being 100 and 150 ms in group I and group II respectively. Echo-doppler can thus provide useful information in choosing the mode of pacing and in programming optimal AV delay. In contrast to normal ventricles the systolic performance in hypertrophic ventricles is highly influenced by variation in the AV delay.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pacemaker-induced mitral regurgitation as a cause of refractory congestive heart failure during pacing therapy in a patient with hypertrophic obstructive cardiomyopathy

This report describes a woman with hypertrophic obstructive cardiomyopathy in whom initial hemodynamic improvement by dual chamber (DDD) pacing with short atrioventricular delay was excellent, but severe mitral regurgitation developed during the subsequent follow-up period, resulting in refractory congestive heart failure. There were two possible explanations for the origin of the complicating mitral regurgitation in this patient: pacing-induced semiclosure of the mitral valve, or left ventricular asynchrony caused by right ventricular pacing. Heart failure in patients with hypertrophic obstructive cardiomyopathy who undergo placement of a DDD pacemaker to improve not only mitral regurgitation but also heart failure symptoms can be associated with systolic mitral regurgitation as the cause of failure in DDD pacing therapy.     

Mechanism of hemodynamic improvement by dual-chamber pacing for severe left ventricular dysfunction: An acute Doppler and catheterization hemodynamic study

Objectives.This study was undertaken to determine the mechanism by which improvement in hemodynamic variables may occur with dual-chamber pacing in patients with severe left ventricular dysfunction.Background.Dual-chamber pacing has recently been proposed as a therapeutic alternative for the relief of symptoms in patients with dilated cardiomyopathy.Methods.Fifteen patients with severe left ventricular systolic dysfunction were studied acutely during atrioventricular (AV) sequential pacing at various AV intervals (60, 100, 120, 140, 180 and 240 ms) with use of combined Doppler velocity curves and pressures obtained by high fidelity manometer-tipped catheters and thermodilution cardiac output.Results.Neither cardiac output nor mean left atrial pressure was significantly different when hemodynamic variables in the baseline state were compared with those during AV sequential pacing at the various AV intervals in all patients. The patients were classified into two groups. In group I (eight patients with PR intervals >200 ms on the rest 12-lead electrocardiogram), cardiac output was significantly increased when AV sequential pacing at the optimal AV interval to output was compared with that at the baseline state (3.0 ± 1.0 vs. 3.9 ± 0.43 liters/min, p ≈ 0.005) because timing of mechanical atrial and ventricular synchrony was optimized. In addition, left ventricular end-diastolic pressure and duration of diastolic filling were increased, and diastolic mitral regurgitation was abolished. In group II (seven patients who had normal AV conduction at rest), cardiac output during AV pacing decreased from the baseline value withcut change in the diastolic filling period.Conclusions.Dual-chamber pacing any improve acute hemodynamic variables in selecetd patients with dilated cardiomyopathy, mainly by optimization of the timing of mechanical atrial and ventricular synchrony. Reestablishment of the optimal diastolic also contribute to hemodynamic improvement.     

Effect of ventricular and sequential stimulation on the left- ventricular systolic function]

Left ventricular systolic function at rest was determined by echocardiography and Doppler in 20 patients after dual chamber pacemaker implantation due to second and third degree A-V block. Measurements were performed in each patient during VVI and DDD mode pacing at three different atrio-ventricular (A-V) intervals: 100, 150 and 200 ms. The essential hemodynamic superiority of DDD stimulation over VVI mode in the form of significant increase of forward stroke volume index (SVI) and cardiac index (CI) during dual chamber stimulation at identical rate stimulation was observed. Closer individual analysis of the values of CI during DDD stimulation at three different A-V intervals (100, 150 and 200 ms) gave the possibility of programming optimal A-V intervals (the highest value of CI) for each patient. The sequential atrio-ventricular stimulation as compared to right ventricular stimulation essentially improves the left ventricular systolic function at rest in patients without symptoms of heart failure. Maximum hemodynamic advantage during DDD stimulation depends on individual selection of A-V delay in each patient.     

The hemodynamic benefit of differential atrioventricular delay intervals for sensed and paced atrial events during physiologic pacing

The ability to program different atrioventricular (AV) delay intervals for paced and sensed atrial events is incorporated in the design of some newer dual chamber pacemakers. However, little is known regarding the hemodynamic benefit of differential AV delay intervals or the magnitude of difference between optimal AV delay intervals for paced and sensed P waves in individual patients. In this study, Doppler-derived cardiac output was used to examine the optimal timing of paced and sensed atrial events in 24 patients with a permanent dual chamber pacemaker. The hemodynamic effect of utilizing separate optimal delay intervals for sensed and paced events compared with utilizing the same fixed AV delay interval for both was determined. The optimal delay interval during DVI (AV sequential) pacing and VDD (atrial triggered, ventricular inhibited) pacing at similar heart rates was 176 +/- 44 and 144 +/- 48 ms (p less than 0.002), respectively. The mean difference between the optimal AV delay intervals for sensed (VDD) and paced (DVI) P waves was 32 ms and was up to 100 ms in some individuals. The difference between optimal AV delay intervals for sensed and paced atrial events was similar in patients with complete heart block and those with intact AV node conduction. At the respective optimal AV delay intervals for sensed and paced P waves, there was no significant difference in the cardiac output during VDD compared with DVI pacing. However, cardiac output significant declined during VDD pacing at the optimal AV delay interval for a paced event and during DVI pacing at the optimal interval for a sensed event.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dual chamber pacing with optimal AV delay in congestive heart failure: a randomized study.

AIM: A prospective randomized trial was set up to evaluate contractile parameters and quality of life in patients with congestive heart failure. METHODS AND RESULTS: We describe the results from 38 patients in sinus rhythm and with chronic heart failure due to congestive cardiomyopathy, prospectively randomized to optimal medical therapy (Group 1, 19 patients) or optimal medical therapy plus dual chamber pacemaker programmed to optimal AV delay (Group 2, 19 patients). At a 6 month follow-up, 7/19 patients in Group 1 had died compared with 5/19 patients in Group 2. During follow-up, there were few significant changes in evaluated parameters except for mitral regurgitation time, which was prolonged in Group 1 and shortened in Group 2. The systolic left ventricular diameter shortened significantly only in Group 2. An energy and activity questionnaire showed that the effect of DDD pacing in the latter patient population was beneficial. CONCLUSIONS: From these results we may conclude that at the 6 month follow-up DDD pacing with echo-optimized AV interval programming can improve quality of life without affecting survival.     

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.