根据QT间期优化双腔心脏起搏器房室延迟的探讨

Optimal atrio-ventricular delay setting determined by QT interval measurement in patients with dual-chamber pacemakers

目的 观察双腔心脏起搏器 (DDD)不同房室延迟 (AVD)时心功能与体表心电图QT间期的变化 ,探讨根据体表心电图QT间期优化AVD的可行性。方法 19例完全性房室传导阻滞植入DDD起搏器患者 ,男10例 ,女 9例 ,平均年龄为 (6 6 .79± 15 .5 2 )岁 ,采用彩色多普勒超声心动图测量不同AVD起搏时心排量 (CO)、左心室收缩末期内径 /舒张末期内径 (LVESd/LVEDd)、左室射血分数 (LVEF)等 ,同时单盲测量不同AVD起搏时 12导联心电图的QT间期。心房起搏频率预设为 75次 /min ,AVD自 90ms起以 30ms步长依次递增至 2 40ms。结果 随着AVD的递增 ,心功能和QT间期随之改善和延长 ,达峰值后又逐渐下降。超声心功能最佳时所对应的AVD与QT间期最大时所对应的AVD的差异无显著性 [分别为 (15 8.80± 13.6 4)ms和 (16 3.30± 30 .41)ms,P >0 .0 5 ];QT间期最大时所对应的心功能各参数与最佳超声心功能各参数相似 [CO分别为(6 .2 9± 1.75 )L/min和 (6 .5 0± 1.5 4)L/min ;LVEF分别为 (6 5 .89± 10 .80 ) %和 (6 7.0 4± 11.19) %;P值均 >0 .0 5 ];QT间期值与CO呈显著正相关性 (r =0 .70 ,P <0 .0 5 )。结论 QT间期随不同AVD时的心功能变化而变化 ,通过测量体表心电图QT间期可进行AVD优化。

Objective To apprasie the optimum atrioventricular delay (AVD) determined by QT interval measurement in patients with implanted DDD pacemakers.Methods Nineteen patients with implanted DDD pacemakers for complete A-V block [aged (66.79±15.52) years] were studied. Cardiac output (CO), Left ventricular ejection fraction (LVEF), left ventricular end-systolic diameter (LVESd) and left ventricular end-diastolic diameter(LVEDd) in different AVDs were measured by colored doppler echocardiography as well as the QT interval by synchronous twelve leads ECGs. The atrial pacing rate was set at 75 bpm and the AVD was prolonged to 240 ms by 30 ms stepwise starting from 90 ms. Results QT intervals changed with the cardiac function at different AVDs. At the maximum CO[(6.50±1.54) L/min], the AVD was (163.30±30.41) ms and the QT interval (463.30±27.83) ms. At the maximum QT interval [(473.33±25.00) ms], CO and AVD were (6.29±1.75) L/min and (158.80±13.64) ms' respectively. There were no significant differences between the “optimum AVD” at which the CO was maximal and the AVD at which the QT interval was the longest [(163.30±30.41) ms vs (158.80±13.64) ms, P>0.05], and there were no significant differences in cardiac function parameters at the maximum QT interval and at the “optimal AVD” [CO:(6.29±1.75) L/min vs (6.50±1.54) L/min, P>0.05; LVEF:(65.89±10.80)% vs (67.04 ±11.19)%;P>0.05]; There was a significant positive correlation between QT interval and CO (r=0.70, P<0.05).Conclusion QT interval changed with cardiac function at different AVDs, the optimal AVD setting can be determined by QT interval measurement.