短时快速激动对肥厚心肌电生理特性的影响及其与室性心律失常的关系

观察短时快速激动对肥厚心肌电生理特性的影响并探讨其与室性心律失常 (VA)发生的关系。以部分结扎腹主动脉方法制作心肌肥厚模型。阻滞自主神经后 ,在心外膜右室流出道 (RVOT)、右室心尖部 (RVA)、左室流出道(LVOT)及左室心尖部 (LVA)四个部位以 2 2 0 ,2 4 0 ,2 6 0次 /分的频率刺激测定各部位的单相动作电位时限 (MAPD)及有效不应期 (ERP)。然后于 1∶1房室传导下 ,随机进入普通右房电刺激组 (2 2 0次 /分 )和快速右房电刺激组 (2 6 0次 /分 ) ,持续 30min后 ,重复上述测定过程。记录心室后除极的发生次数。最后诱发心室颤动 (VF) ,记录诱发率和VF持续时间。结果 :心肌肥厚组快速激动后除RVA外 ,其他各部位的ERP值均显著延长 (2 2 0 ,2 4 0 ,2 6 0次 /分频率刺激下的前后ERP值 (ms)为 :RVOT 15 1± 18vs181± 2 1,14 5± 17vs173± 14 ,14 0± 15vs 16 7± 14 ;RVA 16 1± 17vs 171± 19,15 5± 16vs 16 6± 19,15 2± 17vs 16 2± 18;LVOT 16 5± 2 7vs192± 2 0 ,16 1± 2 5vs187± 2 1,15 4± 17vs178± 15 ;LVA 170±15vs191± 15 ,16 5± 15vs189± 11,15 9± 13vs 182± 11)。而对照组在快速激动后的ERP延长并不显著。心肌肥厚组和对照组在普通刺激下 ,ERP均无明显延长。各组在刺激前后的MAPD?

Electrophysiological Characteristics Due to Short-term Tachycardia in Cardiac Hypertrophy and It's Role in Genesis of Ventricular Arrhythmia

Electrical remodeling of atrium is a well recognized pathophysiological process in patient and animal studies.But the manifestation of ventricular electrical remodeling in cardiac hypertrophy and it's role in the genesis of ventricular arrhythmias (VA) have not been previously evaluated.Japanese white rabbits were subjected to partial ligation of abdominal aorta for 10 weeks to induce cardiac hypertrophy (group A).The same procedure was performed in the control group except the ligation of abdominal aorta (group B).With atropine and metoprolol pretreated,the monophasic action potential duration (MAPD) and effective refractory period (ERP) were measured (S 1S 1 rate=220,240,260 ppm) at four sites (right ventricular outflow track,RVOT;right ventricular apex,RVA;left ventricular outflow track,LVOT;and left ventricular apex,LVA) on the epicardium.Then the right atrium was paced at a rate of 260 or 220 ppm with 1:1 AV conduction for 30 minutes.After pacing,the MAPD and ERP were measured as before.Finally with S 1S 2S 3 protocol,the ventricle was stimulated to induce ventricular fibrillation (VF).The lasting time of VF was recorded.Results:In the group A1 (hypertrophy with 260 ppm atrial pacing, n =9),the ERP was significantly increased after pacing.In group B1 (the control with 260 ppm atrial pacing, n =10),although the trend of ERP increase was observed,the increase was significantly less than that of group A1.In the group A2 (hypertrophy with 220 ppm atrial pacing, n =8) and the group B2 (the control with 220 ppm atrial pacing, n =9),no increase of ERP was observed.No significant increase MAPD 90 was observed in each group.The successful VF inducing rate and the mean time of VF lasting in each group were:A1:6/9,73 seconds;A2:2/8,27 seconds;B1:1/10,5 seconds;B2:0/11.After depolarization was observed in group A1:12/9,group A2:3/8,group B1 1/10 and group B2 1/9.Conclusion:In cardiac hypertrophy the increase of ERP due to rapid atrial pacing with normal AV conduction were more significant than that of the normal.This may contribute to the genesis of VA in hypertrophy.