绝对不应期电刺激对正常及心力衰竭右心室乳头肌收缩功能的影响

Effects of Electric Stimulations Applied During Absolute Refractory Priod on Right Ventricular Papillary Muscle of Normal and Heart Failure Rabbits

为观察绝对不应期 (ARP)电刺激对健康和慢性心力衰竭 (简称心衰 )兔离体乳头肌收缩功能的影响。将 34只家兔随机分为健康和心衰兔两组 ,复制心肌梗死 (MI)心衰模型 ,分离兔右心室乳头肌、灌流并给予 1Hz刺激使其等长收缩 ,于该基础刺激的ARP给予双相方波电流刺激 (称之CCM)。观察乳头肌的最大张力 (PT)及其微分 ( +dT/dt)的变化。结果 :CCM刺激时健康组PT及其 +dT/dt比刺激前分别增加 1 5 %和 1 9% (P <0 .0 5 ) ,心衰组增加1 8%和 2 0 % (P <0 .0 5 ) ,且两组PT皆随着CCM刺激就开始增加 ,在几次CCM刺激后达到稳定的水平 ,不同时间点之间PT无差异 ,CCM刺激一旦停止 ,张力就恢复到刺激前的水平。结论 :于ARP发放电刺激能明显增强正常及衰竭心肌的收缩功能 ,且起效快 ,稳定性强 ,研究提示该方法是一种新的有效的调节心肌收缩的途径。

To investigate the influences of electric signals applied during absolute refractory period(ARP) on the contractility of isolated papillary muscle of normal and myocardial infarcted(MI) rabbits. 34 rabbits were assigned to 2 groups at random. MI was produced by left coronary ligation. Papillary muscle was exercised from the right ventricle and was paced at 1Hz. Biphasic square wave pulse was delivered during the ARP(called CCM) in superfused, isometrically contractility rabbit papillary muscle. The peak tension (PT) of papillary muscle , as well as its + dT/dt were observed. Results : Compared with the baseline, both PT and + dT/dt significantly increased during CCM stimulation in two groups ( P <0.05). In addition, PT increased significantly following CCM signal application and reached a new steady level after a few beats. Once the CCM signals were turned off, the PT returned to the approximately baseline level. Conclusion: Electric signals delivered during the ARP can rapidly enhance the contractility of myocardium, which suggests that CCM stimulation is a novel potent method for contractility modulation.