急性心包填塞对兔心肌单相动作电位的影响

实验用接触电极记录右心室内膜单相动作电位（ＭＡＰ）和体表记录心电图（ＥＣＣ）方式观察厂急性心包填塞对ＭＡＰ和ＥＣＣ的影响。结果表明：急性心包填塞可使ＭＡＰ波幅下降，ＭＡＰ复极达５０％水平时动作电位持续时间延长（Ｐ＜０．０１），ＱＲＳ波幅下降（Ｐ＜０．０１），心率减慢（Ｐ＜０．０１）。本文提示：急性心包填塞对心肌细胞的复极活动有很大影响。急性心包填塞可能会改变心肌细胞高子通道或离子泵的活性。

THE EFFECT OF ACUTE CARDIAC TAM-PONADE ON MONOPHASIC ACTION POTEN- TIAL OF MYOCARDIUM IN RABBITS

Experiments were performed on 15 rabbits anesthetized with sodium pentobarbital.A contactelectrxxie was used to recond monophasic action potential(MAP)of endocardium of the right ventricle and a surfaceelectrode for electrocardiogram(ECC).Acute cardiac tamponade was made by injection of warm saline into thepericardial cavity.The resdts were as follows:there were no marked changes in QRS amplitude,the heart rate and thedifferent indices of MAP when small amount of saline(< 4ml)was injected.If the volume of saline injection increasedto 6ml,the amplitude of MAP(MAPA)started to lower asuIts indicated that MAP duration at 50% repolariation(MAPO50)prulorlged about 13.6ms(P<0.01)QRS ampliiude fell about 0.3mv(P<0.01)and the heart mte decreasedto 54 beats/min(P< 0.01)All the above criteria changed more obviously as the volume of saline injection increasedto more than 10ml. It is suaested that besides the diastolic filling of the ventricle of myocardial cell was also affected.The activityof the ionic channel or ionic pumps of the heart muscle cells may be affceted by acute cardiac tamponade. Thisproblem should be cousidelxld when acute tamponade is treated clinically.