猫冠状动脉缺血与再灌注对房室传导的影响

ATRIOVENTRICULAR CONDUCTION CHANGES IN ACUTE ISCHEMIC AND REPERFUSED CORONARY ARTERY OF CATS

急性下壁心肌梗塞常引起房室传导功能障碍，然而这种障碍与心肌缺血的内在联系并不很清楚。本实验在去植物性神经传出纤维的猫上进行。通过模板匹配方法从Ｈｉｓ束电图检测Ａ，Ｈ，Ｖ波并测量两心房间期（ＡＡ），心房波与Ｈｉｓ波间期（ＡＨ），Ｈｉｓ波与心室波间期（ＨＶ）和心房波与心室波间期（ＡＶ）。结果如下：结扎右冠状动脉后，２０只动物的ＡＨ间期１４只出现增加（Ａ组），６只未出现增加（Ｂ组）。对Ｂ组进行快速心房起搏后再结扎右冠状动脉，ＡＨ间期增加。运用程序控制多步起搏诱发试验，缺血后的房室结功能曲线向右上移位，引起房室传导阻滞点的ＡＡ间期明显增大。对ＡＢ两组动物进行再灌注可使增大了的ＡＨ间期缩小。结果表明：心肌缺血可引起房室传导功能的延长或隐性延长、并使房室结传导调节功能减弱。这种异常成为心肌梗塞在某些条件下（如心率加快）发生房室传导阻滞的潜在危险因素和病理基础。

Acute inferior wall infarction is freguently complicated by conduction disturbance, but the relationship between ischemia and atrioventricular (AV) conduction disturbance is not well understood. The present experiments were made on cats with heart efferent completely denervated.A,H and V waves were picked up by a template maching algorithm from His bundle electrogram, AA interval (cardiac cycle length), AH interval (AV conduction time), HV and AV intervals were measured . Of 20 cats, 14 showed prolongation of AH interval (Group A), while not in 6 cats (Group B) after ligation of right coronary artery. A fast pacing of right atrium (AA interval=267 ms) was produced in Group B and AH interval was also prolonged after ligation of the artery. By multiple step pacing, the curve of AV nodal function shifted to the right, AH intrval which induced AV nodal block was prolonged after ischemia. After reperfusion, AH interval was shortened both in Group A and B. The above results show that myocardial ischemia may cause abnormality of AV conduction and accommodation function. The abnormality appears to be a potential danger which will induce AV conducton block during tachycardia.