Investion of cardiac alternating electric phenomenon in experimental acute myocardial infarction

It has been gerenally known that cardiac alternating electric phenomenon（CAEP）is not a common electrocardiography（ECG）disturbance,with which the presence of myocardial lesion may be suspected.The purpose of present work is to investigate the relation between acute myocardial ischaemia and CAEP.The dogs in which coronary arteries were ligated and normal controls were used for constant monitering ECG changes.The results showed that the incidence of CAEP on epicardial ECG was 100 per cent in the ischaemic zone.The first appearance of CAEP was 2 min after ligation and the late appearance was 12 min.The mean time of development of CAEP was 5.75 min.However,the no such changes in ECG were recorded on the body surface and zones of the heart without ischaemia at the mean time.CAEP was not found also in the control dogs.Tt seems that there is a close relationship between the appearance of CAEP and fatal ventricular fibrillation（VF）,for CAEP is an important ECG disturbance before the occurrence of VF in the dogs with conorary artery ligation.In 7 out of 8 dogs with CAEP VF occarred in a shortly time.Thus,we suggest that CAEP gives a risk signal of the development of VF in acute myocardial infarction.