[Electrophysiologic study of ischemic ventricular arrhythmia].

Epicardial composite electrode and isochronal mapping were used in this study to detect ventricular late potentials and ventricular activity sequence during sinus rhythm and ventricular tachycardias. 20 dogs were studied before and during acute ischemia induced by coronary artery ligation, 11 dogs 3-7 days after two-stage ligation of the left anterior descending coronary The effect of lidocaine and verapamil on VLP and reentrant ventricular arrhythmias was studied. The results demonstrated that: (1) Ventricular arrhythmias occurred right after ligation and 3-7 days later after ligation were related to the reentry in infarct myocardia zone; (2) The inhomogeneous conduction and dispersive refractory period provided a suitable milieu for reentry; (3) Reentrant excitation always occurred in a figure 8 configuration and delayed depolarization and continuous activation were reflected as VLPs at composite electrode; (4) Lidocaine in therapeutic dose prolonged the VLPs and interval of V-VLP. The effect of lidocaine on the ischemic zone was directly related to its ability to abolish reentrant ventricular arrhythmias; (5) Verapamil shortened the VLPs and interval of V-VLP, so the action of slow-response action potentials could not be excluded. Further study should be performed in order to demonstrate the precise mechanism of VLP.