[Comparative study of ventricular late potentials recorded on the body surface and epicardium in experimental myocardial infarction].

A noninvasive method for detecting ventricular late potentials (VLPs) was described. Signal averaging technique with high pass bidirectional digital filter was used to record signal-averaged electrocardiograms (SA-ECGs) on the body surface and epicardium. The SA-ECGs were performed with local ventricular electrograms (LVEs) simultaneously in order to compare the difference in records from the two methods. The LVEs have been recorded by epicardial composite electrodes. The signal averaging system was made in Fudan University (Shanghai) and Suzhou Medical College. Duration of filtered QRS (DQRS), duration of the under 40 microv low-amplitude signal (D40) and last 20 ms voltage of the filtered QRS (V20) were measured. VLPs were defined as the presence of two or more abnormal values. Experiments were performed on 20 anesthetized dogs with ligation of the left anterior descending artery. This study has demonstrated that: (1) DQRS greater than or equal to 60 ms, D40 greater than or equal to 20 ms, V20 less than or equal to 16 microv were considered as abnormal values. These values almost did not overlap with the values detected from normal epicardium and body surface; (2) VLPs were shown on the body surface in 12 of 18 dogs (66.6%) in 3 hours after coronary artery ligation, but decreasing to 42.8% (6/14) in 3-6 days later; (3) the fractionated ventricular electrograms were directly recorded on epicardium of the infarction region by composite electrodes and signal averaging system in late stage of myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)