1981 Volume 22 Issue 5 Pages 801-813
This study was performed to investigate the prophylactic effect of disopyramide phosphate on ventricular fibrillation in acute myocardial infarction. Lidocaine and disopyramide phosphate were compared in terms of their effects on the lowered ventricular fibrillation threshold in experimental myocardial infarction produced by coronary ligation in dogs. The following results were obtained:
1) The effect of lidocaine i.v.+infusion appeared promptly and the ventricular fibrillation threshold exceeded control levels from 45min onwards (p<0.01).
2) The i.m. injection of lidocaine was effective in a dose of 10mg/Kg. The minimally effective blood level was 1.7mcg/ml.
3) Disopyramide phosphate 5mg/Kg i.v. produced a tendency towards recovery from 15min onwards. After 30min, the ventricular fibrillation threshold was significantly higher than control (p<0.01).
4) Disopyramide phosphate 5mg/Kg i.m. was initially effective after 45min. The effect was significant from 1 hour and 30min onwards, compared with control (p<0.01). The minimally effective blood level was 2.4mcg/ml.
5) Disopyramide phosphate 2mg/Kg i.m. produced a tendency towards recovery but the difference from the control was not significant.
6) In equivalent i.m. doses, disopyramide phosphate tended to be more potent than lidocaine in increasing the ventricular fibrillation threshold.
7) In the aforementioned doses, disopyramide phosphate did not cause any marked changes in PQ interval or QT time in ECG.
These results suggest that the intramuscular injection of disopyramide phosphate is a hopeful clinical treatment to prevent ventricular fibrillation in the very early stages of acute myocardial infarction.
