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Effect of Procainamide, Mexiletine, and Propranolol on Ventricular Activation Time Recorded at Cardiac Mapping in Chronic Canine Myocardial Infarction
Author(s) -
DENNISS A. ROBERT,
ROSS DAVID L.,
WAYWOOD JUDITH A.,
COOPER MARK J.,
UTHER JOHN B.
Publication year - 1991
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.1991.tb01706.x
Subject(s) - procainamide , medicine , mexiletine , propranolol , myocardial infarction , cardiology , anesthesia , sinus rhythm , atrial fibrillation
Delayed potentials detected during sinus rhythm appear to be markers for ventricular tachyarrhyth mias associated with ch ronic myocardial infarction. This study investigated whether intravenous Class I and Class II antiarrhythmic drugs could affect delayed potentials detected at cardiac mapping in dogs studied 1–2 weeks after anterior myocardial infarction. Procainamide at therapeutic serum levels (17–34 μmol/L) caused prolongation of delayed potentials (first degree block), the mean change in duration of ventricular activation being + 19.4 ± 5.0 msec (n = 4, p <0.05). At serum levels above the therapeutic range, procainamide caused first degree block in delayed potentials in three of six animals tested (50%), second degree block (Wenckebach, 2:1 or 3:1 block) in another two animals, and third degree block (complete abolition of delayed potentials) in the remaining animal. Mexiletine at therapeutic serum levels (3.5–9.0 μmol/L, caused no significant change in delayed potential duration (+3.1 ± 5.7 msec, n = 4). At serum levels above the therapeutic range, first degree block occurred in four of five animals tested (80%), there being no change in the fifth animal. After propranolol (0.2 mg/kg), there was no significant change in delayed potential duration (−2.5 ± 2.5 msec, n = 4). In conclusion: (1) at standard doses, mexiletine and propranolol have no effect on delayed potentials, but procainamide causes first degree block; (2) at serum levels above the therapeutic range, mexiletine typically causes first degree block, while procainamide causes either first degree or high grade block; (3) ventricular tachyarrhythmias may still be inducible after drugs if delayed potentials persist unchanged or with first degree block.