Anti-arrhythmic efficacy of beta-adrenergic blockade during acute ischemia in myocardium with scar.
Ventricular arrhythmia production in the ischemic heart is considered to be influenced by prior infarction. Although beta-adrenergic blockade is known to have beneficial effects during acute ischemia, its anti-arrhythmic efficacy during post-infarction ischemia is not known. To explore this question, we have used a model with a relatively high incidence of ischemic arrhythmias. Mongrel dogs 2 to 3 years of age were studied intact under anesthesia. An irreversible injury of the infero-posterior myocardium was produced with an electrode catheter 1 week earlier. The arrhythmic response to acute ischemia was assessed using serial, transient 15-minute occlusions of the left-anterior descending coronary artery with a balloon catheter. During ischemia alone, the incidence of ventricular fibrillation in animals who underwent all phases of the study was 6 of 9; with atenolol (0.2 mg/kg intravenously) and ischemia, 1 of 9 (p < 0.05). To assess the role of the bradycardic response, the latter was repeated 1 week subsequently during atrial pacing at the heart rate that existed before ischemia. Fibrillation occurred in 8 of 9, a significant reversal of the therapeutic effect. To exclude the potential artifact of a fixed intervention protocol, a study was undertaken with the short-acting esmolol, in which three ischemic periods were alternated at 1-hour intervals: (A) ischemia without treatment, (B) ischemia with continuous infusion of 150 micrograms/kg/min esmolol, and (C) same as B except that heart rate was maintained by atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)
Patel
J
J
Department of Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark 07103-2714.
Lee
W
W
Fusilli
L
L
Regan
T J
TJ
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000818:Animals; D001262:Atenolol / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D004195:Disease Models, Animal; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009203:Myocardial Infarction / Q000150:complications*; D017202:Myocardial Ischemia / Q000150:complications*; D011412:Propanolamines / Q000627:therapeutic use*; D014693:Ventricular Fibrillation / Q000209:etiology / Q000517:prevention & control*
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D001262:Atenolol; C036604:esmolol