Cardiac and hemodynamic effects of diltiazem during exercise-induced myocardial dysfunction in dogs.
The effects of diltiazem were tested in chronically instrumented dogs in a model of exercise-induced myocardial dysfunction. Since various bradycardiac agents have beneficial effects on myocardial function during ischemia, it was of interest to find out how a decrease in afterload, possibly combined with a decrease in myocardial oxygen demand, influences dysfunction. Therefore, diltiazem (1 mg/kg i.v.) was tested during critical stenosis of the circumflex branch of the left coronary artery, which led to exercise-induced myocardial dysfunction. At rest, diltiazem causes a reflex increase in heart rate. During exercise, a decrease in heart rate and hence in myocardial oxygen demand was neutralized by a decrease in arterial blood pressure and hence a lowered myocardial perfusion pressure. Therefore, systolic shortening in the ischemic area improved neither at rest nor during exercise after diltiazem.
Abteilung für Herz-Kreislauf-Pharmakologie, Universität Wien, Vienna, Austria.
J G
JG
Grohs
G
G
Fischer
G
G
Raberger
D000787:Angina Pectoris / Q000503:physiopathology; D000818:Animals; D009202:Cardiomyopathies / Q000503:physiopathology*; D004110:Diltiazem / Q000494:pharmacology*; D004285:Dogs; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D010805:Physical Conditioning, Animal
D004110:Diltiazem