Electrophysiologic and hemodynamic effects of verapamin. Correlation with plasma drug concentrations.
Verapamil was administered intravenously to 30 open-chest dogs and the electrophysiologic and hemodynamic effects of the drug were correlated with the corresponding plasma concentrations. At concentrations below 152 ng/ml, verapamil prolonged the A-H interval, abolished ventriculoatrial conduction, but did not significantly change sinus rate, cardiac output, left ventricular dp/dt, of systemic vascular resistance. Concentrations above 200 ng/ml were associated with slowing of the sinus rat, high degree atrioventricular block during atrial pacing, 24% decrease in mean aortic pressure, and decreased cardiac output and left ventricular dp/dt. Sinus arrest, high degree atrioventicular block during sinus rhythm, decreased systemic vascular resistance and increased left ventricular end-diastolic pressure occurred when plasma verapamil concentrations exceeded 400 ng/ml. These results show that plasma verapamil concentrations reliably reflect the electrophysiologic and hemodynamic actions of the drug, and that "therapeutic" drug effects can be achieved at plasma concentrations at which myocardial depressant effects are unlikely.
D000818:Animals; D001283:Atrioventricular Node / Q000187:drug effects; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D006325:Heart Atria / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D012849:Sinoatrial Node / Q000187:drug effects; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects; D014700:Verapamil / Q000097:blood / Q000494:pharmacology*
D014700:Verapamil