Effects of ketamine on canine cardiovascular function.

Left ventricular contractility was assessed before and during the peak effect of ketamine in eight canine right heart bypass preparations. Myocardial contractility was defined in terms of maximum left ventricular dp/dt, the ejection fraction, and left ventricular end-diastolic and left atrial pressures at constant heart rate and cardiac inflow. Ketamine produced significant decreases in contractility and there were some indications of a dose-response pattern. The action of ketamine was dependent partly on changes in arterial pressure, as the drug caused a mild but sustained vasodilatation which was not dose-dependent. These data offer further evidence of a small and transient negative inotropic effect of ketamine.