Effects of preload, afterload and temperature on the cardiac function and ECG in the isolated perfused heart of carp.

Abstract

The isolated perfused heart of carp was examined to study the effects of input pressure (preload), ventral aortic pressure (afterload) and temperature on the intrinsic mechanical properties and ECG of the heart. Increase in both cardiac output ( ?? b) and stroke volume (SVh) and no marked change in heart rate (HR) with increasing preload indicates that the cardiac function is determined basically by preload. No marked response was observed in any of parameters of cardiac function to changing afterload. SVh, HR and ECG intervals were highly temperature-sensitive, but ?? b was rather constant in a range of 15 to 35°C. At temperatures lower than 10°C, marked decrease in both ?? b, bradycardia and abnormal extension of ECG intervals were observed. At temperatures higher than 37.5°C, although atrial pulsation was still high, ?? b began to rapidly decrease and the arrest of ventricular pulsation was often observed. At 40°C, a complete cardiac arrest was observed in all preparations.