Acute hemodynamic effects of coronary artery ligation in conscious rats

Because of the growing interest in the use of coronary artery ligation (CAL) in rats as a model for studies on heart failure, we have investigated the acute hemodynamic changes following CAL in conscious rats. Animals were equipped for measurement of cardiac output (CO), arterial pressure (MAP), and central venous pressure (CVP). These parameters were measured before CAL, immediately after, and 24 h after. Furthermore, peak CO, obtained by rapid infusion of 12 ml Ringer's solution (in 1 min) was measured 2 days before and 1 day after CAL. CAL resulted in immediate reduction of CO, because of reduced stroke volume (SV). CO as well as SV were inversely correlated with infarct size as determined 24 h after CAL. Heart rate (HR) and MAP did not change. Twenty-four hours later, CO was still reduced. MAP was now reduced, possibly as a result from resetting of nervous reflex mechanisms. Before CAL, peak CO and SV were similar in CAL and sham animals. At 24 h after CAL, these parameters were greatly reduced in CAL rats. Peak values were strongly correlated to infarct size. Results indicate that CAL in rats leads to hemodynamic changes similar to the ones observed following myocardial infarction in man. Cardiac function is related to infarct size and is altered both at rest and during maximal stimulation.