Coronary perfusion under general and selective cardiac hypothermia

Experiments to assess left ventricular function in dogs during and after 2 hours of hypothermic cardioplegia are reported. During the experiment myocardial temperature was maintained between 15 degrees C and 18 degrees C by controlling the rate of flow of a cool cardioplegic solution into the coronary vessels. Before and after the period of hypothermia the left atrial pressure was gradually changed and the aortic flows and pressures that changed in response were recorded. The left ventricular stroke work (gm) was then calculated using the relationship: LVSM = (formula: see text) where: SV = stroke volume (ml), AP = arterial pressure (mmHg), LAP = left atrial pressure (mmHg). Comparison of the calculated values indicated that this method of maintaining cardiac hypothermia reduced cardiac function only slightly.