RECOVERY OF SYSTOLIC AND DIASTOLIC LEFT-VENTRICULAR FUNCTION EARLY AFTER CARDIOPULMONARY BYPASS

Background: Impairment of left ventricular function after cardiopulmon ary bypass (CPB) is well recognized, but little is known about the tim e course of recovery of cardiac function early after separation from C PB. Therefore, recovery of left ventricular function was evaluated ear ly after separation from CPB in patients undergoing coronary artery su rgery. The authors tried to determine whether this recovery might be a ttributed to autoregulation of function by preload. Methods: Left vent ricular pressure was measured with fluid-filled catheters. Data were d igitally recorded during increased pressure induced by elevating the l egs. Transgastric short-axis echocardiographic views of the left ventr icle were simultaneously recorded on videotape. Systolic function was evaluated with the slope (Ees, mmHg/ml) of the systolic pressure-volum e relation. Diastolic function was evaluated with the chamber stiffnes s constant (Kc, ml(-1)) of the diastolic pressure-volume relation. Car diac function was assessed before CPB, after termination of CPB, and 5 , 10, and 15 min later. Two different separation procedures from CPB w ere compared: in protocol 1, left ventricular function was documented during the standard procedure (n = 24); in protocol 2, the heart was o ptimally filled 10 min before separation from CPB (n = 12). Results: I n protocol 1, Ees was 2.88 +/- 0.21 mmHg/ml (mean +/- SEM) and Kc was 0.012 +/- 0.001 ml(-1) before CPB. Within 10 min after separation from CPB, Ees increased from 1.10 +/- 0.32 to 2.92 +/- 0.34 (P = 0.001) an d Kc decreased from 0.022 +/- 0.002 to 0.011 +/- 0.001 (P = 0.001). Th e parameters remained stable thereafter. In protocol 2, Ees was 2.92 /- 0.51 mmHg/ml and Kc was 0.011 +/- 0.002 ml(-1) before CPB. Depressi on of systolic and diastolic function was not observed in these patien ts. At time 0, Ees was 2.46 +/- 0.16 and Kc was 0.012 +/- 0.002. These values remained stable throughout the entire observation period. Conc lusions: Significant functional recovery was observed early after sepa ration from CPB, which was suggestive of time-dependent changes in bot h systolic and diastolic left ventricular function induced by preload restoration.