LEFT-VENTRICULAR DIASTOLIC FUNCTION AFTER CORONARY-ARTERY BYPASS-GRAFTING - A CORRELATIVE STUDY WITH 3 DIFFERENT MYOCARDIAL PROTECTION TECHNIQUES

Background: This study was designed to examine the effect of myocardia l protection on diastolic function after cardiac operations. Methods: Subjects were patients with normal preoperative diastolic function who were scheduled for coronary artery bypass grafting. Group I received anterograde cardioplegia; group II received anterograde and retrograde cardioplegia; and group III was protected with ventricular fibrillati on and intermittent aortic crossclamping. Operations were performed wi th mild hypothermia and ventricular venting through the left superior pulmonary vein in all cases, Left ventricular diastolic function was e valuated with pulsed-wave Doppler transesophageal echocardiography (sa mples at the mitral valve leaflet; four-chamber view) and left superio r pulmonary vein flow velocity. The flow patterns were stored on video tape and sent to an independent investigator for analysis. Left ventri cular ejection fraction was calculated,vith transesophageal echocardio graphy (short-aids view, two-dimensional and M-mode). Results: Left ve ntricular diastolic function, as measured by the ratio between the pea k velocities during early filling and atrial contraction and by systol ic diastolic superior pulmonary venous flow ratio, was significantly i mpaired in all three groups 5 minutes after discontinuation of cardiop ulmonary bypass. At 1 hour after operation, these values had returned to control levels only in group III. There was an increased incidence of supraventricular arrhythmias in group III, There were no significan t hemodynamic differences among the three groups. Conclusions: Left ve ntricular diastolic function was severely impaired after cardiopulmona ry bypass. The degree of impairment depended on the myocardial protect ion used. The impairment in diastolic function was less when ventricul ar fibrillation and intermittent aortic crossclamping were used, and g reater when anterograde and retrograde cardioplegia were used.