Left ventricular diastolic function after coronary artery bypass grafting: A correlative study with three different myocardial protection techniques

Background: This study was designed to examine the effect of myocardial 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 fibrillation and intermittent aortic crossclamping. Operations were performed with mild hypothermia and ventricular venting through the left superior pulmonary vein in all cases, Left ventricular diastolic function was evaluated with pulsed-wave Doppler transesophageal echocardiography (samples at the mitral valve leaflet; four-chamber view) and left superior pulmonary vein flow velocity. The flow patterns were stored on videotape and sent to an independent investigator for analysis. Left ventricular ejection fraction was calculated,vith transesophageal echocardiography (short-aids view, two-dimensional and M-mode). Results: Left ventricular diastolic function, as measured by the ratio between the peak velocities during early filling and atrial contraction and by systolic diastolic superior pulmonary venous flow ratio, was significantly impaired in all three groups 5 minutes after discontinuation of cardiopulmonary 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 significant hemodynamic differences among the three groups. Conclusions: Left ventricular diastolic function was severely impaired after cardiopulmonary bypass. The degree of impairment depended on the myocardial protection used. The impairment in diastolic function was less when ventricular fibrillation and intermittent aortic crossclamping were used, and greater when anterograde and retrograde cardioplegia were used.