This clinical study was peformed to clarify the postoperative cardiac functions after coronary artery bypass graft surgery in the cases associated with decreased left ventricular ejection fraction (EF) or increased end-diastolic volume index (EDVI). The patients were divided into two groups by preoperative EF. The EF of Group I ranged from 31 to 39% in 42 cases, and the EF of Group II was below 30% in 27 cases. Several parameters of cardiac function such as EF, peak ejection rate (PER), peak filling rate (PFR) or early diastolic peak filling rate were evaluated with radionuclide ventriculography. Postoperative mean values of these parameters significantly improved in both Group I and Group II compared to preoperative values. Although these parameters and left ventricular wall motion did not improve in the 7 cases with an EDVI over 140ml/m² in Group II, the clinical results of these 7 cases were good during the follow-up period except one case which preoperatively had frequent ventricular arrythmia. The clinical condition improved remarkably in the 3 patients who had preoperative angina pectoris among these 7 cases. Surgical indications must be carefully determined in cases with increased EDVI and frequent ventricular arrythmia.

Postoperative cardiac function and the occurrence of arrythmia depend upon myocardial protection during open heart surgery in severe concentric hypertrophy. The effect of myocardial protection was evaluated in terms of several released cardiac enzymes before and after reperfusion, and postoperative left ventricular (LV) cardiac function from cardiac pool scintigram in 21 cases with aortic stenosis (AS Group). These data were compared with 20 cases with aortic regurgitation (AR Group). Heart weight and aortic cross-clamping time were not significantly different in these two groups. The enzymatic values in peak total creatine-kinase (CK) and peak CK-MB fraction were higher in the AS group than in the AR group, and peak GOT was significantly elevated in the AS group (peak GOT: 93±32 in AS group, 64±17IU/l in the AR group, p<0.01). Among the cases in the AS group, six cases with LV small cavity (LVDd<4cm) and severe concentric hypertrophy were associated with high values of released enzyme and the occurrence of ventricular arrythmia. Postoperative cardiac function was estimated from both systolic parameters such as LV ejection fraction (LVEF) or peak ejection rate (PER) and diastolic parameters such as peak filling rate (PFR) or early diastolic filling rate (1/3PFR). Postoperative LVEF and PER improved to normal control levels in the AS group with preoperatively depressed systolic function, although values were decreased in the AR group with impaired systolic function. The postoperative early diastolic peak filling rate did not recover to control levels in the AS group as well as the AR group, and was impaired in the AS group with severe concentric hypertrophy due to elevated chamber stiffness and the delay of time to peak filling rate. In severe concentric hypertrophy, we used several techniques for myocardial protection of terminal blood cardioplegia, and gradually increased reperfusion pressure and LV venting after reperfusion. Late results revealed a good clinical course in all 21 cases except for the occurrence of arrythmia in three.