The assessment of function of left ventricle and patency of aorta-coronary bypass after operation. A study of systolic time intervals.

The effect of aorta-coronary bypass surgery on left ventricular function was evaluated in 39 patients by cardiac catheterization and recording of the systolic time intervals (STI) before and an average of 4.5 months following myocardial revascularization. All patients were in sinus rhythm, had normal QRS intervals on the electrocardiogram, and had taken no medication for at least 3 weeks prior to the study. The STI was unchanged postoperatively in patients with the following characteristics: freedom from angina; heart rate not more than 15 beats greater than the preoperative level; all grafts patent; and no progression of disease in coronary arteries. Deterioration in left ventricular function after operation as represented by shortened left ventricular ejection time, (LVET) prolonged pre-ejection period (PEP), and increased ratio of PEP/LVET was found in patients with the following characteristics: persistent angina; heart rate more than 14 beats faster than the preoperative level; occlusion of any grafts; progression of disease in the coronary arteries; evidence for postoperative myocardial infarction. Worsening of left ventricular performance as determined by STI was more apparent in patients with occluded grafts and no collateral circulation than in those with occluded grafts and collateral circulation which may have offered protection against ischemia. These investigations supported the use of STI in assessing changes in left ventricular function after coronary bypass and, by inference, in assessing the status of the graft.