Assessment of the effect of coronary artery bypass grafting on left ventricular performance by Doppler measurement of the aortic blood velocity during exercise.

The effect of coronary artery bypass grafting (CABG) on left ventricular (LV) function is studied noninvasively in 30 male patients with a mean age o 55.4 years using the continuous-wave Doppler technique of transcutaneous aortovelography (TAV). With a transducer applied in the suprasternal notch the main-stream aortic blood velocity recordings were obtained before and at maximum-tolerated supine exercise both prior to, and six weeks after, CABG. From the TAV recordings the stroke distance (Sd: or the systolic velocity integral which is a measure of the stroke volume) and minute distance (Md: or the measure of cardiac output) were derived as well as the percentage changes in these parameters with exercise (% delta Sd and % delta Md successively). Whereas no significant change following CABG was observed in the resting values for Sd, a significant improvement in the maximal exercise values for Sd and Md as well as the % delta Sd and % delta Md was noticed after CABG (p less than 0.001). Prior to CABG the % delta Sd (an indicator of left ventricular function) was significantly lower in 13 patients with a history of an old myocardial infarction (MI). The % delta Sd in these 13 patients was also significantly lower than that in the 17 patients without a history of MI though the improvement in the % delta Sd following CABG was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)