Noninvasive cardiac output monitoring during exercise before and after coronary artery bypass surgery.

A computerized continuous wave Doppler instrument was used to monitor changes in cardiac output and stroke volume during supine symptom limited graded bicycle exercise in 30 subjects. Eight patients were studied before and after coronary artery bypass graft (CABG) and were found to have patent grafts (group 1). Six patients were symptomatic after CABG and had at least one graft occluded (group 2). Sixteen age matched asymptomatic subjects served as controls (group 3). In group 1 patients before CABG, the duration of exercise was 5 +/- 2 mins (mean +/- standard deviation), the double product was 162 +/- 25, the percentage change in cardiac output with exercise was 33 +/- 7 and the percentage change in stroke volume was 1 +/- 5. Following CABG in group 1 patients, the duration of exercise increased to 9 +/- 2 mins, the double product to 186 +/- 16, the percentage change in cardiac output to 74 +/- 14 and the stroke volume to 13 +/- 12% (P less than 0.05). These results were not significantly different from those obtained in the group 3 patients (controls) in whom the duration of exercise was 10 +/- 3 mins, double product 211 +/- 24, percentage change in cardiac output 95 +/- 30 and the percentage change in stroke volume was 13 +/- 5.(ABSTRACT TRUNCATED AT 250 WORDS)