[Quantitative hemodynamic assessment of internal thoracic artery grafts using transthoracic duplex imaging].

The hemodynamics of blood flow in internal thoracic artery (ITA) grafts were studied using transthoracic duplex imaging prior to and following coronary artery bypass grafting (CABG) in 37 patients. Transthoracic images of the ITA were obtained through the first intercostal space using a 7.5 MHz probe, and their diameter and area were measured by B-mode imaging. Systolic, diastolic, mean and end-diastolic blood flow velocity (Vs, Vd, Vm, and Ved) were determined based on Doppler signals and systolic, diastolic, and total blood flow (Fs, Fd, and Ftotal) were calculated by the following formula: Flow = Vm x area x 60/10(3). The diameter of the ITA increased following CABG. Prior to CABG, Vs, and Fs, were dominant, while following CABG, the hemodynamic pattern was diastolic dominant, although individual variation existed. The ITA blood flow was measured in 4 groups, in patients who had had a previous anterior myocardial infarction and no redistribution on myocardial scintigraphy (group I), in patients with 99-100% coronary artery stenosis who had not had an anterior myocardial infarction or who had an anterior myocardial infarction and had redistribution (group IIa), in patients with the same criteria as group IIa but who had 90% coronary stenosis (group IIb), and in patients with 75% coronary stenosis who had not had anterior myocardial infarction (group IIc). Blood flow was 57, 73, 44mL and 34 mL/min, and the percentage of diastolic flow was 72, 69, 61, 59% respectively. These results show that ITA blood flow competes with native coronary artery flow in patients with moderate coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)