POSTOPERATIVE FLOW CHARACTERISTICS OF LEFT INTERNAL THORACIC ARTERY GRAFTS

Twenty patients whose left internal thoracic artery (LITA) was anastom osed to the left anterior descending artery (LAD) underwent postoperat ive coronary angiography and Doppler ultrasound velocimetry. During an giography, the diameter of the LITA conduit was measured at three poin ts: proximal, mid, and distal. The degree of left anterior descending artery stenosis proximal to the anastomotic site was evaluated by dens itometry. The LITA now velocity pattern was obtained at the three poin ts to calculate the total, systolic, and diastolic flow volume. There were significant differences in the total LITA now among the three poi nts (proximal, 36.0 +/- 17.2 mL/min; mid, 29.9 +/- 15.2 mL/min; distal , 27.2 +/- 14.0 mL/min; p < 0.001 between the proximal and the mid or distal portions). The degree of left anterior descending artery stenos is affected the distal LITA now and diameter (r = 0.823 and 0.811, res pectively). There were significant differences in the systolic LITA fl ow among the three points (proximal, 13.2 +/- 6.5 mL/min; mid, 8.1 +/- 4.7 mL/min; distal, 5.6 +/- 3.4 mL/min; p < 0.001 between the proxima l and the mid or distal portions). However, there was no statistically significant difference in the diastolic LITA flow among the three poi nts (proximal, 22.9 +/- 11.0 mL/min; mid, 21.7 +/- 10.8 mL/min; distal , 21.6 +/- 10.8 mL/min). We conclude that a lower degree of LAD stenos is significantly reduces the LITA flow inducing the string phenomenon. Additionally, during the diastolic phase, the LITA graft transports t he blood primarily to the coronary artery but not to the side branches . Therefore, the steal phenomenon might not apply in the setting of an LITA graft.