CHANGING FLOW PATTERN OF THE INTERNAL THORACIC ARTERY UNDERGOING CORONARY-BYPASS GRAFTING - CONTINUOUS-WAVE DOPPLER ASSESSMENT

Surgeons hale limited ability to evaluate intraoperatively the patency of internal thoracic artery graft as a bypass for coronary artery rev ascularization. We used continuous-wave Doppler ultrasonography to stu dy the velocity of the internal thoracic artery before harvesting and after grafting (scanning probe, 8 MHz). Systolic and diastolic frequen cy shift (in kilohertz) and systolic frequency/diastolic frequency ind ex were analyzed. Twenty four internal thoracic artery grafts in 15 pa tients were studied, Fourteen internal thoracic artery grafts were ana stomosed to the left anterior descending artery, one to a diagonal art ery, and nine to the circumflex artery, The mean systolic frequency be fore harvesting was 1.19 +/- 0.40 KHz acid no significant differences were found between the right and the left internal thoracic artery (fi ght, 1.17 +/- 0.37; left, 1.19 +/- 0.42 kHz). There was a 40% drop in systolic frequency related to the harvesting. Mean systolic frequency decreased after grafting (1.19 +/- 0.40 versus 0.87 +/- 0.32 kHz; p < 0.011) whereas mean diastolic frequency doubled (0.32 +/- 0.12 versus 0.83 +/- 0.4 kHz; p < 0.001) and mean diastolic frequency / systolic f requency index increased from 28% +/- 11% to 101% +/- 39% (p < 0.001), indicating an increased myocardial vascularization during diastole, N o significant difference was found between grafted arteries (left ante rior descending versus circumflex). All patients had an uneventful pos toperative course and no perioperative myocardial infarction was repor ted, Doppler flow quantification of internal thoracic artery bypasses mag give the surgeon an opportunity to evaluate intraoperatively the p hysiologic features and patency of the internal thoracic artery before and after coronary artery bypasses.