Transthoracic colour doppler ultrasonography in the evaluation of internal thoracic artery bypass graft patency

Abstract

The internal thoracic artery (ITA) is the most important conduit for coronary artery bypass grafting. The quality of the anastomosis joining the ITA to the left anterior descending coronary artery has a major impact on left ventricular perfusion. The rapid detection of flow disturbances due to sub-optimal anastomosis is, therefore, of great prognostic significance. In this study, 47 coronary bypass patients were examined using colour Doppler ultrasonography peri-operatively and 4 - 6 months post-operatively. Findings were correlated with clinical observations and a treadmill exercise test. The pre-operative ITA flow pattern was normally triphasic, but changed post-operatively to simulate the normal biphasic flow pattern of left anterior descending coronary artery. A 35-case-control group was used to compare pre-operative ITA flow characteristics. The authors conclude that Doppler parameters, clinical findings and the treadmill test can be used in combination for the routine evaluation of graft patency, and to select cases that require more invasive coronary angiography.