Use of duplex imaging to assess suitability of the internal mammary artery for coronary artery surgery.

The internal mammary artery is the preferred conduit for coronary artery surgery. To determine the role, if any, of preoperative duplex imaging in assessing the suitability of this vessel, preoperative noninvasive measurements of internal mammary artery diameter and blood flow were performed in 243 patients. The left internal mammary artery was insonated through the third intercostal space by use of duplex scanner (5.0 MHz probe) before coronary artery surgery. Internal mammary artery diameter (millimeters), peak systolic velocity (centimeters/second), and mean velocity (centimeters/second) were measured, and internal mammary artery flow was calculated from velocity and cross-sectional area. In 45 of these patients the internal mammary artery diameter also was measured during surgery with a sterile caliper, and blood was collected for 30 seconds from the transected internal mammary artery to measure flow. These findings were compared to the preoperative values. In 243 patients the mean internal mammary artery diameter was 2.34 +/- 0.03 mm, and mean peak systolic blood flow was 226.7 +/- 6.3 ml/min. In the 45 patients in whom intraoperative measurements were obtained, preoperative mean internal mammary artery diameter was 2.39 +/- 0.05 mm and was not significantly different from the intraoperative mean internal mammary artery diameter of 2.36 +/- 0.04 mm. Preoperative peak systolic flow was 231.3 +/- 8.1 ml/min, and mean flow was 110.3 +/- 7.1 ml/min; intraoperative flow measured 136 +/- 3.6 ml/min. Noninvasive determinations correlated with operative findings for internal mammary artery diameter (r = 0.87) (p less than 0.05), peak systolic blood flow (r = 0.70) (p less than 0.05), and mean blood flow (r = 0.60) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)