Intraoperative measurement of saphenous vein bypass graft flow with transesophageal echocardiography.

The value of transesophageal echocardiography (TEE) for detecting saphenous vein coronary graft (SVG) flow was investigated. Thirty-five consecutive patients undergoing elective coronary artery bypass grafting (CABG) were studied intraoperatively. SVG flow characteristics obtained by TEE were compared with those gathered by an electromagnetic flowmeter (EMF). A total of 59 patent bypass grafts were examined. Pulsed-wave Doppler signals could be detected in 38/59 of the grafts studied (64.4%). The detection rate was the same for all types of grafts encountered (left anterior descending, right coronary, left circumflex, and lateral ventricular branches). The flow profiles obtained by TEE were very similar to those detected by EMF. Both profiles showed a bifid appearance with maximal flow in late diastole. The peak velocity seen in a SVG during diastole was 39.0 +/- 12.7 cm/sec. Graft volume determined by TEE correlated well with data obtained by EMF (r = 0.84). TEE is an attractive technique for noninvasively detecting phasic flow in SVGs; however, the flow detection rate is too low for the routine evaluation of graft patency.