Assessment of internal mammary artery and saphenous vein graft patency andflow reserve using transthoracic Doppler echocardiography

Objective-To investigate transthoracic Doppler echocardiography in the iden tification of coronary artery bypass graft (CABG) flow for assessing graft patency, Design-The initial study group comprised 45 consecutive patients with previ ous CABG undergoing elective cardiac catheterisation for recurrent ischaemi a. The Doppler variables best correlated with angiographic graft patency we re then tested prospectively in a further 84 patients (test group). Setting Three tertiary referral centres. Interventions-Flow velocities in grafts were recorded at rest and during hy peraemia induced by dipyridamole (0.56 mg/kg/4 min), under the guidance of transthoracic colour Doppler flow mapping. Findings on transthoracic Dopple r were compared with angiography. Main outcome measures-Feasibility of identifying open grafts by Doppler and diagnostic accuracy for Doppler detection of significant (greater than or equal to 70%) graft stenosis. Results-In the test group the identification rate for mammary artery grafts was 100%, for saphenous vein grafts to left anterior descending coronary a rtery 91%, for vein grafts to right coronary artery 96%, and for vein graft s to circumflex artery 90%. Coronary flow reserve (the ratio between peak d iastolic velocity under hyperaemia and at baseline) of < 1.9 (95% confidenc e interval 1.83 to 2.08) had 100% sensitivity 98% specificity, 87.5% positi ve predictive value, and 100% negative predictive value for mammary artery graft stenosis. Coronary flow reserve of < 1.6 (95% CI 1.51 to 1.73) had 91 % sensitivity, 87% specificity, 85.4% positive predictive value, and 92.3% negative predictive value for significant vein graft stenosis. Conclusions-Transthoracic Doppler can provide non-invasive assessment of CA BG patency.