Noninvasive assessment of left and right internal mammary artery graft patency with high-frequency transthoracic echocardiography

Objectives: The aim of this study was (1) to visualize internal mammary art ery grafts (IMAG) on coronary artery by transthoracic echocardiography and (2) to assess the patency of the grafts. Methods: Twenty-three patients (21 men, 56 +/- 6 years) with previous coron ary artery bypass grafting were studied at baseline and after they underwen t low-dose dipyridamole infusion. The parameters obtained were systolic (SP V) and diastolic (DPV) peak velocities and their ratio (DPV/SPV); the dipyr idamole infusion to baseline ratio of DPV was an index of IMAG blood now re serve (FR). Two groups of patients were selected at baseline: group A, (n = 12) with a DPV/SPV >1, and group B (n = 11), with a DPV/SPV <1. Results: The IMAG was identified in all patients. Intraluminal now signals obtained with pulsed wave Doppler showed a biphasic pattern (1 systolic and 1 diastolic wave). After dipyridamole infusion was administered, flow velo cities increased in 11 of 12 patients in group A and in 5 of 11 patients in group B. In group A the DPV/SPV increased from 1.79 +/- 0.47 to 1.8 +/- 0. 43 (P = not significant), and the FR was 1.8 +/- 0.4. In group B the DPV/SP V increased from 0.46 +/- 0.05 to 0.5 +/- 0.09 (P = not significant), and t he FR was 1.3 +/- 0.41. Coronary angiography showed the graft patency in al l patients in group A and in 5 patients in group B with increased flow velo city after dipyridamole infusion. In the identification of graft stenosis a t baseline, DPV/SPV showed 100% sensibility and 58% specificity, and FR sho wed 92% sensibility and 84% specificity. Conclusion: Doppler echocardiographic evaluation of the IMAG is a simple no ninvasive method to assess the functional impairment of the vessel.