Background: Evaluation the patency of right internal mammary artery (IMA) graft remains clinically challenging. The study tested the feasibility of transthoracic Doppler echocardiography (TTDE) to evaluate the patency of the right IMA graft in patients with coronary artery bypass grafting (CABG).
Methods: The patients consisted of 58 consecutive ischemic heart disease patients who underwent CABG with right IMA. The right IMA was grafted to the left anterior descending artery (LAD) in 24 patients and to the left circumflex artery (LCX) in 34 patients. Proximal right IMA flow was visualized from the suprasternal approach using TTDE. Diastolic to systolic mean velocity ratio (D/S), the diastolic velocity time integral fraction to that throughout 1 cardiac cycle (DVI fraction) were evaluated. Patients were divided into 3 groups; group of A (<50% stenosis), group B (50% to 90% stenosis), and group C (≥90% stenosis) according to the coronary angiographic findings.
Results: 1) Proximal right IMA flow was visualized in 47 patients (81%). However, the visualizing rate of LCX (68%) was significantly decreased compared to that of LAD (100%). 2) The D/S and DVI fraction were significantly decreased in group C compared to those in groups A and B, and those in group B were significantly decreased compared to those in Group A. 3) The D/S <0.25 predicted graft stenosis ≥90% with a sensitivity 88%, specificity 97%, and accuracy 96%, respectively. The DVI fraction <0.4 also predicted graft stenosis ≥90% with a sensitivity 100%, specificity 97%, and accuracy 98%, respectively.
Conclusions: Evaluation of the proximal right IMA flow seems to be feasible in patients with CABG. This method seems to be useful for detecting severe graft stenosis.

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