Evaluation of the internal mammary artery graft: Usefulness of transcutaneous Doppler sonography

The purpose of this study is to evaluate the usefulness of transcutaneous Doppler sonography for assessment of internal mammary artery graft patency after coronary bypass graft. Doppler sonography of internal mammary artery was performed in 23 patients, who underwent postoperative cardiac catheterization studies. Doppler signals from the proximal part of the internal mammary artery graft were studied from the supraclavicular fossa in the left internal mammary artery and from the high intercostal space in the right internal mammary artery. According to the coronary angiographic studies, internal mammary artery grafts were divided into two groups: Group A with significant stenosis (>75% stenosis) of the internal mammary artery, and Group B with no significant stenosis of the internal mammary artery. The diastolic/systolic peak velocity ration and diastolic/systolic flow-volume ratio between the two groups were analyzed. Doppler spectrum of the internal mammary artery were obtained from 21 patients, but not from 2 patients, because of the poor sonic window. According to the coronary angiographic studies, there were 6 cases in Group A and 16 cases in Group B. The diastolic/systolic peak velocity ration and diastolic/systolic flow-volume ration in Group A were significantly smaller than in group B (p<0.05). A diastolic/systolic peak velocity ratio <0.4 predicted significant internal mammary artery graft stenosis (>75% stenosis) with a sensitivity and specificity of 100% and 75% respectively. A diastolic/ systolic flow-volume ratio <0.45 predicted significant internal mammary artery graft stenosis (>75% stenosis) with a sensitivity and specificity of 83% and 88% respectively. Transcutaneous doppler sonography is useful for non-invasive assessment of the internal mammary artery graft patency.