Non-invasive assessment of the composite radial artery and in situ left internal thoracic artery Y-graft for myocardial revascularization.

BACKGROUND: It is controversial whether composite arterial grafts can provide adequate blood flow for myocardial revascularization. We assessed at transthoracic echography and myocardial scintigraphy the composite radial artery-in situ left internal thoracic artery Y-graft. METHODS: In 32 of 36 consecutive patients who underwent myocardial revascularization using this composite arterial graft, successful postoperative transthoracic images of the main stem of the Y-graft were obtained at rest and early after standard exercise. The main stem diameter, cross-sectional area and blood flow velocity and volume were measured. The coronary flow reserve (CFR) was calculated. The patients were divided into three groups according to the number of coronary artery systems bypassed with the Y-graft: group I included 11 patients with one coronary system bypassed, group II 18 patients with two, and group III 3 patients with three coronary systems bypassed. In 14 patients myocardial scintigraphy was performed at rest and after stress. RESULTS: After exercise, the diameter, cross-sectional area, and blood flow velocity and volume increased. The mean CFR in group III was greater than in group I (p = 0.00045) and in group II (p = 0.049). In 2 patients, the nuclear stress test was positive (reversible ischemia in the distribution area of the Y-graft) and the mean CFR was lower than in the patients with a negative nuclear stress test (p = 0.046). CONCLUSIONS: This composite arterial graft is a compliant conduit, able to regulate its flow capacity to myocardial demand. Non-invasive assessment of this Y-graft using transthoracic echography is possible, and correlates with the results of myocardial scintigraphy.