Free internal mammary artery graft as canine femoral artery substitute

Both right and left internal mammary artery (IMA) were dissected free in six dogs via median sternotomy, the left together with 2 cm-wide surrounding tissue and the right as naked artery. Free IMA grafts (3 cm long) were anastomosed end-to-end to the femoral arteries as bypass. Graft patency was assessed by palpation and Doppler analysis twice monthly. At 6 months all grafts were patent. They were harvested for light and scanning electron microscopy (SEM). Intimal thickening was seen in one specimen from each side. Medial fibrosis was more common in the IMA grafts with surrounding tissue. SEM showed endothelium in all grafts, but with some degeneration of endothelial cells. The study thus demonstrated maintenance of patency in free IMA grafts, which did not differ if the graft had been taken with or without surrounding tissue.