The long-term success of skeletal muscle in aortic repair.

To determine the efficacy of skeletal muscle for aortic repair, 23 swine underwent repair of descending thoracic aortic defects. In one group, a vascularized muscle flap was used to patch a 2- to 3-cm aortic defect. In two other groups, a short segment of aorta was removed and a 2-cm tube graft of freshly harvested but devascularized skeletal muscle or Vicryl mesh was used to repair the aorta. Swine were followed for up to sixteen months after implantation. There were no deaths or graft-related complications in the vascularized muscle patch group, and after sixteen months, there were no stenoses or aneurysmal dilatations of the flaps. Histologically, a mature pseudointimal layer had been deposited under the muscle flap and was grossly indistinguishable from normal arterial wall. In the group that received devascularized muscle tube grafts, however, suture line dehiscences occurred in 3 of 7 animals within two weeks of operation. There were no dehiscences in the 9 recipients of a Vicryl tube graft, a finding suggesting that deposition of pseudointimal elements was rapid enough to ensure vascular integrity as the Vicryl was absorbed. Postmortem examination of these animals demonstrated stenoses ranging from 30 to 50%, thereby indicating a lack of growth in the new pseudointimal wall. These results demonstrate the long-term reliability of vascularized skeletal muscle for use in major vascular reconstruction, and suggest the beneficial effects of avoiding prosthetic material and promoting optimal pseudointimal formation.