An internal thoracic artery homograft as a new small caliber vascular substitute

The authors have examined the possibility of usage of an internal thoracic artery (ITA) homograft as a new small caliber vascular substitute. Left subclavian artery to left atrial appendage shunts with fresh ITA homografts (n = 6) or ITA autografts (n = 5) were made by modified techniques of coronary artery bypass grafting in mongrel dogs (body weight, 11-16.5 kg). All recipient dogs had no anticoagulant therapy or immunosuppression. Inner diameter of the grafts was between 1.4 and 2.0 mm. Blood flow in ITA grafts was measured by electromagnetic flow meter. The graft flow was 6-14 ml/min before harvest and 67-220 ml/min just after implantation, and there was no significant difference between groups. Flow in the ITA homografts decreased significantly compared with ITA autografts 1 month after operation, but five of six ITA homografts were patent. Histopathology of the grafts showed vascular rejection in the homograft group. These results suggest that an ITA homograft with postoperative immunosuppression might be a new small caliber vascular substitute for coronary artery bypass grafting in ischemic heart disease and the systemic-pulmonary shunt operation in congenital heart diseases.