INDIRECT MYOCARDIAL REVASCULARIZATION - AN EXPERIMENTAL-STUDY IN THE DOG

It has been shown in previous studies that grafting a free skeletal mu scle flap onto the heart of the dog produces myocardial revascularizat ion. In order to evaluate the functional aspect of these neovessels, a n Ameroid constrictor was implanted into the LADs (left anterior desce nding coronary artery) of five dogs. At the same time, the free muscle flap was grafted onto the anterior wall of the heart. The arterial an astomosis was achieved with the internal mammary artery. Venous flow w as drained into the right atrium. About 12 months later, the regional myocardial blood flow was evaluated adopting the radioactive microsphe re technique. This was carried out with the LAD occluded by the Ameroi d constrictor and the circumflex artery (CX) open (control conditions) . Then the CX was occluded in order to exclude collateral blood flow. Afterwards another occlusion of the CX was performed (''preconditionin g'') to produce maximal opening of the anatomical collaterals. It was found that regional myocardial blood flow was unchanged in the antero- lateral parts of the hearts despite complete occlusion of the coronari es supplying this area. In the parts supplied by the CX, though, flow was minimal. ''Preconditioning'' positively influenced the perfusion o f this region only in the epicardial parts. Histologically large sinus oid-like blood conductors connected the graft and the heart. Thus, gra fting a free skeletal muscle flap onto the heart in the dog produces f unctional myocardial revascularization in the dog.