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In order to evaluate the functional aspect of myocardial neovascularization after grafting a free skeletal muscle flap onto the heart in the dog with an arterial anastomosis to the internal mammary artery (IMA), a gradual occlusion of the left anterior descending coronary (LAD) was induced. This was achieved implanting an Ameroidconstrictor on the LAD, that due to its hygroscopical material induces a gradual coronary occlusion. The occlusion of the LAD was angiographically confirmed in vivo. In one dog the selective angiographical demonstration of the IMA anastomosed to the graft was achieved. This showed retrograde filling of the LAD occluded by the Ameroidconstrictor. These findings were confirmed in all dogs by a microvascular corrosion cast preparation of the vasculature induced from the graft, that was differentiated from the coronaries by a different coloured casting material. The occluded LAD was filled in all preparations by the casting material applied into the IMA. Thus, grafting of a free skeletal muscle flap anastomosed to the IMA onto the dog's heart produces a functional myocardial neovascularization.

In plastic surgery, free skeletal muscle flaps are used for treatment of non-healing injuries like chronic osteitis or radiation ulcers. We wanted to evaluate if the neoangiogenesis induced by these flaps can also constitute a method for revascularization in ischemic heart disease. In diffuse small vessel coronary heart disease, patients are not suitable for bypass surgery because it is impossible to create a microanastomosis with the coronary artery. As an alternative, a free striated muscle flap, transplanted onto the heart, can constitute a source of neovessels. With the induction of extra-intracardial collaterals that develop within 4 weeks after transplantation of the flap, a new surgical approach may be offered to those patients. Our experimental work was performed with 20 dogs. In these, a myocardial infarction of the anterior wall was selectively produced using the Judkins-technique (Radiology 89: 815-824, 1967) for injection of Sephadex-microspheres. Four weeks later a free pectoralis muscle flap was transplanted onto the anterior wall of the heart. Arterial blood supply was achieved with an anastomosis with the internal mammary artery. The venous flow was directed into the right atrium. Four to eight weeks after surgery, the patency of the anastomosis was studied by angiography, showing patency in almost all surviving animals. Histological examination of the hearts revealed a prominent vascular network penetrating into the underlying myocardium. Corrosion cast preparations, as well as a postmortem angiography, showed even further penetration of the neovessels into the uninjured parts of the myocardium. Thus, myocardial revascularization may be achieved by transplantation of a skeletal muscle onto the heart.