One of the major problems in cardiology today is how to more effectively treat individuals with coronary artery disease who have symptoms refractory to conventional therapy, including antianginal drugs and coronary artery bypass surgery. One potential approach we are currently investigating is implantation of the internal mammary artery (IMA) into ischemic regions of the left ventricle. This operation has been performed on patients in the past, but the blood flow through the IMA was found to be generally insufficient, incapable of delivering enough blood flow to importantly influence symptoms. A potent growth factor, known to cause the proliferation of blood vessels (angiogenesis factor) has recently been derived from he greater omentum of the cat. Our experiment is designed to assess the ability of this angiogenesis factor as well as heparin (which has been shown to be angiogenic in vitro, to potentiate the growth of vascular connections derived from IMA's implanted in chronically ischemic myocardium in a canine model. Foxhounds will under go IMA implantation into the anterior wall of the left ventricle (Vineberg Procedure). Animals will randomly be assigned to receive continuous administration into the IMA of either angiogenesis factor, heparin, or normal saline. The area of the left ventricle in which the IMA graft is placed will be rendered ischemic over a two to four week period by positioning Amerois constrictors around the left anterior descending coronary artery and the first marginal branch of the circumflex coronary artery. Animals will be studied eight weeks postoperatively to determine both the baseline myocardial blood flow and the maximum capacity for myocardial blood flow (vasodilator reserve) in the ischemic zone. The gross anatomic and microscopic distribution of vascular anastomoses as well as the density of coronary arteries within the ischemic area will subsequently be determined.
