Evaluation of Procedures Designed to Enhance Coronary Collateral Blood Flow

Three procedures reported to improve the coronary collateral circulation were carried out in dogs: (1) placement of 0.25 to 0.5 Gm. of sterile shredded asbestos over the surface of the heart; (2) suturing of the mediastinal fat pad to the abraded left lateral surface of the heart in conjunction with the application of asbestos; (3) implantation of the internal mammary artery into the left ventricular wall in conjunction with application of Ivalon sponge to the denuded surface of the left ventricle. The effectiveness of these measures was determined in dogs with previously narrowed left circumflex coronary arteries. As judged by retrograde flows and peripheral coronary pressures, the collateral vessel development was not increased over and above that produced by narrowing alone. Coronary artery injection studies revealed that only internal mammary artery implantation produced vascular connections between cardiac and extra-cardiac vessels.