Adequate flow through the internal mammary artery graft achieved by a dilatation technique

From Jan. 1984 to Dec. 1988 941 patients had internal mammary artery grafting alone or with vein grafts. There were 1705 associated vein grafts and 957 internal mammary grafts, for a total of 2 662 grafts (2.8 per patient). Use of the internal mammary artery was indicated in patients younger than 70 years with a significant stenosis of the main stem or the proximal left anterior descending artery in elective operations. The overall operative mortality was 3.4%, 2.9% for men and 6.2% for women. It rose to 9.6% in patients who were in New York Heart Association Class IV. Incidence of bleeding requiring reexploration was 5.5% and an intra-aortic balloon pump was implanted in 3% because of low cardiac output. At cardiac recatheterization (on average after 12 months) 88.3% of the internal mammary grafts and 63.3% of the vein grafts were patent. In investigation of, reasons for operative mortality, measuring the free flow of the internal mammary artery showed flow rates of 32-208 ml/min only slightly depending on the blood pressure. A technique of dilatation is described that significantly increases the flow rate up to 85%. The technique has been used regularly since Nov. 1987: from that date the IMA is only used if it has a flow rate of at least 60 ml/min.