DOUBLE GRAFTING OF THE LEFT ANTERIOR DESCENDING ARTERY - IS THE DISTANCE BETWEEN THE INTERNAL MAMMARY ARTERY AND SUPPLEMENTAL VEIN GRAFT ANASTOMOSES RELEVANT IN GRAFT-SURVIVAL

Introduction: Under certain conditions (small internal mammary artery (TMA) or large runoff), double grafting of the left anterior descendin g (LAD) artery system is necessary to avoid the ominous consequences o f myocardial hypoperfusion. Previous studies have shown that a sapheno us vein (SVG) adjacent to an IMA graft leads to failure of the IMA. Th is study compares IMA flow patterns when adjacent (<1 cm) and separate d (3-4 cm) from a SVG placed on a proximally occluded LAD. Methods: A SVG and right IMA (PIMA) to proximal LAD (2.5-3 mm) coronary bypass we re performed in 12 mongrel dogs. The left IMA (DIMA) was anastomosed t o the distal LAD (1.5 mm). All anastomoses were carried out without ca rdiopulmonary bypass. The native LAD was occluded proximally to the PI MA anastomosis, and all graft flows were measured in competitive and n on-competitive Bow conditions. Results: Isolated graft to LAD Bow's we re similar for the three conduits. There was a drop in flow in both th e PIMA and DIMA when placed in competition with the SVG (10.1 +/- 3.0 vs. 19.1 +/- 4.6 ml/min; P < 0.05). The total drop in flow was signifi cantly greater in the PIMA (67.6 vs. 39.9%; P < 0.05). Diastolic flow was better preserved in the distal IMA graft (19.6 +/- 5.6 vs. 10.2 +/ - 3.0 ml/min; P < 0.05). The patterns of flow were much different duri ng competition and there was significant retrograde systolic Bow in al l PIMA grafts while there was no (n = 5) or minimal retrograde flow (n = 7) in the DIMA grafts. Conclusion: An IMA graft, when adjacent to a SVG, sustains a significant decrease in both total and diastolic flow s and develops an oscillating pattern of Bow in early systole (retrogr ade then antegrade). Placing the IMB mon distally on the LAD improves Bow and decreases retrograde flow. In clinical situations requiring do uble grafting on the LAD, distance between grafts may be an important factor in maintaining IMA patency. (C) 1998 Elsevier Science B.V.