Comparison of fractional flow reserve of composite Y-grafts with saphenous vein or right internal thoracic arteries

Background Composite Y-grafts, using the left internal thoracic artery as the inflow, allow a more efficient use of conduits without the need to touch a diseased ascending aorta. Among other conduits, the saphenous vein graft may be an alternative to the radial artery in elderly patients. Patients and Methods We evaluated the hemodynamic characteristics of 17 composite Y-grafts made with the left internal thoracic artery anastomosed to the left anterior descending coronary artery in all cases and with either the free right internal thoracic artery (RITA group, n=10) or a saphenous vein graft (SVG group, n=7) implanted proximally to the left internal thoracic artery and distally to the circumflex territory 6 months after the operation. Results At baseline, the pressure gradient measured with a 0.014-inch pressure wire was minimal between the aorta and the internal thoracic artery stem (2 ± 1 mm Hg), the internal thoracic artery and left anterior descending (4 ± 2 mm Hg), the internal thoracic artery and left circumflex (3 ± 1 mm Hg), and the saphenous vein graft and left circumflex (2 ± 2 mm Hg). During hyperemia induced by adenosine, the pressure gradient increased significantly to 6 ± 2 mm Hg in the internal thoracic artery stem, 9 ± 4 mm Hg in the internal thoracic artery and left anterior descending artery, 9 ± 3 mm Hg in the internal thoracic artery and left circumflex, and 7 ± 4 mm Hg in the saphenous vein graft and left circumflex. Fractional flow reserve was 0.94 ± 0.02 in internal thoracic artery stem, 0.90 ± 0.04 mm Hg in the internal thoracic artery and left anterior descending, 0.91 ± 0.03 mm Hg in the internal thoracic artery and left circumflex, and 0.92 ± 0.06 mm Hg in the saphenous vein graft and left circumflex. No difference between the two types of composite Y-grafts was observed for pressure gradients or fractional flow reserve measured in internal thoracic artery stem or in distal branches. Conclusions Composite Y-grafts with saphenous vein or right internal thoracic arteries allow similar and adequate reperfusion of the left system with minimal resistance to maximal flow and an even distribution of flow in both distal branches.