Resistance to flow of arterial Y-grafts 6 months after coronary artery bypass surgery.

BACKGROUND The use of both internal thoracic arteries (ITAs) as a Y-graft configuration has been proposed as a technique allowing complete arterial revascularization. Controversy remains, however, about the capacity of this Y-graft configuration to provide sufficient blood flow to the whole left coronary system and about possible steal phenomenon occurring during periods of maximal myocardial blood flow demand. METHODS AND RESULTS To evaluate graft conductance 6 months after Y-graft revascularization of the left coronary system with both ITAs, 11 consecutive patients were studied during cardiac catheterization. In all of the cases, the left ITA had been connected to the left anterior descending coronary artery (LAD) territory (mean, 1.3 anastomoses), and the free right ITA was anastomosed proximally to the left ITA and distally to the left circumflex (LCX) territory (mean, 1.9 anastomoses). Pressure and fractional flow reserve (FFR) were recorded using a 0.014-inch pressure wire advanced distally in the left ITA main stem close to the proximal anastomosis of the free right ITA (ITA-stem) and in the distal part of each ITA branch at the site of their implantation to the LAD (ITA-LAD) or LCX (ITA-LCX) system. At each of these sites, the pressure gradient between aorta and the graft was measured in basal condition and during maximal hyperemia induced by intragraft bolus injection of 40 microg of adenosine. In basal conditions, the pressure gradient was minimal between the aorta and the ITA-stem (2+/-2 mm Hg), the ITA-LAD (3+/-3 mm Hg), and the ITA-LCX (3+/-2 mm Hg; P value was not significant versus ITA-LAD). During maximal hyperemia, the pressure gradient increased to 7+/-2 mm Hg in the ITA-stem, to 9+/-5 mm Hg in the ITA-LAD, and to 9+/-3 in the ITA-LCX (P value not significant versus ITA-LAD). The fractional flow reserve was 0.93+/-0.03 in the ITA-stem, 0.91+/-0.04 in the ITA-LAD, and 0.91+/-0.03 in the ITA-LCX. CONCLUSIONS A Y-graft configuration with a free right ITA attached to a pedicled left ITA allows an adequate revascularization of the whole left coronary system with an even distribution of perfusion pressure in both distal branches and minimal resistance to maximal blood flow.