Postoperative Changes in Duplex Ultrasound Velocity Characteristics in the Nonmobilized Right Internal Mammary Artery in Patients with Left Internal Mammary Artery Bypass Grafting

The internal mammary artery (IMA) is the conduit of choice in coronary revascularization because of its long-term patency. We analyzed the effect of left internal mammary artery (LIMA) harvesting on sternal perfusion. Diameters and velocity parameters of the nonmobilized right internal mammary artery (RIMA) were noninvasively analyzed with duplex ultrasound in 41 patients with LIMA myocardial revascularization pre- (2.6 ± 5 days) and postoperatively (4.9 ± 3.9 months). Data of 41 patients were analyzed; 38 patients underwent all examinations with adequate supraclavicular signals. The proximal RIMA diameter and all velocity parameters increased significantly at follow-up (3.1 ± 0.6 vs. 3.2 ± 0.5 mm, p = 0.03; diastolic peak velocity [DPV] 15 ± 7 vs. 27 ± 9 cm/sec, p < 0.0001; systolic peak velocity [SPV] 90 ± 24 vs. 105 ± 29 cm/sec, p < 0.02). This was more pronounced for the diastolic parameters and for all parameters in the proximal part of the RIMA than in the distal part (DPV 11.9 ± 10.1 vs. 9.5 ± 10.2 cm/sec, p = NS; SPV 14.9 ± 33.9 vs. 7.4 ± 26.0 cm/sec, p = NS). With longer time intervals of follow-up the increase in all diastolic velocity parameters became less pronounced. As demonstrated in the RIMA velocity parameters, patients with skeletonized LIMA grafts ( n = 4) had significantly more flow, suggesting hyperemic flow, than patients with pedicled LIMA grafts ( n = 34). Only in diastolic velocity integral (DVI) and systolic/diastolic velocity ratio (SDVRA) were there significant differences between diabetics ( n = 9) and nondiabetics ( n = 29) and only in DVI between female, ( n = 8) and male ( n = 30) patients. This study indicates that duplex ultrasound is a useful tool for noninvasive RIMA follow-up in LIMA myocardial revascularization.