The Role of Color Doppler Ultrasonography in the Perioperative Period of Coronary Artery Bypass Grafting: Comparison with Transit-Time Flow Measurement

Abstract

Introduction: The value of color Doppler ultrasonography (CDUS) with the supraclavicular approach for preoperative evaluation of the native left internal mammary artery (LIMA) as well as for the postoperative detection of LIMA graft patency was recently suggested. However, the parameters such as the flow volume and pulsatile index (PI) have not been studied in detail. Objectives: The objectives of this study were to analyze the LIMA data in the perioperative period and explore the relationships between the intraoperative graft flow with transit-time flow measurement (TTFM) and the postoperatively measured parameters with CDUS. Methods: Fifty-eight patients with significant stenosis (≥70%) or occlusions in left anterior descending artery (LAD) who were referred for isolated coronary artery bypass grafting (CABG) were enrolled in this study and examined by CDUS prior to CABG from April to July 2016. The perioperative measurements of proximal LIMA by CDUS were compared. In addition, the correlation between the intraoperative graft flow, such as the mean graft flow (MGF) and PI, and the immediate postoperative measurements of CDUS in LIMA bypassed grafts was statistically analyzed. Results: Six patients were excluded due to screening failure, or insufficient visualization of CDUS images for analysis. Fifty-two patients with in situ LIMA-LAD graft, with or without additional arterial grafts or saphenous vein grafts, were included in the final analysis. The postoperative diameters of proximal LIMA were not significantly different from preoperative diameters (2.21 ± 0.18 vs. 2.27 ± 0.22 mm, p = 0.070). The flow volume on the early postoperative CDUS significantly increased (39.77 ± 21.59 vs. 25.96 ± 13.17 mL/min, p < 0.001) and the PI significantly decreased (1.43 ± 0.46 vs. 4.20 ± 1.49, p < 0.001) versus those of preoperative measurements. The MGF had a moderate correlation with the flow volume on the early postoperative CDUS (r = 0.414, p = 0.002), and the PI by TTFM had a weak correlation with that by CDUS (r = 0.353, p = 0.010) as well. Conclusions: The MGF and PI by TTFM in CABG were associated with in situ LIMA graft parameters measured by CDUS studies. CDUS is a useful functional noninvasive tool for the preoperative screening and postoperative follow-up of patients with in situ LIMA bypass.