Effect of transit time flow meter spike waveform on graft patency and its hemodynamic characteristics in coronary artery bypass grafting

Abstract

Objective

During coronary artery bypass grafting(CABG), surgeons commonly use transit time flow meter (TTFM) to determine the graft patency. This study is to explore the effect of a special “spike waveform” in CABG on graft patency and its hemodynamic environment.

Methods

We collected the data of 1154 patients undergoing CABG, including intraoperative TTFM waveform and coronary CTA at 1 week after surgery. 239 patients had 1-year follow-up CTA. We divided the grafts into spike and non-spike waveform groups, and assessed the patency of grafts. Additionally, we constructed an ideal model of CABG, we also calculated and extracted the hemodynamic parameters of the grafts.

Results

For immediate patency, the occlusion rates of spike and non-spike waveforms of left internal mammary artery(LIMA) were 0 and 5.13%, those of saphenous vein graft(SVG) were 8.59% and 5.79%. As for medium-long term patency, the occlusion rates of spike and non-spike waveforms were 0 and 12.56% for LIMA, and 42.47% and 16.84% for SVG. Regarding hemodynamics, the relative residence time(RRT) and Max Oscillating shear index(MaxOSI) of the LIMA spike waveform were significantly higher than those of the non-spike waveform, and the mean OSI and MaxOSI of the SVG spike waveform were substantially higher than those of the non-spike waveform.

Conclusions

Spike waveform slightly reduces the immediate patency of SVG and significantly reduces the medium-long term patency, while no effect on the patency of LIMA is found. In terms of hemodynamics, both LIMA and SVG with spike waveforms exhibit unfavorable hemodynamic conditions within the grafts.