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Wall Shear Stress Differences Between Arterial and Venous Coronary Artery Bypass Grafts One Month After Surgery
Nhien Tran-Nguyen1, Francesca Condemi2, Andrew Yan3,4
1Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada. nhien.tran.nguyen@mail.utoronto.ca.
Insights
Computational fluid dynamics revealed arterial grafts in coronary artery bypass surgery have significantly less abnormal wall shear stress than venous grafts. This may explain differences in long-term graft patency rates after bypass surgery.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Medical Imaging
Background:
- Coronary artery bypass graft (CABG) surgery is a common intervention for coronary artery disease.
- Graft failure remains a significant challenge, with underlying mechanisms not fully understood.
- Different graft types (arterial vs. venous) exhibit varying long-term patency rates.
Purpose of the Study:
- To investigate hemodynamic differences among CABG graft types one month post-surgery using computational fluid dynamics (CFD).
- To explore the relationship between graft hemodynamics and long-term graft patency.
- To identify potential mechanisms contributing to differential graft failure rates.
Main Methods:
- Prospective study involving 10 participants (24 grafts) one month after CABG surgery.
- Graft imaging using coronary CT angiography and 4D flow MRI.
- Image-guided CFD analysis to quantify blood flow rate and abnormal wall shear stress (WSS) area.
Main Results:
- Arterial grafts (LIMA, RA) showed significantly lower abnormal WSS area compared to saphenous vein grafts (SVG) (17.9% vs. 70.1%, p=0.001).
- Left internal mammary artery (LIMA) grafts also demonstrated lower abnormal WSS area than SVG (13.8% vs. 70.1%, p=0.001).
- Abnormal WSS area positively correlated with lumen diameter and negatively with flow rate.
Conclusions:
- This is the first prospective CFD study to demonstrate hemodynamic differences in abnormal WSS area among CABG graft types one month post-surgery.
- Findings suggest that abnormal WSS may play a role in the differential long-term failure rates observed between arterial and venous grafts.
- CFD analysis of graft hemodynamics offers insights into graft performance and potential strategies to improve long-term patency.
Abstract:
Although coronary artery bypass graft (CABG) surgery is a well-established intervention, graft failure can occur, and the underlying mechanisms remain incompletely understood. The purpose of this prospective study is to utilize computational fluid dynamics (CFD) to investigate how graft hemodynamics one month post surgery may vary among graft types, which have different long-term patency rates. Twenty-four grafts from 10 participants (64.6 ± 8.5 years, 9 men) were scanned with coronary CT angiography and 4D flow MRI one month after CABG surgery. Grafts included 10 left internal mammary arteries (LIMA), 3 radial arteries (RA), and 11 saphenous vein grafts (SVG). Image-guided CFD was used to quantify blood flow rate and wall area exposed to abnormal wall shear stress (WSS). Arterial grafts had a lower abnormal WSS area than venous grafts (17.9% vs. 70.1%; p = 0.001), and a similar trend was observed for LIMA vs. SVG (13.8% vs. 70.1%; p = 0.001). Abnormal WSS area correlated positively to lumen diameter (p < 0.001) and negatively to flow rate (p = 0.001). This CFD study is the first of its kind to prospectively reveal differences in abnormal WSS area 1 month post surgery among CABG types, suggesting that WSS may influence the differential long-term graft failure rates observed among these groups.
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