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Abnormal Wall Shear Stress Area is Correlated to Coronary Artery Bypass Graft Remodeling 1 Year After Surgery
Nhien Tran-Nguyen1, Andrew T Yan2,3, Stephen Fremes4,5,6
1Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada. nhien.tran.nguyen@mail.utoronto.ca.
Insights
Left internal mammary artery grafts show lower abnormal wall shear stress (WSS) and less remodeling than venous grafts after bypass surgery. Abnormal WSS correlates with graft lumen changes, suggesting a role in graft failure.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Medical Imaging
Background:
- Coronary artery bypass graft (CABG) surgery is a primary treatment for coronary artery disease.
- Graft failure remains a significant challenge, with mechanisms not fully elucidated.
- Understanding graft hemodynamics is crucial for improving surgical outcomes.
Purpose of the Study:
- To investigate the relationship between graft hemodynamics and post-operative remodeling in coronary artery bypass grafts.
- To compare hemodynamic profiles and remodeling patterns between arterial and venous grafts.
- To identify potential mechanisms contributing to graft failure.
Main Methods:
- Computational fluid dynamics (CFD) simulations with deformable vessel walls were performed.
- Data from CT and 4D flow MRI were used to quantify lumen diameter and wall shear stress (WSS) one month post-surgery.
- Lumen remodeling was assessed via CT one year post-surgery.
Main Results:
- Left internal mammary artery (LIMA) grafts had significantly lower abnormal WSS area compared to venous grafts at one month (13.8% vs. 70.1%, p=0.001).
- LIMA grafts exhibited less inward lumen remodeling at one year compared to venous grafts (-2.4% vs. -16.1%, p=0.027).
- Abnormal WSS area at one month post-surgery correlated with the percentage change in graft lumen diameter at one year (p=0.030).
Conclusions:
- This study prospectively demonstrates a correlation between abnormal WSS one month post-surgery and graft lumen remodeling one year later.
- Shear-related mechanisms may influence post-operative graft remodeling.
- Hemodynamic factors, particularly WSS, may help explain differential failure rates between arterial and venous grafts.
Abstract:
Coronary artery bypass graft surgery is a common intervention for coronary artery disease; however, it suffers from graft failure, and the underlying mechanisms are not fully understood. To better understand the relation between graft hemodynamics and surgical outcomes, we performed computational fluid dynamics simulations with deformable vessel walls in 10 study participants (24 bypass grafts) based on CT and 4D flow MRI one month after surgery to quantify lumen diameter, wall shear stress (WSS), and related hemodynamic measures. A second CT acquisition was performed one year after surgery to quantify lumen remodeling. Compared to venous grafts, left internal mammary artery grafts experienced lower abnormal WSS (< 1 Pa) area one month after surgery (13.8 vs. 70.1%, p = 0.001) and less inward lumen remodeling one year after surgery (- 2.4% vs. - 16.1%, p = 0.027). Abnormal WSS area one month post surgery correlated with percent change in graft lumen diameter one year post surgery (p = 0.030). This study shows for the first time prospectively a correlation between abnormal WSS area one month post surgery and graft lumen remodeling 1 year post surgery, suggesting that shear-related mechanisms may play a role in post-operative graft remodeling and might help explain differences in failure rates between arterial and venous grafts.
