Modeling the hemodynamics of vein grafts in heart bypass patients

2021 Research Internship Project

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Faculty Name

Owais Khan

Project Title

Modeling the hemodynamics of vein grafts in heart bypass patients

Project Description

Coronary artery bypass grafting (CABG) surgery is performed to re-direct blood flow around blocked heart (coronary) vessels, which reduces risks of heart attacks. The grafts are typically patients' own vein, harvested from their inner thigh, and implanted around blocked heart vessels. However, these vein grafts fail at high rate, 25% in 1-year, which increases patient mortality. Biomechanical forces play a key role in vein graft failure, but no imaging modality exists that can measure these stresses. The proposed research will utilize patient-specific and multi-scale computational simulation approaches to study the biomechanics of vein graft failure. An existing cohort of 31 patients from Sunnybrook Hospital will be utilized. The cohort contains computed tomography angiography (CTA) images of patients' heart taken at 1-year and 5-year after surgery. The computational simulation will be performed using an open-source software package, SimVascular. The pipeline involves segmentation of patients' heart vessels to build 3D models, and fluid-structure interaction (FSI) simulations of these models. The boundary conditions used to solve governing equations will be derived from clinical data of the patient (e.g., cardiac output). Simulated velocity and pressure data will then be processed to compute relevant biomarkers, such as shear stresses and wall strains. These biomarkers will be correlated with changes in vein graft lumen area between 1- and 5-year CTA scans. This research will establish the role of biomechanical forces in vein graft disease and remodeling, and lead to predictors that can identify high-risk patients who may benefit from earlier intervention.

Student Responsibility

The student will interact with our technician to reconstruct 3D models of patients' heart vessels from CTA and extract clinical data from medical reports. Once the data has been gathered, the student will generate 1D flow circuit models of patients' coronary physiology and tune the input parameters to match clinical data (e.g., cardiac output). Lastly, the student will use these tuned parameters as boundary conditions to perform high-resolution 3D FSI simulations of 31 pre/post-CABG patients.

Specific Requirements

Good understanding of Electric Circuits (ELE202) and Physiology (BLG601).