Flow-Based Coronary Artery Bypass Graft Patency Metrics: Uncertainty Quantification Simulations to Guide Development

Area of Science:

• Cardiovascular physiology
• Biomedical engineering
• Medical device evaluation

Background:

• Transit time flow measurement (TTFM) is a valuable tool for intra-operative assessment of coronary artery bypass grafts (CABGs).
• Current TTFM metrics for graft patency exhibit significant variability, hindering definitive diagnosis of graft status.
• Quantifying uncertainty in these metrics is crucial for improving diagnostic accuracy.

Purpose of the Study:

• To quantify uncertainty in commonly used TTFM patency metrics for CABGs.
• To identify key physiological parameters influencing this uncertainty.
• To evaluate novel metrics for improved graft assessment.

Main Methods:

• Utilized a realistic multiscale numerical model of coronary circulation for uncertainty quantification.
• Employed Morris screening sensitivity analysis on a simpler lumped-parameter model.
• Qualitatively validated simulation results against a recent clinical study.

Main Results:

• Simulation results showed reasonable correspondence with clinical data.
• Stenosis severity, cardiac period, and graft diameter were identified as influential parameters.
• Mean flow rate and pulsatility index were particularly affected by cardiac period and graft diameter.

Conclusions:

• Metrics reflecting diastolic flow dominance demonstrate high sensitivity to graft stenosis.
• The diastolic resistance index emerged as a highly sensitive indicator of stenosis severity.
• This simulation-based approach can guide the development of improved TTFM patency metrics and clinical study design.