Parameter estimation to study the immediate impact of aortic cross-clamping using reduced order models
Résumé
Aortic cross-clamping is a common strategy during vascular surgery, however its instantaneous impact on the distribution of pressure and flow in the arterial network is unknown. We therefore developed two numerical models to investigate the immediate impact of aortic clamping on the mechanical properties of the human vessels. To assess the validity of the models, we recorded continuous invasive pressure signals during aneurysm repair surgery immediately before and after clamping. The first model is a zero-dimensional (0D) three-element Windkessel model which we coupled to a parameter estimation method with a gradient-based algorithm to identify patient-specific parameters such as resistance and compliance. We found a 10% increase in total resistance and 20% decrease in total compliance with clamping. The second model is a 9-artery network corresponding to an average human body in which we solved the one-dimensional (1D) blood flow equations. We developed a technique to construct the 1D network to match the global mechanical properties of the Windkessel model. We found that with such definition, the 1D model is sufficient to predict and reproduce numerically the impact of surgical clamping on the morphology of pressure waves. Both models gave an accurate description of the pressure wave with a high correlation (R 2 > 0.95) between experimental and simulated blood pressure data.
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