MAGNETIC VASCULAR POSITIONER FOR AUTOMATIC CORONARY ARTERY BYPASS GRAFTING DOES NOT SIGNIFICANTLY INCREASE THE RISK OF FAILURE RELATED TO LOCAL FLUID DYNAMICS: A NUMERIC STUDY

摘要

Anastomotic devices have been recently introduced in cardiac surgery, in order to make the anastomosis procedure more quick, automatic and efficient. The Ventrica magnetic vascular positioner (MVP) constitutes an attractive anastomotic option that significantly shortens the ischemic time when creating the coronary anastomosis on the beating heart [1]. However, the implantation of the MVP connector modifies the graft configuration, consistently affecting the hemodynamics usually found in the traditional anastomosis. As local fluid dynamics could play a significant role on the onset of vessels' wall pathologies, in this study a computational approach was designed to investigate the flow patterns in presence of the MVP. To do this, a model of standard hand-sewn anastomosis and a model of automated anastomosis were constructed, and CFD was used to simulate realistic graft hemodynamics. Synthetic analytical methods were calculated and compared for the quantitative assessment of the role played by the fluid dynamics in the activation of mechanotransduction pathways at the vessel wall, i.e., time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) [2], and the very recent helical flow index HFI [3, 4]. This allowed to evaluate if the use of the MVP design increases the risks of failure related to the local bypass fluid dynamics.