Optimal Pressure in Bypass Graft to Prevent Failure Bypass Graft in Carotid Artery to Middle Cerebral Artery Bypass using Computational Fluid Dynamic Method

Abstract

The proper pressure in bypass graft can produce adequate Cerebrovascular Transmural Pressure (CVTMP), which prevents cerebrovascular bypass failure. This study investigated the relation of sufficient pressure in Cerebrovascular bypass graft and inlet bypass angle using a Computational Fluid Dynamics (CFD) method. The geometry of this study was reconstructed from the CT modality of a specific patient. Region of Interest (ROI) was Internal Carotid Artery (ICA) to M2-Middle Cerebral Artery (MCA) without partial left sacrificed ICA. The bypass graft was then reconstructed in the diameter of the Saphenous Vein (SV) from unilateral ICA to M2-MCA. The inlet angle was varied from 15°, 30°, 45°, 60°, 75°, and 90°. Assuming a vessel wall was a rigid tube with a no-slip condition. Blood was incompressible Newtonian with 0.04 P of viscosity and 1.06 gr/cm3 of density. Inlet pressure was pulsatile blood flow velocity. The result shows 75° model had the highest pressure and pressure drop. The 15° model had the lowest pressure. The 30°, 45°, 60°, and 90° had similar pressure. Moreover, the 60° model had the lowest pressure drop among all models. This can be concluded that the 75° model may cause the exceeded CVTMP and bypass failure. However, there are more factors else that cause the bypass failure, such as types of bypass graft, additional preparation methods, and antithrombosis medications.