Emboli Transport in a Full-Length Patient-Specific Aorta: Assessment of Abdominal Organ Injury Risk During Cardiopulmonary Bypass

Cardiopulmonary bypass (CPB), though indispensable in cardiac surgery, carries significant risks of systemic embolization and organ injury. While cerebral and cardiac complications have been thoroughly investigated, the impact of emboli on abdominal organs remains largely unexplored. This study integrates computational fluid dynamics (CFD) with Lagrangian particle tracking (LPT) to simulate emboli transport and hemodynamics under clinically relevant CPB conditions in a patient-specific aorta model. A validated OpenFOAM-based framework was used to assess the effects of CPB pump flow rate (3-5 LPM), hemodiluted blood viscosity (1.5-3.5 cP), and embolus size (0.5-2.5 mm) on embolic distribution across major abdominal branches, including the renal, hepatic, splenic, mesenteric, and iliac arteries. Key results showed that lower blood viscosity (1.5 cP) and higher flow rate (5 LPM) significantly affected embolic transport, both individually and combinedly. Under these combined conditions, renal artery emboli transport increased from 17% to 27%, and hepatic artery transport rose from 7.1% to 10.7%. Also, larger emboli (2.5 mm) consistently exhibited greater deviation from central flow and had higher side-branch entry, resulting in increased escape rates of 14% and 26% for renal and hepatic branches, respectively. These tendencies correlated well with clinical observations of post-CPB acute kidney and liver injury. This study presents the first CFD-based quantitative analysis of embolic transport to abdominal organs, revealing critical emboli pathways previously overlooked in both clinical and computational studies. The findings highlight the need for optimized CPB perfusion strategies to minimize embolic burden and enhance intraoperative protection of abdominal organs during cardiac surgery.