Human Heart Conjugate Cooling Process: Unsteady Thermo-Fluid-Stress Analysis

The main objective of this work was to demonstrate computationally that realistic human hearts can be cooled much faster by performing conjugate heat transfer consisting of pumping a cold liquid through the cardiac chambers and major veins while keeping the heart submerged in cold gelatine filling a cooling container. The human heart geometry used for simulations was obtained from three-dimensional, high resolution MRI scans. Two fluid flow domains for the right (pulmonic) and left (systemic) heart circulations, and two solid domains for the heart tissue and gelatine solution were defined for multi-domain numerical simulation. Detailed unsteady temperature fields within the heart tissue was were calculated during the conjugate cooling process. A linear stress analysis was performed to assess the stresses applied on the heart due to the coolant fluid shear and normal forces and to examine the thermal stress caused by temperature variation inside the heart. It was demonstrated that an unoptimized conjugate cooling effort with coolant temperature at +4°C is capable of reducing the average heart temperature from +37°C to +8°C in 25 minutes in for cases in which the coolant was pumped only through major heart veins and cavities. when heart vasculature is not included in the perfusion cooling scheme.