Date of Award

5-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry and Chemical Engineering

First Advisor

Venkat Keshav Chivukula

Second Advisor

Darshan Pahinkar

Third Advisor

Manolis Tomadakis

Fourth Advisor

Jessica Smeltz

Abstract

Organ storage and transportation are critical steps for the success of organ transplantation. Static cold storage (SCS) of hearts for heart transplantation (HTx) remains the standard approach. However, SCS may involve damage to the tissue resulting from extended hypothermic preservation, potentially affecting organ viability. More over, the temperature distribution on and within the heart is unknown during heart transplantation. Therefore, there is an interest to study different stages of the heart transplantation process towards determining the 3D temperature distribution on and within the heart. There could be a possibility of having a hypothermic injury in different parts of the heart due to the temperatures that are being used currently in specific parts of the heart transplantation process such as SCS icebox storage and transport. The heart transplantation process was divided into four stages: (i) when the heart is cooled within the donor via cardioplegia. (ii) when it is extracted from the donor and checked outside the body. (iii) when it is stored and transported via SCS Icebox, (iv) when it is checked after removal and (v) when it is implanted within the recipient. To determine the 4D (3D + time) temperature distribution for each of the above stages, we utilize a custom-developed heat transfer and computational fluid dynamic simulation of the heart using COMSOL Multiphysics. The transient Bioheat transfer equation was solved using time-dependent simulations on an anatomically accurate 3D model of the heart with empirically obtained thermal properties for the cardiac muscle and surrounding tissues. Stage 1 was modelled using transient conduction by the cardioplegia fluid flow for several initial temperature conditions. For the second stage of the process, the heart simulation was performed by using the equilibrium temperature reached in the first stage as an initial condition. Stage 3 was modelled for several hours of transport using transient conduction within the icebox. Stage 2 and 4 take into ac count a external heat transfer resistance in comparison to the other stages. The data obtained was compared to clinical experimental data in order to obtain a quantitative analysis of the simulations as well as validation of the models.

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