University of Twente Student Theses


EX-Situ Heart Validator : Novel system for testing the donor heart prior to transplantation.

Nijhuis, F. (2022) EX-Situ Heart Validator : Novel system for testing the donor heart prior to transplantation.

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Embargo date:1 January 2040
Abstract:The heart is one of the most critical components of the human body, if it fails death is imminent. Patients with severe heart failure are eligible for heart transplantation. In heart transplantation the heart is harvested from a diseased patient, the donor, and implanted in the patient in need for a new heart. The pool of donor hearts is (too) small in relation to the patients on the waiting list for heart transplantation. Currently, potential good hearts are rejected because of the unknown damage the heart sustained during the dying process, and the inability to test the heart after the potential donor died. In this thesis a novel system is proposed to validate the quality of the donor heart in an ex-situ test setup. With this system it is possible to evaluate the donor heart, during the period the heart is outside the body, in a beating and working mode. During the cardiac cycle of the heart beat it is possible to measure a pressure volume curve of the ventricular cavity. This PV curve is of great value for the thoracic surgeon to determining the quality of the donor heart prior to transplantation. The heart validating system is constructed out of two main components, the coronary perfusion system, and the pre and afterload system. The coronary perfusion system is an adapted Kidney Assist system from Organ Assist. This system perfuses the coronaries of the heart with a perfusion solution containing red blood cells (RBCs). This system oxygenates the perfusion solution and controls the perfusion pressure and temperature. The second system is the pre and afterload system that is composed of a bellow, balloon, motor and a control unit. The measurement of this PV curve is superior to the parameters measured by the competitors. Also, the proposed system can be used in a clinical application and not only in an experimental setup like most studies do. The proposed system is built out of a bellow placed on the mitral valve of the heart, a balloon that is placed in the left ventricle that has a fluidic connection with the bellow, and a motor that pressurizes the bellow via Bowden cables. The Bowden cables are used to run from the sterile field to the unsterile field. The motor can be controlled with software and therefore it is possible to simulate a physiologic load on the ventricle. Requirements of the lose components are determined. A simplified fluidic impedance of the ventricular load during the systolic ejection phase (blood outflow phase) was found. A bracket was needed to connect the bellow to the mitral valve without damaging the heart. This bracket must be placed behind the mitral valve leaves and must then be connected to the bellow. Static tests were performed to verify the pressure and volume measurement of the system. The first dynamic test of the pre and afterload system was done with an artificial heart. Second a test on real pig heart was performed. For real heart testing the heart was obtained from a slaughterhouse. The mitral valve bracket construction was simulated and tested with a real pig’s heart. It was seen that the proposed system can be used to generate a pre and afterload on the left ventricle wall. A PV curve was made during the artificial heart testing and during the real heart testing. The mitral bracket system could hold more than 39N. Oscillation occurred during the experiment and this reduced the ability to measure reliable data. The current test showed that the concept is proven to be feasible for testing ex situ donor hearts. More repetitive tests of the system are needed to test the system’s tolerances, resolution and speed.
Item Type:Essay (Master)
XVIVO, Groningen, NL
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:44 medicine, 53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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