Optimisation of in vitro tissue cooling tests using the CryoTherapeutics system : Characterization and selection of an effective test medium for mimicking coronary atherosclerotic tissue properties.

Abstract

This Master Thesis results from a collaboration with CryoTherapeutics, a company developing a therapeutic device designed for applying coronary cryotherapy. The aim of the therapy is the stabilization of vulnerable atherosclerotic plaque. The objective of the present thesis was to investigate suitable test materials for simulating the thermal behaviour of both healthy and atherosclerotic coronary artery tissues in order to optimize the in-vitro testing setup for the testing of CTS system performance. In this context, we aimed to make an initial material selection based on the state-of-the-art and define an experimental protocol to determine which material provides the highest mimicking performance. This experiment protocol was composed of two central testing phases : theoretical and practical. During the theoretical testing phase, the comparison of the thermal properties of the different materials with the thermal properties of human tissues allow us to define “Agar 52 PPG 192” as the material mimicking the coronary artery conditions the best. During the practical testing phase, the comparison of the thermal behaviour during a CTS treatment of the different materials with the thermal behaviour observed during clinical trial POLARSTAR allow us to define “Agar 52 PPG 96” and “Agar 52 PPG 192” as the materials mimicking respectively the healthy and diseased coronary artery conditions the best. The intricacies of the functioning principle of the CTS system and its nascent state of advancement presented certain obstacles in this undertaking. Nevertheless, these challenges were anticipated, as the objective of this project was to contribute to the advancement of this novel technology. To conclude and to return to our initial objective, the use of these new tissue-phantoms enables to improve the in-vivo testing environment and offers the possibility to pursue the development of the CTS system in better testing conditions. Consequently, it can be posited that the objective of this project has been achieved.