Hearts Ablaze: Radio Frequency Ablation as Treatment for Cardiac Arrythmia

This project analyzes several of the parameters involved in the use of radiofrequency ablation (RFA) in the treatment of cardiac arrhythmia. Arrhythmia is an irregular beating of the heart that can be caused by improperly timed contractions within the heart, which can, in certain circumstances, be corrected by ablating tissue. One out of every five hundred people is born with an arrhythmia and others acquire the condition through heart disease. For heart attack victims, it is the most common cause of sudden death. RFA is a common way to treat serious arrhythmia cases by cutting the short circuit through the destruction of certain tissues. We used finite element analysis along with prototyping software to determine the duration of treatment, with special attention to the damage caused to surrounding tissue. We found that the optimal parameters for most effective treatment were to administer 30V for 120 seconds ? which happens to be the standard method of operation. This destroys the necessary part of the AV node while maintaining the surrounding tissue at relatively normal temperatures

In vitro calibration of a system for measurement of in vivo convective heat transfer coefficient in animals

BACKGROUND: We need a sensor to measure the convective heat transfer coefficient during ablation of the heart or liver. METHODS: We built a minimally invasive instrument to measure the in vivo convective heat transfer coefficient, h in animals, using a Wheatstone-bridge circuit, similar to a hot-wire anemometer circuit. One arm is connected to a steerable catheter sensor whose tip is a 1.9 mm × 3.2 mm thin film resistive temperature detector (RTD) sensor. We used a circulation system to simulate different flow rates at 39°C for in vitro experiments using distilled water, tap water and saline. We heated the sensor approximately 5°C above the fluid temperature. We measured the power consumed by the sensor and the resistance of the sensor during the experiments and analyzed these data to determine the value of the convective heat transfer coefficient at various flow rates. RESULTS: From 0 to 5 L/min, experimental values of h in W/(m(2)·K) were for distilled water 5100 to 13000, for tap water 5500 to 12300, and for saline 5400 to 13600. Theoretical values were 1900 to 10700. CONCLUSION: We believe this system is the smallest, most accurate method of minimally invasive measurement of in vivo h in animals and provides the least disturbance of flow

Computational Modelling Of Radiofrequency Cardiac Ablation To Study The Effect Of Cooling On Lesion Parameters

Radiofrequency ablation (RFA) is a technique used to treat cardiac arrhythmias. It creates lesions in the heart by creating thermal damage. Due to limitations associated with in vivo as well as in vitro studies, computational methods assist in further analysis of the problem by allowing for quicker and more diverse parametric studies and hence, a more thorough understanding of the physics involved. These computational models have been proven to be good representations of the process by accurately modelling the catheter with simplified geometry and boundary conditions. Although these studies have inconsistencies in material properties (due to the variation of thermal and mechanical properties in biological tissue) as well as different methods of creating the geometry and applying the boundary conditions, overall they are quite similar. The effects of esophageal cooling were investigated to understand its effect on the process. It was determined that using the standard model found within the literature, the esophageal cooling changed the lesion depth by less than 18%, while changing the maximum tissue temperature by as much as 13.4%

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018