Measuring contact area and temperature during radio-frequency cardiac catheter ablation.

摘要

Radio-frequency (RF) catheter ablation uses RF current to destroy irregular cardiac tissue to cure various cardiac arrhythmias. This work presents methods, measurement systems, experimental results, and numerical results for the study of measuring temperature change and contact area during RF cardiac catheter ablation. I built a temperature measurement system using 3 thermocouples and 1 thermistor to record myocardial temperature during RF ablation. I set up a flow system to simulate the blood flow inside the heart chamber for in vitro experiments. I used bi-plane X-ray technique to localize the thermal sensors inside the heart for in vivo experiments. I also used X ray to obtain the myocardial deformation during ablation and provided the impedance-depth penetration relationship for the prediction of the myocardium-electrode contact (MEC). Finally I developed an algorithm for automated FEM analysis of RF ablation.; I presented the myocardial temperature recordings during ablation and showed that myocardial temperature in the vicinity of the electrode is higher than the thermistor temperature at the catheter tip. I showed that high blood flow increases the power consumption during temperature-controlled ablation. It then increases the lesion dimensions and increases the myocardial temperature because of the larger delivered power. I used bi-plane X-ray technique to calculate the positions of the thermocouples and presented temperature recording during in vivo RF ablation.; I presented a method to predict the MEC during cardiac ablation using electrical impedance. During the in vitro experiment, I presented the impedance-depth calibration curve for prediction of MEC and also other methods that may provides improved prediction. I used the FEM to analyze the impedance of MEC and showed that the myocardial deformation is critical for numerical analysis. The numerical results matched the experiment well.; Finally I presented an algorithm to perform automated FEM analysis for catheter ablation, which increases the designer's productivity. I simulated the PID controller of the equipment power generator that controls the temperature-controlled ablation. I also analyzed some parameters such as blood flow and time step that may affect the performance of the PID controller.