The comparison of lesion outline and temperature field determined by different ways in atrial radiofrequency ablation.

BACKGROUND

The aim of this study is to research the lesion outline and temperature field in different ways in atrial radiofrequency ablation by using finite element method.

METHODS

This study used the method which considered the thermal dosage to determine the boundary between viable and dead tissue, and compared to the 50 °C isotherm results in analyzing lesion outline. Besides, we used Hyperbolic equation which considered the relaxation time to calculate the temperature field and contrasted it with Pennes' bioheat transfer equation.

RESULTS

As the result of the comparison of the lesion outline, when the ablation time was 120 s, the isotherm of the thermal dosage was larger than the 50 °C isotherm and with the increasing of the voltage the gap increased. When the ablation voltage was 30 V, the 50 °C isotherm was larger than the thermal dosage isotherm when the ablation time was less than 160 s. The isotherms overlapped when the time was 160 s. And when the ablation time was more than 160 s, the 50 °C isotherm was less than the thermal dosage isotherm. As to the temperature field, when the ablation voltage was 30 V with the ablation time 120 s the highest temperature decided by Hyperbolic was 0.761 °C higher. The highest temperature changed with relaxation time. In most cases, the highest temperature of the Hyperbolic was higher otherwise the relaxation time was 30-40 s.

CONCLUSIONS

It is better to use CEM43 °C to estimate the lesion outline when the ablative time within 160 s. For temperature distribution, the Hyperbolic reflects the influence of heat transmission speed, so the result is more close to the actual situation.