In Vitro Experiment of the Radiofrequency Ablation of Renal Sympathetic Denervation

To study the temperature field changes of renal sympathetic denervation under different ablation parameters, a biological model was used for simulating renal artery. The 0.9% salt solution was used to imitate blood flow. A blood circulation platform was built and radiofrequency ablation (RFA) was performed. The temperature was collected above the ablation point 0-8 mm in the vertical distance and the center of the vascular flow. When the flow rate increases from 0.2 m/s to 0.4 m/s, the ΔT value of the ablation points at different distances in the peripheral tissue shows a downward trend. When the heating time increases from 2 min to 4 min, the ΔT values of peripheral tissue and blood flow center increase and the maximum ΔT value of the blood center is only 0.29℃. When the vertical distance between the temperature measurement point of the peripheral tissue and the ablation point is 0, 4 and 8 mm, the average temperature rise values are 3.90, 5.13, 0.59℃, respectively. When the temperature changes from 65℃ to 75℃, the maximum ΔT value of the peripheral tissue is 6.67℃, and the maximum ΔT value of the blood center is 2.76℃. When performing RFA, part of the heat can be carried away due to the rapid flow of blood, which can achieve a certain degree of cooling effect and avoid tissue and blood over-heat damaged. When the velocity is 0.2 m/s, the temperature rise of the tissue is up to 2.67℃, and when the velocity is 0.4 m/s, the temperature rise of the tissue is up to 1.00℃. Compared with the control group that the velocity is zero, the maximum temperature rise value is 5.02℃, and its cooling effect is more obvious. The ablation time increases from 2 min to 4 min, there is a certain additive effect on the heat accumulation of tissues and blood. The superposition effect at 8 mm farther from the RF electrode is weaker, which cannot reach the treatment temperature. The heat in peripheral tissue dissipates slowly due to far away from the blood. When the distance between the temperature measurement points at the peripheral tissue and the ablation point is 4 mm, the temperature rises 6.67℃. It can achieve the sympathetic nerve the damage within 4 mm. It has little effect on the blood when the maximum temperature rise of blood does not exceed 2.76℃ within 4 min and 75℃. The effectiveness of renal denervation is validated by in-vitro experiment.