肾交感神经射频消融术的离体实验研究

In Vitro Experiment of the Radiofrequency Ablation of Renal Sympathetic Denervation

为了探究肾交感神经射频消融术在不同消融参数下温度场变化情况,采用3D打印技术打印血管并制备生物体模模拟肾动脉,应用质量分数为0.9%的盐溶液模拟血液流动,构建开环式血液循环系统,执行射频消融术.同时采集消融点上方垂直距离为0~8 mm处及血管液体中心处的温度,研究射频消融对血管壁外围组织和血液的影响.液体流速由0.2 m/s上升至0.4 m/s时,血管外围组织与消融点不同距离下的ΔT均呈下降趋势;射频加热时间由2 min增加至4 min时,血管壁外围组织和液体中心的ΔT值均增加,液体中心的最大ΔT值仅0.29℃;位于外围组织的测温点与消融点垂直距离为0、4和8 mm时平均温升值分别为3.90、5.13、0.59℃;温控温度从65℃变化至75℃时,血管外围组织最高ΔT值为6.67℃,液体中心最高ΔT值为2.76℃.射频消融时,液体的快速流动能够带走部分热量,可以起到一定程度的冷却作用,避免组织和血液热损伤;液体流速在0.2 m/s时,组织的温升值最高为2.67℃,液体流速接近层流速度阈值0.4 m/s时组织的温升最高为1.00℃;相比对照组流速为0时组织最高温升5.02℃而言,冷却作用均较为明显;消融时间从2 min增加到4 min对组织和血液的热量累积均具有一定的叠加效应.但是,对于组织,距离射频电极8 mm测温点处的叠加效应比较微弱,达不到治疗温度,对组织影响较小;血管壁外围组织因远离管内血液而热量散失较慢,位于外围组织的测温点与消融点垂直距离为4 mm时升温6.67℃,可实现位于血管外膜4 mm内交感神经纤维的损毁;时间在4 min内和温控温度小于75℃时,液体最大温升不超过2.76℃,可见对血液温升影响较小.本研究基本验证了血管内执行去肾交感神经术的有效性.

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,theΔT 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,theΔT values of peripheral tissue and blood flow center increase and the maximumΔT 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 maximumΔT value of the peripheral tissue is 6.67℃,and the maximumΔT 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.