Department of Electrical Engineering and Department of Medical Engineering, University of South Florida, Tampa, FL, USA.
Research and Development, Oscor Inc, Palm Harbor, FL, USA.
BMC Cardiovasc Disord. 2021 Oct 16;21(1):500. doi: 10.1186/s12872-021-02305-x.
Renal denervation with radiofrequency ablation has become an accepted treatment for drug-resistant hypertension. However, there is a continuing need to develop new catheters for high-accuracy, targeted ablation. We therefore developed a radiofrequency bipolar electrode for controlled, targeted ablation through Joule heating induction between 60 and 100 °C. The bipolar design can easily be assembled into a basket catheter for deployment inside the renal artery.
Finite element modeling was used to determine the optimum catheter design to deliver a minimum ablation zone of 4 mm (W) × 10 mm (L) × 4 mm (H) within 60 s with a 500 kHz, 60 Vp-p signal, and 3 W maximum. The in silico model was validated with in vitro experiments using a thermochromic phantom tissue prepared with polyacrylamide gel and a thermochromic ink additive that permanently changes from pink to magenta when heated over 60 °C.
The in vitro ablation zone closely matched the size and shape of the simulated area. The new electrode design directs the current density towards the artery walls and tissue, reducing unwanted blood temperature increases by focusing energy on the ablation zone. In contrast, the basket catheter design does not block renal flow during renal denervation.
This computational model of radiofrequency ablation can be used to estimate renal artery ablation zones for highly targeted renal denervation in patients with resistant hypertension. Furthermore, this innovative catheter has short ablation times and is one of the lowest power requirements of existing designs to perform the ablation.
射频消融的肾去神经支配已成为治疗耐药性高血压的一种公认的治疗方法。然而，仍需要开发新的导管以实现高精度、靶向消融。因此，我们开发了一种射频双极电极，用于通过 60 至 100°C 的焦耳加热感应进行受控、靶向消融。双极设计可以轻松地组装到篮状导管中，以便在肾动脉内部部署。
使用有限元建模来确定最佳的导管设计，以便在 60 秒内以 500kHz、60Vp-p 信号和 3W 的最大功率传递最小消融区 4mm(W)×10mm(L)×4mm(H)。使用热致变色 phantom 组织（由聚丙烯酰胺凝胶和热致变色油墨添加剂制备）和热致变色 ink 添加剂的体外实验对计算机模型进行了验证，这种添加剂在加热到 60°C 以上时会从粉红色永久变为洋红色。
体外消融区与模拟区域的大小和形状非常吻合。新的电极设计将电流密度引导至动脉壁和组织，通过将能量集中在消融区来减少不必要的血液温度升高。相比之下，篮状导管设计在进行肾去神经支配时不会阻止肾血流。
这种射频消融的计算模型可用于估计对耐药性高血压患者进行高度靶向肾去神经支配的肾动脉消融区。此外，这种创新的导管具有较短的消融时间，并且是现有设计中功率要求最低的一种，可实现消融。
