A new radiofrequency balloon angioplasty device for atherosclerosis treatment.

BACKGROUND: Restenosis remains a challenge in the treatment of atherosclerosis due to damage to the endothelial layer and induced proliferation of smooth muscle cells. A novel radiofrequency (RF) heating strategy was proposed to selectively ablate atherosclerosis plaque and to thermally inhibit the proliferation of smooth muscle cells while keeping the endothelial cells intact. METHODS: To realize the proposed strategy, a new radiofrequency balloon catheter, consisting of three ports, a three-channel tube, a balloon and an electrode patch, was designed. To evaluate the feasibility of this new design, a phantom experiment with thermocouples measuring temperatures with different voltages applied to the electrodes was conducted. A numerical model was established to obtain the 3D temperature distribution. The heating ability was also evaluated in ex vivo diseased artery samples. RESULTS: The experimental results showed that the highest temperature could be achieved in a distance from the surface of the balloon as designed. The temperature differences between the highest temperature at 0.78 mm and those of the surface reached 9.87 °C, 12.55 °C and 16.00 °C under applied 15 V, 17.5 V and 20 V heating, respectively. In the circumferential direction, the heating region (above 50 °C) spread from the middle of the two electrodes. The numerical results showed that the cooling effect counteracted the electrical energy deposition in the region close to the electrodes. The thermal lesion could be directed to cover the diseased media away from the catheter surface. The ex vivo heating experiment also confirmed the selective heating ability of the device. The temperature at the targeted site quickly reached the set value. The temperature of the external surface was higher than the inner wall surface temperature of the diseased artery lumen. CONCLUSION: Both the experimental and numerical results demonstrated the feasibility of the newly designed RF balloon catheter. The proposed RF microelectrodes heating together with the cooling water convection can realize the desired heating in the deeper site of the blood vessel wall while sparing the thin layer of the endothelium.