Radiofrequency ablation facilitated by confined microchannel jet flow

• RF balloon catheter with adjustable jet flow system is proposed to shape lesions. • Jet flow can significantly enlarge the protection depth, 0.43 mm, 79 % larger than before. • Jet flow provide the ablation angle of 107.64° around the balloon circumference. • Different jet angle and size are shown to create various ablation zone morphologies. Radiofrequency catheter ablation (RFCA) is an effective minimally invasive treatment for arterial vascular diseases. However, current techniques face limitations in treating deep irregular lesions (e.g., atherosclerotic plaques in the media layer and perivascular nerves in the adventitia) while protecting the intimal layer from thermal damage. This study proposes a novel RF balloon catheter with adjustable microchannel jet flow cooling. It enables dynamic control of ablation morphology through localized convective cooling. A three-dimensional multiphysics model coupling electric, thermal, and flow fields was developed to analyze temperature distributions during the treatment. The microchannel jet flow creates a localized high-efficiency cooling region (convective heat transfer coefficient up to 4547 W/(m²·K)) that can be precisely positioned by rotating the inner catheter. Compared to conventional uniform cooling, the jet flow cooling achieves 79 % larger protection depth (average 0.43 mm vs. 0.24 mm) while maintaining similar ablation depths. By rotating the microchannel from 0° to 90°, the system generates diverse ablation morphologies (crescent, semicircular, and kidney-shaped) with a controllable ablation range of 107.64° around the balloon circumference. Validation through tissue-mimicking phantoms and ex vivo porcine arteries confirmed effective ablation of deep arterial targets while preserving the intimal and medial layers. This technology offers a promising solution for precise thermal therapy of complex arterial pathologies with improved clinical safety.