797 - Exploring the Mechanisms of High-Intensity Focused Ultrasound in Vein Ablation: Thermal Effects, Tissue Interaction, and Clinical Outcomes

Learning Objectives: To understand the biophysical principles of high-intensity focused ultrasound (HIFU) for varicose vein ablation, including its thermal mechanisms, tissue-specific interactions, and evolving clinical applications in non-invasive vein therapy.

Background: High-intensity focused ultrasound (HIFU) is an emerging, non-invasive modality for vein ablation that uses precisely focused acoustic energy to thermally damage target tissues while preserving the overlying skin and adjacent structures. Unlike endovenous laser or radiofrequency ablation, HIFU does not require vascular access, tumescent anesthesia, or catheter insertion, making it especially appealing for patients with challenging anatomy or needle phobia. The therapeutic efficacy of HIFU is based on its ability to induce controlled thermal coagulation of the vein wall, leading to endothelial denaturation, vessel contraction, and eventual fibrosis. Understanding the mechanisms of energy delivery and tissue response is essential to optimizing treatment parameters and expanding clinical use.

Clinical Findings/Procedure Details: This exhibit details the physics of HIFU energy propagation, focusing on how converging ultrasound beams generate localized temperatures of 60–85°C, sufficient to induce vein wall protein denaturation without damaging non-target tissue. Using imaging-guided platforms, energy is delivered with millimeter-level precision to the incompetent segment of the great saphenous vein or perforator veins. Histopathologic and imaging-based evidence of endothelial disruption, collagen remodeling, and perivascular inflammation has been demonstrated following HIFU therapy. Case examples demonstrate technical setup, pre- and post-procedure duplex ultrasound findings, and typical clinical outcomes such as vein occlusion rates, symptom resolution, and complication profiles. Comparisons are made with conventional endovenous ablation modalities, focusing on efficacy, recovery time, and patient satisfaction.

Conclusion and/or Teaching Points: HIFU is a novel, non-invasive approach to varicose vein treatment that relies on precise thermal energy delivery to ablate target veins without direct contact. The controlled tissue interaction spares surrounding structures while achieving effective vein closure. As imaging guidance and acoustic focusing technology advance, HIFU holds significant promise for broader clinical adoption. A strong understanding of its thermal mechanisms and biological effects is critical for safe and effective integration into venous intervention practice.