Varicose veins are dilated, tortuous superficial veins resulting from chronic venous insufficiency due to valvular incompetence. This condition leads to venous reflux, increased venous pressure, and venous stasis, manifesting clinically as leg pain, swelling, skin changes, and, in severe cases, venous ulcers and thrombotic events. Globally, varicose veins affect approximately 25% of adults, with higher prevalence in women (up to 40%) compared to men (up to 25%) [1].

Traditional management includes conservative measures like compression therapy and invasive procedures such as vein stripping, endovenous thermal ablation (EVTA), and sclerotherapy. While effective, these treatments are associated with drawbacks like invasiveness, need for anesthesia, risk of complications, and limited suitability for certain patient populations.

High-Intensity Focused Ultrasound (HIFU) has emerged as a revolutionary non-invasive treatment modality, offering precise targeting of affected veins without skin penetration. This review aims to explore HIFU’s mechanism, clinical applications, efficacy, and its potential to transform varicose vein management.

HIFU utilizes focused ultrasonic waves to generate thermal and mechanical effects at specific tissue depths, causing coagulative necrosis and subsequent fibrosis of the target veins. The focused energy raises the temperature at the focal point to approximately 85°C–90°C, inducing immediate vein wall shrinkage and occlusion while sparing surrounding tissues [2].

The HIFU system integrates diagnostic ultrasound imaging for real-time guidance and a therapeutic transducer for energy delivery. Devices like the Sonovein^® system employ advanced algorithms to adjust energy parameters based on vein depth and patient anatomy. Cooling mechanisms protect the skin surface, enhancing patient comfort and safety.

Key parameters influencing HIFU efficacy include frequency, energy density, and pulse duration. First, higher frequencies (up to 7.5 MHz) allow for precise targeting of superficial veins. Second, energy density controls to achieve optimal thermal effects without causing excessive tissue damage. Finally, short pulses minimize collateral damage and allow for cooling periods between emissions.

1. Treatment of great saphenous vein (GSV) incompetence

HIFU has been extensively studied for treating GSV reflux, a common cause of varicose veins. Clinical trials demonstrate high occlusion rates, with studies reporting closure rates exceeding 95% at 12-month follow-ups [3]. The non-invasive nature allows treatment of patients unsuitable for traditional interventions due to comorbidities or anticoagulant therapy.

2. Management of venous ulcers

Refluxing perforator veins contribute significantly to venous ulceration. HIFU effectively targets these perforators, promoting ulcer healing. Case studies, such as a 95-year-old patient with chronic ulcers achieving complete healing within three months post-HIFU, highlight its potential [4].

3. Patients with compromised skin integrity

Patients with skin conditions like lipodermatosclerosis are at higher risk of complications from invasive procedures. HIFU offers a safe alternative, reducing infection risks and promoting better outcomes due to its extracorporeal approach.

4. Anticoagulated patients

HIFU’s non-invasive nature eliminates bleeding risks associated with catheter-based interventions, making it suitable for patients on anticoagulation therapy without the need to discontinue medication.

5. Treatment of telangiectasia and superficial venous lesions

While HIFU has been primarily studied for larger varicose veins, its precise targeting capabilities suggest potential applications in treating smaller superficial venous lesions, such as telangiectasia (spider veins). Further research is needed to optimize treatment parameters for these smaller vessels. Preliminary reports in aesthetic medicine suggest that focused ultrasound may have utility in targeting superficial facial telangiectasia and other small-caliber vascular lesions. As HIFU technology advances, it may provide a non-invasive alternative or adjunct to sclerotherapy, laser, or other conventional methods commonly used for such lesions.

1. Efficacy studies

In 2022, a multicenter study involving 250 patients reported a GSV closure rate of 96% at 6 months, with significant improvements in symptom scores and quality of life measures [5]. Obermayer et al. [6] evaluated HIFU in treating small saphenous vein incompetence, demonstrating a closure rate of 94% at 12 months, comparable to EVTA techniques.

2. Safety profile

Minor complications include transient skin erythema and paraesthesia, occurring in less than 5% of cases. No major complications like deep vein thrombosis or nerve injury were reported in the reviewed studies.

Patients reported lower pain scores compared to EVTA, attributed to the absence of tumescent anesthesia and invasive instruments.

3. Histological findings

Post-treatment histological analyses reveal vein wall thickening, collagen hyalinization, and endothelial denudation, confirming the effective thermal damage induced by HIFU [7].

HIFU is completely non-invasive procedure, eliminating risks associated with skin penetration, such as infection and nerve injury. Procedure-related minimal anesthesia requirements enhance patient comfort. Patients can resume normal activities immediately post-procedure. HIFU has suitability for high-risk patients; safe for those with bleeding disorders, on anticoagulants, or with poor skin integrity [8]. In addition, advanced imaging allows for selective treatment of affected vein segments, preserving healthy veins.

HIFU has relatively longer procedure times. Cooling periods between energy deliveries extend treatment duration compared to EVTA. High equipment costs and the need for specialized training limit widespread adoption. HIFU may be less efficient for treating extensive vein segments compared to traditional methods. Also, this procedure requires expertise in ultrasound imaging and HIFU technology for optimal outcomes.

HIFU represents a significant advancement in varicose vein treatment, aligning with the trend towards minimally invasive and patient-centered care. Its ability to deliver effective therapy without skin penetration is particularly beneficial for patients contraindicated for traditional interventions.

The technology supports hemodynamic preservation strategies by allowing selective vein ablation, potentially reducing recurrence rates associated with extensive vein removal. The integration of robotics and automated treatment protocols is underway, aiming to reduce procedure times and enhance precision.

Challenges remain in terms of cost-effectiveness and accessibility. Wider adoption may drive down costs and stimulate further technological improvements. Ongoing clinical trials and longer-term studies are essential to establish HIFU’s role relative to established treatments.

Regarding vein size and depth, HIFU is generally more effective for treating superficial and medium-sized varicose veins. Larger diameter veins or those located deeper beneath the skin may require higher energy levels, multiple treatment sessions, or may present challenges in achieving complete closure. Further studies are necessary to determine optimal parameters and techniques for treating these challenging cases.

To minimize adverse events, careful patient selection is crucial. Adequate skin cooling during the procedure helps protect the epidermis from thermal damage. Selecting appropriate energy parameters based on vein diameter, depth, and patient characteristics is essential. Mild erythema or discomfort may occur post-treatment but typically resolves within a few days. Compression therapy, if indicated, can further enhance outcomes by reducing edema and supporting treated vessels.

HIFU systems typically integrate a diagnostic ultrasound imaging unit with a therapeutic transducer. Real-time imaging allows accurate localization of the target vein and monitoring of surrounding structures. The therapeutic transducer then delivers focused ultrasound energy, inducing thermal ablation of the vein without skin penetration. Cooling mechanisms are incorporated to protect the skin surface. While direct inclusion of high-resolution device images may be limited, readers can refer to previous studies [8] for visual representations of HIFU equipment and treatment configurations.

HIFU emerges as a transformative modality in the management of varicose veins, offering a non-invasive, safe, and effective alternative to traditional treatments. Its advantages make it particularly suitable for patients who are poor candidates for invasive procedures. As technology advances and becomes more accessible, HIFU has the potential to become a standard treatment option, improving patient outcomes and quality of life.

The authors declare no conflicts of interest.

This report was presented under the title of HIFU - Is it ready for prime time?, at the 47th annual academic meeting of The Korean Society for Phlebology.