HIFU treatment of varicose veins

HIFU stands for high-intensity focused ultrasound. The energy involved belongs to the same physical family as diagnostic ultrasound, at a higher intensity. A transducer concentrates the beam into a small volume located deep beneath the skin. Outside this focal point, the energy passes through tissue without damaging it. At the focal point, it is absorbed and converted into heat. The target is a superficial vein carrying reflux, most often a saphenous trunk.

The treatment combines two ultrasound functions performed at the same time. An imaging probe, the ultrasound, continuously visualizes the target. A power transducer, the HIFU, treats it. This combination imposes a technical constraint: the vein must stay visible throughout the procedure, otherwise the focal point cannot be positioned.

The physical principle

Venous HIFU treatment works by raising temperature. The beam converges at a millimeter-sized focal point, where acoustic absorption produces rapid, strictly localized heating. The temperature there reaches up to 90°C.

This rise denatures the collagen of the vein wall. The wall retracts, then closes. Closure interrupts the reflux that fed the varicose dilation. The body then resorbs the treated segment. This mechanism was characterized by numerical modeling, then verified in an animal model before any clinical use.

The safety of the process rests on the geometry of the beam. Energy density stays low along the entire path and becomes damaging only at the point of convergence. A cooling system keeps the skin at a low temperature during the pulses, and temperature and pressure sensors continuously regulate the circuit. Treatment proceeds by successive pulses, each covering a short segment, until the selected path is treated.

The course of the procedure

Mapping precedes treatment. Duplex ultrasound identifies the incompetent segments and measures the reflux. In the superficial network, reflux is defined by a flow reversal lasting more than 0.5 seconds. This mapping determines the path to be treated.

The procedure takes place on a robotic HIFU platform. An imaging probe integrated into the treatment head visualizes the vein throughout the procedure. The operator follows the target on a screen and controls each pulse, guided by real-time ultrasound imaging. The robotic head moves the transducer along the defined path. No instrument enters the lumen of the vessel: the treatment is performed without incision or breach of the skin, and the patient stays awake. It is a fully non-invasive (extracorporeal) treatment.

This course differs from that of endovenous techniques on one documented point. The 2022 European guidelines on chronic venous disease state that endovenous thermal ablation requires ultrasound-guided tumescent anesthesia. This anesthesia creates a fluid sleeve that protects neighboring tissue from the heat source introduced into the lumen. The extracorporeal route places no heat source inside the vessel; it delivers the energy from a distance.

The indication and level of evidence

The indication covered by the CE marking is the coagulation of blood vessels in patients with superficial venous reflux. The main target is the great saphenous vein. Publications also document the small saphenous vein and perforating veins.

A body of peer-reviewed publications built up between 2019 and 2026, in phlebology and vascular surgery journals. Its formation follows the usual order for medical technologies: preclinical work, animal studies, then clinical series.

Deployment extends beyond the scope of studies. More than 4,000 procedures have been performed, in more than 12 centers across more than 10 countries. Two versions of the device have followed one another, Sonovein® and Sonovein® HD, brought to market in 2019 and 2022, complemented by a SpeedPulse mode in 2026. The patent portfolio of Theraclion, the company behind Sonovein®, holds 149 titles.

The published data report 96.8% occlusion (VEINRESET pivotal study). This value is a study result, measured in a population followed under a given protocol. It does not constitute a prognosis for a specific patient.

Three limits bound this level of evidence. Clinical follow-up is shorter than for established modalities: endovenous laser and radiofrequency have been documented for longer, in larger numbers. In France, the procedure is not reimbursed by the national health insurance. In the United States, the device keeps an investigational status. No randomized controlled trial comparing venous HIFU with endovenous techniques is available to date.

The regulatory framework

The supporting device has carried a European CE marking since 2019.

Class IIb covers devices with a potentially high risk, subject to assessment by a notified body. The scope of the indication bounds what can be claimed: any assertion of effect beyond this scope falls outside the marking. The European status and the US status are distinct and are not to be conflated.

Distinction from neighboring modalities

Modalities for treating superficial veins are ranked by degree of breach, that is, by the penetration of the body the technique requires.

Three degrees emerge. Incision opens the skin. Puncture crosses the skin and the vein wall, alone or to introduce a catheter. The extracorporeal route crosses nothing.

HIFU treatment shares its agent with endovenous laser and radiofrequency: these three modalities close the vein with heat. They part ways on where that heat is applied. Laser and radiofrequency introduce a source into the lumen of the vessel. HIFU delivers the energy from outside the body.

The degree of breach ranks modalities by their access route. It ranks them neither by efficacy, nor by safety, nor by level of evidence, dimensions that depend on clinical data specific to each technique. A modality without breach is not, on that basis alone, superior to one that involves it. The target, however, is shared: the valvular incompetence at the origin of reflux, foremost among the trunks the great saphenous vein.