Ann Phlebology 2022; 20(2): 111-112
Introduction of a New Device Using Impedance Controlled Radiofrequency Ablation (IC-RFA) Technique for the Treatment of Chronic Venous Disease
Insoo Park, M.D., Junseong Kwon, M.D. and Sujin Park, M.D.
Charm Vascular Clinic, Seoul, Korea
Correspondence to: Insoo Park, 488 Bongcheon-ro, Gwanak-gu, Seoul 08738, Korea, Charm Vascular Clinic
Tel: 02-6959-1550, Fax: 02-6959-1551
Published online: December 31, 2022.
© Annals of phlebology. All rights reserved.

Chronic venous disease with incompetent saphenous veins has variable treatment methods, including radiofrequency ablation (RFA) technique. RFA is a thermal treatment technique that is widely used worldwide with excellent treatment outcomes reported in many studies and currently recommended as the preferred treatment in guidelines of chronic venous diseases. Recently, in Korea, IC-RFA technique, which has different concept and principle from the existing RFA, has been developed and used in clinical practice. Unlike RFA that uniformly reproduces the ablation time and energy in incompetent saphenous veins, IC-RFA automatically controls the ablation time and energy according to the surrounding intravascular conditions. This technique has a theoretical benefit of transferring more energy for veins with larger diameters and reduced energy for small veins. Herein, we briefly introduce IC-RFA.
Keywords: Varicose veins, Venous insufficiency, Radiofrequency, Endovascular, Ablation

In RFA for chronic venous disease, ClosureFast system (Medtronic, USA) is the most commonly used equipment worldwide. This thermal ablation technique emits thermal energy through an electrode that maintains a constant temperature of 120 degrees Celsius in the veins and transfers thermal energy through conduction heat to the intima and the wall of veins. As a result, this damages the veins walls, inducing obliteration and fibrosis of veins. The technique has been named RFA for its mechanism of using electromagnetic field energy generated by alternating the current generated inside the catheter. However, the heat energy transmitted to the tissues is actually not electro-magnetic field energy, but conduction heat from a heated catheter (1-3).

Treatments using radiofrequency energy to ablate tissues is already widely used in medicine. A key example is treatment of thyroid nodule. The company that developed IC-RFA is already producing catheters that treat thyroid nodule using the same principle (4,5).

The difference between conventional RFA and IC-RFA catheters used in treatment of chronic venous disease is that IC-RFA catheters have dual sensors and a cooling system (Fig. 1). Conventional RFA catheters only have a tempera-ture sensor, which enables the system to detect the temperature and adjust the output energy (Watt) in real-time for 20 seconds to maintain a constant temperature of 120 degrees Celsius. In contrast, IC-RFA has a temperature sensor as well as an impedance sensor, which detects the impedance value in real time to stop ablation when the value rises by more than 5 ohms from the baseline value where ablation starts. As a result, the temperature and ablation time become highly variable.

Fig. 1. VENISTAR (STARmed, Korea).

In general, impedance is the concept of resistance in an AC circuit that is used in a DC circuit. When the tissues are heated, the moisture in the tissues boils and vaporizes. In this process, the tissues lose moisture, and the resistance increases (6,7). IC-RFA transfers electromagnetic field energy to the tissues, causing direct frictional energy of cells. As the tissue vaporizes, the resistance increases, and the short circuit is stopped when the resistance increases by more than 5 ohms.

This new mechanism of function is the key feature of IC-RFA. Conventional RFA provides a constant tempera-ture and ablation time regardless of the surrounding environment. However, in large-diameter veins, extra heat energy must be transferred for sufficient damage to the large vein walls. Additionally, excessive heat energy to veins with small diameters may cause unnecessary heat damage to the outer surface of veins. Thus, transfer of adequate heat may help to reduce complications (8,9). This could be achieved by IC-RFA, in which the ablation time increases for large veins that require a high level of energy. In contrast, the ablation time is shortened for veins with small diameters that cause a rapid increase in impedance. As a result, IC-RFA has a theoretical advantage of lowering the recurrence rate in large-diameter vessels and reducing unnecessary pain and complications in small-diameter vessels.

One disadvantage of IC-RFA is the cooling system. Carbonization is an inevitable event for catheters as the electrode, which has an alternating flow of current, is directly exposed to the tissues. The conventional RFA has a metal component surrounding the electrode. This metal component generates heat instead and transfers conductive heat. To prevent carbonization, the metal component in conventional RFA is coated. In contrast, in IC-RFA, the catheter that generates a high-frequency electromagnetic field with alternating current must be in direct contact with the tissues as closely as possible. Therefore, as the temperature increases rapidly, the catheter is carbonized, and this increases as the temperature is raised higher (10,11). To prevent carbonization through cooling, IC-RFA has an equipment connected to an external source of cooled normal saline for circulation inside the catheter.

Currently, IC-RFA is only approved in Korea, and CE certification has been completed in Europe. Although clinical results in humans have not been published in document form yet, the initial outcomes of IC-RFA in 52 saphenous veins have been presented in an oral presentation during the 2020 21st Asian Society of Vascular Surgery (ASVS) Congress (12). The clinical trial and long-term results in humans are expected in future studies.


The author declares no potential conflict of interest.

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