In Vivo Evaluation of a Hand-Held, Battery-Operated Therapeutic Ultrasound Device for the Noninvasive Treatment of Varicose Veins

Abstract

Current treatments for varicose veins and other vascular malformations are to some degree invasive and may therefore be painful and associated with complications such as infection, thrombophlebitis, and bleeding. The development of entirely noninvasive techniques has been hampered by the high cost, large size, and power requirements of candidate technologies, such as high-intensity focused ultrasound (HIFU) imaging. Our group has developed a HIFU device that is hand-held and battery-operated, and we have previously demonstrated that it is capable of venous ablation ex vivo. The purpose of this study was to determine whether it is capable of transcutaneous venous ablation in vivo. Our HIFU device weighs 560 grams and has an intensity of 2500 W/cm2 that focuses at a focal length of 3.3 mm. A midline laparotomy was performed on four Sprague-Dawley rats to expose the IVC. The HIFU transducer was covered in a plane 2 mm from the focal point with a piece of previously harvested rat skin, and under direct visualization, the device was applied to the IVC and activated for 60 seconds. Compared with the condition of the IVC before HIFU treatment, the IVC after HIFU was marked by significant contraction and coagulation necrosis. There was no antegrade blood flow from the IVC after transection at the level immediately superior to the treated area, indicating complete venous occlusion. Furthermore, there was no evidence of necrosis in any of the adjacent tissues. In contrast to previous HIFU devices, ours is hand-held, portable, and relatively inexpensive. Although subsequent prototypes will incorporate visualization capabilities, the current device required a modified experimental design that allowed for direct visualization while assessing the ability to effectively ablate veins in a transcutaneous fashion. Our results indicate that this device is capable of successful, targeted, transcutaneous venous ablation in vivo. Because this technique is completely noninvasive, it has the potential to minimize the visible scars and other complications that can be associated with more invasive procedures. Accordingly, we believe that interventions based upon this technology may provide a superior treatment option for varicosities and other vascular malformations.