Noninvasive Venous Ablation via a Hand-Held, Battery-Operated, High Intensity Focused Ultrasound Device
Aleid Koppius, BA1, Allie M. Sohn, BS1, Peter W. Henderson, MD MBA1, George K. Lewis, Jr., BS2, Alyssa J. Reiffel, MD1, William L. Olbricht, PhD2, Jason A. Spector, MD1.
1Weill Cornell Medical College, New York, NY, USA, 2Cornell University, Ithaca, NY, USA.
BACKGROUND: Varicose veins and other vascular malformations warrant intervention due to both the undesirable cosmetic appearance, as well as the risk of complications, such as ulceration and thrombophlebitis. Because of the limitations of currently available treatment modalities (including varying degrees of invasiveness, and the subsequent risk of complications), the authors have developed a novel, hand-held, battery-powered, high-intensity focused ultrasound (HIFU) device that may, for the first time, allow for the entirely transcutaneous ablation of venous varicosities and venous malformations. The purpose of this study was to evaluate the efficacy of this therapeutic ultrasound device in clinically relevant scenarios.
METHODS: The HIFU device is housed in a casing that measures 3.5-inch by 5.5 inch and weighs 630 grams, has an intensity of 2000-2500W/cm2 with a focal length of 3.3mm, and is powered by 4 rechargeable lithium ion batteries. Initial testing involved an ex vivo testing platform which consisted of sequentially layered skin, fat, and blood-filled vein. The transducer was applied directly to the outer surface of the skin until gross changes to the vein occurred. The vein was processed for histology, stained with hematoxylin and eosin, and the cross-sectional area of the lumen treated portion of the vein was measured and compared to that of the non-treated portion. In vivo, 3 Sprague-Dawley rats underwent midline laparotomy and exposure of the infrarenal inferior vena cava (IVC). Utilizing a custom-designed cover that allowed a sample of harvested rat skin to be secured directly adjacent to the transducer, therapeutic ultrasound treatment was performed by direct application to the IVC.
RESULTS: In both the ex vivo and in vivo series, treatment with HIFU resulted in significant narrowing and coagulation necrosis of the vein at the focal point. Furthermore, there was no evidence of coagulation necrosis or other changes to either the skin or adjacent fat or muscle in either model. The cross-sectional area of HIFU-treated ex vivo vein lumen was reduced to 0.46 ± 0.25 mm2, compared to 3.96 ± 0.30 mm2 in untreated control specimens (P<0.001).
CONCLUSIONS:The results of this study confirm indicate that this hand-held, portable, and inexpensive HIFU device achieves effective transcutaneous venous ablation both ex vivo, without flow through the lumen and in vivo, with flow through the vessel. This suggests that when diagnostic imaging capabilities are incorporated in subsequent prototypes, this HIFU device is capable of treating vascular abnormalities in a completely transcutaneous, non-invasive fashion. Therefore, this therapeutic ultrasound device has the potential to significantly reduce the morbidity and expense of treating venous varicosities and vascular malformations, and creates an opportunity for plastic surgeons to more easily and cost effectively treat these common pathologic conditions.
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