Augmentation of reperfusion by noninvasive, transcutaneous delivery of low-frequency, high-intensity ultrasound

There is a need for developing alternative safe, inexpensive and noninvasive methods for rapid and effective recanalization of thrombosed arteries and veins that can be commenced immediately upon admission to hospital, or even prior to admission. Transcutaneous delivery of low-frequency, high-intensity ultrasound has the potential to be used clinically in various types of thrombotically occluded blood vessels including acute myocardial infarction, strokes, ischemic limbs, obliteration of A-V fistulas of patients undergoing hemodialysis, retinal vein thrombosis, deep vein thrombosis, and even thrombotically stuck prosthetic heart valves. Thus far, various noninvasive ultrasound systems have been used in several animal models. These systems vary in the mode of ultrasound delivery (continuous versus pulse, diffuse versus concentrated or pulsed beam), frequency (between 20 kHz and 1 mHz), and intensity. In general, lower frequencies have better penetration through overlying tissue (skin, fat, bone) and, probably, better efficacy.