Fracture and Fragmentation of Vascular Calcifications by Focused Ultrasound

Peripheral artery disease results in ischemia necessitating interventions such as balloon angioplasty. However, calcified lesions resist balloon and stent expansion, leading to poor outcomes. We hypothesized that focused ultrasound can fracture vascular calcifications and enable balloon angioplasty. In a first experiment, focused ultrasound was applied to ex vivo human calcified plaque specimens to determine its effects based on micro-CT imaging. In a second experiment, ultrasound was applied to an in vitro phantom to evaluate whether the effects enable balloon expansion. Fractures, thinning, and disintegration of calcified sections were observed in 15 of 18 treated human plaque samples. Minor mechanical disruption to soft plaque was found in 33% of samples. In tissue phantoms, n = 10/10 samples were successfully expanded by a water-filled angioplasty balloon with ultrasound applied prior to or during expansion. No controls (n = 0/10) were expanded. These results indicate focused-ultrasound plaque fracture is feasible and may enhance balloon angioplasty.