Controlled Ultrasound Tissue Erosion

TLDR

The study addresses the need for a noninvasive method to perforate the neonatal atrial septum in treating hypoplastic left heart syndrome. The authors investigated ultrasound’s ability to produce highly controlled tissue erosion. They generated 232 holes in 40 excised porcine atrial walls with a 788 kHz transducer, systematically varying pulse repetition frequency, pulse duration, and liquid gas saturation to assess erosion rate and energy efficiency, and performed a preliminary in‑vivo canine septal perforation. Short pulses at specific PRFs maximized erosion rate and energy efficiency, enabling precisely located perforations in the atrial wall via the CUTE process.

Abstract

The ability of ultrasound to produce highly controlled tissue erosion was investigated. This study is motivated by the need to develop a noninvasive procedure to perforate the neonatal atrial septum as the first step in treatment of hypoplastic left heart syndrome. A total of 232 holes were generated in 40 pieces of excised porcine atrial wall by a 788 kHz single-element transducer. The effects of various parameters [e.g., pulse repetition frequency (PRF), pulse duration (PD), and gas content of liquid] on the erosion rate and energy efficiency were explored. An Isppa of 9000 W/cm2, PDs of 3, 6, 12, and 24 cycles; PRFs between 1.34 kHz and 66.7 kHz; and gas saturation of 40-55% and 79-85% were used. The results show that very short pulses delivered at certain PRFs could maximize the erosion rate and energy efficiency. We show that well-defined perforations can be precisely located in the atrial wall through the controlled ultrasound tissue erosion (CUTE) process. A preliminary in vivo experiment was conducted on a canine subject, and the atrial septum was perforated using CUTE.