High Intensity Focused Ultrasound Effect on Cardiac Tissues: Potential for Clinical Application

Abstract

High intensity focused ultrasound (HIFU) is an evolving technology with potential therapeutic applications. Utilizing frequencies of 500 kHz to 10 MHz, HIFU causes localized hyperthermia at predictable depths without injuring intervening tissue. Applications in neurosurgery, urology, oncology and, more recently, cardiology for selective cardiac conduction tissue ablation have been promising. A 'noninvasive' technique for causing localized tissue damage to relieve hemodynamic and life-threatening obstruction in patients with congenital cardiac anomalies could replace more invasive procedures. We, therefore, investigated the ability of HIFU to create lesions in mammalian cardiac tissues ex vivo. Porcine valve leaflet, canine pericardium, human newborn atrial septum, and right atrial appendage were studied. Specimens were mounted and immersed in a water bath at room temperature. Using a 1-MHz phased array transducer, ultrasound energy was applied with an acoustic intensity of 1630 W/cm(2) or 2547 W/cm(2) until a visible defect was created (duration 3 to 25 sec). Macroscopic and microscopic examination demonstrated precise defects ranging from 3 to 4 mm in diameter. No damage was identified to the surrounding tissues. Our study concluded that HIFU can create precise defects in different cardiac tissue without damage to the surrounding tissue. Further investigation is needed to assess potential clinical uses of this technology.

Computer-Aided Automatic Delivery System of High-Intensity Focused Ultrasound for Creation of an Atrial Septal Defect

“…HIFU also enables us to create defects in cardiac tissues such as ventricles or cusp of the aortic valve in vitro or ex vivo (Otsuka et al, 2005;Fujikura et al, 2006;Lee et al, 2000;Xu et al, 2004;Strickberger et al, 1999). Particularly in fetal cardiac intervention, less invasiveness of HIFU is effective for the mother as well.…”

Heart ablation using a planar rectangular high intensity ultrasound transducer and MRI guidance

“…Furthermore, in contrast to radiofrequency (RF) waves, therapeutic ultrasound does not require direct contact with target tissue. The use of therapeutic ultrasound to create focal, ablative lesions in the heart has been reported in experimental models [17][18][19].…”

“…Several studies have examined the histological changes related to therapeutic ultrasound ablation in various tissues [20,19,21,22,18,[23][24][25][26][27].…”

“…Early study [36], revealed that, therapeutic ultrasound can create precise defects in different cardiac tissue without damage to the surrounding tissue. A multicenter clinical trial in 2005 [37], showed that after 6-month follow-up, epicardial, off-pump, beating-heart ablation with acoustic energy is safe and cures 80% of patients with permanent atrial fibrillation associated with long-standing structural heart disease.…”

Innovative Treatment of a Fetal Lung Mass Model Using High-intensity Focused Ultrasound (HIFU)

“…Therapeutic HIFU delivery could potentially allow much less invasive surgeries with ef cient tissue coagulation and/or perforation, and with little thermal damage to the underlying or overlying tissues [5][6][7][8] . Currently, further investigation of HIFU treatment, including its use for fetal surgical interventions, is underway 9 10 .…”