Feasibility of noncontact intracardiac ultrasound ablation and imaging catheter for treatment of atrial fibrillation

Abstract

Atrial fibrillation (AF) affects 1% of the population and results in a cost of $2.8 billion from hospitalizations alone. Treatments that electrically isolate portions of the atria are clinically effective in curing AF. However, such minimally invasive catheter treatments face difficulties in mechanically positioning the catheter tip and visualizing the anatomy of the region. We propose a noncontact, intracardiac transducer that can ablate tissue and provide rudimentary imaging to guide therapy. Our design consists of a high-power, 20 mm by 2 mm, 128-element, transducer array placed on the side of 7-French catheter. The transducer will be used in imaging mode to locate the atrial wall; then, by focusing at that location, a lesion can be formed. Imaging of previously formed lesions could potentially guide placement of subsequent lesions. Successive rotations of the catheter will potentially enable a contiguous circular lesion to be created around the pulmonary vein. The challenge of intracardiac-sized transducers is achieving high intensities (300-5000 W/cm 2 ) needed to raise the temperature of the tissue above 43 C. In this paper, we demonstrate the feasibility of an intracardiac-sized transducer for treatment of atrial fibrillation. In simulations and proof-of-concept experiments, we show a 37 C temperature rise in the lesion location and demonstrate the possibility of lesion imaging.

Transthoracic cardiac ultrasonic stimulation induces a negative chronotropic effect

“…The available literature indicates the possibility of using ultrasound for nonpharmacological treatment of heart failure [1], defibrillation [2], pacing [3], cardiac gene therapy [4], and ablation for treating arrhythmias [5]. …”

The acoustic lens design and in vivo use of a multifunctional catheter combining intracardiac ultrasound imaging and electrophysiology sensing

“…In 2004, the use of a highly integrated multifunctional catheter was described [24] as a 14F device with a 2-D matrix array of 112 elements for 5-MHz imaging surrounded by an ablation annulus operating at 10 MHz, and EP sensors near the catheter tip. Recently, a new 7F catheter integration effort was reported to guide EP interventions with a dual-purpose side-looking 128-element imaging and therapy array operating at 10 MHz [25], which is designed to image as well as ablate tissue around the ostia of left atrium (LA) pulmonary veins.…”

Real-time photoacoustic assessment of radiofrequency ablation lesion formation in the left atrium

“…Ultrasound imaging studies [14,15] showed promising results in monitoring RF ablation lesions in animal models but the small field of view of the imaging catheters that were used limits the assessment of the lesion as a whole. In addition, the image features characterizing ablation lesions were neither consistent between studies [16] nor persistent in ex-vivo evaluation setups [17]; a necessary feature for post-ablation lesion continuity assessment. Optical methods, such as near infrared spectroscopy (NIRS), or polarization sensitive-/ optical coherence tomography (PS-/OCT), were also considered for the problem of lesion monitoring [[18], [19], [20], [21]].…”