Feasibility of Near Real‐Time Lesion Assessment During Radiofrequency Catheter Ablation in Humans Using Acoustic Radiation Force Impulse Imaging

Abstract

Background Visual confirmation of radiofrequency ablation (RFA) lesions during clinical cardiac ablation procedures could improve procedure efficacy, safety, and efficiency. It was previously shown that acoustic radiation force impulse (ARFI) imaging can identify RFA lesions in vitro and in vivo in an animal model. This is the “first-in-human” feasibility demonstration of intracardiac ARFI imaging of RFA lesions in patients undergoing catheter ablation for atrial flutter (AFL) or atrial fibrillation (AF). Methods and Results Patients scheduled for right atrial (RA) ablation for AFL or left atrial (LA) ablation for drug refractory AF were eligible for imaging. Diastole-gated intracardiac ARFI images were acquired using one of two equipment configurations: (1) a Siemens ACUSON S2000™ ultrasound scanner and 8/10Fr AcuNav™ ultrasound catheter, or (2) a CARTO 3™ integrated Siemens SC2000™ and 10Fr SoundStar™ ultrasound catheter. A total of 11 patients (AFL = 3; AF = 8) were imaged. ARFI images were acquired of ablation target regions, including the RA cavotricuspid isthmus (CTI), and the LA roof, pulmonary vein ostia, posterior wall, posterior mitral valve annulus, and the ridge between the pulmonary vein and LA appendage. ARFI images revealed increased relative myocardial stiffness at ablation catheter contact sites after RFA and at anatomical mapping-tagged RFA treatment sites. Conclusions ARFI images from a pilot group of patients undergoing catheter ablation for AFL and AF demonstrate the ability of this technique to identify intra-procedure RFA lesion formation. The results encourage further refinement of ARFI imaging clinical tools and continued investigation in larger clinical trials.

Recent Advances in Lesion Formation for Catheter Ablation of Atrial Fibrillation

“…Finally, ARFI imaging has been successfully adapted to clinical ultrasound and mapping systems during routine clinical catheter ablation procedures with demonstrated feasibility of acquiring ARFI images of radiofrequency lesions from clinically by guest on May 12, 2018 http://circep.ahajournals.org/ Downloaded from relevant ablation target regions in both the right and the left atria ( Figure 4). 73 Although ARFI imaging shows promise as a tool to evaluate cardiac ablation lesions in situ, and has potential to offer a new and complimentary procedure end point for therapeutic ablation by providing direct information about whether a radiofrequency lesion set is complete (contiguous and transmural lesions without gaps), further development of imaging catheters to enhance imaging depth and studies to establish the role of this technology in clinical practice are needed.…”

Validation of an intracardiac ultrasonic therapy–imaging dual mode transducer

“…Other groups demonstrated the feasibility of similar techniques with the same approach [13,14]. However this approach necessitates the use of two catheters, one for ablation and one for ultrasonic monitoring.…”

Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation

“…Nevertheless, multiple groups have now shown that deformability as indexed by these techniques drops immediately following RF ablation in vivo. (Bahnson et al, 2014; Kwiecinski et al, 2014) Interestingly, this shear stiffness is quite stable from 2-30 minutes after ablation in the center of the lesion, while the stiffness of adjacent myocardium increases more slowly; (Eyerly et al, 2015) Eyerly et al suggested that the immediate response may reflect changes in tissue properties due to thermal damage, while the slower response in adjacent tissue reflects edema. (Eyerly et al, 2015) Less is known about the evolution of mechanical properties beyond the first few minutes post-ablation, other than the fact that scar tissue forms in damaged regions and is presumably stiffer than the surrounding myocardium.…”