Near real time evaluation of cardiac radiofrequency ablation lesions with intracardiac echocardiography based acoustic radiation force impulse imaging.

Abstract

[Cardiac radiofrequency (rf) ablation is used to treat cardiac arrhythmias. Multiple rf lesions are created to form lines of electrical block to disrupt arrhythmic wavefronts. However, image based lesion evaluation is not performed and clinicians rely on changes in electrical propagation to evaluate lesion quality. A near real time lesion evaluation system was developed and tested in vitro and in canines using acoustic radiation force impulse imaging (ARFIi) combined with a catheter tracking system (CARTO, Biosense Webster). rf ablation was performed and delivery sites were indicated on a CARTO electroanatomic map. A CARTO spatially tracked SoundStar® catheter was then used to steer the imaging plan to transect lesions, and intracardiac echocardiography (ICE) based ARFIi (Siemens, S2000 Acuson) was used to evaluate lesion contiguity and transmurality. Imaging was gated to diastole when unablated tissue is soft; motion filtering was employed to reduce the effects of catheter and cardiac movement. ARFIi based evaluation of rf lesions demonstrated a resolution of less than 2mm in vitro and lesion assessment correlated with electrical block in animal studies (λ=0.8). Combining catheter tracking with ICE based ARFIi allows near real time evaluation of cardiac ablation lesions. [Work supported by Siemens Medical, Biosense Webster, and NIH Grant No. R01‐EB‐012484 and R37‐HL096023.]