Near-Field Ultrasound Imaging of Ablation Lesion Formation: More Than Meets the Eye?

Abstract

See Article by Haines et al Effective lesion formation with radiofrequency (RF) catheter ablation in current practice relies on the monitoring of variables which serve as surrogates to tissue destruction. Impedance drop, electrogram diminution, adequacy of contact force and power titration, and lack of pace capture after ablation all suggest effective RF delivery to targeted tissue, but none come close to a gold standard of pathological examination (Figure).1–5 Intracardiac echocardiography can improve the safety and efficacy of catheter ablation because of its ability to offer direct visualization of the catheter-tissue interface, but in most cases provides insufficient resolution to adequately assess the depth of lesions created during RF delivery.6,7 Near-field imaging to directly visualize lesion formation would offer a substantial improvement with potential to improve the safety and efficacy of catheter ablation; not only could near-field imaging confirm that targeted tissue was truly being affected by RF, but the power, contact force, and duration of RF delivery could be titrated in a manner to avoid delivery of excessive or unnecessary ablation which could otherwise put neighboring structures (phrenic nerve, periesophageal vagal nerve, or the esophagus itself) at risk.8–10 The near-field ultrasound (NFUS) ablation catheter is designed to offer just that—NFUS imaging from the catheter tip to directly monitor lesion formation in hopes to ultimately improve the efficacy and safety of catheter ablation. Figure. Parameters which can be used to assess or predict the effectiveness of radiofrequency delivery and ablation lesion formation. NFUS indicates near-field ultrasound. In the current issue of Circulation: Arrhythmia and Electrophysiology , Haines et al11 investigate the application of …