Deliberate Epicardial Catheter Ablation Lesions Making Outside Contact

One of the major limitations of complex catheter ablation procedures is the inability to ensure predictable effective lesion creation at a large number of sites, including linear or contiguous applications used for isolating pulmonary venous antra or for interrupting ventricular tachycardia.1–3 This is of particular importance for arrhythmias that have a deep intramyocardial or epicardial substrate, most frequently in nonischemic cardiomyopathies.4,5 Multicenter experiences with catheter access to the pericardial space have increased substantially during the past decade,6 increasing our understanding of the associated risks and limitations. We still need better understanding of the influence of epicardial fat on mapping and ablation, the risk of collateral injury to coronary arteries, the phrenic nerve or other extracardiac structures, and epicardial lesion creation using radiofrequency energy. Article see p 1222 Irrigation of the catheter tip permits greater power delivery and the production of larger lesions but uncouples the temperature of the tip from that of the tissue, removing important biophysical feedback and hence lesion predictability.7,8 This trade-off of safety for effectiveness requires greater care by physicians to deliberately deliver ablation lesions where they are needed and to purposely avoid damage to nontarget tissues. The advent of clinically available catheter tip contact force–sensing technology has opened a new window for the delivery of radiofrequency ablation and returns a degree of control over lesion creation. In endocardial studies, contact force has demonstrated greater correlation with lesion size than other frequently used clinical markers, such as tip temperature, electrogram amplitude, or impedance changes, and has influence on lesion size similar to that of delivered power.9–14 The potential benefit of contact …