Percutaneous catheter ablation has revolutionized the care of patients with atrial fibrillation. Pulmonary vein isolation has become the cornerstone of most ablation procedures for the treatment of atrial fibrillation following the observation by Haissaguerre et al 1 Haissaguerre M. Jais P. Shah D.C. et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998; 339: 659-666 Google Scholar that pulmonary veins were a frequent source of ectopic beats initiating atrial fibrillation. Pulmonary vein isolation may be combined with linear ablation or ablation of other targets for treatment of persistent or longstanding persistent atrial fibrillation. Pulmonary vein electrical reconnection to the left atrium is not uncommon and may be the primary reason for procedure failure among patients with paroxysmal atrial fibrillation. 2 Callans D.J. Gerstenfeld E.P. Dixit S. et al. Efficacy of repeat pulmonary vein isolation procedures in patients with recurrent atrial fibrillation. J Cardiovasc Electrophysiol. 2004; 15: 1050-1055 Google Scholar , 3 Shah A.N. Mittal S. Sichrovsky T.C. et al. Long-term outcome following successful pulmonary vein isolation: pattern and prediction of very late recurrence. J Cardiovasc Electrophysiol. 2008; 19: 661-667 Google Scholar , 4 Cheema A. Dong J. Dalal D. et al. Incidence and time course of early recovery of pulmonary vein conduction after catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol. 2007; 18: 387-391 Google Scholar Pulmonary vein reconnections also have been demonstrated to be important triggers in patients with persistent atrial fibrillation undergoing repeat ablation. 5 Haissaguerre M. Jais P. Shah D.C. et al. Catheter ablation of chronic atrial fibrillation targeting the reinitiating triggers. J Cardiovasc Electrophysiol. 2000; 11: 2-10 Google Scholar Recovery of conduction across linear ablation lesions is also likely to play a role in procedure failure among patients with persistent atrial fibrillation. 6 Rostock T. O'Neill M.D. Sanders P. et al. Characterization of conduction recovery across left atrial linear lesions in patients with paroxysmal and persistent atrial fibrillation. J Cardiovasc Electrophysiol. 2006; 17: 1106-1111 Google Scholar With current technology, some tissue that is ablated recovers electrical activity. Any technology that could safely increase the probability that ablated tissue would remain ablated would be an important contribution. Real-time lesion assessment using a novel combined ultrasound and radiofrequency ablation catheterHeart RhythmVol. 8Issue 2PreviewAssessment of lesion size and transmurality is currently via indirect measures. Real-time image assessment may allow ablation parameters to be titrated to achieve transmurality and reduce recurrences due to incomplete lesions. Full-Text PDF