Saurabh Kumar1, Jorge Romero2, William G Stevenson3, Lori Foley3, Ryan Caulfield3, Akira Fujii3, Shinichi Tanigawa3, Laurence M Epstein3, Bruce A Koplan3, Usha B Tedrow3, Roy M John4, Gregory F Michaud5. 1. Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Cardiovascular Division, Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia. 2. Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Arrhythmia Services, Department of Medicine (Cardiology), Montefiore-Einstein Center for Heart and Vascular Care, Bronx, New York. 3. Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts. 4. Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Arrhythmia and Electrophysiology Program, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee. 5. Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Arrhythmia and Electrophysiology Program, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee. Electronic address: gregory.michaud@vanderbilt.edu.
Abstract
OBJECTIVES: The authors sought to investigate the effect of low irrigation flow rate on lesion characteristics and ablation outcomes in a clinicopathological study. BACKGROUND: Irrigated ablation produces deeper lesions compared with nonirrigated ablation, which may not be desirable in the thin-walled posterior left atrium (LA), where collateral esophageal injury is possible. METHODS: Lesions were placed on the smooth posterior right atrium in 20 swine and posterior LA in 60 patients at a maximum power of 20 to 25 W with either: 1) power-controlled ablation at an irrigation flow rate of 17 ml/min (high-flow group 10 swine; n = 40) or 2) temperature-controlled ablation at an irrigation flow rate of 2 ml/min (low-flow group 10 swine; n = 20). Safety and efficacy was also compared in 326 patients undergoing AF ablation using high-flow (n = 160) or low-flow settings (n = 166) for posterior LA ablation. RESULTS: Low-flow, compared with high-flow, lesions in swine had a higher incidence of lesions with: impedance fall ≥10 Ω, loss of pace capture, electrograms characteristic of transmural lesions, and visible lesions on anatomic inspection (p < 0.05 for all). Low-flow lesions had a maximal diameter at the endocardial surface, whereas high-flow lesions had a maximal diameter at the epicardial surface. In humans, impedance, pace capture, and transmurality data also strongly favored low-flow lesions. There was no difference in acute pulmonary vein isolation, complications, or 12-month arrhythmia-free survival between the groups. CONCLUSIONS: Low-flow irrigated ablation provides favorable lesion characteristics for posterior LA ablation without increasing the risk of adverse events.
OBJECTIVES: The authors sought to investigate the effect of low irrigation flow rate on lesion characteristics and ablation outcomes in a clinicopathological study. BACKGROUND: Irrigated ablation produces deeper lesions compared with nonirrigated ablation, which may not be desirable in the thin-walled posterior left atrium (LA), where collateral esophageal injury is possible. METHODS: Lesions were placed on the smooth posterior right atrium in 20 swine and posterior LA in 60 patients at a maximum power of 20 to 25 W with either: 1) power-controlled ablation at an irrigation flow rate of 17 ml/min (high-flow group 10 swine; n = 40) or 2) temperature-controlled ablation at an irrigation flow rate of 2 ml/min (low-flow group 10 swine; n = 20). Safety and efficacy was also compared in 326 patients undergoing AF ablation using high-flow (n = 160) or low-flow settings (n = 166) for posterior LA ablation. RESULTS: Low-flow, compared with high-flow, lesions in swine had a higher incidence of lesions with: impedance fall ≥10 Ω, loss of pace capture, electrograms characteristic of transmural lesions, and visible lesions on anatomic inspection (p < 0.05 for all). Low-flow lesions had a maximal diameter at the endocardial surface, whereas high-flow lesions had a maximal diameter at the epicardial surface. In humans, impedance, pace capture, and transmurality data also strongly favored low-flow lesions. There was no difference in acute pulmonary vein isolation, complications, or 12-month arrhythmia-free survival between the groups. CONCLUSIONS: Low-flow irrigated ablation provides favorable lesion characteristics for posterior LA ablation without increasing the risk of adverse events.