title: High Incidence of Low Catheter-Tissue Contact Force at the Cavotricuspid Isthmus During Catheter Ablation of Atrial Flutter: Implications for Achieving Isthmus Block.
abstract: BACKGROUND
  Recurrent atrial flutter following cavotricuspid isthmus (CTI) ablation remains a significant problem. The prevalence of low contact force (CF) during CTI ablation using standard tools is unknown. Our aim was to characterize the prevalence of low CF applications when experienced operators performed CTI ablation using "traditional" markers of contact blinded to CF measurements.
  
  
  RESULTS
  Average CF (grams, g) and force-time integral (FTI) was analyzed in 458 lesions in 17 patients undergoing CTI ablation. The isthmus was divided into the annular, mid and caval segments for region-specific analysis. Despite "good" contact using traditional markers, there was significant variability in CF within each isthmus segment (e.g., annular CTI 1-57 g). A high proportion of lesions had a CF <10 g (40%). Lowest CF was the annular (median 9 g), followed by the mid (12 g) and the caval CTI (18 g, P < 0.001). Sites of acute CTI re-connection had a lower average CF and FTI than nonreconnected sites (P < 0.05). Each 1 g increase in CF was associated with a 16% reduction in risk of recovered CTI conduction (95% confidence interval: 4-27%, P = 0.01).
  
  
  CONCLUSIONS
  Use of surrogate markers of "good contact" during ablation by experienced operators in the absence of real-time CF sensing resulted in nearly half of all lesions being delivered with low CF with marked region-specific variability in CF. Low CF was implicated in longer time to achieve conduction block and increased risk of acute reconnection. These findings underscore the importance of real-time CF measurements for optimizing ablation of typical atrial flutter.
authors.affiliation: Department of Cardiology, The Royal Melbourne Hospital, and Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.|Department of Medicine, University of Melbourne, Victoria, Australia.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Cardiology, The Royal Melbourne Hospital, and Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.|Department of Medicine, University of Melbourne, Victoria, Australia.
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Morton
authors.affiliation: Department of Cardiology, The Royal Melbourne Hospital, and Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.|Department of Medicine, University of Melbourne, Victoria, Australia.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Lee
authors.affiliation: Department of Medicine, University of Melbourne, Victoria, Australia.
authors.forename: Karen
authors.initials: K
authors.lastname: Halloran
authors.affiliation: Department of Medicine, University of Melbourne, Victoria, Australia.|Department of Cardiology, Alfred Hospital and Baker IDI, Prahran, Victoria, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kistler
authors.affiliation: Department of Cardiology, The Royal Melbourne Hospital, and Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.|Department of Medicine, University of Melbourne, Victoria, Australia.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Kalman
mesh_terms: D000200:Action Potentials; D000368:Aged; D001282:Atrial Flutter / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D062906:Cardiac Catheters; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation*; D002983:Clinical Competence; D018572:Disease-Free Survival; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D013997:Time Factors; D014160:Transducers, Pressure; D016896:Treatment Outcome
keywords: atrial flutter; catheter ablation; cavotricuspid isthmus; contact-force sensing; reconnection