title: Novel contact force sensor incorporated in irrigated radiofrequency ablation catheter predicts lesion size and incidence of steam pop and thrombus.
abstract: BACKGROUND
  An open-irrigated radiofrequency (RF) ablation catheter was developed to measure contact force (CF). Three optical fibers measure microdeformation of the catheter tip. The purpose of this study was to (1) validate the accuracy of CF sensor (CFS) (bench test); and (2) determine the relationship between CF and tissue temperatures, lesion size, steam pop, and thrombus during RF ablation using a canine thigh muscle preparation.
  
  
  RESULTS
  CFS measurements (total 1409) from 2 catheters in 3 angles (perpendicular, parallel, and 45 degrees ) were compared with a certified balance (range, 0 to 50 g). CFS measurements correlated highly (R(2) > or =0.988; mean error, < or =1.0 g). In 10 anesthetized dogs, a skin cradle over the thigh muscle was superfused with heparinized blood at 37 degrees C. A 7F catheter with 3.5-mm saline-irrigated electrode and CFS (Endosense) was held perpendicular to the muscle at CF of 2, 10, 20, 30, and 40 g. RF was delivered (n=100) for 60 seconds at 30 or 50 W (irrigation 17 or 30 mL/min). Tissue temperature (3 and 7 mm depths), lesion size, thrombus, and steam pop increased significantly with increasing CF at each RF power. Lesion size was greater with applications of lower power (30 W) and greater CF (30 to 40 g) than at high power (50 W) with lower CF (2 to 10 g).
  
  
  CONCLUSIONS
  This novel ablation catheter, which accurately measures CF, confirmed CF is a major determinant of RF lesion size. Steam pop and thrombus incidence also increases with CF. CFS in an open-irrigated ablation catheter that may optimize the selection of RF power and application time to maximize lesion formation and reduce the risk of steam pop and thrombus.
authors.affiliation: Heart Rhythm Institute and Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Yokoyama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Dipen C
authors.initials: DC
authors.lastname: Shah
authors.forename: Hendrik
authors.initials: H
authors.lastname: Lambert
authors.forename: Giovanni
authors.initials: G
authors.lastname: Leo
authors.forename: Nicolas
authors.initials: N
authors.lastname: Aeby
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ikeda
authors.forename: Jan V
authors.initials: JV
authors.lastname: Pitha
authors.forename: Tushar
authors.initials: T
authors.lastname: Sharma
authors.forename: Ralph
authors.initials: R
authors.lastname: Lazzara
authors.forename: Warren M
authors.initials: WM
authors.lastname: Jackman
mesh_terms: D000818:Animals; D001831:Body Temperature; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation*; D004285:Dogs; D008422:Materials Testing; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000601:surgery*; D055100:Optical Fibers; D015203:Reproducibility of Results; D007507:Therapeutic Irrigation; D013848:Thigh; D013927:Thrombosis / Q000209:etiology; D014160:Transducers, Pressure