title: Impact of irrigation flow rate and intrapericardial fluid on cooled-tip epicardial radiofrequency ablation.
abstract: The optimal irrigation flow rate (IFR) during epicardial radiofrequency (RF) ablation has not been established.
  
  
  
  This study specifically examined the impact of IFR and intrapericardial fluid (IPF) accumulation during epicardial RF ablation.
  
  
  
  Altogether, 452 ex vivo RF applications (10 g for 60 seconds) delivered to the epicardial surface of bovine myocardium using 3 open-irrigated ablation catheters (ThermoCool SmartTouch, ThermoCool SmartTouch-SF, and FlexAbility) and 50 in vivo RF applications delivered (ThermoCool SmartTouch-SF) in 4 healthy adult swine in the presence or absence of IPF were examined. Ex vivo, RF was delivered at low (≤3 mL/min), reduced (5-7 mL/min), and high (≥10 mL/min) IFRs using intermediate (25-35 W) and high (35-45 W) power. In vivo, applications were delivered (at 9.3 ± 2.2 g for 60 seconds at 39 W) using reduced (5 mL/min) and high (15 mL/min) IFRs.
  
  
  
  Ex vivo, surface lesion diameter inversely correlated with IFR, whereas maximum lesion diameter and depth did not differ. While steam pops occurred more frequently at low IFR using high power (ThermoCool SmartTouch and ThermoCool SmartTouch-SF), tissue disruption was rare and did not vary with IFR. In vivo, charring/steam pop was not detected. Although there were no discernible differences in lesion size with IFR, surface lesion diameter, maximum diameter, depth, and volume were all smaller in the presence of IPF at both IFRs.
  
  
  
  Cooled-tip epicardial RF ablation created using reduced IFRs (5-7 mL/min) yields lesion sizes similar to those created using high IFRs (≥10 mL/min) without an increase in steam pop/tissue disruption, whereas the presence of IPF significantly reduces the lesion size.
authors.affiliation: Mercy General Hospital, Dignity Health Heart and Vascular Institute, Sacramento, California. Electronic address: a_aryana@outlook.com.
authors.forename: Arash
authors.initials: A
authors.lastname: Aryana
authors.affiliation: Mercy General Hospital, Dignity Health Heart and Vascular Institute, Sacramento, California.
authors.forename: Padraig Gearoid
authors.initials: PG
authors.lastname: O'Neill
authors.affiliation: Division of Cardiothoracic Surgery, Baylor College of Medicine, Houston, Texas.
authors.forename: Deep K
authors.initials: DK
authors.lastname: Pujara
authors.affiliation: Division of Cardiothoracic Surgery, Baylor College of Medicine, Houston, Texas.
authors.forename: Steve K
authors.initials: SK
authors.lastname: Singh
authors.affiliation: Mercy General Hospital, Dignity Health Heart and Vascular Institute, Sacramento, California.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Bowers
authors.affiliation: Mercy General Hospital, Dignity Health Heart and Vascular Institute, Sacramento, California.
authors.forename: Shelley L
authors.initials: SL
authors.lastname: Allen
authors.affiliation: Instituto de Pesquisa em Arritmia Cardiaca, Hospital Cardiologico, Florianopolis, Santa Catarina, Brazil.
authors.forename: André
authors.initials: A
authors.lastname: d'Avila
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation / Q000295:instrumentation*; D004195:Disease Models, Animal; D004867:Equipment Design; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery*; D010496:Pericardium / Q000601:surgery*; D013552:Swine; D007507:Therapeutic Irrigation / Q000295:instrumentation*
keywords: Catheter ablation; Electrophysiology; Epicardial; Pericardium; Radiofrequency