title: Open-irrigated laser catheter ablation: influence of catheter-tissue contact force on lesion formation.
abstract: OBJECTIVE
  Catheter-tissue contact force (CF) is a major determinant for radiofrequency (RF) ablation lesion size and quality. We sought to test the influence of catheter CF on lesion formation by using an open-irrigated electrode-laser mapping and ablation (ELMA) catheter.
  
  
  METHODS
  With the ELMA catheter in a stable vertical position, continuous wave 1064 nm laser impacts at 15 W (9.5 W/mm(2)), 30 s (285 J/mm(2)), irrigation flow 30 mL/min, were aimed at the endocardial surface of bovine myocardium in heparinized stagnant blood (ACT >350 s) at room temperature (18 °C). Lesions were produced with CFs of 100 g, 10 g, in contact but without pressure, with the catheter tip 2.0 mm, and 5.0 mm away (n = 10, each). Lesions were evaluated morphometrically and were compared by the unpaired t tests.
  
  
  RESULTS
  There were no significant differences between volumes of lesions achieved with catheter-tissue CF of 100 g, 10 g, and in contact without pressure: 297 ± 56.0 vs. 300 ± 39 vs. 320 ± 24, respectively (p > 0.05). However, volumes of lesions produced at a distance of 2 mm (95 ± 14 mm(3)) were significantly smaller (p < 0.0001), whereas at a distance of 5.0 mm, no lesions were produced. No steam-pop with crater or thrombus formation occurred.
  
  
  CONCLUSIONS
  By using an open-irrigated ELMA catheter, catheter-tissue CF is not a determinant for laser ablation lesion size and quality. Maximum sizes of lesions can be achieved with the catheter in intimate endocardial contact without pressure. However, lesions can be produced also at a catheter-tissue distance of 2.0 mm. Noticeably, there is no thrombus formation during laser application with the free floating ELMA catheter in the stagnant blood.
authors: Department of Anesthesiology, Hospital Neuperlach, Teaching Hospital of the Ludwig-Maximilian-University of Munich, Munich, 81737, Germany.
authors: Michaela
authors: M
authors: Sagerer-Gerhardt
authors: Helmut P
authors: HP
authors: Weber
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D002417:Cattle; D006352:Heart Ventricles / Q000601:surgery*; D053685:Laser Therapy / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D053844:Lasers, Solid-State / Q000627:therapeutic use; D023421:Models, Animal; D009206:Myocardium / Q000473:pathology*; D011312:Pressure; D012680:Sensitivity and Specificity; D007507:Therapeutic Irrigation; D013927:Thrombosis / Q000209:etiology / Q000473:pathology