title: Deep myocardial ablation lesions can be created with a retractable needle-tipped catheter.
abstract: RF catheter ablation of ventricular tachycardia is sometimes limited by inadequate lesion depth. This study investigated the use of a retractable needle-tipped catheter to create deep RF lesions in vivo in porcine myocardium. An 8 Fr electrode catheter with an extendable 27-gauge needle at the tip was modified for RF ablation by embedding a thermocouple and attaching a pin connector. In three swine (32-58 kg) the left ventricle was entered via the femoral artery and endocardial contact was made. The needle was advanced 10 mm and 13 RF applications were made under a controlled temperature (90 degrees C x 120 s). Nine control lesions were made using a standard 4-mm tip catheter (60 degrees C x 120 s). The lesions were fixed, serially sectioned from the endocardium, digitally imaged, and quantified. Needle ablation lesions were deeper (10.15 +/- 0.77 vs 5.67 +/- 0.37 mm, P < 0.001) and more likely to be transmural (77 vs 11%, P = 0.008) than control lesions. The volume of control lesions, however, was larger (358.4 +/- 56.2 vs 174.7 +/- 18.6 mm(3), P = 0.002) due to a significantly larger cross-sectional area at the endocardium (0.548 +/- 0.04 vs 0.151 +/- 0.01 cm(2), P < 0.001). At depths > 6 mm, the needle electrode lesions had a greater cross-sectional area (0.136 +/- 0.01 vs 0.005 +/- 0.004 cm(2), P < 0.001). Catheter-based needle ablation is feasible and allows creation of deeper lesions that can be transmural. Although deep, the lesions had a small cross-sectional area such that precise targeting would be required for success.
authors.affiliation: Cardiovascular Division, Department of Internal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: John Lewis
authors.initials: JL
authors.lastname: Sapp
authors.forename: Joshua Morrey
authors.initials: JM
authors.lastname: Cooper
authors.forename: Kyoko
authors.initials: K
authors.lastname: Soejima
authors.forename: Timothy
authors.initials: T
authors.lastname: Sorrell
authors.forename: Gustavo
authors.initials: G
authors.lastname: Lopera
authors.forename: Srinivasa Dinakar
authors.initials: SD
authors.lastname: Satti
authors.forename: Bruce Andrew
authors.initials: BA
authors.lastname: Koplan
authors.forename: Laurence Mark
authors.initials: LM
authors.lastname: Epstein
authors.forename: Elazer
authors.initials: E
authors.lastname: Edelman
authors.forename: Campbell
authors.initials: C
authors.lastname: Rogers
authors.forename: William Gregory
authors.initials: WG
authors.lastname: Stevenson
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D004867:Equipment Design; D005240:Feasibility Studies; D008297:Male; D009206:Myocardium / Q000473:pathology*; D013552:Swine