Biophysical Properties, Efficacy, and Lesion Characteristics of a New Linear Cryoablation Catheter in a Canine model.

Abstract Background The cryoballoon (CB) catheter is an established tool for isolation of the pulmonary veins (PVI), however, its use is limited to that end. Objective This study was conducted to investigate biophysical properties of a newly developed linear cryoablation catheter (LC) for creation of linear ablation lesions in an in vivo model. Methods Twenty-nine (14 acutely ablated, 15 chronically followed) dogs underwent cryoablation using the LC. Regions of interest included the cavotricuspid isthmus (CTI), mitral isthmus (MI), left atrial (LA) roof, and the LA posterior wall in an acute study. Cryoablations for CTI and MI were performed in 14 atrial fibrillation animals after PVI and followed over 1 month in the chronic study. Tissue temperature during cryoablation was monitored using implanted thermocouples in the regions of interest. Gross and microscopic pathologic characteristics of the lesions were assessed. Results In acute animals, lesion length (transmurality) was CTI: 34±4mm (89±11%), MI: 29±4mm (90±13%), LA roof: 19±3mm (90±8%) and LA posterior wall: 19±2mm (81±13%) respectively with 1 or 2 freezes. Chronic bidirectional block was achieved in 13 of 14 (93%) CTI and 10 of 14 (71%) MI ablations after 1 month follow-up and was consistent with lesion continuity and transmurality upon pathology. The lowest tissue temperature correlated well with the closest distance to the linear cryocatheter (r=0.688; p Conclusions This linear cryocatheter has created continuous and transmural linear lesions with a "single shot" cryoenergy application and thus has the potential for clinical use in the setting of various arrhythmias.