Effect of catheter tip length and position on lesion volume in temperaturecontrolled RF ablation in canine tricuspid valve annulus

Background: Radiofrequency (RF) energy has been delivered to the tricuspid valve annulus (TVA) in humans with both 4 mm and 8 mm long catheter tip ele ctrodes to treat atrial Butter However, lesion volume with temperature cont rolled RF delivery systems has not been previously characterized. Methods: In 10 anesthetized canines, a single pulse of temperature controll ed BE energy at a 70 degrees C set point, 30 second duration was delivered with either a 7 Fr/4 mm tip or a 7 Fr/8 mm tip electrode in a position both anterolateral and posteroseptal to the tricuspid valve annulus (TVA). Surf ace echocardiogram was obtained prior and after ablation. The animals were sacrificed after ablation and the lesions underwent gross and histological examination. Results: Lesion size, tip temperature and power were related to tip electro de surface area (SA). Eight mm tips (SA = 59 mm(2)) tended to create signif icantly larger lesions than 4 mm tips (SA = 29 mm(2)). Median lesion volume was 22 vs. 1.5 mm(3), respectively. Eight mm tips were also associated wit h higher power requirements and lower temperatures than 4 mm tips. Posteros eptal TVA lesions tended to be larger than anterolateral lesions. No signif icant complications were noted. Conclusions: Using temperature controlled RF ablation, large lesions may be safely created on the canine TVA using 7 Fr catheters with 8 mm long tips.