Catheter Ablation -> Atrial Fibrillation & Atrial Flutter: -> Experimental methods D-PO04 - Poster Session IV (ID 15) Poster

D-PO04-143 - How Does Catheter Motion Affect Radiofrequency Lesion Formation? (and How Does One Deal With It?) (ID 462)


Background: The effect of catheter instability / motion on lesion dimensions during RF ablation has not been well studied.
Objective: To assess the effect of catheter motion on lesion size in an ex vivo model.
Methods: Motion was studies using a custom pneumatic device to precisely move the catheter tip laterally (to and fro) to simulate catheter sliding across tissue. The Thermocool ST SF (Biosense Webster Inc) was positioned on chicken breast (contact force 8-12 gm, and bath impedance 90-115 Ohms) to study 5 different motions (0, 5, 10, 15 or 20 mm lateral movement), at 5 different RF energies (20W x 20s, 35W x 20s, 35W x 60s, 50W x 20s and 50W x 60s), and with both perpendicular and parallel configurations. We examined the surface lesion morphology, depth and surface length x width. We assessed impedance drop, and steam pops with each delivery. Each motion and application were repeated 5 times, and medians presented.
Results: With increasing extent of motion, the lesions were wider, but also shallower, and occasionally split into two smaller lesions: at 35W x 20sec, the lesion was 5.1mm deep (0 motion), but only 3.1mm at 10mm motion, and split into 2 lesions, 2.4/2.5mm, with 20mm motion (Figure). Higher power, and longer applications attenuated both this loss of depth and lesion splitting. The effect of motion was greater with the parallel approach. The impedance drop did not predict depth in the presence of motion.
Conclusion: Lateral catheter motion of 10 mm or more decreases lesion depth regardless of the catheter orientation; with extreme motion, the lesion splits into 2 smaller ones. This attenuation in lesion formation can be partly overcome by increasing the power and/or duration of delivered energy.