Electrogram-gated radiofrequency ablations with duty cycle power delivery negate effects of ablation catheter motion
William W B Chik1, Michael Anthony Barry1, Jim Pouliopoulos1
1From the Cardiology Department, Westmead Hospital (W.W.B.C., M.A.B., J.P., K.B., C.M., A.B., G.S., S.P.T., D.L.R., P.K., A.T.), Sydney Medical School (W.W.B.C., M.A.B., J.P., C.M., A.B., G.S., S.P.T., D.L.R., P.K., A.T.), and School of Electrical and Information Engineering (M.A.B., A.M.), University of Sydney, Sydney, New South Wales, Australia.
Background:
Cardiac and respiratory movements cause catheter instability. Lateral catheter sliding over target endocardial surface can lead to poor tissue contact and unpredictable lesion formation. We describe a novel method of overcoming the effects of lateral catheter sliding movements using an electrogram-gated pulsed power ablation.
Methods And Results:
All ablations were performed on a thermochromic gel myocardial phantom. Ablation settings were randomized to conventional (nongated) 30 W versus electrogram-gated at 20% duty cycle (30 W average power) at 0-, 3-, 6-, and 9-mm lateral sliding distances. Forty-eight radiofrequency ablations were performed. Deeper lesions were created in electrogram-gated versus conventional ablations at 3 mm (4.36±0.08 versus 4.05±0.17 mm; P=0.009), 6 mm (4.39±0.10 versus 3.44±0.15 mm; P<0.001), and 9 mm (4.41±0.06 versus 2.94±0.16 mm; P<<0.001) sliding distances. Electrogram-gated ablations created consistent lesions at a quicker rate of growth in depth when compared with conventional ablations (P<0.001).
Conclusions:
(1) Lesion depth decreases and length increases in conventional ablations with greater degrees of lateral catheter movements; (2) electrogram-gated pulsed radiofrequency delivery negated the effects from lateral catheter movement by creating consistently deeper lesions irrespective of the degree of catheter movement; and (3) target lesion depths were reached significantly faster in electrogram-gated than in conventional ablations.
