Cryoablation time-dependent dose-response effect at minimal temperatures (-80 degrees C): an experimental study.
OBJECTIVE
To establish a temporal safety window for cryoablation at minimal temperatures and to assess the electrophysiological and histological changes as a function of the application duration.


RESULTS
Twenty mini-pigs underwent AV nodal cryoablation at -80 degrees C without prior cryomapping. The duration of the cryoapplication following atrioventricular block (AVB) was randomized to 0, 10, 20, 40, or 60 s. Atrioventricular block was obtained in all animals after a median of 3 (1-8 interquartile range) applications. One week later, AV nodal conduction fully recovered in animals with application duration <10 s, whereas persistent AVB incidence increased as a function of time in animals with longer applications duration. Cryoablation application duration following AVB was the only independent predictor of persistent AVB (OR, 1.116; 95% CI, 1.013-1.229; P = 0.026). There was no difference in lesion location or size between animals with vs. those without persistent AVB at 1 week. However, animals randomized to longer application duration demonstrated higher degree of cell destruction and fibrotic content.


CONCLUSIONS
In this closed-chest pig model, there was a relation between cryoapplication duration following AVB at -80 degrees C and recovery of conduction. A safety window of at least 10 s was observed in all cases.
Atienza
Felipe
F
Cardiology Department, Hospital General Universitario Gregorio Marañón, 28007 Madrid, Spain. fatienzaf@secardiologia.es
Almendral
Jesús
J
Sánchez-Quintana
Damián
D
Zaballos
Matilde
M
Murillo
Margarita
M
Jimeno
Concepción
C
Parra
Verónica
V
Fernández-Avilés
Francisco
F
D000818:Animals; D054537:Atrioventricular Block / Q000503:physiopathology* / Q000601:surgery*; D001283:Atrioventricular Node / Q000503:physiopathology* / Q000601:surgery*; D003452:Cryosurgery / Q000379:methods*; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery*; D013552:Swine; D013556:Swine, Miniature; D013696:Temperature; D013997:Time Factors; D016896:Treatment Outcome