Selective myocardial isolation and ventricular fibrillation.
BACKGROUND
Few experimental studies have analyzed the effects of selective radiofrequency (RF) lesions upon ventricular fibrillation (VF). The RF-induced isolation of selected zones would make it possible to determine whether these zones are essential for existence of the arrhythmia.


METHODS
In 31 Langendorff-perfused rabbit hearts, the characteristics and inducibility of VF were analyzed before and after the induction of RF lesions comprising: (1) the posterior zone of the septum and of the walls of both ventricles (n = 10); (2) the anterior zone of the septum and of the walls of both ventricles (n = 11); and (3) the midseptal zone (n = 10).


RESULTS
Complete isolation of the zone encompassed by the lesions was obtained in 5, 6, and 5 experiments of series 1, 2, and 3, respectively. In these experiments, the arrhythmia was only induced from within the zone encompassed by the lesions in one experiment belonging to series 2 (P < 0.05 with respect to baseline). In contrast, in all but one of the cases in series 2, VF could be induced from outside the isolated zone (ns vs baseline). Partial isolation was obtained in five experiments of each series. In these experiments, on pacing from within the partially isolated zone, sustained VF was not induced in any experiment (P < 0.05 with respect to baseline), while in all cases VF could be induced on pacing from the external zone (ns vs baseline).


CONCLUSIONS
In the experimental model used, the three zones studied were not essential for maintaining VF. In most cases, their partial or total isolation avoided inducibility of the arrhythmia in those zones, though not in the remaining myocardium.
Chorro
Francisco J
FJ
Service of Cardiology, Valencia University Clinic Hospital, Valencia, Spain. Francisco.J.Chorro@uv.es
Blasco
Estrella
E
Trapero
Isabel
I
Cánoves
Joaquín
J
Ferrero
Angel
A
Mainar
Luis
L
Such-Miquel
Luis
L
Sanchis
Juan
J
Bodí
Vicente
V
Cerdá
José M
JM
Alberola
Antonio
A
Such
Luis
L
D000818:Animals; D018780:Body Surface Potential Mapping; D017115:Catheter Ablation; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery*; D011817:Rabbits; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000601:surgery*