Mapping of atrial activation patterns after inducing contiguous radiofrequency lesions: an experimental study.
High resolution mapping techniques are used to analyze the changes in atrial activation patterns produced by contiguous RF induced lesions. In 12 Langendorff-perfused rabbit hearts, left atrial activation maps were obtained before and after RF induction of epicardial lesions following a triple-phase sequential protocol: (phase 1) three separate lesions positioned vertically in the central zone of the left atrial wall; (phase 2) the addition of two lesions located between the central lesion and the upper and lower lesions; and (phase 3) the placement of four additional lesions between those induced in the previous phases. In six additional experiments a pathological analysis of the individual RF lesions was performed. In phase 1 (lesion diameter = 2.8+/-0.2 mm, gap between lesions = 3+/-0.8 mm), the activation process bordered the lesions line in two (250-ms cycles) and four experiments (100-ms cycles). In phase 2, activation bordered the lesions line in eight (250-ms cycles, P < 0.01 vs control) and nine experiments (100-ms cycles, P < 0.001), and in phase 3 this occurred in all experiments except one (both cycles, P < 0.001 vs control). In the experiments with conduction block, the increment of the interval between activation times proximal and distal to the lesions showed a significant correlation to the length of the lesions (r = 0.68, P < 0.05, 100-ms cycle). In two (17%) experiments, sustained regular tachycardias were induced with reentrant activation patterns around the lesions line. In conclusion, in this acute model, atrial RF lesions with intact tissue gaps of 3 mm between them interrupt conduction occasionally, and conduction block may be frequency dependent. Lesion overlap is required to achieve complete conduction block lines. Tachycardias with reentrant activation patterns around a lesions line may be induced.
Service of Cardiology, Valencia University Clinic Hospital, Spain.
F J
FJ
Chorro
L
L
Mainar
J
J
Sanchis
J
J
Cánoves
E
E
Llavador
L M
LM
Such
M
M
Cerdá
V
V
López-Merino
L
L
Such
D000818:Animals; D016275:Atrial Function / Q000502:physiology; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D006325:Heart Atria / Q000503:physiopathology*; D006327:Heart Block / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology; D010477:Perfusion; D011817:Rabbits; D013610:Tachycardia / Q000503:physiopathology; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology