Transcatheter modification of the atrioventricular node in dogs, using radiofrequency energy.
OBJECTIVE
To develop a protocol for reliably inducing atrioventricular (AV) block (ideally first- or second-degree), using radiofrequency energy.


METHODS
An electrosurgical unit was coupled to an ammeter, which was connected to the distal pole of an electrode catheter positioned at the AV node. Control settings had previously been calibrated to the power output in a circuit with a 100-ohm resistance.


METHODS
10 clinically normal dogs.


METHODS
Transcatheter AV nodal modification was attempted, using progressive power applications of 10 to 20 W for progressive durations of 10 to 30 seconds. Atrioventricular nodal conduction and refractivity were measured before and 20 minutes and 1 month after ablation. Electrocardiograms were monitored throughout the 1-month period.


RESULTS
Eight of the 10 dogs developed complete AV block, I developed stable 2:1 AV block, and another had no long-term change in AV nodal conduction. Four dogs attained their maximal degree of AV block in 2 to 5 days. Three of these had no AV nodal conduction changes until 2 to 4 days after ablation.


CONCLUSIONS
An electrosurgical unit can be economically modified for radiofrequency transcatheter ablation. Stable, incomplete AV block was rarely induced using this protocol, whereas complete AV block often developed. A major finding was frequent delay between energy delivery to the AV nodal region and induction of AV block.


CONCLUSIONS
Induction of complete AV block using this technique, followed by permanent pacemaker placement, is an effective alternative to long-term antiarrhythmic treatment in animals with chronic atrial arrhythmias. Transcatheter ablation could be used to treat other forms of tachycardia, as it is in human medicine.
Wright
K N
KN
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville 37901, USA.
Bright
J M
JM
Cox
J W
JW
McCracken
M D
MD
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000601:surgery / Q000662:veterinary; D001283:Atrioventricular Node / Q000502:physiology* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods / Q000662:veterinary*; D004283:Dog Diseases / Q000503:physiopathology / Q000601:surgery; D004285:Dogs / Q000502:physiology* / Q000601:surgery; D004562:Electrocardiography / Q000662:veterinary; D005260:Female; D005355:Fibrosis / Q000473:pathology / Q000662:veterinary; D006327:Heart Block / Q000209:etiology / Q000503:physiopathology / Q000601:surgery / Q000662:veterinary; D008297:Male; D013610:Tachycardia / Q000503:physiopathology / Q000601:surgery / Q000662:veterinary