Sep 1, 1985

Controlled cryothermal injury to the AV node: feasibility for AV nodal modification

Pacing and Clinical Electrophysiology : PACE
G J KleinD L Jones

Abstract

Elective subtotal injury to the AV node-His bundle region may create a negative dromotropic effect to provide a therapeutic advantage in some patients with supraventricular tachycardia without creating complete AV block. We examined the effects of cryosurgery to the AV nodal region, varying temperature and time using a 15 mm circular cryoprobe applied directly to the canine AV node-His bundle region. Twelve dogs were anesthetized and the heart was exposed through a right thoracotomy. Electrophysiological data obtained included conduction intervals, incremental pacing, and extrastimulus testing. Under inflow occlusion, the cryoprobe was positioned over the AV node-His bundle region using anatomical landmarks and a single freeze was applied (-15 degrees C to -60 degrees C, 15 to 60 seconds). Dogs were allowed to recover for 1 month, after which time electrophysiological testing was repeated under similar conditions; then the animals were sacrificed. With probe temperatures of -60 degrees C for 15 to 60 seconds, five of six dogs experienced complete heart block with dense fibrosis observed in the AV nodal-His bundle region. After freezing with higher temperatures, the remaining seven dogs had return of atrioventricular conduction ...Continue Reading

Mentioned in this Paper

Cryosurgery
Supraventricular Tachycardia
Heart Block
Left Bundle Branch of His
Anatomical Landmark
Congenital Heart Block
Atrioventricular Block
Body Surface Area Formula for Dogs
Obstruction
Cardiac Conduction System

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