Surgical treatment of the two types of tachycardia caused by Kent bundles with only retrograde function.

Accessory pathways of atrioventricular (AV) conduction of the Kent type, with only retrograde conduction, have been implicated in from 25% to 40% of reentry supraventricular tachycardias. In the 22 patients with Kent bundles of this type, the subject of this report, two different kinds of reentry tachycardia were found. Sixteen patients had a narrow QRS reentry paroxysmal tachycardia similar to that found with the usual bidirectional pathway. Their Kent bundles were located in the following areas: posterior septum, two; anterior septum, two; right free wall, one; and left free wall, 11. The pathways had the electrophysiological characteristics of working myocardium. A second and unusual group of six patients had a tachycardia described by Coumel as permanent or incessant junctional reciprocating tachycardia. The pathways were all in the posterior septal area. The electrophysiological characteristics of the Kent bundles were slow conduction with decremental properties similar to the AV node. Operation was successful in correcting both types of tachycardias. His bundle interruption was used as an elective procedure in two and after failure to divide the Kent bundle in two others. Kent bundle interruption was successful in the remaining 18 patients. Some of the electrophysiological aspects of special surgical interest are discussed.