His bundle recordings were performed in 2 patients in whom AV nodal bypass tracts coexisted with intermittent AV conduction disturbances occurring below the site from which the His bundle deflection was recorded. Case 1 had: (a) tachycardia dependent right bundle branch block, (b) persistent HV prolongation, and (c) bradycardia dependent AV block. Case 2 showed: (a) intra atrial conduction delay, (b) tachycardia dependent left bundle branch block with HV prolongation, (c) bradycardia dependent HV conduction disturbance, (d) tachycardia bradycardia syndrome of an unusual type; the latter presumably resulted, during atrial flutter, from the alternation of rapid AH conduction through the bypass tract with intermittent (complete) distal His bundle block or bilateral bundle branch block.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine