Observations on Atrioventricular Conduction in Patients with Bilateral Bundle-Branch Block
Atrioventricular conduction was studied in three patients, each representing a different grade of bilateral bundle-branch block. His bundle activity was recorded by a catheter technic. Two of the three patients had experienced Adams-Stokes attacks.
The first patient had right bundle-branch block with left axis deviation at the time of catheterization. Increases in the atrial driving rate resulted in progressive lengthening of the A-H interval, the H-V interval remaining constant and within normal limits. Second degree A-V block occurred at atrial rates higher than 140/min. The site of this block was located above the His bundle. On no occasion was the impulse blocked distally to the His bundle.
The second patient had a Mobitz type II A-V block with complete left bundle-branch block and a prolonged P-R interval in the conducted beats. The block of the nonconducted beats could be located distal to the His bundle. H-V block occurred more frequently when the atrial rate was increased. Second degree A-H block occurred at rates above 140/min. At these rates interesting patterns were seen due to conduction impairment at two levels in the A-V conduction system.
The third patient presented with complete A-V block. The site of this block could be located at a level lower than the His bundle. A-H conduction studied with increases of atrial rate and with atrial premature beats seemed to be normal. There was evidence for the existence of retrograde V-A conduction in this patient.
- Complete A-V block
- Mobitz type II A-V block
- Wenckebach phenomenon
- Right bundle-branch block with left axis deviation
- V-A conduction in A-V block
- His bundle recordings
- Atrial pacing
- Atrial premature beats
- A-V conduction
- Heart rate
- Received December 15, 1969.
- Accepted February 19, 1970.
- © 1970 American Heart Association, Inc.