Labile Variations of Intraventricular Conduction Unrelated to Rate Changes
An example of unstable intraventricular conduction is presented. Several unusual features of this type of conduction are described. These are: (1) variable intraventricular conduction which was sensitive to multiple stimuli but not clearly related to changes in heart rate, (2) mid and terminal QRS changes reflected only in the left lateral chest leads and in the mid and terminal QRS portions of the vectorcardiogram, (3) constant association of prolonged P-R interval suggesting that this is a variety of bilateral bundle-branch block, and (4) apparent persistence of the peculiar intraventricular conduction for at least 4 years. Multiple involvement of the conduction system is probably present, and functional variations in distal portions of the left ventricular conduction system account for these labile changes. Predictable QRS patterns can be produced by various stimuli which alter intraventricular conduction.
- Bilateral bundle-branch block
- Left bundle-branch conduction
- Intraventricular conduction disturbances
- Computer electrocardiogram
- © 1968 American Heart Association, Inc.