Tachycardia and bradycardia-dependent bundle branch block alternans: clinical observations.

Tachycardia and Bradycardia-dependent Bundle Branch Block Alternans

Eleven patients with tachycardia-dependent, bradycardia-dependent, or "pseudobradyeardia-dependent" bundle branch block (BBB) alternans were studied. This classification is based on the following criteria: 1) When alternans is initiated by a sudden acceleration in ventricular rate, or it appears with aberration of the second beat after a pause, the alternans is tachycardia-dependent and results...

Tachycardia-Dependent Left Bundle Branch Block Associated with Bradyeardia-Dependent Variable Left Bundle Branch Block

This report describes tachyeardiaand bradycardia-dependent left bundle branch block in a patient who exhibited normal intraventricular conduction with impulses intermediate in timing. During bradyeardia, longer cycles were associated with increasing degrees of incomplete left bundle branch block. These clinical observations support the existence of slow Phase 4 depolarization of latent pacemake...

Tachycardia-dependent left bundle branch block associated with bradycardia-dependent variable left bundle branch block.

Tachycardia-dependent versus bradycardia-dependent intermittent bundle-branch block.

Analysis of I6 cases with intermittent bundle-branch block showing rate-dependence revealed the presence of 12 instances with tachycardia-dependent bundle-branch block, 3 with bradycardiadependent bundle-branch block, and one instance showing both types at two different occasions. Tachycardia-dependent bundle-branch block was explained on the basis of cycle length-recovery time relation and rev...

Effects of isoproterenol on bradycardia-dependent intra-His and left bundle branch blocks.

The electrophysiologic study of a patient with a history of fainting showed first- and second-degree Mobitz type I intraatrial and intra-His (IH) bundle blocks. Tachycardia and bradycardia-dependent IH block and bradycardia-dependent left bundle branch block were also present. Bradycardia-dependent block was probably caused by slight hypopolarization plus a slow rising slope of phase 4 depolari...