Electrocardiographic demonstration of intermittent left bundle branch block because of the "linking" phenomenon.

The authors describe a patient who showed intermittent left bundle branch block at a slow heart rate. The perpetuation of left bundle branch block is suggested because of rate dependent bundle branch block and trans-septal retrograde concealed penetration by the contralateral bundle as it is resolved by a premature ventricular extrasystole. This phenomenon is called "linking." This case report aims to present and emphasize this interesting phenomenon.