Correction of Bundle Branch Block by So-Called Nonselective His Bundle Pacing: the Potential Role of Accessory Connections in the Ventricular Septal Crest.

When those carrying out pacing of the His bundle found the procedure was able to correct the pattern of left bundle branch block, they presumed that the block was the consequence of discrete lesions in the His bundle. They further presumed that pacing distal to a discrete lesion produced normalization of the QRS complex.1,2 This novel concept was dependent on the assumption that the lesion was located in a longitudinally dissociated His bundle, ignoring evidence of functional lateral connections within the His bundle, which could theoretically circumvent an area of conduction block.