Iatrogenic Right Bundle Branch Block Correction by Left Bundle Branch Area Pacing.

BACKGROUND

Correction of right bundle branch block (RBBB) by left bundle branch area pacing (LBBAP) has traditionally been attributed to capture within a longitudinally dissociated His bundle. Based on this theory, conduction block in the distal right bundle would not be expected to resolve.

CASE SUMMARY: We describe a 90-year-old man with cardiac amyloidosis who underwent pacemaker implantation. During the procedure, advancement of the delivery catheter toward the right ventricular septum induced iatrogenic complete RBBB. Remarkably, pacing from this site corrected the block. The lead was then advanced >2 cm intraseptally, achieving successful LBBAP. Postoperatively, intrinsic conduction remained as RBBB, but unipolar pacing consistently corrected it.

DISCUSSION: Correction of an iatrogenic RBBB by LBBAP suggests the involvement of a septal intramyocardial conduction network as a potential mechanism.

TAKE-HOME MESSAGE: RBBB due to a lesion distal to the His bundle may be correctable with LBBAP.