The Right Ventricular Outflow Tract: A Comparative Study of Septal, Anterior Wall, and Free Wall Pacing

BACKGROUND: There is marked heterogeneity in right ventricular outflow tract (RVOT) pacemaker lead placement using conventional leads. As a result, we have sought to identify a reproducible way of placing a ventricular lead onto the RVOT septum. METHODS AND RESULTS: A major determinant is the shape of the stylet used to deliver the active-fixation lead. We compared stylet shapes and configurations in patients who initially had a ventricular lead placed onto the anterior or free wall of the RVOT and then had the lead repositioned onto the septum. All leads were loaded with a stylet fashioned with a distal primary curve to facilitate delivery of the lead to the pulmonary artery, then using a pullback technique the lead was retracted to the RVOT. All lead placements were confirmed by fluoroscopy and electrocardiography. Anterior or free wall placement was achieved by the stylet having either the standard curve or an added distal anterior angulation. In contrast, septal lead positioning was uniformly achieved by a distal posterior angulation of the curved stylet. This difference in tip shape was highly predictive for septal placement (P < 0.001). With septal pacing, a narrower QRS duration was noted, compared to anterior or free wall pacing (136 vs 155 ms, P < 0.001). All pacing parameters were within acceptable limits. CONCLUSION: Using appropriately shaped stylets, pacing leads can now be placed into specific positions within the RVOT and in particular septal pacing can be reliably and reproducibly achieved. This is an important step in the standardization of lead placement in the RVOT.