Use

  • Determine if retrograde conduction is via a septal accessory pathway (AP) or the AV node (AVN).
  • Useful when SVT is not inducible or post-ablation to exclude continued retrograde AP conduction.

Technique

  • Using a deflectable catheter, position at apex and then at posterior base of RV in 30° RAO view.
  • Ventricular pacing at each site at same pacing cycle length.
  • Measure stimulus to atrium (S-A) at each site.

Results

  • S-A is shorter pacing at base compared with apex in patients with AP conduction only.
  • S-A is longer pacing at base compared with apex in patients with retrograde AVN conduction only.
  • Note that patients with combined retrograde AP and AV nodal conduction were excluded from the study population. However change in atrial activation sequence when pacing at the 2 sites suggests combined retrograde AP and AVN conduction.
  • Note that only patients with posteroseptal APs were included in the study, though the technique is probably also applicable to patients with anteroseptal or para-Hisian APs, as long as basal pacing site is close to the AP.

Reference

Martínez-Alday JD, Almendral J, Arenal A, et al. Identification of concealed posteroseptal Kent pathways by comparison of ventriculoatrial intervals from apical and posterobasal right ventricular sites. Circulation. 1994;89(3):1060-1067. https://doi.org/10.1161/01.cir.89.3.1060