INTRODUCTION: In some patients with left AV accessory pathway (AP), double potentials are recorded along the coronary sinus (CS) during retrograde AP conduction only. This electrophysiologic study was performed to clarify the origin and clinical significance of double potentials in 11 patients. METHODS AND RESULTS: The direction of activation of the first, relatively blunt component (DP1) was lateral to septal in 5 patients with anterior or anterolateral AP, centrifugal in 2 patients with posterior or posterolateral AP, and septal to lateral in 4 patients with posteroseptal AP, suggesting the earliest activation of DP1 was near the AP. The direction of activation of the second, sharper potentials (DP2) were septal to lateral in all patients. The double potentials were fused in the paraseptal CS region. Pacing from the lateral CS musculature or lateral left atrium reproduced the double potentials. The effective refractory period of the double potentials was reached by ventricular extrastimulation, and the left atrial deflection preceded the double potentials, excluding a ventricular or AP origin. CONCLUSION: In patients with connections between the paraseptal CS musculature and left atrium but no connections more laterally, retrograde left AP conduction is associated with double potentials in the CS recordings. The double potentials represent activation of the left atrial insertion of the AP (DP1) and later activation of the CS musculature (DP2) via connections between the paraseptal CS musculature and left atrium, respectively. The activation pattern of DP1 depends on AP location, thus providing important information for AP localization during CS mapping.
INTRODUCTION: In some patients with left AV accessory pathway (AP), double potentials are recorded along the coronary sinus (CS) during retrograde AP conduction only. This electrophysiologic study was performed to clarify the origin and clinical significance of double potentials in 11 patients. METHODS AND RESULTS: The direction of activation of the first, relatively blunt component (DP1) was lateral to septal in 5 patients with anterior or anterolateral AP, centrifugal in 2 patients with posterior or posterolateral AP, and septal to lateral in 4 patients with posteroseptal AP, suggesting the earliest activation of DP1 was near the AP. The direction of activation of the second, sharper potentials (DP2) were septal to lateral in all patients. The double potentials were fused in the paraseptal CS region. Pacing from the lateral CS musculature or lateral left atrium reproduced the double potentials. The effective refractory period of the double potentials was reached by ventricular extrastimulation, and the left atrial deflection preceded the double potentials, excluding a ventricular or AP origin. CONCLUSION: In patients with connections between the paraseptal CS musculature and left atrium but no connections more laterally, retrograde left AP conduction is associated with double potentials in the CS recordings. The double potentials represent activation of the left atrial insertion of the AP (DP1) and later activation of the CS musculature (DP2) via connections between the paraseptal CS musculature and left atrium, respectively. The activation pattern of DP1 depends on AP location, thus providing important information for AP localization during CS mapping.