Abstract 2708: The Amazing Sinoventricular Conduction System: The Lateral, Medial and Superior Atrionodal Bundles, Proximal AV Bundle and AV Node Can Pace the SA node: The New Coincident Recording Technique - Decreasing Morbidity of Clinical Procedures
IINTRODUCTION: The lateral (LAB), medial (MAB) and superior (SAB) atrionodal bundles, and proximal AV bundle are part of the Sinoventricular Conduction System by their unique transmembrane (TAPs), extracellular (EAPs) potentials and transmission properties shown with: pacing, high extracellular K, dye marking and photoablation of Lucifer Yellow (LY). Here, one of the ABs or AV node (AVN) is shown to pace SAN.
METHODS: In 30 superfused canine hearts with exposed AVN, simultaneous unipolar catheter (CE) recordings at the SA node, one of the 3ABs, and AVN and coincident wire (WE) and 5% LY-filled micropipet (ME) electrodes at the high-amplitude EAP and plateau-atrial TAP, or AB-EAP and plateau-AB TAP were made (Fig⇓. Inset). LY was iontophoresed using 20 nA hyperpolarizing current into one of the ABs or atrial myocyte at the AB site during spontaneous or paced SAN rhythms.
RESULTS: Retrograde pacing of SAN was evoked in 7 hearts, but in none of the 23 hearts in which atrial myocytes were injected. Phase 4 pacemaker activity (diastolic DS and upstroke slope US potentials in Figs. A, B⇓) was seen in:
AVN TAPs showed Phase 4 depolarization during antero- (not shown) and retrograde transmission. The ABs depolarized before the atrial myocardium at the same site during both antero- (not shown) and retrograde (Figs. A, B⇓) transmission. DS and US potentials of EAPs and TAPs are indicative of pacemaker activity.
CONCLUSIONS: ABs and AVN can pace the SAN thereby whole heart. The ABs and PAVB are conduits for AVNRT and AV Junction rhythms and must be evaluated along with SAN and AVN during ablations of AVNRT to decrease morbidity.