Abstract 11131: Structure/Function of the Accessory Pathway in a Heritable Canine Model of Wolff-Parkinson-White-Syndrome
Introduction: WPW syndrome results from ventricular pre-excitation through an accessory pathway (AP) and is treated by ablation. Functional properties of APs have been studied using extracellular electrode-based techniques. However, the connection between the 3D anatomical structure of the AP and the cardiac activation pattern has not previously been directly demonstrated. Using high-resolution optical mapping, we characterized this relationship in a family of canines with WPW syndrome, diagnosed by delta waves in ECG.
Methods: Standard clinical programmed stimulation protocols were used to measure AP effective refractory period (ERP), atrial ERP, AV nodal ERP and ventricular ERP in open-chest dogs (n=3, females, 2 years old). Subsequently, hearts were excised, coronary perfused for epicardial optical mapping. Histological analysis followed.
Results: In open chest experiments, pre-excitation was confirmed by ECG: short P-R, and a slurred upstroke of the QRS-complex (delta-wave). Pathways were localized using standard mapping techniques (left lateral, right lateral and right septal). Animals #1 and #2 had only anterograde conduction through the AP, while animal #3 demonstrated both anterograde and retrograde conduction. The APERP, AVERP, AERP and VERP were 193±39 ms, 190±14 ms, 113±12 ms and 171±3 ms, respectively. In two dogs, optical mapping successfully revealed AP conduction. Optical action potentials (OAPs) from the APs had three upstroke components, which corresponded to the separate excitation of atria, AP and ventricular myocardium. The AV interval through the AP was 71±8 ms, while AV conduction through the AV node resulted in an AV interval of 262±58 ms. Histology demonstrated a clear myocardial bridge between the atria and ventricle corresponding to the location of mapped APs.
Conclusion: For the first time accessory pathway activation sequence has been characterized using optical mapping with clear histological correlation.
- © 2010 by American Heart Association, Inc.