Author + information
- Received May 28, 1986
- Revision received December 3, 1986
- Accepted January 7, 1987
- Published online June 1, 1987.
- Julio Przybylski, MD1,
- Pablo Ambrosio Chiale, MD1,
- Rubén Alberto Sánchez, MD1,
- Julio Daniel Pastori, MD1,2,
- Héctor Gustavo Francos, MD1,
- Marcelo Víctor Elizari, MD, FACC1 and
- Mauricio Bernardo Rosenbaum, MD, FACC*,1
- ↵*Address for reprints: Mauricio B. Rosenbaum, MD, Chief, Service of Cardiology, Ramos Mejía Hospital, Urquiza 609, 1221 Buenos Aires, Argentina.
It was recently shown that supernormal conduction in the diseased His-Purkinje system is more common than previously thought, and is always associated with prolongation of refractoriness. To assess whether supernormal conduction could also occur in the accessory pathway of patients with ventricular pre-excitation, 21 patients with manifestly prolonged refractoriness in the accessory pathway were studied. Under these conditions, programmed atrial stimulation revealed a phase of supernormal conduction in 16 (76%) of the 21. Therefore, what was believed to be a nonexistent or exceptional physiologic event was shown to be a rather common finding, at least under certain circumstances. Supernormal conduction occurred in all 7 patients with an anterograde refractory period of 480 to 980 ms, and in 5 of 10 patients with a refractory period >1.0 second or with no anterograde conduction. Supernormal conduction could not be demonstrated in four patients with a refractory period ≤440 ms, but appearedin all four patients after the refractory period was prolonged by a rapid rate of stimulation or administration of ajmaline.
The electrophysiologic changes underlying the occurrence of supernormal conduction in the accessory pathway are similar to those previously reported for the bundle branch system. The demonstration of supernormal conduction in the accessory pathway may uncover the presence of concealed ventricular pre-excitation. Supernormal conduction over the accessory pathway may facilitate a rapid ventricular response during atrial fibrillation, even if the refractory period is prolonged.
- Received May 28, 1986.
- Revision received December 3, 1986.
- Accepted January 7, 1987.
- American College of Cardiology Foundation