Key result
Two patients demonstrated supernormal excitability and conduction, unexpected phenomena sharing a common electrophysiological substrate mediated by functional Na+ channels during repolarization.
Why the study?
Supernormal phenomena in electrocardiographic evaluation have an unclear electrophysiological substrate and controversial clinical significance.
Case Report (n=2)
Supernormal excitability and conduction are uncommon electrocardiographic findings that share a common electrophysiological mechanism during phase 3 repolarization.
Answers are grounded in this paper and cite their sources.
May inform ECG interpretation in select conduction disorders; leaves open prospective validation of Na+ channel mechanisms.
Supernormal phenomena are uncommon findings in routine electrocardiographic evaluation, and both their electrophysiological substrate and their clinical significance remain controversial. We present two cases with electrocardiographic tracings consistent with supernormal excitability in a patient with a dysfunctional epicardial pacemaker, and supernormal conduction in another patient with complete atrioventricular block. In addition to their unexpected nature, both phenomena share a common electrophysiological substrate, which is thought to be mediated, at least in part, by the availability of functional Na + channels during the terminal portion of phase 3 of repolarization, known as the supernormal phase.
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González‐Torrecilla et al. (2026) conducted a case report in Supernormal excitability and conduction (dysfunctional epicardial pacemaker, complete AV block) (n=2). Supernormal electrocardiographic phenomena was evaluated. Two patients demonstrated supernormal excitability and conduction, unexpected phenomena sharing a common electrophysiological substrate mediated by functional Na+ channels during repolarization.
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