Reentry
Also calledre-entry · circus movement
Definition
An arrhythmia mechanism in which an activation wavefront travels around an anatomic or functional obstacle (or core) and re-excites tissue that has recovered, including its own site of origin, so the arrhythmia sustains itself instead of dying out. Classic circus-movement reentry needs an area of unidirectional block, conduction in the alternate path slow enough for the tissue ahead to recover, and a circuit whose path length equals or exceeds the impulse wavelength (conduction velocity multiplied by refractory period); reentry can also occur without an anatomic obstacle (functional reentry). Reentry underlies AV nodal reentrant tachycardia and AV reentrant tachycardia (the usual causes of paroxysmal SVT), atrial flutter (macroreentry) and most sustained monomorphic ventricular tachycardia in scarred ventricles.
Sources
- Antzelevitch C, Burashnikov A. Overview of basic mechanisms of cardiac arrhythmia. Card Electrophysiol Clin. 2011;3(1):23-45. doi.org/10.1016/j.ccep.2010.10.012
- Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Circulation. 2018;138(13):e272-e391. doi.org/10.1161/CIR.0000000000000549
- Page RL, Joglar JA, Caldwell MA, et al. 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia. Circulation. 2016;133(14):e506-e574. doi.org/10.1161/CIR.0000000000000311
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.