EKG Dictionary
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Rate, rhythm & mechanisms

Regular rhythm

Also calledregular · regular R-R

Definition

A rhythm in which successive R-R intervals are essentially constant, so the QRS complexes are evenly spaced. Regularity matters for measuring rate: the large-box (300) and small-box (1500) shortcuts apply only to regular rhythms. Beat-to-beat variation in a sinus rhythm that follows breathing (the rate rising with inspiration) is called sinus arrhythmia.

Sources

  1. Meek S, Morris F. ABC of clinical electrocardiography. Introduction. I: Leads, rate, rhythm, and cardiac axis. BMJ. 2002;324(7334):415-418. doi.org/10.1136/bmj.324.7334.415
  2. Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623

Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.

More in Rate, rhythm & mechanisms

Aberrant conduction Ashman phenomenon Asystole Automaticity AV dissociation Bradycardia Capture beat Compensatory pause Ectopic beat Escape beat Fusion beat Heart rate Irregularly irregular rhythm Normal sinus rhythm Pulseless electrical activity (PEA) Reentry Regularly irregular rhythm Sinus arrhythmia Tachycardia

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