Normal sinus rhythm
Also calledNSR
Definition
The normal cardiac rhythm, originating in the sinoatrial node and conducted to the ventricles: P waves are upright in leads I and II (and aVF), each P wave is followed by a QRS complex, and the rate is 60 to 100 bpm by the traditional definition (the 2018 ACC/AHA/HRS bradycardia guideline uses below 50 bpm, rather than below 60 bpm, for sinus bradycardia; above 100 bpm is sinus tachycardia). AV conduction is normal, with a PR interval of 120 to 200 ms, and the rhythm is essentially regular; variation of the sinus rate with breathing is called sinus arrhythmia.
Sources
- Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay. Circulation. 2019;140(8):e382-e482. doi.org/10.1161/CIR.0000000000000628
- 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
- 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
- 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
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.