R wave
Also calledR-wave
Definition
A positive (upward) deflection of the QRS complex; when there are two, the second is labeled R prime (R'). Across the precordial leads the R wave is normally small in V1 and grows toward V5 and V6 (R-wave progression), with the transition zone usually at V3 or V4. Delayed R-wave progression is seen, for example, with left bundle branch block, and a tall R wave in V1 and V2 can reflect right ventricular hypertrophy or, when it is broad (over 40 ms) with an R/S ratio above 1, a prior myocardial infarction.
Sources
- 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
- Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Circulation. 2018;138(20):e618-e651. doi.org/10.1161/CIR.0000000000000617
- Meek S, Morris F. ABC of clinical electrocardiography. Introduction. II: Basic terminology. BMJ. 2002;324(7335):470-473. doi.org/10.1136/bmj.324.7335.470
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.