Hexaxial reference system
Also calledhexaxial system · hexaxial diagram · hexaxial reference · frontal plane axis system
Definition
A frontal-plane diagram of the six limb leads (I, II, III, aVR, aVL and aVF) drawn as axes through a common center, so that the lead directions are spaced 30 degrees apart; it is used to determine the cardiac axis. By convention lead I is at 0 degrees, lead II at +60, aVF at +90 and lead III at +120, while aVL is at -30 degrees; positive angles point downward (inferiorly) and negative angles point upward (superiorly).
Sources
- Gao Q, Dai Z, Hu Y, et al. A new method to determine the QRS axis: QRS axis determination. Clin Cardiol. 2020;43(12):1534-1538. doi.org/10.1002/clc.23477
- Kligfield P, Gettes LS, Bailey JJ, et al. Recommendations for the standardization and interpretation of the electrocardiogram: part I: the electrocardiogram and its technology. Circulation. 2007;115(10):1306-1324. doi.org/10.1161/CIRCULATIONAHA.106.180200
- 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.