Left posterior fascicular block (LPFB)
Also calledLPFB · left posterior fascicular block · left posterior hemiblock · LPHB
Definition
Conduction delay in the left posterior fascicle of the left bundle branch, which shifts the main direction of left ventricular activation downward and to the right. Diagnosed by right axis deviation (frontal QRS axis +90 to +180 degrees in adults), an rS complex in leads I and aVL, a qR pattern in leads III and aVF, and a QRS duration under 120 ms.
Clinical noteThe criteria apply only when right ventricular hypertrophy, an old lateral myocardial infarction and a slender body build are absent.
Sources
- Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances. Circulation. 2009;119(10):e235-e240. doi.org/10.1161/CIRCULATIONAHA.108.191095
- 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
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.