Attention! Before reading this page, check out our introduction to the P wave for an explanation of the basics of atrial enlargement.
Biatrial enlargement is diagnosed when criteria for both right and left atrial enlargement are present on the same ECG.
The spectrum of P-wave changes in leads II and V1 with right, left and bi-atrial enlargement is summarised in the following diagram:
The diagnosis of biatrial enlargement requires criteria for LAE and RAE to be met in either lead II, lead V1 or a combination of leads.
In lead II
Bifid P wave with:
Amplitude ≥ 2.5mm
Duration ≥ 120 ms
Biphasic P waves with:
Initial positive deflection ≥ 1.5mm tall
Terminal negative deflection ≥ 1mm deep
Terminal negative deflection ≥ 40 ms duration
P wave positive deflection ≥ 1.5 mm in leads V1 or V2
Notched P waves with duration >120 ms in limb leads, V5 or V6
Combination of both left and right atrial enlargement.
Right atrial enlargement
Pulmonary hypertension due to:
- Chronic lung disease (cor pulmonale)
- Tricuspid stenosis
- Congenital heart disease (pulmonary stenosis, Tetralogy of Fallot)
- Primary pulmonary hypertension
Left Atrial Enlargement
- Mitral valve disease
- Aortic valve disease
- Aortic stenosis
- Mitral incompetence
- Hypertrophic cardiomyopathy (HOCM)
Biatrial enlargement due to idiopathic cardiomyopathy:
- Biphasic P waves in V1 with a very tall positive deflection (almost 3 mm in height!) and a negative deflection that is both deep (> 1 mm) and wide (> 40 ms).
- P waves in lead II are tall (> 2.5mm) and wide (> 120 ms).
- P waves in V2 are tall (> 1.5 mm), while the terminal negative portion of V1 is deep (> 1mm) and wide (> 40 ms).
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