The P wave in V1 is often biphasic. Normally the positive and negative components are equal. If the negative component is larger than normal (>1 mm wide and tall), there may be left atrial enlargement. If the positive component is taller than normal (>1.5 mm), there may be right atrial enlargement. This sign is not diagnostic.
See also: P wave
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- Hampton, J and Hampton, J (2019) - The ECG Made Easy, 9th edn, Elsevier
- Goldberger, A (2006) - Clinical Electrocardiography: A Simplified Approach, 9th edn, Elsevier
- Anna Pickens (2015) - EKG interpretation, (Accessed: 11/08/2019)