Right Atrial Enlargement

Atrial enlargement can be determined by analyzing the P waves in leads II and V1. The first half of the P wave represents right atrial depolarization, while the second half represents left atrial depolarization. In right atrial enlargement, a tall P wave in lead II (greater than 2.5mm) can be seen.

P wave morphologies for atrial enlargement in leads II and V1.

Examples

Right Atrial Enlargement

This ECG is a mimic of left ventricular hypertrophy and right atrial enlargement in a very young, thin individual. Just as increased soft-tissue impedance from adipose or edema can influence the surface ECG by dampening the conduction of electrical impulses, an especially slender body habitus can have the inverse effect. In this case, the various electrocardiographic abnormalities were simply amplifications of normal cardiac activity. One potentially helpful hint is the combination of LVH with RAD – the former when truly representative of ventricular hypertrophy being more commonly associated with leftward axis deviation.

Right Atrial Enlargement

This patient was discovered to have a pulmonary embolism with right heart strain. The ECG demonstrates early R wave progression, right axis deviation, right atrial enlargement, ST-segment depressions and T-wave inversions in inferolateral leads – all consistent with right heart strain.

References

Wagner GS, Strauss DG. Marriott’s Practical Electrocardiography. 12th ed. Lippincott Williams & Wilkins; 2014.