Right atrial enlargement (RAE) involves dilatation of the right atrial cavity and hypertrophy of its muscular wall.
Changes in the ECG seen with right atrial enlargement:
(1) P wave frontal axis +65 to +90°
(2) normal duration of the P wave
(3) tall P wave > 0.25 mV (2.5 mm) in lead II with an initial deflection
(4) qR pattern in V1 in the absence of coronary artery disease
(5) decreased QRS amplitude in V1 relative to V2, with amplitude < 6 mm
(6) ratio of QRS amplitudes V2/V1 > 3
The changes in the P wave may be referred to as P pulmonale.
