Anatomic correlates that serve as memory aids for atrial patterns are that the normal two humps to the P wave are comprised of a right and left atrial component:

q      The right atrial notch is first (because the Sinus node is in the superior vena cava above the right atrium) representing the depolarization of the right atria.  The right atria makes up the right border of the heart (thus pulling the P wave vector to the right towards AVF)

q      Right atrial enlargement or P-pulmonale: tall, peaked P waves (greater than 2.5 millimeters high or 0.25 millivolts amplitude) with a vertical axis (seen in II, III, AVF) - associated with lung disease, pulmonary embolus, or other causes of pulmonary hypertension.

These changes from the normal P wave morphology are called abnormalities since it is not clear if they are due to hypertrophy, dilation or altered electrical activation.

Right atrial abnormality not present on prior ECGs: If the Right atrial abnormality or P-pulmonale is new when comparing to previous ECGs, consider the clinical presentation for pulmonary embolus (tachycardia, pleuritic chest pain, presence of cancer, immobilization) or exacerbation of lung disease. The patient may require hospitalization and treatment with heparin for PE or bronchodilators, antibiotics and steroids for COPD. Right atrial enlargement statement is not printed for rates of 120 or above, because it is unclear whether increased P amplitude at elevated rates should be attributed to enlargement.

Right atrial abnormality on prior ECGs: If the RAA is a stable finding, examine the patient for lung disease (prolonged expiration, hyperresonance, rhonchi and distant breath sounds, lowered diaphragms) and consider history and exposures including asbestos, coal dust and cigarette smoking. Pulmonary function testing may be indicated.