S1 - S2 - S3 Pattern


When an S wave is present in all of the limb leads the frontal plane axis is indeterminate. This can be a normal variant but when the QRS complex is net negative in limb lead I, consistent with a rightward axis, usually right ventricular hypertrophy or dilation is the underlying cause. However, this is a rare ECG finding in asymptomatic adults.


If the patient has no signs or symptoms of lung disease this is a normal variant requiring no further evaluation. Otherwise an abnormal physical exam (hyper-resonant lung fields with wheezes and prolonged expiration) requires a chest x-ray and possibly pulmonary function testing.

View an ECG Example