ECG - advanced - chest pain - 4 

Pulmonary embolus

The ECG changes in pulmonary embolus are not very sensitive i.e. abscence of ECG changes does not rule out PE as a cause of chest pain.

If all the changes are present, the ECG is relatively specific for PE, but its continued use in PE evaluation is more a reflection of the lack of a good cheap test for thromboembolic disease.    

 ECG changes in pulmonary embolism
The 'classic' changes are:
- sinus tachycardia (most common)
- S I, Q III, T III (S wave in lead I, Q and T waves in lead III)

Other changes which may be present include:
- Right axis deviation
- Right Bundle Branch Block
- P Pulmonale (large/peaked p wave)
- S I, S II, S III
- 'pseudoinfarction' ST abnormalities   

Sinus tachycardia with SI QIII TIII pattern