A 40 year old woman with pleuritic chest pain and breathlessness.

Acute pulmonary embolus

The following, often transient, changes may be seen in a large pulmonary embolus.

• an S1Q3T3 pattern
  • a prominent S wave in lead I
  • a Q wave and inverted T wave in lead III
• sinus tachycardia
• T wave inversion in leads V1 - V3
• Right Bundle Branch Block
• low amplitude deflections