Pulmonary embolism 


Pulmonary embolism (PE) is a blockage of an artery in the lungs by a blood clot (thrombus) that has moved from elsewhere in the body through the bloodstream. Usually arises from a thrombus that originates in the deep venous system of the lower extremities.

Clinical presentation 

  • dyspnea
  • chest pain
  • cough
  • cyanosis
  • lightheadedness or dizziness
  • syncope

  • tachycardia
  • hypoxia
  • leg pain or swelling, or both, usually in the calf caused by a deep vein thrombosis

ECG manifestation 

Pulmonary embolism cannot entirely be diagnosed using just an ECG, it is neither sensitive nor specific for PE. 

ECG changes are related to 

  • dilatation of the right heart 
  • right ventricular ischemia 
  • increased stimulation of the sympathetic system

  • T wave inversion in the precordial leads V1-V4 (best correlated to the severity of the PE)
  • sinus tachycardia
  • complete or incomplete RBBB - associated with increased mortality 
  • dominant R wave in V1 - sign of acute right ventricular dilatation 
  • P pulmonale - peaked P wave in lead II > 2.5 mm
  • right axis deviation 
  • non-specific ST segment and T wave changes, including ST elevation and depression

S I, Q III, T III - sign of acute cor pulmonale 

  • Deep S in I
  • Q and negative T in III
  • T wave inversion anterior

ECG 1 Pulmonary embolism (sinus tachycardia, RBBB, neg. T waves V1-V4, S I, Q III, T III) 

ECG 2 Pulmonary embolism (sinus tachycardia, iRBBB, flat T waves V1-V2, S I, Q III, T III)



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  4. https://litfl.com/ecg-changes-in-pulmonary-embolism/