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 

    1) dilatation of the right heart 

    2) right ventricular ischemia 

    3) 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/