ECG Findings in Massive Pericardial Effusion

Massive pericardial effusion produces a triad of…

Electrical alternans is…

  • when consecutive, normally-conducted QRS complexes alternate in height.
  • produced by the heart swinging backwards and forwards within a large fluid-filled pericardium.

Patients with this ECG pattern need to be immediately assessed for clinical and echocardiographic evidence of tamponade.


Learn From The Experts!

Consolidate your learning with lessons from the masters of ECG interpretation. Follow the links below for expert commentary, video lessons, case-based discussion and detailed explanations to take your learning to the next level.

Take The Next Step.

You’ve made the ECG diagnosis, now what? Think beyond the ECG with lessons on advanced diagnosis and management.

  • Ultrasound Podcast  — How to diagnose pericardial tamponade on bedside echo, Part 1 and Part 2 (video lessons)

Further Reading

Author Credits


  • Chan TC, Brady WJ, Harrigan RA, Ornato JP and Rosen PR. ECG in Emergency Medicine and Acute Care. Elsevier 2005
  • Mattu A, Brady W. ECGs for the Emergency Physician 2, BMJ Books 2008.
Print Friendly