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electrical alternans

- beat to beat alteration in the electrocardiogram. - may be most prominent in ECG lead V2 - lead V6 Etiology: - total electrical alternans involving the p-wave, the QRS complex, the ST segment & the T-wave with sinus tachycardia is a relatively specific sign of pericardial effusion, often with pericardial tamponade Pathology: - occurs from a periodic swing of the heart in the effusion at a frequency of 1/2 the heart rate. Complications: - ST-T electrical alternans is a sign of electrical instability & may signal impending ventricular fibrillation

Related

electrocardiogram (ECG, EKG) pericardial effusion ventricular fibrillation (V Fib)

General

electrocardiogram feature

References

  1. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1246
  2. Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025