electrical alternans
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Introduction
A beat to beat alteration in the electrocardiogram.
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. This occurs from a periodic swing of the heart in the effusion at a frequency of 1/2 the heart rate.
ST-T electrical alternans is a sign of electrical instability & may signal impending ventricular fibrillation.
More general terms
Additional terms
References
- ↑ Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1246