electrical alternans

Introduction

• 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

More general terms

• electrocardiogram feature

Additional terms

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