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Cardiology
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Electrical Alternans → Pericardial Tamponade
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Alternating QRS amplitude → think large pericardial effusion.
Decision
Outcome
Decision
ECG shows alternating QRS amplitude (electrical alternans). Suspected diagnosis?
✓
Large pericardial effusion / tamponade
✗
Ventricular bigeminy
✗
Atrial fibrillation
Decision
Next test?
✓
Bedside transthoracic echocardiogram
✗
Stress test
Outcome
Echo confirms effusion ± tamponade physiology (RV diastolic collapse, IVC plethora)
Tamponade with hemodynamic compromise → urgent pericardiocentesis. Beck's triad: hypotension, JVD, muffled heart sounds.