SAQ 423 – Cardiology – low-voltage ECG with electrical alternans

Cardiology – low-voltage ECG with electrical alternans.

a. ECG interpretation

• Sinus tachycardia, approximately 130-140/min.
• Low-voltage QRS complexes.
• Electrical alternans.
• QTc may be prolonged.
• Overall appearance is concerning for large pericardial effusion, especially if clinically compatible with tamponade.

b. Differential diagnoses

• Pericardial effusion or cardiac tamponade.
• Pleural effusion.
• Emphysema/COPD, pneumothorax, or pneumopericardium.
• Severe hypothyroidism/myxoedema.
• End-stage dilated cardiomyopathy or old large myocardial infarction.
• Infiltrative cardiomyopathy such as amyloidosis.
• Obesity or subcutaneous emphysema.

c. Disposition features

• Haemodynamic status and any clinical/echo evidence of tamponade.
• Bedside echocardiography: effusion size and haemodynamic effect.
• Likely cause, such as infection, malignancy, uraemia, autoimmune disease, trauma, or myocardial infarction.
• Need for urgent pericardiocentesis, ICU/HDU, telemetry, or specialist review.
• Reliability of follow-up and social circumstances if outpatient care is considered.