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Cardiac tamponade
In tamponade the fluid in the pericardial sac compresses the heart and stops it filling, so the treatment is immediate drainage — and meanwhile fluids, with no diuretics and no vasodilators.
Why it matters in the exam
Questions present a patient with low blood pressure, distended neck veins and muffled heart sounds (Beck's triad), tachycardia, and pulsus paradoxus — a fall of more than 10 mmHg in systolic pressure on inspiration. The ECG shows low voltage and electrical alternans. The diagnosis is made by echocardiography: diastolic collapse of the right atrium and right ventricle, a dilated inferior vena cava that does not collapse, and exaggerated respiratory variation of flow across the valves.
The causes are also asked — metastases (lung and breast cancer), after catheterisation or cardiac surgery (perforation), uraemia, tuberculosis, aortic dissection and ventricular free-wall rupture after infarction — and the choice of drainage: echo-guided needle pericardiocentesis in most cases, and surgical drainage for blood from a dissection or rupture, for purulent fluid, or for recurrent fluid (a "pericardial window"). Know that positive-pressure ventilation can make things worse.
In case questions the patient usually arrives after a cardiac procedure, with known cancer or with advanced kidney failure. An unstable patient with high clinical suspicion and a fitting echo is drained at once, without waiting for further tests.
Key points
- Beck's triad: low blood pressure, distended neck veins, muffled heart sounds.
- Pulsus paradoxus: a fall of more than 10 mmHg on inspiration.
- Echo diagnosis: diastolic collapse of the right heart chambers.
- Treatment: urgent drainage; fluids as a bridge, no diuretics or vasodilators.
- Dissection or rupture: surgery instead of needle drainage.
Summary table
| Item | Finding | Meaning | Action |
|---|---|---|---|
| Clinical | Beck's triad: low blood pressure, distended neck veins, muffled heart sounds | Falling cardiac output | Immediate echocardiogram |
| Pulsus paradoxus | Systolic fall of more than 10 mmHg on inspiration | A sensitive sign of tamponade | Also found in severe asthma and COPD |
| ECG | Low voltage, electrical alternans, tachycardia | The heart "swings" in the fluid | Not diagnostic on its own |
| Echocardiogram | Diastolic collapse of the right atrium and ventricle, dilated inferior vena cava | Diagnosis | Drainage |
| Drainage | Echo-guided needle pericardiocentesis | Most cases | Surgical drainage for blood from dissection or rupture, pus and recurrences |
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Sources
- ESC Guidelines for the diagnosis and management of pericardial diseases, 2015 — Cardiac tamponade and pericardiocentesis
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Pericardial Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.