Cardiac Tamponade
Definition
Cardiac tamponade is a pericardial effusion that raises intrapericardial pressure until it compresses one or more cardiac chambers and impairs filling. The diagnosis requires haemodynamic compromise, not merely the presence of fluid. Because the pericardium cannot acutely distend, pressure rises steeply with small volume changes, which is why a rapidly accumulating effusion of only about 200 mL can tamponade while a slowly accumulating litre may not.
Key Concepts
Causes
Neoplastic; pericarditis, infective or non-infective; uraemia; iatrogenic cardiac instrumentation; trauma; acute pericarditis treated with anticoagulants; idiopathic. See concepts/Pericardial-Effusion and concepts/Pericarditis. (sources/Handbook-HA-2024, rating: high)
Clinical signs
- Tachypnoea, tachycardia, small pulse volume and pulsus paradoxus.
- Raised JVP with a prominent x descent, and Kussmaul's sign.
- Absent apex impulse, faint heart sounds, hypotension — and a clear chest.
- The clear chest is the discriminator that matters clinically: raised JVP with clear lungs is tamponade, whereas raised JVP with crackles is pulmonary oedema. (sources/Handbook-HA-2024)
Investigations
| Test | Finding |
|---|---|
| ECG | Low voltage, tachycardia, electrical alternans |
| CXR | Enlarged cardiac silhouette once the effusion exceeds ~250 mL, with clear lung fields |
| Echocardiography | RA, RV or LA collapse; distended IVC; exaggerated inspiratory increase in tricuspid and decrease in mitral inflow |
(Table: sources/Handbook-HA-2024)
Management
- Expand intravascular volume — D5, normal saline or plasma, at full rate if the patient is in shock. Tamponade is a filling problem, so preload is the only physiological lever available before drainage.
- Avoid positive-pressure mechanical ventilation where possible, because positive intrathoracic pressure further impairs cardiac filling.
- Echo-guided pericardiocentesis, apical or subcostal, with the risks of damaging an epicardial coronary artery or perforating the heart.
- Open drainage under local or general anaesthesia permits pericardial biopsy and is the option when the effusion is recurrent or loculated; watch for recurrent tamponade from catheter blockage or reaccumulation.
- For malignant effusion drained urgently, seek an oncology opinion on pericardiectomy or pericardial window, and on subsequent oncological treatment of the underlying disease.
The lethal misdiagnosis
The handbook's most emphatic warning: treating tamponade as congestive heart failure with diuretics, ACE inhibitors or vasodilators can be lethal. All three lower preload in a patient whose cardiac output is preload-dependent, so the error converts a compensated obstruction into circulatory arrest. The diagnostic fork is the chest — clear lungs with a raised JVP is tamponade.
Contradictions / Open Questions
- "Clear chest" is a bedside rule of thumb, not a criterion. Tamponade and pulmonary oedema coexist in mixed states — uraemic pericarditis with volume overload, or tamponade complicating decompensated heart failure — and the discriminator fails precisely in the patients who are hardest to assess. See concepts/Decompensated-HF-Management for the other side of the same fork. (sources/Handbook-HA-2024, rating: high)
- The definition is qualitative where a number is needed. "Haemodynamic compromise" is not operationalised, and no ingested source in the wiki supplies the invasive threshold — pericardial pressure exceeding atrial pressure across the cardiac cycle — that would let the diagnosis be confirmed rather than suspected.
- Pulsus paradoxus is listed without a magnitude or a limitation. No threshold is given, and there is no note that it cannot be measured in atrial fibrillation, in whom the diagnosis must rest on imaging and the JVP.
- Fluid loading is recommended before drainage without qualification. Volume expansion buys time in the hypotensive patient, but in a normotensive or already-volume-overloaded patient it may raise filling pressures on the wrong side of the pericardial pressure-volume curve; the source does not distinguish.
- Pericardiocentesis and surgical drainage are presented without ranking. There is no comparative evidence in the wiki, and no rule for which effusions should go straight to theatre.
- Positive-pressure ventilation is contraindicated here and first-line in pulmonary oedema. The two conditions both present as a dyspnoeic, hypotensive patient, and the handbook's advice sits in different chapters — nothing in the wiki sets out how to distinguish them when the chest is not clean.
Connections
- Related to concepts/Pericardial-Effusion — the fluid, and the effusion whose size does not determine the diagnosis
- Related to concepts/Pericarditis — the commonest non-malignant cause, and the setting in which anticoagulation turns it into tamponade
- Related to concepts/Constrictive-Pericarditis — the other pericardial filling disease: same raised JVP, different mechanism, different treatment
- Related to concepts/Cardiogenic-Shock — tamponade is the reversible cause of obstructive shock, and the one where vasopressors and diuretics both make it worse
- Related to concepts/Cardiopulmonary-Resuscitation — a 5T, and a cause of PEA arrest that resuscitation cannot fix
- Related to concepts/Acute-Aortic-Syndrome — retrograde rupture into the pericardium is a route to tamponade
- Related to concepts/Right-Ventricular-Failure — chamber collapse is predominantly right-sided, which is why the JVP rises before the blood pressure falls