Cardiac Tamponade
Fluid, blood, pus or gas in the pericardial sac raises the pressure around the heart until the ventricles cannot fill, so cardiac output falls despite normal contractility.
Definition
Cardiac tamponade is a clinical syndrome in which fluid, blood, pus or gas in the pericardial space raises intrapericardial pressure. Filling in diastole is impaired, cardiac output falls, and the result is obstructive shock. It is diagnosed clinically, from shock with a raised jugular venous pressure and a compatible cause, and confirmed on echocardiography showing a pericardial effusion with tamponade physiology.
First principles
Tamponade is a filling problem, not a pump problem
Pericardial fluid under pressure limits diastolic expansion, and the thin-walled right atrium and right ventricle give way first. Stroke volume falls while the myocardium itself contracts normally. That is why inotropes achieve little, and why the treatment is removing the fluid rather than supporting the heart. The governing document is the 2025 European Society of Cardiology (ESC) guideline on myocarditis and pericarditis, which states that it replaces the 2015 ESC pericardial diseases guideline.
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