Hypotension, raised jugular venous pressure, muffled heart sounds
Mnemonic
Beck’s triad, the three signs of tamponade:
- Hypotension
- Raised JVP, with a absent y descent
- Muffled heart sounds
“Low pressure, high JVP, quiet heart.”
The full triad appears in a minority, so the supporting signs matter: pulsus paradoxus over 10 mmHg, tachycardia, electrical alternans and low voltage complexes on the ECG, and a globular heart on the chest radiograph.
The volume matters less than the speed: a rapidly accumulating 150 ml can tamponade, while a slowly accumulating litre may not, because the pericardium has time to stretch.
Management is drainage, and fluids in the meantime: the patient is preload dependent, so vasodilators and diuretics are dangerous. Kussmaul’s sign is classically absent in tamponade, which distinguishes it from constrictive pericarditis.
Expansion
- Hypotension - the stiff pericardium prevents ventricular filling, so stroke volume falls
- Raised jugular venous pressure - venous return is obstructed and pressure backs up
- Muffled heart sounds - fluid between the heart and the chest wall damps transmission
All three follow directly from one anatomical fact: the fibrous pericardium does not stretch acutely. The rate of accumulation therefore matters more than the volume.
Look also for pulsus paradoxus, an exaggerated inspiratory fall in systolic pressure of more than 10 mmHg, caused by the two ventricles competing for a fixed total volume within the rigid sac.