Beck's triad is a collection of three medical signs associated with acute cardiac tamponade, a medical emergency when excessive fluid accumulates in the pericardial sac around the heart and impairs its ability to pump blood.

The signs are low arterial blood pressure, distended neck veins, and distant, muffled heart sounds.

The concept was developed in 1935 by Claude Beck, a resident and later Professor of Cardiovascular Surgery at Case Western Reserve University.

[2][3] The components are:[2] The rising central venous pressure is evidenced by distended jugular veins while in a non-supine position.

It is caused by reduced diastolic filling of the right ventricle, due to pressure from the adjacent expanding pericardial sac.