Cardiology Heart Sounds

Pericardial Knock

The pericardial knock is a loud, high pitched sound in early diastole that occurs in patients with constrictive pericarditis. It is the result of rapid deceleration of blood due to the inelastic pericardium. It occurs well outside the range for a split S2, and the opening snap of mitral stenosis, but not as far from S2 as an S3. In patients with suspected constrictive pericarditis, try to identify a constellation of supportive physical findings, including Kussmaul’s sign, Friedreich’s sign, the W sign, and the pericardial knock.
Card Tutorial

Patient 2

A middle-aged woman was admitted to the hospital with exertion dyspnea six months after an episode of acute pericarditis caused by anterior chest wall trauma related to a boogie boarding accident. She was found to have a pericardial knock on examination, as well as other evidence of constrictive pericarditis.

Pericardial Knock

Annotated

Pericardial Knock