Friedreich’s sign in constrictive pericarditis: BMJ case rep
An 82-year-old man with chronic atrial fibrillation treated with anticoagulation was admitted to the hospital for subacute progressive exertional dyspnoea.

On examination, the jugular venous waveform was elevated to the mandibular angle with the patient sitting upright. Heart sounds were muffled. Transthoracic echocardiography (TTE) revealed a large circumferential pericardial effusion with early tamponade physiology.

Pericardiocentesis yielded a large volume of sanguineous fluid. Following the procedure, there was improvement in jugular venous pressure to 14 cm H2O. The height of the waveform increased with inspiration (Kussmaul’s sign) and there was a prominent y descent, known as Friedreich’s sign (see video 1). Repeat TTE revealed thickened pericardium, early diastolic septal bounce and respirophasic changes in early diastolic filling consistent with constrictive pericardial physiology.

This patient was managed with diuretics, and the constrictive physiology resolved over a period of weeks. The aetiology of transient pericardial disease in this case was not definitively determined.

Virtually any cause of acute pericarditis can lead to constriction which usually develops months to years later as a result of irreversible pericardial fibrosis. In some cases, particularly in association with tamponade, transient acute constriction may ensue for days to weeks following the initial pericardial insult as a result of reversible inflammation and oedema.

Learning points:-
• Friedreich’s sign, originally coined Friedreich’s diastolic collapse of the cervical veins, describes a sharp and deep y descent of the jugular venous waveform. It can be a clue to the diagnosis of constrictive pericarditis.

• Preservation of both the x and y descents of the jugular venous waveform in patients with constrictive pericarditis is a distinguishing feature from cardiac tamponade, in which the y descent is typically absent.

• Transient constrictive pericarditis is characterised by an acute decrease in pericardial compliance due to inflammation and oedema, in contrast to the irreversible chronic fibrocalcific changes of classic constrictive pericarditis.

Read more here: