In medicine, Friedreich's sign is the exaggerated drop in
diastolic
Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are re-filling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventricu ...
central venous pressure seen in constrictive
pericarditis
Pericarditis is inflammation of the pericardium, the fibrous sac surrounding the heart. Symptoms typically include sudden onset of sharp chest pain, which may also be felt in the shoulders, neck, or back. The pain is typically less severe when sit ...
(particularly with a stiff calcified
pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...
) and manifested as abrupt collapse of the neck
vein
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
s or marked descent of the central venous pressure waveform.
The normal jugular venous waveform contains two descents, x and y. The x descent, which corresponds to the combination of right atrial relaxation and depression of the atrial floor during ventricular contraction, is normally dominant. The y descent occurs as a result of passive ventricular filling during early diastole and is usually absent in patients with tamponade. In constrictive pericarditis, the characteristic sharp and deep y descent reflects rapid filling in early diastole which occurs when the unyielding pericardium elevates atrial pressure and limits ventricular filling to the early diastolic period.
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.
The sign is named after
Nikolaus Friedreich
Nikolaus Friedreich (1 July 1825 in Würzburg – 6 July 1882 in Heidelberg) was a German pathologist and neurologist, and a third generation physician in the Friedreich family. His father was psychiatrist Johann Baptist Friedreich (1796–1862) ...
.
References
Symptoms and signs: Vascular
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