What is this sign?

What is this sign?

Written by Kai Swenson, MD
Edits and video by Alex Perino, MD

A 45 year old woman with a past medical history of Hodgkin’s lymphoma treated with mantle field radiation whose neck veins were incidentally noted on a thorough physical exam. The patient was in sinus rhythm on telemetry throughout the exam.

What is the name of this finding, and what it is the most likely underlying diagnosis?

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(Spoiler Alert -> Answer below….)







Answer:  Kussmaul’s sign, in the context of constrictive pericarditis


What is the underlying physiology of Kussmaul’s sign?

In the clip above, the patient’s jugular venous pulsation (or JVP) increases with inspiration and decreases with expiration. This is a reversal of the normal physiology; as one takes a breath, the diaphragm contracts downwards, creating a strong negative intrathoracic pressure which in turn draws blood from the systemic venous system into the right side of the heart. This dramatic increase in blood flow is correlated with the fall in the column of blood collected in the neck veins, leading to a drop in the visible JVP on inspiration.

The presence of Kussmaul’s sign confirms an underlying inelasticity of the right side of the heart; the inability of the right ventricle to expand to accommodate an increase in blood flow leads to equalization of right-sided pressures throughout the respiratory cycle. While this explanation accounts for the lack of a decrease in JVP during inspiration, it does not explain the paradoxical increase. The most likely theory is that the inspiratory rise in abdominal pressure transmits elevated systemic venous pressures to the neck veins; for a full description of this phenomenon, please see the references below. This is practically similar to how manual compression of the liver can distend neck veins to make them more visible on exam (hepatojugular reflux).


What the full video of the exam here:


What conditions are associated with Kussmaul’s sign?

Causes of Kussmaul’s sign include constrictive pericarditis, acute cor pulmonale, right ventricular infarction, restrictive cardiomyopathy, tricuspid regurgitation and, rarely, cardiac tamponade. The patient had no symptoms or echocardiographic findings suggestive of right heart failure, tricuspid regurgitation or a pericardial effusion.  In this patient’s case, Kussmaul’s sign most likely portends the presence of constrictive pericarditis, given the patient’s history of mantle field radiation.


What is constrictive pericarditis?

Constrictive pericarditis is caused by scarring leading to a thickened, fibrous pericardium; this loss of elasticity impairs cardiac filling and leads to equalization of end-diastolic pressures in all chambers of the heart. The condition is further sub-divided into time course (acute vs. chronic) and the presence or absence of an associated pericardial effusion (effusive-constrictive form). The most common causes are idiopathic, viral infections, post-surgical or post-radiation changes, and connective tissue disorders; less common causes include post-infectious (bacterial or tuberculous pericarditis), malignancy and drug-induced. Signs of constrictive pericarditis include peripheral edema (including diffuse anasarca and ascites), hepatic congestion with strong hepatojugular reflux, a prominent “y” descent in the venous pulsations, a pericardial knock, pulsus paradoxus, and Kussmaul’s sign. Classically, the lungs should remain uncongested.


Learn more about venous waveforms and the jugular venous pulse.


Who was Dr. Kussmaul?

Adolf Kussmaul was a prominent German physician who lived from 1822-1902.  He first described the sign which now bears his name in 1873, based on evaluation of two patients with known constrictive pericarditis. He is also associated with two other physical exam findings. He coined the term “pulsus paradoxus” (an exaggerated inspiratory decrease in systolic blood pressure). In describing this finding, Dr. Kussmaul himself noted that it was not the inspiratory decrease in blood pressure which was paradoxical, but rather the loss of a palpable radial pulse while the precordial heart sounds remain audible. Dr. Kussmaul also lent his name to the pattern of deep breathing often seen in patients with severe metabolic acidosis (known as Kussmaul breathing).


To learn more about the interpretation of neck veins and the various pathologic patterns visit our post on this which contains this video clip (created in 1957) is a useful and entertaining resource:



  1. Little WC, Freeman GL. Pericardial disease. Circulation. 2006;113(12):1622-32.
  2. Meyer TE, Sareli P, Marcus RH, Pocock W, Berk MR, McGregor M. Mechanism underlying Kussmaul’s sign in chronic constrictive pericarditis. The American journal of cardiology. 1989;64(16):1069-72.
  3. Bilchick KC, Wise RA. Paradoxical physical findings described by Kussmaul: pulsus paradoxus and Kussmaul’s sign. 2002;359(9321):1940-2.