Kussmaul's sign is the observation of a jugular venous

pressure (JVP, the filling of the jugular vein) that rises

with inspiration. It can be seen in some forms of heart

disease.

Ordinarily the JVP falls with inspiration due to

reduced pressure in the expanding thoracic cavity.

Kussmaul's sign suggests impaired filling of the right

ventricle due to either fluid in the pericardial space or a

poorly compliant myocardium or pericardium.