with AV dissociation (third degree heart block), when the atrium is contracting against a closed tricuspid valve, or even in ventricular tachycardia. Another abnormality, "c-v waves", can be a sign of tricuspid regurgitation. The absence of 'a' waves may be seen in atrial fibrillation. An exaggerated "y" wave or diastolic collapse of the neck veins from constrictive pericarditis is referred to as Friedreich's sign. See also Wiggers diagram References External links Clinical Examination page on JVP Normal jugular vein waves – Merck Manual Cardiovascular physiology Physical examination Internal medicine Interventional cardiology Nephrology articles by importance