constrictive pericarditis

In constrictive pericarditis the pericardium has become thickened, scarred, and sometimes calcified, turning the soft sac into a rigid shell around the heart. Picture the heart encased in a tight, inflexible armour: it can fill freely for the first moment of diastole, then abruptly hits the rigid wall and stops, like water poured into a jar that fills to the brim and can take no more.

Because filling is limited, blood backs up into the venous system, producing the features of right-sided congestion: distended neck veins, fluid in the abdomen and legs, and an enlarged tender liver. A characteristic early diastolic sound called a pericardial knock may be heard. The condition is often slow and chronic, and can be hard to tell apart from restrictive cardiomyopathy.

Common causes include prior cardiac surgery, radiation therapy, tuberculosis (a major cause worldwide), and earlier viral or idiopathic pericarditis. Some cases settle with anti-inflammatory treatment if caught early, but established constriction usually requires surgical removal of the pericardium, an operation called pericardiectomy.