Constrictive pericarditis is a pericardium that has become fibrotic (scarred), thickened and adherent to the heart, restricting diastolic filling, the filling of the ventricles between beats, even when there is little or no fluid inside the sac. It is the chronic counterpart of a pericardial effusion: fluid under pressure compresses the heart within minutes to hours, whereas constriction develops insidiously, over months to years.
What causes it
Constriction follows chronic pericardial inflammation, and the risk is concentrated in particular causes. Tuberculous pericarditis, mediastinal radiotherapy, cardiac surgery, and uraemic or purulent pericarditis are the usual antecedents. In a prospective cohort of 500 first episodes of acute pericarditis followed for a median of 72 months, constrictive pericarditis developed in 9 patients (1.8%) overall, in fewer than 1% of those whose episode was idiopathic or viral, and much more often after tuberculous or purulent pericarditis. The cause of the acute episode is therefore the main determinant of this later risk.
Clinical features and diagnosis
Because the stiff sac limits filling, constriction presents as right heart failure: raised jugular venous pressure, peripheral oedema, ascites, hepatomegaly and fatigue. Two signs are characteristic. Kussmaul’s sign is a rise in jugular venous pressure on inspiration, and the pericardial knock is a high-pitched early diastolic sound. In addition, the ventricles become interdependent, so filling of one affects the other.
Diagnosis combines imaging with haemodynamics:
- computed tomography or magnetic resonance imaging shows pericardial thickening and calcification;
- echocardiography shows a respirophasic septal shift, a movement of the septum between the ventricles with breathing, with dissociation between intrathoracic and intracardiac pressure changes;
- catheterisation shows equalised diastolic pressures with a dip-and-plateau, or square-root, filling pattern.
The distinction from restrictive cardiomyopathy, a disease in which the heart muscle itself is stiff, is the classic difficulty, because both produce raised filling pressures with a stiff heart and a normal ejection fraction, the proportion of blood the ventricle ejects with each beat.
Treatment
Pericardiectomy, the surgical stripping of the constricting pericardium, is the treatment, so the distinction from restrictive cardiomyopathy has to be made before the operation rather than after it. That comparison is developed further among the cardiomyopathies.