Constrictive pericarditis presents with symptoms of heart failure such as dyspnoea, orthopnoea and fatigue. The most common causes of constrictive pericarditis are cardiac surgery and radiation therapy. Other causes include infection (viral, tuberculous), connective tissue disease, uraemia, neoplasm or idiopathic. The aetiology is unknown in many cases, presumed to be secondary to an occult viral pericarditis and other causes of pericarditis. Outside the USA, the most common cause is probably infectious. Any insult to the pericardium can progress from an acute pericarditis with pericardial effusion to a subacute stage of resorption of the effusion with organisation, and then to a chronic phase of fibrous scarring, pericardial thickening and obliteration of the pericardial cavity. Constrictive pericarditis is the condition in which a thickened, fibrotic and often calcified pericardium restricts diastolic filling of the heart. Constriction caused by neoplastic infiltration of the pericardium is most commonly secondary to carcinoma of the lung or breast, lymphoproliferative malignancies and melanoma. Pericardial constriction after mediastinal irradiation, usually performed to treat breast carcinoma or Hodgkin's disease, may occur months to years after treatment. Pericardial thickening is seen in up to 88% of confirmed cases of constrictive pericarditis. In the majority of cases, constrictive pericarditis involves the entire pericardium, restricting filling of all cardiac chambers.
Occasionally, in particular, anterior to the right ventricle in postoperative patients, the pericardial thickening is more localised. Constrictive pericarditis and restrictive cardiomyopathy are both characterised by restriction in diastolic filling which leads to increases in diastolic pressure in all four chambers and equalisation of pressures. The clinical manifestations and findings on cardiac catheterisation and echocardiography are similar in both conditions. It is important to differentiate between these two conditions because the management approach will differ. Patients with pericardial constriction may benefit from pericardial stripping, while restrictive cardiomyopathy is managed medically or by cardiac transplantation. Diagnosing constriction often proves challenging and usually requires more than one investigation before surgery. The hallmarks of pericardial constriction are pericardial thickening, calcification and abnormal diastolic ventricular function. Although echocardiography is routinely performed and provides an excellent assessment of haemodynamic function, it is not highly accurate at depicting pericardial thickening. CT and MRI are significantly more sensitive, with CT having the advantage over MRI of being able to demonstrate the presence of calcification, which is associated with pericardial constriction. Pericardial calcification can be seen in the atrioventricular groove (Fig. 1).
Pericardial thickening of greater than 4 mm, when accompanied by clinical features of constriction, is highly suggestive of constrictive pericarditis. Both CT and MRI may show the secondary effects of constriction on the central cardiovascular structures. The right ventricle tends to have a conical configuration and reduced volume. A sigmoid-shaped interventricular septum or prominent leftward convexity of the septum may be seen. The right atrium, superior and in particular inferior venae cavae and hepatic veins may be dilated. Hepatomegaly and ascites may be seen. Cardiac MRI can also be used to provide a more detailed assessment of cardiac function. Diastolic septal bounce can be seen on cardiac MR. A free-breathing sequence on cardiac MR in which a patient performs a 'sniff' while the images are acquired, which demonstrates an exaggerated septal bounce (often referred to as ventricular interdependence), is helpful in leading to the diagnosis.
FIGURE 1 ■ Constrictive pericarditis. A 48-year-old man with end-stage renal disease presented with chronic shortness of breath and poor exercise tolerance. Axial unenhanced (A) and contrast medium-enhanced (B) CT images demonstrate pericardial calcification most pronounced in the region of the atrioventricular groove. There is flattening and indentation of the free wall of the right ventricle and the base of the left ventricle. (C) Three-dimensional reconstruction in the twochamber short-axis plane of the heart shows the belt-like calcification surrounding the heart.
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