Diseases Of The Pericardium II: Constrictive Pericarditis
When the pericardium is the seat of chronic inflammatory processes, it undergoes firbosis and calcification. It forms a tough cover around the heart, restricting diastolic filling. Majority of cases are tuberculous. Less common causes include rheumatoid disease, hemopericardium, pyogenic pericarditis, amoebic pericarditis and uremia. Sometimes, malignant secondaries develop in the pericardial cavity and give rise to a clinical picture of constrictive pericarditis. Clinical features resemble those of pericardial effusion, but the cardiac size is not grossly enlarged. Atrial fibrillation supervenes in one-third of the cases.
Diagnosis of constrictive pericarditis and pericardial effusion are the same. Skiagram of the chest shows cardiomegaly with clearcut borders and clear lung fields. The heart shadow is flask-shaped with the narrow and uppermost. In tuberculosis, there may be coexistent pleural effusion. Calcification of the pericardium is seen most conspicuously on the diaphragmatic and posterior surfaces and it is brought out better in the lateral views. Fluoroscopy reveals the diminution of cardiac pulsations and the heart may even appear to be silent.
The ECG shows low voltage complexes and nonspecific ST and T-wave changes. In acute pericarditis, there is elevation of ST segments in all leads (concordant ST elevation).
Ultrasonography clearly delineates the effusion, thickened pericardium and calcification and therefore, it is the method of choice for establishing the diagnosis. In some cases, where the pericardium is thickened without effusion, echocardiogram may not be diagnostic. In such cases, cardiac catheterization and angiocardiography may be required to visualize the ventricular cavity and the thickened pericardium. Normally, the right heart border is only 5mm or less from the tip of a catheter positioned against the right atrial border. In pericardial effusion, this distance is considerably increased.
Pericardiocentesis and examination of the fluid
These help in determining the aetiology in many cases. The pericardial fluid is examined in the same manner as described for pleural fluid. Pericardial effusion and constrictive pericarditis should be differentiated from gross cardiomegaly occurring in cardiomyopathy and congestive cardiac failure. Acute pericarditis has to be differentiated from acute myocardial infarction with pericardial involvement. Other conditions such as pleurisy, pneumonia and mediastinitis may resemble acute pericarditis at times.
© 2014 Funom Theophilus Makama