subject: Constrictive pericarditis aetiology and pathogenesis [print this page] Constrictive pericarditis results from thickening andfibrosis of the pericardium with, in some cases, extensive calcification.
Aetiology
There may be an antecedent history of acute pericarditisor radiotherapy. Tuberculous pericarditis is now rare inwestern countries, but is the classic cause of calcific constrictivepericarditis.
Pathogenesis
The heart is effectively encased in a rigid box, which eventuallyprevents it from filling. Haemodynamically, the diastolicpressures or filling pressures of the two sides of theheart become the same as the intrapericardial pressure;as this rises, the patient goes into bilateral heart failure, in which features of right-sided failure predominate.Sometimes the constriction is selective, so that the left orthe right side, inflow or even outflow, can be compromised most.
Clinical features
Symptoms
The major symptom is severe oedema, often with ascites,liver engorgement and progressive weight loss secondaryto hepatic engorgement and low cardiac output. Patientswith long-standing disease look cachectic, and with theliver enlargement and a degree of jaundice are easily thought to have carcinomatosis or cirrhosis of the liver.The absence of significant left-sided heart failure symptomsis characteristic. The patient can often lie flat withoutproblems and does not have a history of paroxysmal nocturnaldyspnoea, but will always have a limited exercisetolerance and dyspnoea on exertion. Constriction mayarise with no previous history of pericarditis. A previoushistory of pericarditis is a valuable clue to the diagnosis.
Signs
A very high venous pressure is invariable, as the enddiastolicpressure in both ventricles is about 25mmHg.The high venous pressure is interrupted by a rapid x andy descent or systolic collapse of the venous pressure. The pulse exhibits pulsus paradoxus, but this is not invariable and the presence of AF in about 30% of cases makes thesign difficult to elicit. The pulse will, in any case, be of smallvolume. The heart is not clinically enlarged and the rigid pericardium may impede palpation of the cardiac impulse.The heart sounds may be faint with a loud additionalsound, the pericardial knock. This is a loud early third heart sound, resulting from the rapid filling of the ventricles being suddenly impeded by the rigid pericardium.Murmurs are uncommon.
Management
The only effective treatment is surgical decompression ofthe heart by removing enough of the pericardium to allowthe heart to fill effectively. This means removing the adherent pericardium from around the great veins and atria,which are extremely thin-walled. Where the pericardium is adherent to the ventricles the coronary arteries are easily damaged, so considerable surgical skill and patience are required.
Constrictive pericarditis aetiology and pathogenesis
