Tuesday, March 29, 2011

Constrictive Pericarditis

Constrictive pericarditis is a chronic inflammation of the pericardium, which is a two-layered sac that wraps the heart and contains the roots of the great vessels. Constrictive pericarditis occurs when a fibrotic, thickened, and adherent pericardium restricts diastolic filling of the heart. It usually begins with an initial episode of acute pericarditis, which may not be detected clinically. This then slowly progresses to a subacute stage of organization and resorption of effusion, followed by a chronic stage consisting of fibrous scarring and thickening of the pericardium with obliteration of the pericardial space, producing uniform restriction of the filling of all heart chambers. In this stage, calcium deposition may contribute to stiffening of the pericardium.

The inflammation causes the pericardium of the heart to become thick and rigid, making it hard for the heart chambers to expand properly when they receive blood. As a result, the heart chambers do not fill up with enough blood. Blood backs up behind the heart, causing heart swelling and other symptoms of heart failure. During inspiration, the negative pressure in the thoracic cavity will cause increased blood flow into the right ventricle. This increased volume in the right ventricle will cause the interventricular septum to bulge towards the left ventricle, leading to decreased filling of the left ventricle.

Although constrictive pericarditis may develop after a heart surgery, heart attack, and radiology, almost half the cases in the developing world are idiopathic in origin. In regions where tuberculosis is common, it is the cause in a large portion of cases. Thus, causes of constrictive pericarditis may include fungal or parasitic infections, tuberculosis, incomplete drainage of purulent pericarditis, heart surgery, radiation therapy, etc. The definitive treatment for constrictive pericarditis is pericardial stripping, which is a surgical procedure where the entire pericardium is peeled away from the heart. This procedure has significant risk involved, with mortality rates of 6% or higher in major referral centers.