Explanation

In most cases of acute pericarditis, the pericardium is acutely inflamed and has an infiltration of polymorphonuclear (PMN) leukocytes and pericardial vascularization. Often, the pericardium manifests a fibrinous reaction with exudates and adhesions. The pericardium may develop a serous or hemorrhagic effusion. A granulomatous pericarditis occurs with tuberculosis, fungal infections, rheumatoid arthritis (RA), and sarcoidosis. Uremic pericarditis is thought to result from inflammation of the visceral and parietal layers of the pericardium by metabolic toxins that accumulate in the body owing to kidney failure The precise pathogenetic changes induced by these toxins when causing uremic pericarditis have not been elucidated, although a rough correlation with the degree and the duration of azotemia exists Uremic pericarditis may be associated with hemorrhagic or serous effusion, although considerable overlap exists. Hemorrhagic effusions are more common and result in part from uremia-induced platelet dysfunction. Some authors distinguish between 2 types of pericarditis in patients with renal failure. One type is uremic pericarditis, which occurs in patients with uremia who have never received dialysis. The other type is dialysis-associated pericarditis, which occurs in patients who are already receiving dialysis. Serous pericarditis is usually caused by noninfectious inflammation such as occurs in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).  Fibrous adhesions rarely occur. Fibrous and serofibrinous pericarditis represent the same basic process and are the most frequent type of pericarditis.  Common causes include acute myocardial infarction (MI), postinfarction (including Dressler syndrome), uremia, radiation, RA, SLE, and trauma.  Severe infections may also cause a fibrinous reaction, as does routine cardiac surgery. Purulent or suppurative pericarditis due to causative organisms may arise from direct extension, hematogenous seeding, or lymphatic extension, or by direct introduction during cardiotomy.  Immunosuppression facilitates this condition.  Clinical features include fever, chills, and spiking temperatures.  Constrictive pericarditis is a serious potential complication. Hemorrhagic pericarditis involves blood mixed with a fibrinous or suppurative effusion, and it is most commonly caused by tuberculosis or direct neoplastic invasion.  This condition can also occur in severe bacterial infections or in patients with a bleeding diathesis.  Hemorrhagic pericarditis is common after cardiac surgery and may cause tamponade. The clinical significance is similar to suppurative pericarditis.