Pathology of the Pericardium
Pericardial Effusions
Before the introduction of HAART, the prevalence of pericardial effusion in asymptomatic AIDS patients was estimated at 11% per year [19]. Although prospective data are lacking, retrospective data suggest that HAART has reduced the overall incidence of pericardial effusion in HIV disease by about 30% [20].
Most pericardial effusions are idiopathic. Infections, neoplasias, myocarditis, endocarditis, or myocardial infarct have been described as possible etiologies. Little is known about the pathogenesis of pericardial effusions in AIDS patients. However, in the absence of cardiac infection or malignancy, the pathogenesis is likely to be multifactorial. The causes can be metabolic or hemodynamic alterations, dysproteinemias, or pulmonary hypertension due to chronic lung disease (i.e., cytomegalovirus pneumonia). The presence of HIV-1 in macrophages inside the pericardium suggests that the virus may play a role in the pathogenesis of pericardial effusions in AIDS patients.Pericarditis
Pericarditis is found at autopsy in 30% of AIDS patients [1]. It can be serous, fibrinous, serofibrinous, purulent, or hemorrhagic [2, 3]. Pericardial phlogosis may be caused by a wide array of pathogens, always in conjunction with disseminated infection.
Mycobacterium tuberculosis hominis and M. avium-intracellulare, herpes simplex (by culture only), Actinomycetales (Nocardia aster- oides), and bacteria such as Staphylococcus aureus and Salmonella typhimurium may be identified in pericardial fluid, even though in a few cases no pathogens can be isolated [1]. Fungal infections by Candida albicans, Cryptococcus neoformans, and Aspergillus fumiga- tus do not often involve the pericardium [2]. The pericardium may also be involved by non-mycobacterial infections such as Actin- omycetales (N. asteroides or Streptomyces species).
Whereas pericardial disease in the immunocompetent host may be associated with a variety of viruses, most commonly coxsackievirus, pericardial involvement in AIDS is more frequently related to infection with other common viral pathogens, especially herpes simplex virus type 1 and 2 and cytomegalovirus [2].Pathologic Features
The most common type of pericarditis is fibrinous or serofibrinous (Fig. 7). There is a variable amount of fibrin on the epicardium, while pericardial effusion may be absent or present in variable degrees [2]. Many cases of fibrinous pericarditis resolve without residual effects. In other instances, the fibrin deposits organize and form fibrous pericardial adhesions [2, 3]. Bacterial pericarditis is characterized by a fib- rinopurulent exudate. On histology, an infiltrate of polymorphonuclear leukocytes is seen in the epicardial connective tissue. Fibrous adhesions may result, leading to pericardial constriction. Hemorrhagic pericarditis shows a serofibrinous or suppurative exudate associated with the presence of serohematic fluid in the pericardium. It is typical of tuberculosis, severe bacterial infections, or pericardial malignancy [2].