Disease Of Heart II
Rheumatic Fever And Rheumatic Heart Disease
Rheumatic fever (RF) is an acute, immunologically mediated, multisystem inflammatory disease that occurs a few weeks following an episode of group A streptococcal pharyngitis. Acute rheumatic carditis during the active phase of RF may progress to chronic rheumatic heart disease
The most important consequence of RF are chronic valvular deformities, characterized principally by deforming fibrotic valvular disease (particularly mitral stenosis), which produces permanent dysfunction and severe, sometimes fatal, cardiac problems decades later
Morphology
During acute RF, focal inflammatory lesions are found in various tissues. They are most distinctive within the heart, where they are called Aschoff bodies. They consist of foci of swollen eosinophilic collagen surrounded by lymphocytes , occasional plasma cells, and plump macrophages . These distinctive cells have abundant cytoplasm and central round-to-ovoid nuclei . Some of the larger macrophages become multinucleated to form Aschoff giant cells
During acute RF, diffuse inflammation and Aschoff bodies may be found in any of the three layers of the heart—pericardium, myocardium, or endocardium—hence the lesion is called a pancarditis. In the pericardium, the inflammation is accompanied by a fibrinous or serofibrinous pericardial exudate, described as a "bread-and-butter" pericarditis, which generally resolves without sequelae. The myocardial involvement—myocarditis—takes the form of scattered Aschoff bodies within the interstitial connective tissue, often perivascular
Concomitant involvement of the endocardium and the left-sided valves by inflammatory foci typically results in fibrinoid necrosis within the cusps or along the tendinous cords on which sit small (1- to 2-mm) vegetations—verrucae—along the lines of closure
Chronic RHD is characterized by organization of the acute inflammation and subsequent fibrosis. In particular, the valvular leaflets become thickened and retracted, causing permanent deformity
Aschoff bodies are replaced by fibrous scar , Fibrosis resulting from healed inflammation outside the valves is usually of no consequence
Clinical Features
Acute rheumatic fever typically occurs 10 days to 6 weeks after an episode of pharyngitis caused by group A streptococci in about 3% of patients. Acute RF appears most often in children between ages 5 and 15, but about 20% of first attacks occur in middle to later life. antibodies to one or more streptococcal enzymes, such as streptolysin O and DNAse B, are present and can be detected in the sera of most patients. The predominant clinical manifestations are those of arthritis and carditis Arthritis is far more common in adults than in children. It typically begins with migratory polyarthritis accompanied by fever in which one large joint after another becomes painful and swollen for a period of days and then subsides spontaneously, leaving no residual disability. Clinical features related to acute carditis include pericardial friction rubs, weak heart sounds, tachycardia, and arrhythmias. The myocarditis may cause cardiac dilation that may evolve to functional mitral valve insufficiency or even heart failure
Pericardial Disease
Pericardial lesions are almost always associated with disease in other portions of the heart or surrounding structures, or are secondary to a systemic disorder; isolated pericardial disease is unusual
Pericarditis
Pericardial inflammation is usually secondary to a variety of cardiac diseases, thoracic or systemic disorders, metastases from neoplasms arising in remote sites, or a surgical procedure on the heart. Primary pericarditis is unusual and almost always of viral origin. Most evoke an acute pericarditis, but a few, such as tuberculosis and fungi, produce chronic reactions. Since it is often impossible from pathologic examination to determine the etiologic basis for the reaction, a morphologic classification follows
Acute Pericarditis
Serous Pericarditis
Serous inflammatory exudates are characteristically produced by noninfectious inflammations, such as RF, SLE, scleroderma, tumors, and uremia
Morphology
Whatever the cause, there is an inflammatory reaction in the epicardial and pericardial surfaces with scant numbers of polymorphonuclear leukocytes, lymphocytes, and macrophages. Usually the volume of fluid is not large (50 to 200 mL) and accumulates slowly
Fibrinous and Serofibrinous Pericarditis
These two anatomic forms are the most frequent type of pericarditis and are composed of serous fluid mixed with a fibrinous exudate. Common causes include acute MI , uremia, chest radiation, RF, SLE, and trauma. A fibrinous reaction also follows routine cardiac surgery
Morphology
In fibrinous pericarditis, the surface is dry, with a fine granular roughening. In serofibrinous pericarditis, an increased inflammatory process induces more and thicker fluid, which is yellow and cloudy owing to leukocytes and erythrocytes (which may be sufficient to give a visibly bloody appearance), and often fibrin. As with all inflammatory exudates, fibrin may be digested with resolution of the exudate or it may become organized
Purulent or Suppurative Pericarditis
This almost invariably denotes the invasion of the pericardial space by infective organisms
Morphology
The exudate ranges from a thin to a creamy pus of up to 400 to 500 mL in volume. The serosal surfaces are reddened, granular, and coated with the exudate . Microscopically there is an acute inflammatory reaction. Sometimes the inflammatory process extends into surrounding structures to induce a so-called mediastinopericarditis. Organization is the usual outcome; resolution is infrequent. Because of the great intensity of the inflammatory response, the organization frequently produces constrictive pericarditis, a serious consequence
Hemorrhagic Pericarditis
An exudate composed of blood mixed with a fibrinous or suppurative effusion is most commonly caused by malignant neoplastic involvement of the pericardial space; in such cases, cytologic examination of fluid removed through a pericardial tap may yield neoplastic cells. Hemorrhagic pericarditis may also be found in bacterial infections, in patients with an underlying bleeding diathesis, and in tuberculosis. Hemorrhagic pericarditis often follows cardiac surgery and sometimes is responsible for significant blood loss or even tamponade, requiring a "second-look" operation. The clinical significance is similar to that of the spectrum of fibrinous or suppurative pericarditis
Caseous Pericarditis
Caseation within the pericardial sac is, until proved otherwise, tuberculous in origin; infrequently, fungal infections evoke a similar reaction. Pericardial involvement occurs by direct spread from tuberculous foci within the tracheobronchial nodes. Caseous pericarditis is rare but is the most frequent antecedent of disabling, fibrocalcific, chronic constrictive pericarditis