Heart

RHEUMATIC FEVER

Is a multisystem inflammatory disease That can involve the heart, joints, skin and brain. The disease develops after A streptococcal infection (A beta-hemolytic – streptococcus pyogenes) – mostly Pharyngitis

CLINICAL FEATURES

·Occur most often in children

·Develop 2-4 weeks after streptococcal Infection

·Fever, malaise, and increased Erythrocyte sedimentation rate

·Rheumatic heart disease – pancarditis; inflammation of the entire heart (3 layers)

oPericarditis – leads to serous effusions

oMyocarditis – leads to cardiac failure

oEndocarditis – leads to valvular damage

§Rheumatic Endocarditis – mitral and aortic valves (mostly); the valves become thickened, Fibrotic, deformed, & calcification (may)

·Joint involvement – arthralgia, arthritis, And migratory polyarthritis

·Skin lesions – subcutaneous nodules and erythema Marginatum (distinctive)

·CNS involvement – Sydenham chorea (involuntary muscular movements)

·If chronic – arrhythmias and Thromboembolic complications 

CAUSES

·Immunologic origin rather than a result Of direct bacterial involvement

·Streptococcal antigens – molecular Mimicry – elicit an antibody cross reactivity

MECHANISM

·Type II hypersensitivity – attributed to Antibodies against group A streptococcal molecules that cross-react with host Myocardial antigens

MORPHOLOGY

Acute rheumatic fever

·Inflammation foci within several tissues

·Aschoff bodies – focal interstitial Myocardial inflammation, with:

oAschoff cells – multinucleated giant Cells

oAnitschkow myocytes or “caterpillar Cells”

oCollagen and fibrinoid material

·Aschoff bodies can be found in all three Layers of the heart

·The pericardium exhibits fibrinous Exudate

·The endocardium may contain verrucae (1-2mm vegetations)

Chronic Rheumatic fever

·Organization of acute diffuse inflammation And scarring

·Aschoff bodies are replaced by fibrous Scar – therefore not seen in chronic RF

·Cardiac valves show leaflet thickening, Commissural fusion and shortening, and thickening of the chordae tendinea

·Calcification creates buttonhole Stenoses

·Neovascularization

Rheumatic Heart disease

·Valvular stenosis and regurgitation

o70% mitral valve

o25% mitral and aortic valves

o5% tricuspid valve

·Mitral valve stenosisà left Atrium dilation à atrial Fibrillation à mural Thrombosis