VALVULAR HEART DISEASE

Learning objectives Describe the etiology and clinical symptoms of acute rheumatic fever. Describe the pathology and natural history of acute rheumatic fever and rheumatic heart disease. Describe an Aschoff body. Describe which parts of the heart are affected in acute rheumatic fever. Describe the long-term consequences of rheumatic fever. Describe the pathology and natural history of chronic rheumatic heart disease, and know which valves are most often involved. Describe the pathology of postrheumatic mitral stenosis. Enlist the components of vegetation.

Rheumatic fever and Rheumatic heart disease

Rheumatic fever Rheumatic fever 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 active phase May progress to Chronic rheumatic heart disease.

Etiopathogenesis Acute rheumatic fever is a hypersensitivity reaction induced by group A streptococci. Antibodies against M proteins of certain strains of streptococci cross react with antigens in heart, joints and other tissues. Genetic susceptibility is suggested Autoimmune response to self antigens also suggested. Chronic sequelae are a result of progressive fibrosis (healing process) and blood turbulance in valvular areas

Pathogenesis CROSS REACTIONS Fibrinous Aschoff body, pericarditis myocardium vegetations

Morphology ACUTE RH. FEVER-- Pancarditis Pericarditis- serofibrinous/ Bread and butter type Myocarditis  Aschoff bodies Endocarditis  Verrucous vegetations (1-2mm) at lines of closure of valves Fibrinoid necrosis along cusps and teninous cords MacCallum plaques in left atrium (Sub endocardial thickenings due to regurgitant jets)

vegetations Aschoff body, myocardium Fibrinous pericarditis

Carditis Aschoff bodies Aschoff/ Anitschow cells Aschoff giant cell

Chronic disease rheumatic aortic stenosis rheumatic mitral valve, With fused commisures rheumatic mitral valve,

Morphology of chronic RHD Mitral valve is most often affected with rheumatic heart disease, followed by mitral and aortic together, then aortic alone, then mitral, aortic, and tricuspid together. Mitral stenosis (99% cases) Fishmouth/ buttonhole stenosis Microscopy Fibrosis/ scarring Neovascularization

Mitral valve as seen from above in the left atrium. Typical "fish mouth" shape with chronic rheumatic scarring. Mitral valve is most often affected with rheumatic heart disease, followed by mitral and aortic together, then aortic alone, then mitral, aortic, and tricuspid together.

Clinical features of ARF The major clinical manifestations of ARF: migratory polyarthritis carditis, subcutaneous nodules, erythema marginatum, and Sydenham chorea. Minor manifestations of ARF: Fever, arthralgias, Increased blood levels of acute phase reactants etc.

DIAGNOSIS Jones criteria: Evidence of preceding group A strept. Infection Presence of two major or one major and two minor manifestations

Clinical features of ARF Age: 5-15 but may be in adults Time: 10 days to 6wks after pharyngitis 3% of pts effected Prognosis of 1st attack good.

Clinical features of chronic rheumatic carditis Valvular disease and its sequelae (yrs later) Murmurs Cardiac hypertrophy, dilatation, heart failure Arrythmias esp Atrial fibrillation Thromboembolic complications Infective endocarditis

In the dilated atrium with a stenotic mitral valve, the blood stagnates. Hence, stasis is a factor in thrombogenesis..

Infective endocarditis

Infection of heart valve or mural endocardium by a microbe leading to formation of bulky friable vegetations and destruction of underlying tissue. Vegetations are composed of thrombotic debris and organisms

Classification Acute Subacute Virulent organism Normal valve Necrotizing ulcerative, invasive infection Maybe fatal Subacute Less virulent organism Damaged valve Treatable with antibiotics

Etiopathogenesis ORGANISMS Most cases are bacterial although chlamydiae and ricketia also implicated Damaged valves: Strept. Viridans (50-60%) Normal/ damaged: Staph. Aureus (10-20%) I/V drug abusers: Staph. Aureus Prosthetic valves: Staph epidermidis Others are enterococci, HACEK Culture negative: 10%

Etiopathogenesis PREDISPOSED VALVES RHD (previously) Myxomatous mitral valve Degenerative calcific valvular stenosis Prosthetic valves HOST FACTORS Immunodeficiency, immunosupression Malignancy Diabetes Alcohol I/V drug abuse

Clinical features Osler’s nodes Splinter hgs Petechiae Janeway lesions

Diagnosis

morphology The more virulent bacteria causing the acute bacterial form of infective endocarditis can lead to serious destruction, as shown here in the aortic valve. Irregular reddish tan vegetations overlie valve cusps that are being destroyed. Portions of the vegetation can break off and become septic emboli.

Here is a valve with infective endocarditis Here is a valve with infective endocarditis. The blue bacterial colonies on the lower left are extending into the pink connective tissue of the valve. Valves are relatively avascular, so high dose antibiotic therapy is needed to eradicate the infection.