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 andRheumatic 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.

EtiopathogenesisAcute 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 suggestedAutoimmune response to self antigens also suggested.

Chronic sequelae are a result of progressive fibrosis (healing process) and blood turbulance in valvular areas

Pathogenesis

vegetations Aschoff body, myocardium

Fibrinouspericarditis

CROSS REACTIONS

Morphology

ACUTE RH. FEVER-- PancarditisPericarditis- serofibrinous/ Bread and butter type

Myocarditis Aschoff bodiesEndocarditis

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)

vegetationsAschoff body, myocardium

Fibrinouspericarditis

CarditisAschoff bodies Aschoff/ Anitschow cells

Aschoff giant cell

Chronic disease

rheumatic aortic stenosisWith 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

MicroscopyFibrosis/ scarringNeovascularization

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 polyarthritiscarditis, 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 adultsTime: 10 days to 6wks after pharyngitis3% of pts effectedPrognosis of 1st attack good.

Clinical features of chronic rheumatic carditis

Valvular disease and its sequelae (yrs later)

MurmursCardiac hypertrophy, dilatation, heart failure

Arrythmias esp Atrial fibrillationThromboembolic complicationsInfective 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 Virulent organism Normal valve Necrotizing ulcerative, invasive infection Maybe fatal

Subacute Less virulent organism Damaged valve Treatable with antibiotics

Etiopathogenesis

ORGANISMSMost 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 VALVESRHD (previously)Myxomatous mitral valve Degenerative calcific valvular stenosisProsthetic valves

HOST FACTORSImmunodeficiency, immunosupressionMalignancyDiabetesAlcoholI/V drug abuse

Clinical featuresSplinter hgs

Petechiae Janeway lesions

Osler’s nodes

Diagnosis

morphologyThe 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. 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.