Rheumatic heart disease

What will we discuss today?

• Etiology and epidemiology of rheumatic heart disease

• Pathogenesis of rheumatic heart disease

• Morphological changes in rheumatic heart disease

• Clinical manifestations

Etiology & overview

Group A streptococcus

Pharyngitis (mainly but not only)

Rheumatic fever (RF) …acute …immunologically mediated …multisystem disease

…a common manifestation of active RF is: …acute rheumatic carditis

may progress to chronic rheumatic heart disease… = RHD

The main cardiac abnormalities in this condition are in ………..???

Epidemiology

• Mortality & incidence of RF and RHD have significantly declined in many parts of the world….Why?

Pathogenesis

• Acute RF results from: immune reaction…cross-reactivity

• Antibodies and CD4+ T cells…damage heart tissue

• Antigens: M protein and cardiac self antigens (cross-reactivity)

Pathogenesis, cont’d

Antibodies T cells (mainly CD4+)

-Cytokine release -Activation of macrophages

stimulate B cells to secrete:

They recognize streptococcal M proteins (cross-react with cardiac self antigens) by T cell receptors (TCRs)

in Aschoff bodies

Activation of complement

Opsonization

Morphology

• In acute rheumatic fever:

…foci of inflammation in various tissues

…especially in the heart…we find: Aschoff bodies

= T cells + occasional plasma cells + activated macrophages

= Anitschkow cells

-plump -abundant cytoplasm -central round-to-ovoid nuclei…occasionally binucleate -chromatin condenses into a central, slender, wavy ribbon…so they are called: caterpillar cells

Pathognomonic for RF

Visit https://en.wikipedia.org/wiki/Caterpillar For references Visit https://en.wikipedia.org/wiki/Anitschkow_cell for references

Morphology of acute RF, cont’d

• Diffuse inflammation and Aschoff bodies may be found in any of the three layers of the heart

…pericarditis, myocarditis or endocarditis

…pancarditis

Mainly: fibrinous exudate …self-limited

Mainly: scattered Aschoff bodies in the interstitium

= valvular involvement: fibrinoid necrosis and fibrin deposition along the lines of closure…verrucae (vegetations)

little disturbance in cardiac function

Acute on top of chronic RHD…an example

Small vegetations (1-2 mm)

Robbins basic pathology 9th edition

Morphology of chronic rheumatic heart disease

• Organization…scarring

• Aschoff bodies are replaced by fibrous scars…also there is calcification

• Valve cusps & leaflets…permanently thickened and retracted

…especially: mitral valve

Robbins basic pathology 9th edition (E, From Schoen FJ, St John-Sutton M: Contemporary issues in the pathology of valvular heart disease. Hum Pathol 18:568, 1967.)

Mitral stenosis in chronic RHD

Clinical notes, acute RF

• Mainly children…carditis

• 20%: in adults…arthritis more

• In all ages: 2-3 weeks after streptococcal infection:

…fever + migratory polyarthritis…then spontaneous resolution

…then: pericarditis, myocarditis or endocarditis…or pancarditis

Pericardial friction rub

Can be so severe to cause mitral insufficiency and congestive heart failure

< 1% mortality

arrhythmias

Clinical notes, acute RF…cont’d

• Cultures are negative

• Serum antibodies against one or more streptococcal antigens (streptolysin O, DNAse..etc.) are positive

• For diagnosis:

serologic evidence of previous streptococcal infection

+

2 or more of the major Jones criteria (1) carditis (2) migratory polyarthritis of large joints (3) subcutaneous nodules (4) erythema marginatum skin rashes (5) Sydenham chorea (also called St. Vitus dance)

*Minor criteria: -fever -arthralgias -ECG changes -elevated acute phase reactants

Clinical notes, chronic RHD

• Valvular stenosis and regurgitation…predominantly stenosis …70%: mitral alone …25%: mitral + aortic …tricuspid…much less frequently …pulmonic…almost always spared …with time…left atrial dilation and atrial fibrillation…mural thrombus …with time…a picture similar to left sided heart failure…followed by rt. sided failure …What about left ventricle??

Clinical notes, chronic RHD

• Recurrent attacks with recurrent streptococcal infections

…cumulative damage

• Chronic disease…after years/decades

• Scarred and deformed valves are more susceptible to infective endocarditis