1. Rheumatic Fever and Heart Disease

8/13/2019 1. Rheumatic Fever and Heart Disease

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Pathology of Cardiovascular System

Lecture 1

Rheumatic Fever and Heart Diseases

Dr. Mohamad Nidal Khabaz

19.2.2006


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Valvular Heart Diseases

The most common abnormalities of heart valves are:

Stenosisof the mitral and aortic valves: valve fails to open

completely, so impair ing forward blood flow.

Regurgitation(I nsuf f iciency): valve fail s to close completely,due to cusp abnormality or disease of supporting structures, soallowing reverse flow.

Valve abnormalities produce abnormal heart sounds calledmurmurs


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Acute Rheumatic Fever

Definition

Rheumatic fever is an acute, immunologically mediated, multi -system inf lammatory disease that follows, after (10 days to 6weeks), an episode of group A beta-hemolytic streptococcal

pharyngitis Occurs in only 3% of patients with group A streptococcal

pharyngitis.

Peak incidence: ages of 5-15 years.

The incidence of rheumatic fever has declined over the past 30years

I t affects large joints causing Ar thr itis.

I t affects the heart dur ing its acute phase acute rheumaticcarditis after many years may cause chronic valvulardeformities


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Etiology

Rheumatic fever follows usually a group A beta-hemolyticstreptococcal pharyngitis. The evidence for this associationinclude:

Epidemiological studies and patient history : show thatstreptococcal pharyngitis are followed by cases of rheumaticfever.

Serology: patients have elevated levels of antibodies tostreptococcal enzymes such as streptolysin O and DNAse B.

Always remember blood cultures of patients with rheumatic feverare ster i le


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Pathogenesis

I t i s strongly suspected that acute rheumatic fever is a

hypersensitivity reaction induced by group A streptococci.

I t is presumed that antibodies dir ected against the Mproteins of group A streptococci cross-react with normalproteins in the tissues, leading to tissue damage.

Alternatively it has been proposed that rheumatic feverresults from an immune response against the offendingbacteria.


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Pathology

I nf lammatory inf i l trates occur in a wide range of tissues:

synovium, joints, skin, and heart.

Focal f ibrinoid necrosis which provokes inf lammatoryresponse

F ibrosis is common especially in cardiac tissues.


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Acute Rheumatic Carditis (Pancarditis):

Pathology

Character ized by inf lammatory changes in all three layers ofthe heart.

Multiple foci of inflammation within the heart connectivetissue called: AschoffBodies

Consisting of central f ibrinoid necrosis sur rounded by acollection of lymphocytes, and large macrophages (withbasophilic cytoplasm and vesicular nuclei) known asAni tschow cells.

I t may become mul tinucleated forming Aschoff giant cells(Caterpil lar cells or cardiac histiocytes).

Acute changes may resolve completely or progress to scarr ingand chronic valvular deformities.


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Pathology

Myocardium Scattered Aschof f bodies lie in close proximity to a small vessel.

Diffuse intersti tial inf lammatory inf i l trates (may lead to generalizeddilation of the cardiac chambers).

Endocardium Common and may affect any valve, mostly mitral and aortic valves.

Valves are edematous and thickened with foci of fibrinoid necrosis.(Aschoff nodules uncommon).

Formation of small vegetations fibrinousclotsalong the lines of

valve closure (Verrucous Endocarditi s).

Pericardial involvement Fibrinous pericarditis, sometime associated with serous or

serosanguinous per icardial effusion.


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Clinical Mani festations

Symptoms:

Pericardial f r iction rubs,

Weak heart sounds,

Tachycardia (rapid beating) and

Arrhythmias.

I n severe cases: myocarditis cardiac dilation

functional mitral valve insuf f iciency or even congestive

heart failure.


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Acute Rheumatic Heart DiseasePathogenesis and Key Morphologic Changes


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Small vegetations (verrucae) are visible along the line of closure of

the mitral valve leaflet (arrowheads). Previous episodes of

rheumatic valvul itis have caused fi brous thickening and fusion of

the tendinous cords.


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Verrucous Endocarditis

in Acute Rheumatic Fever


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Aschoff Body in Acute Rheumatic Carditis


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Aschoff body in acute rheumatic carditis.Collection of mononuclear inf lammatory cells, including some large histiocytes

with prominent nucleoli , a prominent binuclear histiocyte, and central necrosis.


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Aschoff Body with Caterpillar Nuclei


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F ibr inous Pericarditis

in Acute Rheumatic Fever


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Chronic Rheumatic Heart Disease

Character ized by irreversible deformity of one or more cardiac valves.

Mitral valve is abnormal in 95% of cases. Combined oartic and mitral valve disease is present in 25% of cases.

Aortic valve alone is rarely affected.

Pulmonary and Tr icuspid valves are extremely rare to be affected.

Clinical manifestations:depend on which valve is involved Cardiac murmurs, Ar rhythmia,

Hypertrophy, Dilation, Congestive heart failure,

Thromboembolic compli cations and infective endocarditi s

Pathological changes: Chronic scarr ing and calcif ication of the valve leafl ets, which invert the

valve into sti f f and thickened structure which may lead to:

Valve orif ice becomes stenotic

Improper closure (regurgitation).

Shor tening and fusion of the chordae tendineae.


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Chronic Rheumatic mitral valvul i tis

I t is the most common cause of mitral stenosis

I t causes stenosis > regurgitation, and occurs in females > males.

I n M itral Stenosis:

Leafl ets are thick, rigid, and inter-adherent.

M itral ori f ice is narrowed fishmouthdeformi ty.

Dilatation and hypertrophy of left atr ium.

Endocardium is thickened particularl y above poster ior mi tral leafl et .

Mural thrombi may be present

Lungs: f irm and heavy (resul t of chronic passive congestion).

I n M itral Regurgitation:

Valve leaflets are retracted

Left ventr icular dilatation and hypertrophy.


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Mitral stenosis with dif fuse fibrous thickening and distortion of the

valve leaflets, commissural fusion (arrow)


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Chronic Aortic Valvul i tis

Males > females and usual ly associated with mitral valvul i tis.

May occur in congeni tal bicuspid aortic valve (2%)

Aortic stenosis:

Valve cusps are thickened, f irm and adherent to each other the aorticvalve ori f ice is reduced to a rigid tr iangular channel.

Aortic stenosis increases the pressure load on left ventricle causinghypertrophy.

Subsequent left ventr icular failure is associated with di lation of thechamber.


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Surgical ly removed specimen of rheumatic aortic stenosis

demonstrating thickening and distortion of the cusps with

commissural fusion (rigid tr iangular channel)


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Calcif ic Aortic Stenosis

DCAS (degenerative calcif ic aortic stenosis)

Part of normal aging process is degenerative changes in the cardiacvalves but it can develop to cause pathologic stenosis.

The aortic valve leaflets are r igid and deformed by calcif ied masses, so

f ibrosis and calci f ication of the valve cusps lead to valve sclerosis.

The calcium deposits lie behind the valve cusps (at the bases of thecusps).

The free edges of the cusps are usually not af fected.

Calcif ic stenosis does not fuse the cusps.

Symptom: severe cases may cause angina, syncope (fainting), congesti veheart failure, L.V. hypertrophy, sudden death due to arrhythmia.


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Degenerative calci f ic aortic stenosis of a normal valve having three cusps.

Nodular masses of calcium are heaped up within the sinuses of Valsalva (arrow).

Note that the commissures are not fused, as in post-rheumatic aortic valve stenosis


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Mitral Valve Prolapse

Pathology

The valve leaflets (poster ior cusp) are soft and enlarged causing acharacter istic ballooning of the valve leaflets into the left atrium dur ingsystole.

The chordae tendineae, which are often elongated and fragile, mayrupture in severe cases.

The valve annulus may be dil ated.

M icroscopic examination

Reveals excessive amounts of loose, edematous, faintly basophi l ic tissue

within the middle layer (spongiosa) of the valve leaflets and chordae.

Complications

M itr al r egurgitation and congestive heart failure.

Sudden death caused by ventr icular ar rhythmias.

I nfective endocardi tis.


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Opened valve showing pronounced hooding of the posterior mitral

leaflet with thrombotic plaques at sites of leafletleft atrium

contact (arrows).


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1. Rheumatic Fever and Heart Disease