Cardiovascular Pathology


Can provide a nidus for infective endocarditis or thrombi  stroke

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Can provide a nidus for infective endocarditis or thrombi  stroke



Myxomatous Degeneration of the Mitral Valve




  • AKA Floppy Mitral Valve, Mitral Valve Prolapse

  • The most common valvular disease in the industrialized world, affects ~ 3% of adults, mostly young women

  • Characterized by redundant, myxoid mitral valve leaflet tissue that protrudes into left atrium on systole

  • May see with Marfan’s, but cause usually unknown – probably a disorder of connective tissue

  • PE: May show a mid or late systolic “click” due to snapping of the chordae or scallop ± late systolic or holosystolic regurg. murmur

  • Echocardiogram  diagnostic

  • Clinical: Usually asymptomatic, but may have dyspnea, fatigue, chest pain, or even psychiatric symptoms




Note:

The leaflets balloon into the LA with “interchordal hooding.” The chordae are frequently elongated and thinned and occasionally rupture. The TV is also affected in 20 – 40% & sometimes even the AV and PV.

Can see “friction lesions” where leaflets strike the LA walls or rub against each other. Can get thrombi on these surfaces.

Microscopic: Attenuation of the fibrosa layer with increased myxoid tissue. Ditto in chordae. Valves may show secondary fibrous thickening, especially in friction areas.

Psychiatric symptoms include depression, anxiety, and personality disorders.

Strictly speaking, if MV prolapse is due to a connective tissue disorder, it might be reasonable to classify it as a congenital valvular disorder.




Complications of Floppy MV (3%)


  • Infective endocarditis

  • Mitral insufficiency – slow onset or sudden with chordal rupture

  • Stroke (thrombi on atrial side)

  • Arrhythmia or sudden death

  • Higher risk for complications in men, older persons, and in patients who already have an arrhythmia, LV enlargement, or MV regurgitation




Rheumatic Heart Disease




  • Rheumatic fever is an immune mediated attack on the heart after a bout of pharyngitis due to group A (beta hemolytic) streptococcus

  • The acute phase of RF causes a pancarditis with:

    • Serofibrinous (“bread and butter”) pericarditis

    • Myocarditis

    • Valvulitis, mainly of left-sided valves

Notes:

Rheumatic disease is an immune mediated inflammatory disease that occurs about 3 weeks (range 1 to 5 weeks) after a bout of acute pharyngitis due to group A (beta hemolytic) streptococcus (not after infections of skin or other sites; not after infections with other strep.) usually in children 5 – 15 years.

Occurs in only about 3% of pts with group A strep pharyngitis & has been declining over 30 years

(? Better treatment, ? decreased virulence of bug).

Diagnosed clinically by the Jones criteria – need 2 major or 1 major + 2 minor along with evidence of a preceding group A strep infection:

Major criteria:

Migratory polyarthritis in large joints

Carditis

Subcutaneous nodules

Erythema marginatum of skin

Sydenham chorea

Minor criteria: Fever, arthralgias, increased serum acute phase reactants

After an initial attack of rheumatic fever, the pt is more vulnerable to a future attack & carditis is likely to worsen with each subsequent attack. Valve damage is cumulative.

Histologically, granuloma-like lesions called Aschoff bodies characterize the acute phase. Aschoff bodies contain plump macrophages called Anitschkow cells, T-lymphocytes, ± a few plasma cells, and fibrinoid material. Aschoff bodies may be found in any layer of the heart (recall from C603 Lab).

The acute valvulitis is characterized by inflammation & fibrinoid necrosis along the lines of closure, especially on the left-sided valves, with small (1 – 2 mm) verrucous vegetations along the lines of closure. Mitral valve regurgitation may cause plaques in the LA (jet lesion) called MacCallum plaques.


Chronic Rheumatic Disease




  • Involves the valves – not the pericardium or myocardium

  • Is due to post-inflammatory thickening and deformation of the leaflets

  • Involves:

    • Mitral valve virtually always (65 – 70% alone)

    • MV + AV if two valves

    • MV + AV + TV if three valves

  • Four valve involvement rare




Basic Features of Chronic Rheumatic Heart Disease




  • Fibrous thickening of the valve leaflets with fusion of the commissures  “button hole” or “fish mouth” appearance

  • Thickening, shortening and fusion of the chordae tendineae

  • LA may dilate & harbor thrombus

  • LV is “protected” – if MV only

  • May eventually get RV hypertrophy

Note:

Microscopic of valves in chronic heart disease shows fibrosis with vascularization and loss of the normal lamination. Rarely, Aschoff bodies may be seen.




Rheumatic Heart Disease – Pearls





  • The severity of joint involvement is inversely proportional to heart involvement

  • In acute RF, heart involvement is typically not symptomatic unless there is heart failure or pericarditis
  • The long term prognosis is highly variable – prosthetic MV replacement may be required


  • Mitral regurgitation may develop quickly (due to restricted mobility of leaflets or ventricular dilatation), but stenosis takes years

  • Chorea is a late manifestation of RF, male > female
    • May last from a week to >2 years!


    • Chorea is never seen with arthritis, but may coexist with carditis

    • Hypotonia and emotional disturbances are typical

  • Subcutaneous nodules – attached to tendon sheaths – extensor surfaces & over bony prominences of upper & lower extremities & mastoid. Histologically  Aschoff bodies

  • Erythema marginatum – red margins progress as center clears – see on trunk and proximal limbs



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