Pathology of Valvular Heart Disease Flashcards
What are the three layers of normal valves (aside from the endothelial covering? What layer faces the highest stress portion (i.e. would face venticular side in AV valves and large vessel side in semilunar valves)
- Fibrosa - dense collagen layer to which supporting structures attach (chordae tendinae) -> face high stress portion
- Spongiosa - central core of loose connective tissue with proteoglycans
- Elastin-rich layer - on inflow surface (atrialis or ventricularis)
What type of murmur is caused by an incompetent mitral valve or stenotic aortic valve?
Systolic murmur
What type of murmur is caused by narrowed mitral valve or incompetent aortic valve?
Diastolic murmur
What is the most common cause of a murmur, and what processes allow this to develop?
A valvular stenosis, most commonly on aortic then mitral valves
- > usually due to calcification or chronic scarring (due to chronic rheumatic heart disease)
- > gradual onset
How can valvular insufficiency arise gradually or suddenly?
Gradually - myxomatous degeneration of mitral valve, ventricular cavity enlargement, dilatation of pulmonary or aortic root
Suddenly - infective endocarditis (hole appears), acute rheumatic heart disease, chordae tendinae or papillary muscle rupture
What valve is most likely involved in dystrophic calcification, and who is most susceptible? How does this appear?
Aortic valve -> highest pressures
Most susceptible = congenitally bicuspid - appears with two cusps of unequal size, larger one containing a midline raphe
How can stenosis from dystrophic calcification be told from stenosis due to chronic rheumatic heart disease?
Dystrophic - commissures will be intact, calcifications extend into base of valve into sinuses of Valsalva
Chronic rheumatic heart disease - affects mitral valve much more than aortic, and appears with fishmouth / buttonhole appearance - thickening and distortion of valve leaflets / cusps with commissural fusion
How will patients with calcific valvular degeneration present and why?
Present with angina -> due to compensatory LV hypertrophy and ischemia
Syncope -> decreased cardiac output
What are the potential complications of mitral annular calcification?
Dysfunction of valve -> stenosis or insufficiency
Arrhythmias -> if calcifications enter into the endocardium
Superimposed thrombosis and infectious endocarditis -> turbulent blood flow injures endothelium
How does it sound to auscultate a mitral valve prolapse? What accounts for this sound?
Midsystolic click, typically heart in young women
Due to long, thin chordae tendinae snapping against the wall during systole
What typically causes mitral valve prolapse (microscopically) and what are the etiologies of this?
Myxomatous degeneration of mitral valve -> dilated valvular annulus with enlarged, thick, rubbery leaflets due to thick loose connective tissue in spongiosa layer of valve (and loss of collagen in fibrosa layer + chordae tendinae)
-> cause usually unknown, but sometimes due to connective tissue diseases such as Marfan syndrome
What secondary changes often occur in mitral valve prolapse?
Friction-induced fibrosis of left atria, with possible thrombi in left atria (due to leaflets hitting endocardium of left atrium)
Friction induced fibrosis of LV endocardium (due to chordae tendinae snapping against the walls of LV)
What are same of the complications of mitral valve prolapse?
Mitral valve insufficiency -> will not always occur w/prolapse
Associated w/ all valve disease: Systemic thromboembolism, infective endocarditis
What is the pathogenesis of rheumatic heart disease? What type of infection does it follow?
Immune-mediated reaction generated in response to group A S. pyogenes pharyngitis only (not following skin infection)
Antibodies to M protein of S. pyogenes cross-reactive with cardiac myosin
What does acute rheumatic heart disease cause overall and what will be seen microscopically in the myocardium?
Pancarditis (all layers of heart)
Aschoff bodies - foci of swollen, degenerated collagen with lymphocytes, plasma cells, macrophages (chronic inflammatory).
Macrophages -> Anitschkow cells - “caterpillar” - condensed, elongated nuclear chromatin
What does acute rheumatic heart disease do to the pericardium?
Causes fibrinous pericarditis
-> friction rub due to Aschoff bodies
What does acute rheumatic heart disease do to the endocardium? What side of the heart does it affect?
Small, sterile thrombi (vegetations) along lines of closure of valves
Affects especially left side of heart, mitral > aortic valve.
What is the pathophysiology of chronic rheumatic heart disease?
Neovascularization of heart valves with fibrotic valular deformities
Valvular stenosis of mitral > aortic valves: thickening and distortion of valves with commissural fusion.
Thickening, fusion, and shortening of chordae tendinae (look like tree trunks)
What antibodies can be tested for to detect acute rheumatic fever?
ASO - anti-Streptolysin O
Anti-Streptococcal DNAse B
What are the JONES criteria? Who does J affect more? Why does S happen?
J - migratory polyarthritis of joints (especially adults)
O - acute pancarditis
N - Subcutaneous nodules
E - Erythema marginatum (redder on margins)
S - Sydenham chorea - due to crossreactivity with BG
What are the potential complications of chronic rheumatic heart disease?
Left sided valvular stenosis -> cardiac hypertrophy and/or dilatation -> arrhythmias, thromboembolic events, IE, and CHF
What arrhythmia commonly occurs as a result of chronic rheumatic heart disease?
Atrial fibrillation -> secondary to dilatation of left atrium due to mitral valve stenosis
What are some predisposing factors to infective endocarditis?
- Pre-existing valvular pathology
- Abnormal intracardiac jet streams -> cause turbulent blood flow
- Decreased immunity
- Portals of entry (indwelling catheters, IV drug use)
What causative pathogen of IE is associated with GI and liver diseases, especially carcinoma of colon?
Streptococcus bovis
What is the most common cause of IE in IV drug users?
S. aureus, especially in right-sided heart (only time this really happens since its normally left-sided valves which are injured)
What is the most common cause of IE on previously diseased valves?
S. viridans -> dental bacteremia
What is the most common cause of IE on prosthetic heart valves?
Coag-negative staph
-> S. epidermidis
How does IE appear grossly and microscopically?
Grossly - usually left-sided, bulky vegetations with destruction / perforation of valve leaflets / cusps
Microscopically - aggregates of acute inflammatory cells, microorganisms, fibrin, platelets (thrombus protects bacteria)
What are the local effects of infective endocarditis?
Valvular regurgitation -> due to perforation
Changing cardiac murmur / separation of prosthetic valve -> due to abscess formation
What is Marantic Endocarditis also called and what are the usual causes? Will there be inflammation?
Nonbacterial Thrombotic Endocarditis (NBTE)
- > Hypercoagulability state associated with debilitating disease like malignancies (especially mucinous adenocarcinoma of pancreas)
- > endocardial injury, often due to intracardiac catheter
Marantic = Marasmus
Only endocarditis w/o significant inflammation
What are the gross and microscopic features of NBTE, and its primary complication?
Gross - small vegetations along lines of valve closure WITHOUT inflammatory valve destruction
Microscopic - Sterile thrombotic material loosely attached to valve surface
Complication - Systemic thromboembolic -> infarcts
What causes Libman-Sacks Endocarditis and how is it distinguished from other sources of endocarditis? Include how it appears grossly?
Associated with SLE
Grossly: Vegetations can be found on both sides of the valves (rather than just inflow surfaces like others), and on chordae tendinae. Can even appear on endocardial lining
How does Libman-Sacks endocarditis appear microscopically and what are its potential complications?
Aggregates of thrombotic material adhering to subendocardial fibrinoid necrosis, associated with inflammation
Complication: Fibrotic valvular deformities
What condition is characterized by systemic flushing, diarrhea, and wheezing, with thickened endocardium due to accumulation of mucopolysaccharide-rich matrix containing smooth muscle cells? What side of the heart does this affect and why?
Carcinoid heart disease -> part of carcinoid syndrome in some neoplasms, due to ectopic serotonin production
Affects the right side of the heart only, since serotonin from venous circulation is broken down in the lungs
What are the pro’s and con’s of mechanical and bioprosthetic valves?
Mechanical: Pros - longer-lived, Cons - need anticoagulation
Bioprosthetic valves - Pros: No anti-coag, Cons: shorter lifespan, tear easily
Other than thrombosis / endocarditis, which is a strange complication of mechanical valves?
Chronic hemolysis -> shearing of red cells on the way thru the valve due to abnormal tissue-prosthesis interface.
