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CV module - Pathology Valvular Heart Disease


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What is the most important cause of Aortic Stenosis?
MCC = Calcification

(1) MC - Acquired (>70yo): Degenerative valvular disease - Senile Calcific Aortic Stenosis

(2) Congenital (<70yo): Calcified bicuspid aortic valve

(3) Chronic Rheumatic HD, AS accompanied by AI

**2/3 of valvular HD is acquired (MC = AS, MS)
What is the most important cause of Mitral Stenosis?
MCC = Chronic Rheumatic heart disease: (mitral annular calcification)
What is the most important cause of Aortic Regurgitation?
MCC = Ascending Aortic Dilation

(1) Long-standing essential HTN
(2) Medial disease in the aortic root (dissection)
(3) Chronic rheumatic HD
(4) Infective endocarditis (MC LEFT-sided valve involved in IV drug abuse (S. aureus)
(5) Dilation of aortic valve ring:
--> syphilitic aortic aneurysm
--> Giant cell aortitis
--> dissecting aortic aneurysm (Marfan syndrome)
--> coarction of th aorta
(6) Ankylosing spondylitis: aortitis
What is the most important cause of Mitral Regurgitation?
MCC = Mitral Valve Prolapse d/t myxomatous degeneration

(2) Left HF d/t stretching of MV ring
Ex: ischemia (papillary muscle dysfunction OR Cardiomyopathy (all 3) OR Myocarditis

(4) Chronic Rheumatic HD

(5) Infective endocarditis

(6) Rupture of the chordae or papilary muslce (usually d/t Right CA Thrombosis)
(4) Infective endocarditis
Describe the pathophysiology of Calcific Aortic Stenosis (acquired)
**MC valvular abnormality

--calcification begins within the valvular fibrosa to form masses within and at the base of the aortic cusps

--functional valve area decrease so that comissural fusion is not produced
-Progressive degeneration with dystrophic calcification related to mechanical stress

Early lesion - cusp attachments and coaptation
Late lesion - valve leaflet (partial or complete)

**Tx surgically
**Mitral Valve is normal, except in RHD
Describe the pathophysiology - Calcific stenosis of congenitaly bicuspid aortic valve
Frequency - 1% live births
Gross: two functional cusps of unequal size

--functionally sufficient early in life
--Calcification occurs initially on the raphe present on the larger cusp
--remains relatively asymptomatic until middle age when stenosis reaches critical pt. and CHF rapidly ensues (pulmonary congestion and edema)
--Becomes incompetant d/t
(1) aortic dilation
(2) cusp prolapse
(3) infective endocarditis

**stenosis develops earlier than in acquired
**Mitral valve is normal
Describe the clinical findings in Calcific Aortic Stenosis
Clinical features:
-causes LVH (angina, syncope, decompensation with development of CHF)
-Myocardia ischemia and fibrosis
-pulmonary vascular disease (P-HTN)
-Endocarditis and emboli
Howe does Mitral Annular Calcification affect valve function
Calcification of the fibrous ring (annulus) of the mitral valve

What are some complications of Mitral Annular Calcification?
Complications of doughnut shaped ring of calcification around mitral valve annulus:
-interferes with systolic contraction
-sudden death
-strokes d/t emboli
-nidus for infectious endocarditis
-severe cases can lead to reguargitation
Who does Mitral Annular Calcification usually affect?
Women >60yo

Pts with myxomatous mitral valve

Pts with elevated left ventricular pressure
Who does myxomatous degeneration of the mitral valve (Mitral Valve prolapse) usually affect?
3% of US adults (mostly young women)

MC form of valvular heart disease in the INDUSTRIALIZED world
What is the etiology of Mitral Valve Prolapse?

(1) CT defect - assoc. with Marfan syndrome, others
(2) Systemic structural abnormalities of CT tissue - scoliosis, straight back, high arched palate
(3) Defects in structural proteins (elastin, microfibrils) and hemodynamics
What is the etiology of Calcific Aortic Stenosis
Etiology undetermined

(1) relates to lipid uptake in atherosclerosis
(2) impaired nionic calcium regulation
(3) impaired regulation of noncollagenous ECM proteins (osteopontin)
Morphology of MVP
1. Intercordal ballooning of the mitral leaflets or portions of the leaflet
2. Leaflets are enlarged and thickened
3. Annular dilation is present (absent in insufficiency d/t other causes) --> MI
4. myxomatous changes may occur seconary to other conditions

**Tricuspid valve is affected in 20-40% of cases
Anatomic complications of MVP
1. linear fibrous thickening of the left ventricular endocardium
2. fibrous thickening of the valve leaflets
3. thrombosis on the atrial surfaces of the leaflets
4. thickening of the mural endocardium of the left ventricle or atrium
5. focal calcifications at the base of posterior mitral leaflet
Clinical features of MVP
1. most pts are asymptomatic
2. 3% pts develop complications

Complications include:
-infective endocarditis
-mitral insufficiency (leaflet deformity or rupture of chordae)
-strok or other systemic infarct d/t embolic complications
**Risk for complication >er in older men, pts with arrhythmias or MR
Define rheumatic fever and rheumatic heart disease
Multisystem inflammatory disease

- an acute, hypersensitivity related, immunologically mediated disease
-follows group A streptococcal pharyngitis
-has chronic valvular implications
Morphology of Rheumatic Heart Disease
can involve all layers of the heart

ACUTE Rheumatic Fever:
Aschoff bodies (area of fibrinoid nerosis and reactive histiocytes)
pancarditis, valvular vegetations
Anitschkow cells or caterpillar cells (MACs)
Aschoff giant cells (multinucleated giant cells)

Valvular thickening, shortening and thickening of chordae tendinae, commissural fusion
--> Left atrial enlargement and mural thrombosis
--> pulmonary vascular and parenchymal changes
Valves most often affect in RHD
1. MC Mitral (MS)
2. Aortic - stenosis, insufficiency

Mitral valve alone 65-70%
Mitral and aortic valve 25%
Pathogenesis of RHD
Cross-reactivity (mimicry) of antigens in M proteins of group A streptococcus and heart proteins

(Type II hypersensitivity reaction)
Major manifestations of RHD
*Erythema marginatum of the skin
Valvular damage
ESR inc.
*Red-hot large joints (migratory polyarthritis)
*Subcutaneous nodules
*Sydneham chorea

Diagnosis and Jones criteria of RHD
(1) Known group A, B-hemolytic streptococcal infection and two of the major manifestations
(2) One major and two minor manifestations (fever,arthralgia, elevated acute phase reactants)

ARF is a consequence of pharyngeal infection with group A, B-hemolytic Strep while RHD is a late sequele
Who gets Acute Rheumatic fever and when?
--is a Usually 10 days->6weeks after infection

--3% of pts with Group A Strep pharyngitis

--Most often in children betwen ages 5 and 15 (20% of cases in middle to late life)
How do you detect Acute Rheumatic fever?
Detection of antibodies to strep enzymes
a. Streptolysin O
b. DNAse B
Clinical Manifestations of Acute Rheumatic Fever
(1) Carditis and migratory polyarthritis (adults)
(2) Fever
(3) Pericarditis - Pericardial friction rub, weak heart sounds
(4) tachycardia
(5) arrhythmias
(6) Cardiac enlargement with mitral valve insufficiency

**Susceptible to reactivation and worsening of the disease following subsequent pharyngal infection
Clinical Manifestations of the organization phase of ARF (chronic)
May manifest years following initial attack

(1) Fibrous pericarditis
(2) Thromboembolisms
(3) Arrhythmias
(4) Infective endocarditis
Define Infective Endocarditis

Define Acute IE
Infection of endothelium of heart (including, but not limited to the valves)

Acute BE - infection of NORMAL valves with a virulent organism (S. aureus)- 10-20% of cases
Define Subacute Infective Endocarditis
Infection of native, previously DAMAGED or congenitally abnl valve with a less virulent organism streptococcus viridans (50-60% of cases)
--Sequele of dental procedures
--Smaller vegetations
--Less valvular destruction than acute form

Granulation tissue at base
Chronic inflammatory infiltrate
Other organisms that can cause Infective Endocarditis
(1) Enterococci
(2) HACEK group of bacteria (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella)
(3) Gram Negative bacteria
(4) Fungi
(5) other sourcs - from gut, oral cavity, trivial injury

**Blood cultures may be sterile in 10% of cases
Predisposing factors to Infective Endocarditis
(1) Abnormal valve:
high risk: prior endocarditis, rheumatic valvular disease, aortic or mitral valve disease, prosthesis

(2) Abnormal risk of systemic infection, bacteremia: IVDA, indwelling venous catheters, poor dentition, hemodialysis, diabetes mellitis
Morphology of Infective Endocarditis
(1) Both acute and subacute form s have bulky, friable destructive valvular vegetations
(2) Vegetations contain: fibrin, inflammatory cells, bacteria, other organisms
(3) Aortic and Mitral valves (are most often affected (IV drug abuse also associated with right-sided lesions)
(4) Ring abscesses
(5) Fungal endocarditis vegetations are usually large
Complications of Infective Endocarditis
(1) Systemic emboli
(2) Emboli produce septic infarts in kidney, brain, myocardium
(2) glomerulonephritis
(3) Microemboli produced features:
-petechiae (conjuntiva, palate), splinter hemorrhages, Janeway lesions, Osler nodes, Roth spots
(4) Cardiac: valvular regurgitation +/- thrill (fenestrated valve or ruptured chordae), pericardial friction rub)
(5) Abdomen: tender splenomegaly
(6) Glomerulonephritis
Clinical features of Infective Endocarditis
Symptoms may be general
(1) fever
(2) nonspecific fatigue
(3) weight loss

Acute endocarditis
(1) rapidly developing fever, chills, weakness, lassitude
(2) Immunologically-mediated Renal disease: d/t entrapped antigen-antibody complexes -->
-renal failure
(3) Murmurs in 90% of cases, left-sided lesions
Duke criteria - pathological findings of IE
(1) Sustained bacteremia by an organism known to cause IE--> Demonstrate with (+)BC, histologic finding in: -active lesion,-intracardiac abscess, -embolus from vegetation
(2) Endocardial involvement - document by: (+) Echocardiog: valve or implant vegetation
(3) New valvular regurgitation

(1) Predisposing condition: heart lesion, IV drug abuse
(2) Fever
(3) Vascular phenomena (emboli, mycotic aneurysms, Janeway lesions)
(4) Immune phenomena ((+) RF, GN, Osler's nodes, Roth spots)

**Multiple blood cultures necessary for diagnosis
Clinical features of Infective Endocarditis using the Duke criteria (clinical findings)
(1) Persistent bacteremia: fever, anorexia, weight loss, night sweats, fatigue
(2) Valvular or perivalvular infection: new murmur, CHF, conduction abnormalities
(3) Septic emboli - systemic or pulmonary emboilism, mycotic aneurysm, MI (CA embolism)
(4) Immune complex phenomena: arthritis, GN, (+) RF, Inc. ESR

Bacteria FROM JANE:
Roth's Spots (retinal hemorrhage + pale center)
Osler's nodes (tender digital nodules)
Janeway lesions (septic emboli---> nontender, hemorrhagic macules on palms or soles)
Nail-bed hemorrhage (splinter hemorrhages on nail bed)
Define Nonbacterial Thrombotic Endocarditis (NTBE)
Small, sterile vegetations on valve leaflets
Who gets NTBE?
debilitated patients (cancer, sepsis)
Complications of NTBE
Embolization and infarction in multiple organs
Morphology of NTBE
1. sterile, single or multiple nondestructive vegetations

2. occurs along lines of closure of the leaflets or cusps

3. thrombus w/out accompanying inflammation or induced valvular damage

4. with time, organization with strands of fibrous tissue
Pathogenesis of NTBE
1. Related to HYPERCOAGULABLE STATE with systemic activation of coagulation cascade

2. Fequently accompanies pulmonary emboli and venous thrombosis (migratory thrombophlebitis or Trousseau syndrome)

3. Endocardial trauma due to indwelling catheters - usually right sided valvular lesions
Associations of NTBE
Associated with malignancies
-mucinous adenocarcinoma
-Acute promyelocytic leukemia

Other relationships
-hyperestrogenic states
-extensive burns
Define NBTE Type II - Endocarditis of systemic lupus erythematosis
Libman-Sacks Disease
Mitral and aortic vavlvulitis

Small, sterile vegetations that rarely embolize, rarely cause problems
-undersurface of valve
valvular endocardium
-chordae tendinae
-mural endocardium of atria or ventricles

Valves show fibrinouid necrosis that become fibrotic and deformed

Development of hematoxylin bodies

Accelerated coronary atherosclerosis
Complications of artificial valves
1. Periprosthetic hemorrhage
2. Thromboembolism
3. Infective endocarditis
4. Structural deterioration (calcification and tering of valve leaflets)
5. Dehiscence of suture lines
6. damage to blood cells with hemolysis
7. mechanical obstruction to blood flow
Describe the thromboembolic complications of artificial valves
Obstruction of vavle function

Distant thromboemboli
Describe how IE d/t artificial valves causes complications
IE on artificial heart valves are located at prosthetic-tissue interface to cause a RING ABSCESS

Direct involvement of prosthetic valve cusps with PARAVALVULAR LEAK
What is the bacteria involved in IE d/t artificial heart valves?
Staph aureus

Staph epidermidis



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