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Path 30: Cardiac Pathology - Valvular Heart Disease

Terms in this set (67)

Markers of cardiac injury
CK-MB, Troponins (I and T), Lactate dehydrogenase (LD), myoglobin (non-specific)
Troponin I and T
most sensitive and specific markers of cardiac injury -> regulate calcium mediated muscle contraction -> normally NOT detectable in circulation, TnI commonly measured clinically (most specific to cardiac injury) -> rise in 2-4 hours, peak at 48 hours, persists for 7-10 days
Creatine Kinase
dimer composed of M and B subunits -> MB most specific for heart, trace amounts in skeletal muscle -> rises within 2-4 hours of MI, peaks at 24 hours, disappears by 72 hours
Reperfused patients
Cardiac markers elevate sooner -> washout of enzymes from the necrotic tissue
Intervention of MI
primary prevention (reduce blood cholesterol), thrombolysis (streptokinase, tissue plasmin inhibitor), defibrillation, angioplasty, coronary bypass graft (CABG)
Chronic ischemic heart disease
insidious onset of CHF in patients who have past episodes or angina attacks -> cardiac decompensation owing to exhaustion of compensatory hypertrophy of non-infarcted viable myocardium or severe coronary obstructive disease leading to diffuse myocardial dysfunction -> arrhythmia, intercurrent MI common and fatal
Gross morphology of chronic ischemic heart disease
enlarged and heavy heart due to hypertrophy and dilation -> discrete gray white scars of healed previous infarcts -> patchy fibrous thickening of mural endocardium
Histological morphology of chronic ischemic heart disease
myocardial hypertrophy, diffuse Subendocardial vacuolization (MYOCYTOLYSIS), scars of previously healed infarcts
Sudden cardiac death
unexpected death without symptoms or within first 24 hours of onset of symptoms -> adults = coronary arterial disease is most common -> Ultimate mechanism is lethal arrhythmia -> left ventricular fibrillation -> 80-90 % of cases due to critical stenosis of one or more coronary arteries -> high grade stenosis associated with acute plaque disruption (10-20% non atherosclerotic in origin)
Sudden cardiac death in younger patients
congenital coronary artery abnormalities, aortic valve stenosis, mitral prolapsed, myocarditis, sarcoidosis, cardiomyopathy, pulmonary hypertension, conduction system defects (autosomal dominant long QT syndrome)
Hypertensive heart disease
presence of left ventricular hypertrophy in an individual with a history of HTN and in whom other causes of hypertrophy have been excluded -> cardiac myocytes terminally differentiated cells - no chance for hyperplasia
Pathogenesis of hypertensive heart disease
stimulus is sustained pressure overload -> growth factors and local mechanical effects cause upregulation of genes controlling expression of actin and myosin -> leads to hypertrophy
Morphology of hypertensive heart disease
concentric hypertrophy of left ventricle - symmetric, circumferential pattern (400-800 grams) -> long standing cases causes right ventricular hypertrophy and dilation -> histologically enlarged myocytes containing large, hyperchromatic rectangular box-car shaped nuclei
Clinical features of hypertensive heart disease
early stages is asymptomatic -> angina pectoris, signs and symptoms of heart failure with progression -> cerebrovascular accidents (stroke) -> SCD
Pulmonary heart disease (cor pulmonale)
disease of right sided cardiac chambers secondary to pulmonary parenchymal or pulmonary vascular diseases -> excluded from this definition are pulmonary HTN due to LHF and pulmonary HTN due to congenital heart disease
Acute cor pulmonale
pulmonary embolism causing sudden increase in burden of the right heart -> right ventricle is dilated but no hypertrophy
Chronic cor pulmonale
COPD is most common cause -> also IPF, CF, marked obesity -> morphology: right ventricular hypertrophy and often right atrial hypertrophy
Valvular heart disease
congenital or acquired -> valvular involvement by diseases can cause stenosis (failure of a valve to open completely, thereby impeding forward flow) or incompetence, regurgitation or insufficiency (failure of a valve to close completely thereby allowing reversed flow) -> abnormalities of flow often produce abnormal heart sounds (murmurs)
Valvular heart lesions
valve lesions, jet lesions, effects on chambers (hypertrophy and dilation), setting for infective endocarditis (adheres to damaged tissue), thromboemboli
Stenosis
Valvular heart disease - chronic, fibrosis, calcification
Regurgitation (incompetence) -> can coexist with stenosis (chronic rheumatic heart disease)
acute or chronic failure to close completely -> valve destruction or distortion of support (e.g. aorta, annulus, chordae, papillary muscles)
Mitral stenosis (MS)
can be caused by CHRONIC rheumatic heart disease -> non-life threatening, chronic
Mitral regurgitation (MR)
can be caused by myxomatous degeneration (valve prolapsed), rheumatic heart disease, infective endocarditis, dilated cardiomyopathy, myocarditis
Aortic stenosis (AS)
can be caused by rheumatic heart disease, senile calcific stenosis (most common cause in western world), calcification of congenitally deformed valve (congenital bicuspid valve -> higher dynamic stress, high incidence of fibrosis and calcification)
Aortic regurgitation (AR)
can be caused by rheumatic heart disease, degenerative aortic dilation (HTN - ring is dilated, valve cusps cannot come together - most common in western world), syphilitic aortitis, Marfan syndrome
Mitral stenosis
dyspnea (pulmonary edema), fatigue, hemoptysis, late low pitched diastolic murmur, crepitations in lungs (edema)
Mitral regurgitation
dyspnea (pulmonary edema), palpitation, fatigue, pansystolic murmur radiating to axilla
Aortic stenosis
angina, syncope, CHF, mid systolic murmur loudest at base, sharp ejection sound just after I heart sound
Aortic regurgitation
volume overload LHF, bounding pulses, diastolic murmur
Rheumatic fever
acute immunologically mediated, multisystem inflammatory disease following episode of group A strep pharyngitis (3% of patients) after a few weeks -> hypersensitivity reaction -> antibodies against M proteins of bacteria cross react with normal proteins of heart, joints and other tissues -> elevated ASLO, AS-DNAase titers, streptococci are absent from the lesions
Acute rheumatic fever
inflammatory changes in all three layers of heart - pancarditis; myocarditis - hallmark of presence of pathognomonic paravascular Aschoff bodies within connective tissue of the heart within the connective tissue of the heart (fibrinoid necrosis - central zone of eosinophilic matrix infiltrated by T cells, plasma cells and plump activated macrophages - Anitschkow cells - wavy ribbon like chromatin - caterpillar cells, giant cells in all 3 layers of heart); endocarditis - edematous and thickened valves with foci of fibrinoid necrosis - multiple tiny 1-2 mm wart like vegetations along the lines of closure of the mitral valve - no effect on cardiac function; pericarditis - fibrinous pericarditis
Rheumatic fever
joints: chronic inflammatory infiltrate and edema in the joints and periarticular soft tissues -> arthritis is self limited and does not cause chronic deformities; Skin: erythema marginatum (maculopapular rash), skin nodules (contain focal lesions that are essentially large Aschoff bodies
Chronic mitral valvulitis due to rheumatic heart disease
conspicuous irregular fibrous thickening (neovascularized) and calcification of the leaflets, often with fusion of the commissures and shortening of the chordae tendinae -> fixed narrow opening (fish mouth, button hole) - mitral stenosis and regurgitation - McCallum patch
Chronic aortic valvulitis due to rheumatic heart disease
cusps are thickened, firm and adherent to each other - valve orifice is reduced to rigid triangular channel
Clinical features of acute rheumatic fever
peak incidence in 5-15 years 10 days -6 weeks after pharyngitis with group A strep -> arthritis (migratory, large joints), carditis (pericardial friction rub, weak heart sounds, CHF
Clinical features of chronic rheumatic carditis
valvulitis (M>A>T>P) murmurs -> cardiac hypertrophy and dilation -> CHF, arrhythmias, infective endocarditis
Diagnosis of rheumatic heart disease
Jones criteria (pancarditis, migratory polyarthritis of large joints, subcutaneous nodules, erythema marginatum of skin, Sydenham chorea - involuntary purposeless, rapid movements; minor manifestations - fever, arthralgia and elevated ESR) -> need presence of 2 majors or 1 major and 2 minors AND evidence of preceding strep infection -> high ASO titers or positive strep throat culture
Calcific aortic stenosis
narrowing of the aortic valve lumen as a result of deposition of calcium in the cusps and the valve ring -> 90% of patients are > 65 years, can also happen in congenital bicuspid aortic valve patients, aortic valve scarred as a result of rheumatic fever
Morphology of calcific aortic stenosis
dystrophic calcification -> leaflets rigid and deformed by irregular calcified masses -> calcium deposits lie behind valve cusps and extend into the sinus of Valsava (coronary ischemia) -> sometimes over congenital bicuspid valve, marked LVH
Clinical features of aortic stenosis
angina pectoris (increased requirement of hypertrophied myocardium), syncope (poor perfusion of brain), death usually occurs due to CHF or arrhythmias
Mitral valve prolapsed
one of the most common cardiac disorders occurring in 3-5% of the general adult population -> most cases are discovered between the ages of 20-40, more common in females -> intrinsic defect of connective tissue synthesis and remodeling -> may arise as complication of Marfan syndrome
Morphology of prolapsed mitral valve (small percentage involve tricuspid valve)
soft puffed up rubbery cusps, ballooning of the valve leaflets into the left atrium during systole -> chordae tendinae which are often elongated and fragile, may rupture in severe cases -> mitral annulus may be dilated -> concomitant TV involvement 20-40%
Histological morphology of prolapsed mitral valve
soft mucoid degenerated -> thinning of fibrosa layer of valve -> expansion of spongiosa layer -> excessive amounts of loose, edematous, faintly basophilic ground substances within the middle layer of the valve leaflets and chordae (myxomatous degeneration)
Clinical features of mitral prolapsed
most patients asymptomatic -> palpitations, fatigue or atypical chest pain, mid-systolic click (abrupt tension on leaflets and chordae when valve tries to close) -> severe complications in 3% of cases (mitral regurgitation and congestive heart failure, infective endocarditis, ventricular arrhythmias - SCD, thromboemboli - stroke) -> rarely syndrome characterized by scoliosis and high arched palate
Infective endocarditis
infection of the cardiac valves or mural surface of the endocardium resulting in the formation of adherent, bulky mass of thrombotic debris and organisms - termed vegetations -> etiology is bacterial, fungal or rickettsial
Acute endocarditis
destructive fulminant infection -> frequently of a previously normal valve with a highly virulent organism that leads to death within days to weeks of more than 50% of patients despite antibiotics and surgery
Sub acute endocarditis
organisms of low virulence cause infection in a previously abnormal valve, particularly on deformed valves -> most patients recover with appropriate therapy
Predisposing factors to infective endocarditis
pre-existing cardiac abnormality -> mitral valve prolapsed (most common factor), chronic rheumatic valvulitis, degenerative calcific aortic stenosis; prosthetic heart valves (10-20% of cases), intravenous drug abuse (TRICUSPID VALVE), transient bacteremia (dental procedures, urinary catheterization, endoscopy
Pathogenesis of infective endocarditis
hemodynamic factors (abnormal blood flow across damaged valve -> endothelial injury -> focal deposition of platelets and fibrin), adherence properties of microorganisms (fibronectin, adhesion factors - polysaccharides)
Causative organisms of native valve endocarditis
most commonly strep viridans (50-60%) on deformed valves, S. aureus (10-20%) on previously healthy or deformed valves, HACEK group (haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella)
Causative organisms of prosthetic valve endocarditis
Staph epidermidis, gram negative bacilli, fungi
Causative organisms of IV drug abuse endocarditis
S. aureus (most common), streptococci, gram negative bacilli, fungi
Morphology of acute endocarditis
mitral and aortic most commonly involved, tricuspid in IV drug abuse, -> Gross: bulky, friable vegetations that may obstruct the valve orifice, rapid destruction of the valves -> rupture of the leaflets, chordae tendinae, papillary muscles -> ring abscess in perivalvular myocardium -> septic emboli (mycotic aneurysms) -> abscesses
Microscopic acute endocarditis
large number of organisms mixed with fibrin and blood cells -> minimal inflammatory response (valves have poor vascularity)
Subacute endocarditis
Gross: vegetations less friable, lesser degree of valve destruction, ring abscesses uncommon; Micro: presence of granulation tissue, fibrosis, calcification, chronic inflammatory infiltrate
Clinical features of acute bacterial endocarditis
high grade fever with chills, features of septicemia
Clinical features of subacute bacterial endocarditis
low grade fever, malaise, weight loss
Clinical features of infective endocarditis
changing cardiac murmurs, splenomegaly, clubbing of fingers, splinter hemorrhages under nail beds -> fever of unknown origin (FUO, PUO)
Persistent bacteremia
complications: seeding of distant sites, cytokine release -> can cause joint, bone, organ disease, constitutional symptoms
Tissue destruction
complications: valvular insufficiency, AV conduction, abnormalities -> can cause CHF, heart blocks (1/2/3 degree)
Fragmentation
complications: peripheral emboli -> can cause CNS emboli and stroke, MI, splenic or kidney infarcts, mycotic aneurysms -> splinter hemorrhages (under nails), Janeway lesions (palms/soles), Roth spots (retinal hemorrhage), Osler nodes (subcutaneous nodules in pulp of digits)
Release of bacterial antigen
complications: immune complex formation -> can cause focal glomerulonephritis (hematuria)
Diagnosis of infective endocarditis
repeated blood cultures for both aerobic and anaerobic organisms, check for changing murmurs -> treatment is difficult (avascular valves) -> antibacterial therapy (intravenous, long term)
Nonbacterial thrombotic endocarditis (Marantic)
conditions associated with debility including malignancies -> characterized by the presence of sterile vegetations on previously normal valves -> pathogenesis understood (endothelial abnormalities, hypercoagulable states - sepsis/DIC, adenocarcinomas - Trousseau's syndrome) -> usually asymptomatic -> embolization and infective endocarditis (possible complications)
Morphology of Marantic endocarditis
gross: multiple small nodules along line of closure, no destruction of valve, mitral valve is most commonly affected, Lambl excrescences (small tags); micro: nodules composed of eosinophilic material (fibrin) and delicate layer of aggregated platelets -> no inflammation or fibrosis
Libman-Sacks endocarditis
characterized by presence of sterile vegetations on the cardiac valves in patients of SLE -> deposition of immune complex -> no special predilection for the lines of valve closure -> BOTH SIDES OF THE VALVE -> haphazard, patchy arrangement
Prosthetic valves
mechanical (pyrolitic carbon) has pores -> problems = life-long anticoagulation (contact sports, deliveries), RBC destruction (hemolysis); bioprosthetic (porcine, bovine, human) -> no anticoagulation needed, less durable, less durable, matrix deterioration, rigidity, calcification (stenosis), can perforate -> both can develop infective endocarditis
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