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Valvular Disease and Endocarditis
Valvular Disease – results in Stenosis, Insufficiency, or both
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Stenosis is the failure of a valve to open completely, thereby impeding forward flow.
Insufficiency (a.k.a. regurgitation or incompetence) caused by incomplete valve closure,
allowing a reversed flow.
o A complication of insufficiency is Prolapse = the paradoxical backward movement of
valve cusps or leaflets
o *Functional regurgitation results from ventricular dilation  papillary muscles pull 
and out incomplete closure
Cause may be acquired or congenital (acquired Stenosis of mitral and aortic valves account
for 2/3 of lesions)
o Stenosis: almost always due to primary cuspal (intrinsic) abnormality and is virtually
always from a chronic process
o Insufficiency: due to intrinsic abnormalities; or *structural damage or distortion of
valvular support structures
Histological layers of Valves:
o (1) Ventricularis (aortic)/Auricularis (mitral)
o (2) Spongiosa
o (3) Fibrosa
o (4) arterialis
Anatomy
o valve components – lined with endothelium; dense collagenous core (fibrosa); loose
connective tissue (spongiosa)
o Annulus is rim of valve that attaches valve to heart and major vessels.
o Free edge of leaflet: is far edge of valve
 free edge – free portion of the valve not in contact with the opposite leaflet
o Closing edge: area where overlapping and non-overlapping portions of valve meet
 closing edge – portion of the valve in contact with the opposite leaflet
Valve Development
o leaflets form from 3 embryonic buds
o bicuspid valves  one of the leaflets do not from and one of the forming leaflets
compensates by becoming larger; this larger leaflet contains a median raphe where
the leaflet should have formed
Major Causes of Acquired Heart Valve Disease
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Mitral Valve Disease
o Mitral Stenosis (Intrinsic)
 Postinflammatory Scaring (rheumatic heart disease)
o Mitral Regurgitation
 Abnormalities of leaflets and commissures (Intrinsic)
 Postinflammatory Scaring
 Infective endocarditis
 Mitral valve Prolapse
 Abnormalities of tensor apparatus (Structural)
 Rupture of papillary muscle
 Papillary muscle dysfunction (fibrosis)
 Rupture of chordae tendineae
 Abnormalities of the left ventricular cavity and or annulus (Structural)
 Left ventricular enlargement (myocaeditis, dilated cardiomyopathy)
 Calcification of mitral annulus
Aortic Valve Disease
o Aortic Stenosis (Intrinsic)
 Postinflammatory Scaring (rheumatic heart disease)
 Senile calcific aortic Stenosis
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 Calcification of congenitally deformed valve
Aortic Regurgitation
 Intrinsic Valvular disease
 Postinflammatory Scaring (rheumatic heart disease)
 Infective endocarditis
 Aortic Disease (Structural)
 Degenerative aortic dilation
 Syphilitic aortitis
 Ankylosing spondylitis
 Rheumatoid arthritis
 Marfan Syndrome
Valvular Diseases Classified by Type of Valvular Dysfunction
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(1) Mitral Valve Prolapse (Myxomatous Degeneration of the Mitral Valve): special form of
regurgitation
o due to inborn error of metabolism (associated with Marfans Syndrome)  tensile
strength of leaflets and chordae tendini  billowing leaflets  snap up into atria
during systole making systolic click. Can progress to regurgitation (murmur)
o affects 3-7% of US adults; mostly women (6:4). If it becomes symptomatic, patients
usually present between 20-40 yo.
o 3% of MVP patients develop:
 (1) Infective endocarditis
 (2) Mitral insufficiency
 (3) Stroke or other infarct, or
 (4) Arrhythmias
o Gross
 Intrinsic abnormalities: Intercordal ballooning (hooding) of mitral leaflets,
which are often thick and rubbery.
 Annular dilation is characteristic (rare in other causes of mitral
insufficiency).
 Support structure abnormalities: often tendinous cords are elongated,
thinned, and occasionally ruptured. Webbing
 Normal Commisures (fusion is seen in Rheumatic heart disease)
o Micro
 Myxoid degeneration: focal thickening of the spongiosa layer with
deposition mucoid (myxomatous) material and degeneration of the fibrous
layer on which the structural integrity of the leaflet depends. Collagen of
cords is also .
 Disorganization
(2) Insufficiency/ Regurgitation
o Intrinsic Abnormalities: perforations or holes, ulcerations, vegetative growths
o Support structure abnormalities: disruption of annulus (stretching due to 
pressures), chordae tendini fusion, and papillary muscle dysfunction caused by MI.
o Endocarditis is the # 1 cause of Aortic and Mitral Insufficiency. The following forms
of endocarditis cause insufficiency:
 (a) Infective Endocarditis: Serious! usually bacterial; creates large (few cm)
vegetations of thrombotic debris and organisms
 Covers and causes destruction to outflow track: valves, mural
endocardium. Grows on free edge and chordae tendini
 On normal and abnormal valves; left > right; lack of circulation to
valves makes it hard for antibiotics to work on them.
 Gross: large friable bulky vegetations; can emboli and cause septic
infarcts. Can cause ulcerations, perferations, abscess etc. These
complications are rare in the other forms of endocarditis.
 Micro: sub-acute  granulation tissue base. Eventually fibrosis,
calcification and chronic inflammatory infiltrates.
 (b) Thrombotic Vegetation (Nonbacterial Thrombotic EndocarditisNBTE):these vegetations are STERILE! and small (1-5mm)
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outflow surface of leaflets are affected by deposition of fibrin and
blood elements from an underlying disease.
 Gross: Forms along the line of closure; valves are usually normal;
and right side is affected as much as left.
 Micro: bland thrombus without accompanying inflammation reaction
or induced valve damage.
 (c) Libman-Sacks Endocarditis (Endocarditis of SLE) Most common of the
CT disease that cause this. This was FYI.
o Rheumatic Heart Disease (causes stenosis (see #3 below) as well as insufficiency;
causes 99% of mitral stenosis)
 Sequela of Rheumatic fever following Group A ( -hemolytic) streptococcal
pharyngitis
 Inflammatory and healing reaction to repeated immunological injury- probably
a type 2 hypersensitivity reaction
 Probably Ab against M protein of some strains of strep cross-react with
glycoproteins in heart, joints and other tissues.
 This leads to cellular immunity as well.
 (a) Acute Rheumatic Fever is one of the only things that leads to
Pancarditis. This stage can result in Insufficiency. Pancarditis involves
inflammation of entirity of any of the three layers of the heart:
 Pericardium: Fibrinous pericarditis – fibrinous or serofibrinous
pericardial exudate (bread and butter pericarditis).
 Myocardium: Myocarditis: deposition of immune complexes leads to
inflammatory lesions that are distinctive in the heart = Aschoff
bodies: foci of fibrinoid necrosis surrounded by lymphocytes (primary
T cells)
 Can see plasma cells and plump macrophages called
Anitschow cells (pathognomonic for rheumatic fever).
 Antischow cells have abundant amphophilic cytoplasm and
central round to ovoid nuclei with the chromatin in a central,
slender wavy ribbon ( the name caterpillar cells) Large
multi nucleated = Aschoff giant cells.
 Myocarditis may cause cardiac dilation that may evolve to
mitral valve insufficiency or heart failure.
 Endocardium: Involvement of outflow track and left valves by
inflammatory foci  fibrinoid necrosis of cusps or cords
 Vegetations sit on top of these along the line of closure.
 Have "bread and butter" appearance (irregular wart
projections); probably result from precipitation of fibrin at
sites of erosion related to underlying inflammation and
fibrinoid degeneration.
 Main threat to life is acute heart failure due to myocardial
inflammation or arrhythmia due to damage to conduction.
 (b) Chronic Rheumatic Heart disease: as already mentioned, causes both
insufficiency and stenosis.
 Characterized by organization of the acute inflammation and
subsequent deforming fibrosis.
 Gross: Valve leaflets become thickened and retracted  permanent
deformity.
 Mitral valve is almost always involved but clinical significance
results when aortic is affected
 Additionally there is commissural fusion; thickening,
shortening and fusion of the tendinous cords.
 Micro: diffuse fibrosis and often neovascularization that obliterates
the layered avascular leaflet architecture.
 Aschoff bodies are replaced by fibrous scars.
(3) Stenosis
o Chronic Rheumatic Heart disease: most frequent cause of mitral Stenosis (99% of
cases)
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65-70% of cases solely involve the mitral valve. 25% involve mitral and aortic.
Similar but less severe involvement of tricuspid possible; pulmonary
involvement rare.
 Fibrous bridging across the valvular commissures and calcification create
fish mouth or button hole Stenosis.
 Tight mitral Stenosis  dilation of left atrium  mural thrombosis.
 Long standing congestion  to pulmonary changes  right ventricular
hypertrophy. LV is normal in mitral Stenosis.
Valvular degeneration caused by Calcification
 Acquired aortic Stenosis is consequence of wear and tear (repeated
bending stiffening like with polymers in credit card)
 Dystrophic calcification with less lipid deposition and cellular proliferation than
atherosclerosis but still similar
 3 Types: (1) senile calcific aortic stenosis, (2) congenitally bicuspid
aortic calcification, (3) mitral annular calcification
 Senile (70-90yo) and Congenitally bicuspid (50-70yo) aortic calcification
involve the same process which accelerates in the bicuspid because wear
and tear is spread over 2 valves instead of 3. Commissures are the points
along the annulus where the leaflets meet and were buds from which the
leaflets separated embryologically. Congenital bicuspid valves result from
one of 3 buds not forming and a raphe forming where the leaflets would have
separated.
 Characterized by heaped up calcified masses within the aortic cusps that
ultimately protrude through the outflow surfaces into the sinuses of valsalva
 preventing the opening of the cusps.
 Begins within the valvular fibrosa at point of maximum flexure (margins of
attachment), distorting architecture at base.
 Free edges not involved, commissural fusion is absent, mitral valve spared.
(Contrast to rheumatic aortic Stenosis).
 Mitral annular calcification: stony, hard, sometimes ulcerating nodules of
Ca build up along annulus behind leaflet.
 Normally does not affect function but can affect AV conduction if Ca
penetrated too far, can cause insuff or Stenosis.
 Appears mostly in women > 60 yo.
Endocarditis – cause of cardiac valvular insufficiency; formation of vegetations on the
endocardium
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Types
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(1) infective (bacterial or fungal)
(2) thrombotic (marantic),
(3) rheumatic (due to rheumatic heart disease)
(4) Libman-Sacks (due to connective tissue disease such as systemic lupus
erythematosus)
(1) Infective Endocarditis – due to colonization or invasion of endocardium of the cardiac
valves by microorganisms
o large
o found on outflow surface of leaflet; along free margin
o on normal or abnormal valves
o endocarditis found on left side of the heart more frequently than the right
o high virulent organisms  destructive, rapidly progressive and may be fatal
o low virulent organisms  insidious, follows a protracted course and may resolve
without dysfunction
(2) Thrombotic (Marantic) Endocarditis
o sterile
o small
o outflow surface of leaflets
o found along line of closure
o found on normal or abnormal valves
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o right valve = left valve
o fusion of the chordae tendinae
(3) Rheumatic Heart Disease
o Definition Rheumatic heart disease follows rheumatic fever which is an acute,
immunologically mediated, multisystem inflammatory disease that occurs a few
weeks after an episode of Group A streptococcal pharyngitis and often involves the
heart.
o Etiology sequelae of rheumatic fever; not a direct infection; inflammation or healing
reaction to repeated immunologic injury  antistreptococcal Ab cross reacting with
cardiac tissue, cardiac Ab or cellular immunity
o Histology characterized by inflammatory changes involving all portions of the heart epicardium, myocardium and endocardium  pancarditis
 Epicardium (Pericarditis)  serofibrinous exudate which may be localized or
generalized ("bread and butter")
 Long Term Sequelae: organization and healing of pericardial
inflammation exudate leads to diffuse pericardial fibrosis with
obliteration of the pericardial sac and pericardial space
 Myocardium  focal interstitial inflammatory lesions; characterized by the
pathognomonic Aschoff Nodule and diffuse interstitial myocarditis
 may injure the myocytes directly or damage the conduction system
 Endocardium  – valvulitis; inflammatory infiltration and edema in the
stroma of the valves with superimposed presence of rheumatic vegetations,
small bead-like projections on the atrial surfaces of the atrio-ventricular
valves and on the ventricular surface of the aortic valve
 pulmonic valve is rarely involved
 Long Term Sequelae: organization and healing of acute inflammatory
lesions leads to scarring and vascularization of the cusps and leaflets
 leads to adhesions between the cusps and leaflets
 thickening, shortening and fusion of the chordae tendineae
 valve rigidity and stenosis of the valve orfice
o Gross Anatomy
 cardiac lesions are usually sterile
 very small
 outflow surface of leaflets
 mitral valve effected more often then aortic
o Prognosis–mild disease may heal by resolution and inflammatory changes disappear
without permanent cardiac damage
 most episodes of acute rheumatic heart disease heal by organization with
permanent cardiac damage
 recurrent attacks of rheumatic fever with accompanying carditis are very
common and additional injury may occur
 arrhythmias may arise from damage to the conducting tissues  major
threat to life
 acute rheumatic inflammatory infiltration of myocardium can inhibit the
contractile properties of the heart  CHF
 Chronic Rheumatic Disease (not "chronic rheumatic fever") – pathologic
status of the heart created by previous cardiac insults; no inflammatory
state
o Epidemiology – nonrheumatic cardiac heart disease is now the most common
valvular disease; rheumatic disease was the most common valvular disease 30 years
ago when rheumatic fever was more common
o Chronic Rheumatic Valvular Disease
 Gross Anatomy  "fishmouth" deformity; leaflet thickening and fibrosis
o Symptoms – fever; malaise; cardiac murmurs may be present with left-sided
vegetations, but probably relate more to the pre-existence of a cardiac anomaly
predisposing to endocarditis than to the endocarditis itself
o Complications – valvular insufficiency or stenosis; cardiac failure;
thromboembolization with visceral infarction; metastatic infection (infective
endocarditis)
Aortic Stenosis
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Etiology – dystrophic calcification of a congenitally bicuspid valve or senile
calcification of a normal tricuspid valve in old age are the most common forms of aortic
valve stenosis
o both causes result in rigidity of the cusps and stenosis of the valve origin
Gross Anatomy - calcifications are usually nodular, found either within the cusps themselves
or along the line of closure and protrude into the sinuses of Valsalva
o Long Term Sequelae: chronic heart failure is most serious
o Angina or syncopal attacks due to  oxygen supply or compromised microcirculation
in the myocardium due to hypertrophy may occur
Valvular Insufficiency and Regurgitation
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Definition – failure of a valve to close completely, therefore allowing retrograde flow
o stenosis and insufficiency often coexist in the same valve, but one defect often
predominates
o prolapse is a paradoxical backward movement of the valve cusps
Cause – Intrinsic  vegetation; ulceration; perforation; stenosis
o Support Structures  dilation or rigidity of annulus; chordae tendinae or papillary
muscle abnormalities
Mitral Valve Prolapse
o Etiology: may be due to congenital anomalies, dystrophic calcification of annulus or
due to an inflammatory disease
 "Floppy Valve" – Primary Myxoid Degeneration – most common cause of
valvular insufficiency
o Floppy Valve – myxoid degeneration leading to a  in tensile strength of the
connective tissue of the valve; results in stretching, elongation and enlargement of all
valve structures
o chordae tendineae become elongated and attenuated forming a web or mesh on the
ventricular surface of the leaflet  may rupture
o interchordal hooding (or ballooning) of the leaflets between the points of attachment
of the chordae tendineae
o Histologically – severe myxoid degeneration in the valves with pools of myxoid
material disrupting or destroying the normal layered valve architecture
o Etiology – unknown; regarded as a congenital anomaly and may be related to other
connective tissue diseases such as Marfan’s syndrome
o Epidemiology – extremely common; 5-10% of the general population in the US;
Men:Women – 4:6; first detected in 20-40 year olds
o Clinical – mid-systolic click corresponding to opening of the prolapsed mitral valve
leaflets in the left atrium