Valvular Heart Disease Flashcards
All cusps of the heart valves are attached to what?
attached to ring of dense tissue (annulus fibrosus) around the orifice
What attaches to the AV valves to prevent them bulging into the atria?
papillary muscles
Coronary arteries come off where?
come off the sinus in the out-flow tract of the aortic valves
Valves consist of
folds of endocardium covering a core of dense fibrous connective tissue which are continuous with the annuli fibrosis and the chordae tendinae
What are valves lined on both sides by
endothelial layers
How are the AV valves histologically different from the semilunar valves?
AV valves have smooth muscle on the atria side and are thicker than semilunar valves
Mechanics of how valves open and close
valves close passively when backflow pressure is greater than chamber pressure
valves open when chamber pressure is greater than outflow pressure
What is directional flow dependent on
competency of the valves
Why is velocity of blood through the semilunar valve greater?
due to smaller openings and greater chamber pressure (ventricles have more muscle than atria); therefore the edges of the pulmonic and aortic valves are subject to greater mechanical abrasion
insufficiency
failure to close completely, allowing regurgitation and backflow into the chamber
stenosis
narrowing or constriction of an orifice; most frequently involving the pulmonic or aortic opening
current formation
abnormal valve function may cause “jet streams” which can damage vessels, or current eddies which allow thrombosis and bacterial deposition on either side of the valve
Left-sided flow disruptions
mitral stenosis; mitral regurgitation; aortic stenosis; aortic regurgitation
mitral stenosis
most often caused by post-inflammation scarring due to rheumatic fever; often coexists with insufficiency; takes decades to develop and is remarkably well tolerated
mitral regurgitation
failure of valves to close completely; caused by infection and papillary muscle abnormality
aortic stenosis
may be congenital or acquired; most commonly caused by calcific degeneration of bicuspid valves; obstruction of left ventricular outflow leads to pressure overload and left ventricular hypertrophy
Infection with aortic stenosis may lead to?
acute cusp destruction and sudden decompensation resulting in rapidly fatal cardiac failure
aortic regurgitation
results from intrinsic valvular disease or aortic root disease (syphilis); leads to volume overload and left ventricular hypertrophy
Insufficient cardiac output leads to
syncopal episodes (acute); chronic results in left ventricular hypertrophy and attempts by the kidney to increase volume by retaining salt and water; increased peripheral resistance also tries to compensate
Mechanical valve damage
“jet stream” damage to aortic and pulmonic outflow tracts
Types of embolic thrombi
- infectious - vegetations in endocarditis
2. thrombotic - vegetations (both infectious and inflammatory); small clots
Clinical consequence of embolic damage
occlusion of vessels; seeding of infections
Congenital valvular lesions
- Bicuspid aortic valve
2. Mitral valve prolapse
Incidence of bicuspid aortic valve
presents in 6th - 7th decade
Pathology of bicuspid aortic valve
nodules restricted to base and lower halves of cusps; rarely involve free margins of leaflets
Pathogenesis of bicuspid aortic valve
congenital bicuspid aortic valve -> progressive calcification of cusps -> calcific aortic stenosis
gross features of bicuspid aortic valve
- heaped-up, calcified masses within aortic cusps that protrude in the sinuses of Valsalva
- architectural distortion
- no comissural fusion
microscopic features of bicuspid aortic valve
fibrosed and thickened cusps
Clinical significance of a bicuspid aortic valve
little functional significance at birth; but predisposes to secondary calcification in adult life
Clinical progression of a stenosed/bicuspid aortic valve
stenosed valve -> increased pressure gradient across valve -> left ventricular hypertrophy -> decompensation -> angina, syncope -> cardiac failure
Incidence of mitral valve prolapse
7% of US population; females:males = 6:4; 20-40 years of age; often associated with Marfan’s syndrome and connective tissue disorders
pathogenesis of mitral valve prolapse
floppy enlarged mitral leaflets balloon into left atrium during systole; snapping or tensing of everted cusps or chordae tendineae; incompetent valve
Murmur heard in mitral valve prolapse
midsystolic click; late systolic click; or holosystolic murmur
gross features of mitral valve prolapse
billowing of mitral valve leaflets (prolapse); pathologic hooding if >4mm above base of cusp; stretched, elongated, or ruptured chordae tendineae; may also have tricupid and pulmonary valve involvement
microscopic features of mitral valve prolapse
degeneration/attenuation of zona fibrosa; thickening of spongiosa layer; loose connective tissue on collage of chordae tendineae; fibrosis of valve/and ventricular surface, also calcification
Clinical correlations with mitral valve prolapse
most are asymptomatic; symptomatic MVP: some chest pain like angina, dyspnea, fatigue, depression, personality disorders, anxiety reactions
Major concerns with mitral valve prolapse
infective endocarditis; mitral valve insufficiency; arrhythmia; sudden death
Inflammatory causes of valvular lesions
- Rheumatic heart disease
2. SLE
Rheumatic heart disease
an acute, recurrent inflammatory disease, principally of children, that follows pharyngeal infection with group A-hemolytic streptococci (S. pyogenes)
Incidence of rheumatic heart disease
steadily declining; important pre-disposing factor for degenerative heart disease in later decades; leading cause of death from heart disease between the ages 5 and 25
pathogenesis of rheumatic heart disease
heightened immunologic activity to streptococcal antigens; antibodies cross react with other tissues; hyaluronate capsules of strep are identical to hyaluronate; antibodies cross react with glycoproteins in heart valves
What kind of antibodies correlate with development of rheumatic heart disease
antibodies to streptolysin O
gross features of rheumatic heart disease
most often involves mitral and aortic valves; mitral valvulitis results in stenosis; acute rheumatic pericarditis (fibrinous)
characteristic vegetations of rheumatic heart disease
verrucae
Major criteria of acute rheumatic fever
i. migratory polyarthritis
ii. pancarditis
iii. subcutaneous nodules
iv. erythemia marginatum
v. sydenham chorea
Pathognomonic for rheumatic myocarditis
Aschoff bodies
Describe an Aschoff body
foci of fibrinous necrosis surrounded by lymphocytes and macrophages, Anitschkow cells (reactive histiocytes with slender, wavy nuclei) giant cells, and fibrinoid material
Anitschkow cells
reactive histiocytes with slender, wavy nuclei; seen in rheumatic myocarditis
valvular lesions of rheumatic heart disease
verrucae vegetations with beading of vegetations along the liens of closure; focal collagen degeneration surrounded by inflammation; ulceration of valve surface with deposition of fibrin;
Where are valvular lesions of rheumatic heart disease also found
also found in pericardium (pericarditis), myocardium, endocardiu, and subendocardium (MacCallum plaques)
friction rub and chest pain are symptoms of
pericarditis
Minor criteria of rheumatic heart disease
history of rheumatic fever, arthralgias, fever, lab tests indicative of inflammation (increased sed. rate, leukocytosis, C-reactive protein), EKG changes
major cause of death with rheumatic heart disease
congestive heart failure from myocarditis (although valve dysfunction may play a role)
clinical correlations with rheumatic fever
increased vulnerability to reactivation of disease with subsequen pharyngeal ifnections
Rheumatic heart disease most often affects which valves
mitral and aortic valves
Describe chronic rheumatic heart disease
may involve recurrent attacks with different forms of streptococci; sometimes subacute form of single attack; permanent deformity of the valves; conspicuous, irregular thickening/fusion of leaflets; MacCallum’s patches
Incidence of Libman-Sacks disease
vegetations on the mitral and tricuspid valves occur in approximately half the cases of SLE; unlike rheumatic heart disease, often involves valves on the RIGHT side of the heart
Libman-Sacks disease often involves which valves
valves on the RIGHT side of the heart
Libman-Sacks vegetations are composed of
composed of necrotic debris, fibrinoid material, disintegrating fibroblasts and inflammatory cells
Describe Libman-Sacks vegetations
small; usually occur on flow side of leaflets, but can occur behind them; usually occur/multiply in random fashion; rarely spread to mural endocardium or chordae tendineae
Pathology of Libman-Sacks disease
“fibrinoid necrosis” with neutrophils and mononuclear infiltrate; myocardial arterioles and small arteries may undergo necrosis
Compare the affected valves in IE, rheumatic endocarditis, and Libman-Sacks
IE: any
rheumatic endocarditis: mitral (sometimes aortic)
Libman-Sacks: mitral > tricuspid > pulmonic
Compare the size of vegetations in IE, rheumatic endocarditis and Libman-Sacks
IE: large
RE: small
LS: small
Distribution of vegetations in infective endocarditis
not widely dispersed; singly or 2-3 in foci; rarely found behind cusps
Distribution of vegetations in rheumatic endocarditis
confined to lines of closure of cusps; “beading” verrucae; almost never behind cusps
Distribution of vegetations in Libman-Sacks endocarditis
multiple, random; usually on flow side, but can occur behind
Endocarditis
colonization or invasion of valves or mural endocardium by a microbial agent leading to the formation of friable vegetations
Endocarditis is most often associated with
pre-existing anomaly, valvular disease, or congenital heart disease
Prophylaxis with endocarditis patients
prophylactic use of antibiotics in any person with cardiac anomalies or artificial valve undergoing dental procedures
Organisms that cause endocarditis
95% bacteria: Strep viridans; Staph; enterococci; Pneumococci; Gram negative rods
5% viruses: rickettsia, chlamydia, fungi
Predisposing conditions to endocarditis
any anomaly leading to abnormal flow, shunting (particularly right to left), exposure of collagen, or damage to valves
Predisposing diseases to endocarditis
Rheumatic heart disease, congenital heart disease, bicuspid aortic valve, mitral valve prolapse, aortic stenosis, cardio-vascular surgery (sutures), IV drug abuse, immunosuppression, bacterial seeding with any of the above agents
IV drug use predisposes to
right sided endocarditis infections (S. aureus, Candida, Aspergillus)
Pathogenesis of endocarditis
for damaged valves or deranged blood flow: deposition of fibrin and agglutinated organisms;
for right to left shunt: bypass filtering of blood by lungs
gross features of endocarditis
friable, bulky, usually bacteria-laden vegetations on heart valves; old lesions become fibrotic, calcified masses
Valves most often affected by endocarditis
mitral and aortic valves
Microscopic features of endocarditis
vegetations: irregular masses of fibrin strands, platelets, blood cell debris, organisms and inflammatory cells
valve leaflets: vascularizations and nonspecific inflammation
What eventually happens to the valves in endocarditis
erosion, destruction of valve leaflets (particularly with acute endocarditis); “fenestration”
deformation of valves leaflets: valvular stenosis, insufficiency
Acute congestive heart failure in endocarditis
cardiogenic shock from acute decompensation of valve
Subacute congestive heart failure in endocarditis
chronic development of CHF
Describe the pericarditis that can occur as a complication of endocarditis
suppurative pericarditis (penetration of heart wall or lymphatic extension); myocardial metastatic abscesses
Extrinsic clinical consequences of endocarditis
- seeding of aortia, kidney, spleen, brian with infective emboli
- arterial thrombotic emboli
Acute bacterial endocarditis
bacterial cause endocarditis; acute caused by highly virulent organism which can lead to death in days to a week; may occur in a normal heart
Most common overall cause of endocarditis
Streptococcus viridans (low-virulence) small vegetations
Most common cause of endocarditis in IV drug users
Staphylococcus aureus (high-virulence) large vegetations
Clinical features of bacterial endocarditis
fever, murmur, Janeway lesions (nontender on palms and soles), Osler nodes (tender on fingers and toes), splinter hemorrhages, Roth spots (embolism), anemia of chronic disease
Clinical circumstances of acute bacterial endocarditis
destructive, tumultuous infection; organisms tend to produce necrotizing, ulcerative, invasive valvular infections; may be predisposed by heart defects, but often occurs in a normal heart; may be associated with IV catheter or prosthetic valves
Leading cause of acute bacterial endocarditis
Staph aureus
Pathogenesis of S. aureus acute bacterial endocarditis
seeding of blood; may develop in any individual when organism is sufficiently virulent, bacterial invasion is sufficiently large, and resistance of host is depressed
Morphology of acute bacterial endocarditis
friable, bulky, bacteria-laden vegetations
Acute bacterial endocarditis may lead to
perforation or erosion of leaflet, invasion of underlying tissue, or may undergo progressive sterilization, fibrosis, organization, calcification
clinical course of acute bacterial endocarditis
prompt diagnosis and treatment greatly improve prognosis; fever most common sign; rapidly developing fever, chills
Subacute bacterial endocarditis usually occurs in the presence of which previous heart diseases/conditions
congenital heart disease (MVP most common); rheumatic heart disease; previous surgery; previous endocarditis; IV drug use
Most common cause of subacute bacterial endocarditis
Strep viridans
Other organisms that can cause subacute bacterial endocarditis
Group D strep, enterococci
How do patients present with subacute bacterial endocarditis
with risk factors; flu-like illness that has been going on for months; heart murmur, signs of systmeic infections
How do you treat subacute bacterial endocarditis
need antibiotics to cure infection; difficult to treat because bacterial hide on valves
Complications from subacute bacterial endocarditis
heart failure; MI from embolism; mycotic aneurysm; glomerulonephritis
How do you get non-bacterial thrombotic endocarditis (NBTE)
endothelial damage -> platelet and fibrin deposition on valve leaflets -> formation of nodular vegetations
What is non-bacterial thrombotic endocarditis associated with
SLE; cachexia, mucin-producing tumors, or damage to endothelium
Occurrence of carcinoid heart disease
1% of all patients who have argentaffinoma and 10% of those with GI carcinoids with hepatic metastases
Clinical features of carcinoid heart disease
distinctive episodic flushing of the skin, and cramps, nausea, vomiting, and diarrhea; cardiac lesions in about 50%
Pathology of carcinoid heart disease
deposits of pearly gray, uniform fibrous tissue on tricuspid and pulmonic valves leading to insufficiency and stenosis
Which side of the heart does carcinoid heart disease affect and why?
Carcinoids affect the right heart because the tumor products are metabolized in the lungs and do not reach the left heart
Fibrous tissue reaction in carcinoid heart disease is due to
elaboration of bioactive products by argentaffinomas, including serotonin, kallikrein, bradykinin, histamine, prostaglandins, and newly described tachykinins P and K
Gross features of carcinoid heart disease
plaque like thickenings composed of an unusual type of fibrous tissue are superimposed on the endocardium of the cardiac chambers and valvular cusps; mainly on the outflow tract of the right ventricle
Microscopic features of carcinoid heart disease
fibrous thickening resembling cellular atheromas
Pathogenesis of ischemic valvular dysfunction
lack of oxygen perfusion mainly affects annulus rings behind valves, not the actual leaflets; leads to calcium deposition with no inflammatory change
ischemia can affect papillary muscles
Indications for artificial heart valve
congenital disorders; valvular stenosis; valvular regurgitation; destruction of cusp by infection
