Valve Disease Flashcards
What is the composition of valves?
collagen, GAGs, and elastin
What is valvular stenosis?
failure of a valve to open completely, impairing blood outflow
Is valvular stenosis typically an acute or chronic event?
chronic
Causes of valvular stenosis?
calcification (very common) or valve scarring (common in chronic rheumatic disease)
What are some things that can cause degenerative valve disease and affect the ECM?
- calcification, which can be cuspal (typically in the aortic valve) or annular (in the mitral valve)
- decreased numbers of valve fibroblasts and myofibroblasts
- alterations in the ECM
- changes in the production of matrix metalloproteinases or their inhibitors
T or F. Valves with congenital anomalies are more prone to injury
T. For example, bicuspid aortic valves are more susceptible to aortic stenosis due to calcification
Where are the calcifications present in calcific aortic valve disease (CAVD)?
more on the leaflets than the edges so you don’t usually see fusion of the cusps (helps differentiate from rheumatic heart disease)
Outline the development of CAVD.
- proinflammatory monocytes are recruited via activated endothelial cells
- macrophages accumulate and release pro-osteogenic cytokines
- cytokines stimulate the differentiation of myofibroblasts and osteoblast-like cells resulting in generation of calcified matrix vesicles or apoptotic bodies followed by formation of micro- and macro calcifications
What is myxomatous degeneration of the mitral valve?
one or both mitral leaflets are floppy and prolapse (balloon back into the left atrium during systole)
What are the main causes of valvular prolapse?
most primary cases have unknown cause, typically benign course, but some increase risk of endocarditis
Marfan syndrome a common cause/risk factor (fibrillin-1 mutations)
What causes rheumatic heart disease?
immune mediated-antibodies to bug are cross reactive (common cause is GAS B-hemolytic) causing inflammation in all area of the heart that leads to valve scarring and mitral stenosis
What happens in RHD?
Antibodies against GAS M proteins bind myocardium and valves and activate complement and Fc receptor bearing cells, including macrophages and CD4 T cells that promote cytokine-mediated inflammation
T or F. Cultures are often negative for GAS at the time of symptom onset
T, but serum titers of one or more streptococcal antigen (SLS or DNAase) are elevated
What valves are most commonly affected by RHD?
aortic and mitral
IV drug use typically affects what valve?
tricuspid (staph aureus mediated usually)
What are some features of rheumatic heart disease?
- pancarditis (pericardium, myocardium, and valve involvement)
How does RHD affect valves?
- fibrinoid necrosis
- fibrin along line of closure (as opposed to CAVD)- not on the leaflets- causing fusion
What are some of the results of recurrent RHD?
chronically lead to scar formation on the valves
valve cusps becomes thickened and retracted and fuse
chordae tendineae become thick and fuse
neo-vascularization
The most important functional consequence of RHD is what?
valvular stenosis and regurgitation (insufficiency)
How is acute rheumatic fever diagnosed?
Jones criteria:
1) serological evidence of previous strep infection
2) carditis
3) migratory polyarthitis of large joints
4) arrhythmia marginatium skin rashes
5) Sydenham chorea
What is Sydenham chorea?
neurologic disorder characterized by involuntary purposeless, rapid movements (aka St. Vitus dance)
50% recover after 2-6 months
What other problems can RHD cause?
- murmurs
- cardiac hypertrophy and dilation
- CHF
- infectious endocarditis due to scarred valves
-a fib and mural thrombi
What is infective endocarditis?
microbial invasion of heart valves or mural endocardium resulting in bulky, friable vegetations composed or necrotic debris, thrombi, and organisms
T or F. Infectious endocarditis is DESTRUCTIVE to the valve
T, the bacteria will eat through it
What are the risk factors for infectious endocarditis?
- pre-exisitng structural heart disease (RHD, ventricular aneurysm, sub-aortic stenosis etc.)
- degenerative valve disease
- cardiac interventions (prosthetic valve, pacemaker, defibrillator)
- congenital heart disease
What is the number one bacteria responsible for infective endocarditis?
50-80% Strep viridans
-some s. aureus and epi (common with valve replacement)
HACEK organisms (difficult to culture)
What are some clinical manifestations of infective endocarditis?
- B symptoms
- development of new murmur or change in old one
- Osler node (on digits)
- Janeway lesions (on palms)
- Roth spots in the eye
- neuro and renal involvement
Oslers and Janeways are small thrombi
Complications of infective endocarditis?
- cardiac failure (volume overload due to regurgitant lesions, infarcts)
- systemic infarcts (emboli)
- systemic abscess (infected emboli)
- aneurysms (infected emboli)
- renal failure (immune mediated glomerulo-nephritis)
What are the HACEK organisms associated with infective endocarditis? 1-2% of cases
Haemophilus parainfluenza
Actinobacillus actinomycetemcomitans
Cardiobacterium hominis
Eikenella species
Kingella species
What two factors are need for establishment of endocardial infection?
endothelial denudation over valve cusp with platt depositions (thrombus)
-episode of bacteremia
Infective endocarditis progression on a prosthetic valve
Endocarditis on a prosthetic valve usually begins in the valve ring and may protrude into the valve orifice causing obstruction and regurg. Over time, vegetation decreases in size and organizes as a fibrous nodule which may calcify
Nonifected vegetations of the heart is aka?
marantic endocarditis
What is marantic endocarditis?
mainly fibrin and platelet deposit on cardiac valves that is non-destructive
When is marantic endocarditis common?
patients in hyper coagulable states and those with mucinous adenocarcinomas (mass in pancreas a common example)!!
What is a common complication of mar antic endocarditis?
can give rise to emboli that can cause infarcts in the brain, heart, etc.
What is Libman-sacks endocarditis?
small to medium-sized inflammatory vegetations that can be attached on either side of valve leaflets; heal with scarring
seen on BOTH sides of the valve
When is Libman-sacks endocarditis common?
Patients with SLE or anti-phospholipid antibody syndrome
What is carcinoid heart disease?
results from bioactive compounds such as serotonin released by carcinoid (aka low grade neuro-endocrine) tumors
What does the release of bioactive compounds such as serotonin from carcinoid tumors result in?
- flushing
- diarrhea
- dermatitis
- bronchoconstriction
- cardiac impact
When do symptoms and carcinoid heart disease occur?
The tumor has to grow large enough to metastasize to the liver and disrupt the liver’s ability to break down the tumors bioactive compounds to cause symptoms
Where are carcinoid tumors common?
GI tract
What do carcinoid tumors do to the heart?
give it a distinctive, glistening white intimal plaque-like thickening on the endocardial surfaces of the cardiac chambers and valve leaflets due to abundant acid mucopolysaccharides
What are the two types of prosthetic valves currently used?
- mechanical
- bioprosthetic
Describe mechanical valves.
made of pyrolytic carbon, durable and long longer but can cause significant red cell hemolysis
require chronic anticoagulation
Describe bioprosthetic valves.
glutaraldehyde-fixed porcine or bovine tissues, or cryo-preserved human valves- less durable and will eventually fail due to matrix deterioration
do not require chronic anticoagulation
