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
