Valvular Heart Disease Flashcards
What are the 3 main conditions that cause aortic stenosis?
- Dystrophic calcification (degeneration)
- Rheumatic heart disease
- Bicuspid valve
The 3 leaflets of the aortic valve open during _______ to allow blood to flow from the ________ to the _________.
The leaflets open during systole to allow blood to flow from the LV to the aorta.
When does aortic valve opening occur?
When does it close?
It opens when LV pressure exceeds aortic pressure.
It closes when the aortic pressure exceeds LV pressure at the end of ejection (systole).
During systole, the aortic valve area normally is what?
What is the pressure gradient between LV and aorta?
The area is 2.5-4 cm squared and there is only a trivial pressure gradient between LV and aorta
In a normal heart, what is the only heart sound that should be associated with the aortic valve?
What does the sound mark the beginning of?
A2 of the second heart sound when the valve closes after ejection (systole) and aorta pressure > LV pressure. This sound marks the beginning of diastole.
Abnormality of aortic valve structure and function can results in ______________during systole or __________ during diastole.
Aortic stenosis (obstruction of LV outflow at the valve level) during systole Aortic regurgitation/insufficiency (backward leakage of aortic blood into LV) during diastole
Aortic stenosis leads to __________ overload of the LV with resultant ____________________ resembling that seen with severe hypertension.
PRESSURE overload of the LV with resultant LV hypertrophy resembling that seen in severe hypertension.
Aortic regurgitation leads to _______ overload of the LV with resultant ___________.
VOLUME overload of the LV that results in LV chamber dilation (cor bovinum)
Who is mainly affected by dystrophic calcification of aortic valves?
Elderly because this is the result of years of atherosclerotic material and calcific deposits on the aortic cusps and commissures.
They do not have clinically relevant evidence of AS until 70-80 years old
When do patients with tricuspid valves present with degenerative AS?
With a bicuspid valve?
normal valve- over 70 years old
bicuspid valve - 40 to 50 years old
How does the deposition product differ between rheumatic heart disease and degenerative AS?
Degenerative- calcific and atherosclerotic deposits
Rheumatic- fibrosis and calcification of the mitral AND aortic valve.
Is AS an acute or chronic problem with the valve?
Chronic- gradual asymptomatic progression of aortic valve obstruction over many years.
0.1cm sq a year in patients diagnosed with AS.
How is flow across a valve calculated? Explain what this means for aortic stenosis.
Flow = area x velocity
The goal is to maintain constant flow to tissues.
In AS, the area is decreased, so you need to increase velocity.
To increase velocity you need to convert potential energy (pressure) to kinetic (velocity) at the valve orifice.
This leads to a pressure decrease just down stream from the valve.
Peripheral autoregulation maintains BP in the aorta to perfuse tissue, so LV pressure has to increase as a result to maintain a pressure gradient over the valve.
What are the pathological changes in heart as a result of the increased LV pressure due to AS?
- compensatory hypertrophy and increased wall thickness of the LV.
- This increases the stiffness, diastolic pressure rises and leads to pulmonary congestion.
- systole fails due to hypertrophy and increased work for ejection
What is the prognosis for someone with AS that has symptoms of:
- CHF
- Syncope
- Angina
- 2 years
- 3 years
- 5 years
What are the 3 main presenting symptoms of someone with aortic stenosis?
- Angina (with exertion due to hypertrophied heart)
- syncope (related to or post exertion)
- CHF (first at exertion then proceeding to rest)
What is heard on auscultation for AS?
What component of the sound tells you it is worse?
- a systolic ejection murmur that peaks in mid-to-late systole.
- S4 gallop due to hypertrophy
- ejection click early in systole (opening)
- paradoxical splitting and diminished A2
The later the peak, the worse the prognosis.
Where do murmurs from aortic stenosis radiate to?
When you palpate this area what do you notice?
It radiates to the carotids.
The carotid pulse will be diminished in amplitude and delayed in time (PULSUS PARVUS EN TARDUS)
Why is it difficult to appreciate pulsus parvus en tardus in the elderly?
They have stiff, atherosclerotic carotid arteries
What does the CXR show in someone with AS?
Are the finding specific and diagnostic?
- calcification of aortic valve
- post-stenotic dilation of ascending aorta
- cardiomegaly
- pulmonary congestion
These findings are non-specific and thus not diagnostic
What is seen on the EKG for AS?
Is this diagnostic and specific?
LVH so:
- R wave >11mm in aVL
- R wave in V4-V6 >25mm
- S in V1 + R in V6 or V5 >35mm
Not specific for AS so, not diagnostic.
What is the most useful non-invasive test for AS?
What exactly is evaluated?
Echocardiography Evaluates: 1. LVH 2. ventricle chamber size and function 3. quantitative aortic valve area
What is the continuity equation and what does it allow you to calculate?
It measures the velocity and cross-sectional area of the LV outflow tract proximal to the aortic valve. The product (VxCSA) is divided by velocity of flow at the stenotic valve to yield the valve area.
What technique allows you to see the direction and speed of RBCs to calculate pressure gradients and aortic valve velocity?
Doppler echo
What are the two main techniques used to measure aortic valve area?
What is a normal aortic valve area?
What is the area for mild stenosis, moderate and severe stenosis?
- Doppler Echo
- Cardiac catheterization
Normal is 2.5 -4 cm sq
Mild is 1.5 to 2 cm sq
moderate is 1.0 to 1.5 cm sq
Severe is less than 1cm sq
What is done in elderly patients with AS to assess the presence of CAD prior to aortic valve surgery?
Cardiac catheterization
What is the main determinant for whether or not to do surgery for someone with AS?
Symptoms (angina, syncope, CHF) NOT valve area
It was found using Doppler echo, that even if a patient has “severe” stenosis (less than 1cmsq), if they are asymptomatic, their risk of mortality is 3-4% (which is less than the risk for surgery)
Who has a higher risk of mortality after aortic valve replacement surgery:
1, an 70 year old who also needs coronary artery bypass
2. a 95 year old
The 70 year old has a higher risk of mortality.
There is not significant risk associated with age but there is a positive relationship between concomitant bypass surgery and valve surgery and mortality.
Describe the structure of the normal mitral valve leaflets.
How are they attached to the LV endocardium?
It has 2 leaflets (anterior and posterior)
Anterior is larger but posterior has a longer circumference (covers 2/3 of the annulus).
they are attached to the LV endocardium by chordae tendineae (avascular) attached to anterolateral and posteromedial papillary muscles
Describe the annulus of the mitral valve.
The posterior annulus is rigid and fibrous while the anterior annulus is thin and continuous with the aortic annulus.
What is the normal area of: 1. aortic valve 2. mitral valve 3 pulmonary valve 4. tricuspid valve
A= 2.5 to 4 cmsq M = 4 to 6 cmsq P = ? T = 6 to 10 cmsq
When does the mitral valve open? When does it close?
The mitral valve opens early in diastole when the LV has relaxed enough that it has less pressure than the LA. Once the valve is open the pressure gradient is trivial (LA pressure = LV pressure)
The mitral valve closes when the LV pressure > LA pressure
Why does blood flow from LA to LV in diastole?
LV pressure when the mitral valve opens is subzero and acts as a vacuum creating suction to fill the LV.
The mitral valve drifts closed during filling, opens again when the atrium contracts in late diastole and then closes shortly after LV contraction starts.
In a normal heart, what sound is associated with mitral closing?
It is a component of S1 (with the tricuspid valve closing)
What is the main cause of mitral stenosis?
What areas of the valve are affected?
Rheumatic heart disease- causes fibrosis and calcification that fuses the valve commissures and narrows the valve orifice. It can also affect the annulus and chordae tendineae
Symptoms of mitral stenosis occur 10-30 years after the GABHS infection
What is the normal valve area for the mitral valve area?
At what area is there a measurable pressure gradient?
Normal valve = 4 to 6 cmsq
measurable pressure gradient at 2cmsq
What are the pathological changes in the heart due to a narrowed mitral valve?
(what happens to LA? LV?)
The LA has increased pressure to keep the gradient to increase velocity to maintain flow across the valve.
The increased pressure dilates the LA (atria don’t generally hypertrophy) and can cause atrial fibrillation.
The pressure in the LA causes increased pulmonary artery pressure
The LV is underfilled and has a diminished stroke volume (although systole can be normal)
Why is the LA so sensitive to HR?
LV fills during diastole. If the HR increases, there will be less time in diastole and this less time to fill. The blood remains in the LA and causes increased pressure.
What exacerbates the symptoms of a person with MS?
What are some of the symptoms?
- The patients will develop symptoms during exercise, stress or arrhythmia because these cause increased HR which decreases diastolic filling time and makes LA pressure worse.
- pulmonary congestion
- fatique (low CO)
- palpitations
What are the ausculatory findings of mitral stenosis?
Where are these finding best heard?
- Loud S1
- opening snap at the beginning of diastole (heard with the diaphragm at the left lower sternal border)
- low pitch diastolic murmur (heard best with the patient in left lateral decubitus position with the bell over the apical impulse)
- Increased P2 intensity b/c of pulmonary hypertension
Which ausculatory finding can tell you the severity of mitral stenosis?
the time between A2 and the opening snap of the mitral valve is the A2-OS interval.
Higher LA pressure shortens this interval so the shorter A2-OS, the more severe the mitral stenosis.
What accentuates the diastolic murmur of MS?
IT is accentuated by the atrial contraction in late diastole