Mitral Regurgitation Flashcards
Describe why mitral valve prolapse occurs?
The fibrosa layer is thinner than the spongiosa layer and this causes it to bend more during systole because of the high pressure gradient.
MVP is defined by what measurement?
Systolic bowing into the LA >2mm
Mitral valve prolapse can be associated with what? (3)
- Pectus excavatum (caved in chest abnormality)
- Marfan’s
- Ehler Danlos syndrome
What is the most common symptom of significant MR?
Dyspnea
What is a very common heart rhythm with MR?
Atrial fibrillation
In acute MR, LA pressures are increased due to what?
LA has not had time to compensate and the MR is going back into the chamber along with all the other inflow volumes
Why is tachycardia usually present in someone with acute MR?
Blood pressure has lowered due to it going back in to the LA and not towards the aorta, theres not enough blood going to the brain so your heart rate will increase to compensate
How does a chamber adapt to volume overload?
Dilation
How does a chamber adapt to pressure overload?
Hypertrophy
What is eccentric hypertrophy?
Dilated chamber, normal wall thickness
With eccentric hypertrophy, the LV mass will do what?
Increase
If LV dilation is left for too long, what could happen?
Irreversible decrease in LV systolic function and LVH
What is the difference between acute and chronic MR?
Chronic MR has had time to develop compensatory mechanisms
With chronic compensated MR, the LA is able to accommodate the extra volume at a lower pressure. How?
The atrium has dilated to keep pressures down.
Chronic compensated MR will do what to forward stroke volume?
Increase
Once chronic compensated MR is maxed out, what will happen?
Chronic decompensated MR
With decompensated MR, the muscle fibers in the LV become damaged and it fails, doing what to EF?
Decreases it
Once the muscle fibers of the LV fail in decompensated MR, what will happen to LVESV and why?
It will increase because the walls can no longer contract to eject all of it
What happens to LVEDP and LAP with chronic decompensated MR?
Both pressures will increase
Why is EF not a good marker of systolic function with chronic MR?
Because a lot of the stroke volume is actually going back into the LA
Which way does a regurg jet shoot in relation to the prolapsed leaflet?
Contralaterally
If the posterior leaflet is prolapsing the jet shoots anterior and vice versa
A tented MV usually has an increased what?
Coaptation depth (depth from MV leaflet tips to annulus)
What causes tented MV?
When the LV dilates the Pap muscles are pulled apart and the MV is pulled into a triangle shape.
Which is more severe, acute or chronic MR?
Acute (small LA + large MR)
Why is acute MR most severe?
Because the MR is taking up more space in the atrium
What are methods of indirect grading of MR?
- Trace MR jet area to LA area % (MR/LA= %)
- Vena contracta
- PISA radius
What is entrainment?
Blood already in the LA gets displaced by incoming jet
What is the concern with entrainment?
Can make MR look worse than it is
What is the best view to measure vena contracta and PISA?
VC: PLAX, uses axial resolution to measure leak
PISA: Apical, same reason
What is the vena contracta?
Narrowest part of the jet downstream from the narrowed orifice
What is the flow convergence zone and how does it indicate severity of MR?
PISA radius
Larger zone = more severe regurg
What are the values for jet width ratio and what is it assessing?
Jet width compares jet area to LA area
Mild = < 4 cm sq or < 20% of LA
Severe = > 8 cm sq or > 40 % of LA
What are the values for Vena Contracta?
Mild: < 0.3 cm
Severe: ≥ 0.7
What are the values for PISA radius in cm?
Mild = < 0.4 cm convergence zone
Severe = ≥ 0.9 cm convergence zone
The higher velocity the E wave, the more MR exists due to what?
Increased preload
Why can MR not be severe if the E wave is less than the A wave?
The E wave would have to be higher than the A
What do you compare the density of the regurgitant jet to when judging the severity of MR?
Inflow signal
What does a triangular contour with MR suggest?
Large regurgitant pressure wave and hemodynamic significance
What does a bright CW signal of MR indicate?
Significant leak
Describe pressure, pressure gradient, and velocity in a severe MR jet:
Increased pressures, decreased pressure gradient (triangular shape), decreased velocity
Late systolic MR can be a sign of what?
MV prolapse
Why does the pressure gradient decrease with severe MR?
Because the LA pressure rises
What are the 3 main methods for assessing MR quantitatively?
- Regurgitant volume
- Regurgitant fraction
- Effective regurgitant orifice area (EROA)
What method does the ASE recommend to assess regurgitant volume?
Stroke volume method
Total stroke volume includes what?
All blood leaving the ventricle no matter what direction
What is forward stroke volume?
The amount of blood leaving the ventricle and going the right way
What is regurgitant stroke volume?
The amount of blood that flows backward across the abnormal valve
What is the formula for determining regurgitant volume?
RV = (SVregurg) - (SVnormal)
RV = (CSAregurg x VTIregurg) - (CSAnormal x VTIregurg)
What is the formula for regurgitant fraction?
RF = (RV/SVregurg) x 100
What are the values for regurgitant volume?
Mild: <30mL
Severe: ≥ 60 mL
What are the values for regurgitant fraction?
Mild : < 30%
Severe: ≥ 50
What are the values for ERO area?
Mild: < 0.2 cm2
Severe: ≥ 0.4 cm2
How does MR and MS affect the LA differently?
MS causes pressure overload
MR causes volume overload
What does MVP look like on m-mode?
Posterior displacement of the leaflets in systole (near end of T-wave)
