Module 6 : Mitral Stenosis Flashcards
definiton of mitral stenosis
- incomplete opening of the MV during diastole with thickened mitral leaflets
MV anatomy
- annulus
- leaflets
+ anterior
+ posterior - chord tendinae
- papillary muscles
+ ant-lat
+ post-med - LV walls
three layers of the MV
- fibrosa
- spongiosa
- atrialis
fibrosa layer
- provides structural support and stiffness when the valve is closed
spongiosa layer
- provides flexibility to the valve with less dense tissue
atrialis layer
- composed mostly of endocardium cells which line the entire atria
- smooth
MV leaflet anatomy
- anterior leaflet = more complex than the posterior leaflet
- one layer extends medially toward the AV to form the aorta-mitral curtain
- both the AML and PML cover roughly the same area of the valve orifice
- PML is connected to annulus along 2/3 of its circumference whereas the AML is connected to 1/3
- PML is about half of the length of the AML
MV scallops
- MV scallops are well demarcated on the PML only
- the apposing regions on the AML are assumed to have the regions as the PML
- scallops are labelled from LATERAL TO MEDIAL A1, A2, A3 and P1, P2, P3
which leaflet is more susceptible to calcification from MAC
- PML
what are the chordae tendinae responsible for
- anchoring the valve
- maintaining ventricular geometry
- preventing prolapse during systole of the leaflets
- over 120 little chord
two pap muscles
- posteromedial
+ more susceptible to complications from ischemia or infarction - anterolateral
+ less susceptible (has 2 vessels)
position of posteromedial pap
-lies along the inferior wall as seen in the PSAX view adjacent to the septum
structure of posteromedial pap
- has 2 bodies which triturates into three heads
blood supply posteromedial pap
- posterior descending artery
position of anterolateral pap
- located along the anterolateral wall as seen in the PSAX view
structure of anterolateral pap
- has 1 body which bifurcated into 2 heads
blood supply of anterolateral pap
- left anterior descending artery and the circumflex
4 etiologies of MV stenosis
- rheumatic
- degenerative MAC
- congential
- masses
rheumatic - MV stenosis
- starts at leaflet tips
- result of inflammation followed by scarring
- MV commisures become thickened and fibrosed
- matting shortening of the chordae
- fish mouth appearance
degenerative MAC - stenosis
- start at BASAL ANNULUS usually posterior
- progresses inward on to the leaflets
- leaflet tips usually spared
congenital - MV stenosis
- usually involves SUBVALVULAR apparatus
- single pap muscles parachute valve
- atrioventricle septal defects
masses - MV stenosis
- mass impeded blood flow
what is MAC (mitral annular calcification) associated with
- systemic hypertension
- diabetes
- hyperglycemia
- renal dialysis
- elderly
- marfans syndrome
pathophysiology of mitral stenosis
- MS reduces size of opening between LV and LA
- LA driving pressure must rise in order to maintain adequate blood flow
- BACK UP OF PRESSURE INTO INCREASE TR
- ends up being similar to backward heart failure
- afib common
patient history - MS
- dyspnea (SOB)
+ absent at rest in mild MS
+ progressively develops with exertion as LA pressure rises - reduced exercise capacity , fatigue
- exacerbating factors (increasing HR and CO)
what are exacerbating factors
- fever
- anemia
- pregnancy
- hyperthyroidism
- rapid arhhythmia
manifestations of MS
- depend on the severity of MS / degree of reduction in valve area
- causes murmur
MS complications
- afib
- thromboembolism
- infective endocarditis fever
- CHF signs
- hemoptysis - frothy bloody sputum in the lungs
three things to asses for 2D assessment on MS
- common on valve - anatomy, mobility, calcification
- image - MV area
- measure thickness of leaflet tips
- LA size
- LV size
- RV size
5 things for doppler assessment of MV
- mean trans-mitral pressure gradient
- calculate MV are by measuring pressure half time
- pulmonary artery pressures
- coexisting mitral regurge
- continuity equation
rheumatic MS 2D characteristics = commissural fusion
- results in doming of anterior leaflet
- restricted mobility of PML
- HOCKEY STICK APPEARANCE
rheumatic MS 2D characteristic = restricted motion
- due to fusion at medial and lateral commisures
- thickening/calcifiactios starts at leaflet tips and moves outward towards annular ring
- thickening and calcifications shortening of chordae tendonae
how to measure MV leaflet thickness
- zoom on the MV
- scroll until valve is at maximal opening and the leaflets are well seen
- valve will no longer have the classic double bump movement during diastole
- optimize gain to reduce over or under estimation
- measure thickness of both leaflet
- ## note any focal calcifications
normal MV leaflet thickness
1-2mm
extensive mitral annular calcification
- MAC starts at the PML annulus and works its way around toward the anterior annulus
- calcification progresses to include the base of the leaflets and sometimes even the chordae
- calcification causes distal shadowing in the LA and posterior to the heart
cor triatriatum sinister
- left atrial membrane
- MV is usually normal
- gradient between LA and LV is caused by perforate membrane in the LA
- membrane impedes the flow from LA to LV symptoms are identical to other forms of MS
- use doppler to assess gradient through the hole in the membrane
left atrial myxoma tumor
- most common primary tumors in the heart and are often benign
- often attach to fossa ovals with pedunculation or foot
- if large can prolapse into the mitral valve during diastole impeding flow through the valve
parachute MV
- MV stenosis due to one pap muscle instead of two
- pap muscle to far superior in LV
- associated with shones syndrome
- which includes
+ supravalvular ring
+ parachute MV
+ subaortic stenosis
+ bicuspid AV
+ aortic coarctation
what is mitral valve planimetry
- most accurate method to quantify MS with direct measurement of the orifice
- traced zoom PSAX and Mv level
- trace around blood tissue interface
what does accuracy of an MV planimetry depend on
- ability to clearly delineate the orifice
- tracing orifice exactly at tehleaflet tips
- gain settings
- operator skill
what does MV planimetry measure
- measures MV area
tips for MV planimetry
- must transect exactly perpendicular to the orifice
color doppler assessment of MV
- place color over the valve in every view when seen
- look for aliasing during diastole
- note the direction of the aliasing jet
3 parts of the functional doppler assessment
- mean trans-mitral pressure gradient
- calculate MV area by measuring pressure half time
- continuity equation
+ pulmonary artery pressures
+ coexisting mitral regurgitation
MV inflow mean pressure gradient
- use CW to trace the capture the highest velocity throughout diastole through the MV
- technique uses the modified Bernoulli equation but instead of the peak instantaneous pressure gradient we use mean
- the mean PG is obtained by tracing MV inflow profile
what is the mean PG
- average pressure gradient over the diastolic cycle
why is mean PG done
- because waveform is not parabolic with a single peak like the AV and PV the PG varies throughout the diastolic cycle
mild MV by mean PG
< 5 mmHg
moderate MV by mean PG
5-10mmHG
severe MV by mean PG
> 10 mmHg
MVA via pressure half time
- assess the severity of the mitral stenosis using the pressure half time
- diastolic blood flow is from the LV to the LA is impeded in MS
- normally the majority of flow through the MV occurs in early diastole
- in MS the rate of atrial emptying is slowed due to the narrow orifice
+ prolongs the decline of the early diastole PG between LV and LA
what is the relationship between MVA and P1/2
- inversely proportional
how is the MVA derived with pressure half time
- the MVA can be derivived by dividing 220 by the pressure half time
- always use 220
does pressure fall slower or faster with a more stenotic valve
- slower
normal pressure gradients with MV doppler
- rapid pressure decline leads to a steep downslope on the MV inflow profile
MS pressure gradient with MV doppler
- the pressure decline is slowed leading to a prolonged deceleration time and therefore pressure half time
MVA via the continuity method
- absence of regurgitation, the stroke volume through all four valves should be the same
- be calculating the SV through the AV using the LVOT and VTI of the LVOT we can measure the VTI of the MV inflow and extrapolate a mitral valve area from it
MVA equation continuity method
MVA = VTIlvot x CSAlvot / VTI MV
two sources of error for continuity equation
- diameter
+ LVOt diameter = any error will be multiplied by factor of 4 - angle
+ must be precisely aligned to the LV inflow and LVOT outflow to accurately calculate MVA
+ a misalignment fo 20 degrees equal a 6-7% reduction in velocity
continuity equation and regurgitation
- if LVOT diameter and VTI and used to calculate the MVA but the AV has a significant leak then the SV through the 2 valves are no longer equal
continuity for MVA less accurate for 3 reasons
- significant MR = MVA underestimated
- significant AR = MVA overestimated
- ASD or other intracardiac shunt
pros of P1/2 of MVA
- quickest method
- uses CW
_ PW is AR present
cons of p 1/2 of MVA
- arrhythmias
- noisy signal
- must acquire peak velocity
tips of P 1/2
- use color to align to flow
- use mid diastolic flow if there is an early peak
pros to mean gradient of MVA
- also quick
- used to calculate continuity
cons to mean gradient of MVA
- no MVA given
- OVER/UNDERESTIMATION IF PRELOAD ALTERED
- less useful with significant MR
tips for mean gradient
- align to flow use CW or PW
pros continuity equation for MVA
- not as preload dependent
cons to continuity equation for MVA
- more time consuming
- all 3 measurements must be precise
tips for continuity equation
- DO NOT USE IF SHUNTS PRESENT
- LESS ACCURATE WITH SIGNIFICANT MR AI
consequences of MS
- left atrial enlargement and clots
Left atrial enlargement - LAE
- chronic pressure overload in the LA causes increased LA size
potential clots
- decrease flow velocity leads to potential clots in the LA appendage or along septal wall
- more common with a fib
- TTE has high specificity but low sensitivity to LA clots
- TEE much better
MS leading to pulmonary hypertension
MS causes pressure back up»_space; increased pulmonary venous pressure»_space; pulmonary arterial hypertension
pulmonary hypertension from MV
- reversible at first
- longstanding PAH causes irreversible PVR increases that do not resolve after MV surgery
- SURGERY TIMING ALSO DEPENDS ON LV/LA/RV function
MV treatments - pharmacologic
- beta blockers \+ slow HR and enhances filling time - diuretics \+ decrease preload \+ unload the lungs - anticoagulants - clot prevention \+ Coumadin - anti-arrhythmics \+ improve hemodynamics / CO
MV treatments - surgical
- valve repair \+ balloon valvuloplasty \+ commissurotomy - valve replacement \+ bioprosthetic \+ mechanical \+ percutaneous
normal MVA MS
4-6 cm ^2
mild MS MVA value
> 1.5 cm^s
moderate MS MVA value
1.0-1.5 cm ^2
severe MS MVA value
< 1 cm^2
