Module 7 : Mitral Regurgitation Flashcards
mitral regurgitation defintion
- a backward flow of blood from the LV to the LA during systole
what time does MR occur
- occurs during systole through both isovolumic periods
annulus pathology causes of MR
- MAC
- dilation og LV from any cause
valve pathology causes of MR
- rheumatic heart disease
- MVP
- infective endocarditis
- trauma
- cleft MC
- connective tissue disorders
- left side myxoma
chordae tendinea pathology causes of MR
- rupture
- trauma
- infective endocarditis
papillary muscles pathology causes of MR
- trauma
- CAD
left ventricle (myocardium) pathology causes of MR
- CAD
- cardiomyopathy
prosthetic valve pathology causes of MR
- prosthetic malfunction
- thrombosis
- ## paravalvular leak
etiology of MR - leaflet abnormalities
- the leaflets need to be in perfect apposition to each other in order to stop any regurge
- leaflets may be malformed , term or regraded which would not allow for perfect apposition
etiology of MR - chordae tendinae abnormalities
- the chords may become elongated
- misdeveloped
- or ruptured
- then can become thickened and matted with inflammation
etiology of MR - mitral valve prolapse
- includes similar diseases as Barlows disease, fibroelastic deficiency and marfans syndrome
- in MVP the fibroma layer is thinner and spongiosa layer is thicker
- makes the leaflet bend with much more pressure when faced with a high pressure gradient during systole
- it leads to one or both leaflets to buckle/ prolapse into LA during systole
mitral valve prolapse characteristics
- has a genetic determinism
- systolic bowing of the belly of the mV leaflets in systole into the LA > 2mm
- prone to choral rupture, bacterial endocarditis and arrhythmias
prevalence of MVP
- 2-5% of pop
- tall slender build
- sometimes with pectus excavatum
- marfans or Euler danlos
etiology of MR - papillary muscle
- contraction of the LV contracts the pap muscle
- contraction pulls down on the valve during systole to prevent prolapse
- misalignment may occur when the LV is dilated or overly muscled as in hypertrophic cardiomyopathy
what is IPMD
- inter-papillary muscle distance
+ increase distance = MR
etiology of MR - ischemic MR
- abnormality at the LV myocardium level
- when artery leading to pap muscle becomes blocked the wall is also affected
- pap muscle moves away from valve plane as the LV dilates
- this tethers the chordae and leads to ischemic MR
4 symptoms of significant MR
- DYSPNEA = SOBOE no associated with mild or moderate unless LV dysfunction or arrhythmias are involved
- palpitations = extra blood moving through the heart can increase stroke volume in normal sinus rhythm
- arrhythmias
- CHF = due to back up into lungs
signs and symptoms of MR
- symptoms similar to CHF \+ dyspnea \+ fatigue \+ low exercise - signs \+ xray = cardio megaly, palm venous congestion \+ LVH on echo and ECG \+ murmur \+ arrhythmia like AFIB
pathophysiology of acute MR
- as a result of large acute MI, trauma, torn leaflet or chordae or pap
- the MR fills a normal sized LA because it has not had time to compensate by dilation
- leads to markedly increased in LA pressure, acute pulmonary edema and y hypertension ensue
- the EF is usually increased, the EDV increases due to MR and arterial BP crops because more blood goes back to the LA than AO
what heart rate is usually seen with acute MR
- tachycardia
what does MR lead to in regards to volume
- significant MR causes volume overload
- MS causes pressure overload to the LA
- both LV and LA have to try to overcome volume overload from MR
what adaptations occur in the LV when volume overload occurs
- eccentric hypertrophy/ remodelling of the muscle fibres (dilatation with little change in LV thickness
what adaptations occur in the LA when volume overload occurs
- dilation»_space; PV congestion»_space; afib»_space; CHF
pathophysiology of chronic MR
- the heart has had time to develop compensatory mechanism
chronic compensated MR
- increased LAP pleads to the LA dilating
- the dilated LA can accommodate the extra volume at a lower pressure
- this will also increase total forward stroke volume
- LVEF remains increased until many years later when it fails and decreases
chronic decompensated MR
- prolonged increased LV volume damages the muscle fibres in the LV when it fails and ef starts to drop
- LVESV increases in the case
chronic decompensated MR leads to what 2 thing s
- decreased forward stroke volume
- increased LVEDP and LAP
is EF a good marker of systolic function with chronic MR
- not a good marker of systolic function because 30-50% of the stoke volume is actually going back into the LA
5 roles of echo in MR assessment
- determine etiology of the lesion
- assess LA size
- assess LV size and systolic function
- estimate severity of regurgitation
- estimate RVSP or other pulmonary pressures
5 things to look for when assessing MV morphology
- thickened, flail or perforated leaflets
- annulus = MAC ( mitral annulus calcification)
- chordal structures = thickened, tethered
- pap structures stretched (post MI?)
- LV dilates = prohibiting computation
+ tenting
how far does the leaflet have to buckle for MVP
> /= 2mm toward the LA said of annular plane
M mode MVP
- posterior displacement o the prolapsing leaflets will occur in systole
LA myxoma with MR/ MS
- mass does physical damage by smashing into LV many times a day
tented MV with dilated LV»_space; ischemic MR
- occurs when the LV has dilated for whatever reason (ischemic heart disease)
- the MV has an increased coaptation depth
- can be measured
- caused by pap muscles being pulled away from the MV as the LV expands
what is coaptiaton depth
- depth form the MV leaflet tips to the MV annulus
how is the amount of regurge put into context
- by relating the jet area to the LA size
what are two ways to indirectly account for acuity
- small LA + large MR = more sever and acute
- large LA + larger MR = less severe and chronic
what type of assessment does color doppler give us
- qualitative assessment
- indirect measure of MR severity
why is color doppler considered an indirect assessment
- many variables act on the color doppler jet
- preload afterload, jet direction, number of jets affect assessment
3 methods of indirect grading of MR
- color Doppler MR jet area to LA area %
- vena contracta
- PISA radius
what is entrainment
- blood already sitting in the LA gets displaced by the incoming jet
with what kind of jet does entrainment usually occur
- central more than eccentric jets
what does the doppler color look like with entrainment
- represented by non aliased colours like darker blue
what does entrainment lead to
- overestimation of MR severity
how do you calculate MR area % of LA area
- trace normal LA area and MR jet area
- MR jet / LA area x 100
vena contracta defintion
- the narrowest part of the jet downstream form the narrowed orifice
what does the oven contracta provide info on
- estimated effective orifice size (size of the hole)
where must the vena contracta be measured
- must be measured parallel to the US bema to maximize axial resolution
- which is best in PLAX
PISA radius (flow convergence zone)
- as flow converges roars a narrowed orific e it asccelreates in a laminar manner forming a flow convergence zone
- this zone is comprimased by a series os concentric hemispheric shells of the same velocity
- as the flow advances toward the orifice the diameter of each shell decreases was the velocity within each shell increases
- measuring the radius of the convergence zone can provide an indirect sign as to the severity of the leak
is a larger or small convergence zone more indicative of a severe regurge
- a large flow convergence zone
what should the color baseline be shifted to and why
- should be shifter downward to 30-40cm/s to enhance the hemispheric shells
how to measure PISA radius
- measure the vertical distance from the leaflets to the top of the convergence zone or red blue interface
jet width ratio with mild MR
- small central jet
- < 4cm^2 or <20% of LA area
jet width ratio with severe MR
- large central jet
- > 8-10 cm^2 or > 40% of LA area
- variable size wall impinging on jet swirling into LA
vena contracta width (cm) with mild MR
- < 0.3
vena contract width with moderate MR
- 0.3-0.69
vena cocntracta width with severe MR
- > /= 0.7
PISA radius with mild MR
- very small or no convergence sone
- < 0.4 cm central jet
PISA radius with severe MR
large flow convergence
- >/= 0.9
4 main methods to indirectly assess MR with spectral
- transmitral flow
- pulmonary venous flow
- intensity of MR signal
- colour of MR jet
transmitral flow velocity - principle
- the higher the more MR exists due to increased preload
- e wave velocity of > 1.2m/s is supportive sign of MR
pulmonary venous systolic flow - principle
- systolic flow reversal in one or more pulmonary veins is specific for severe MR
CW signal intensity - principle
- the brighter the CW signal of MR the more significant the leak
CW of MR jet from MVP - timing principle
- MR jet seen in mid to late systole only
- regular MR jet is holosystolic
CW MR jet contour - principle
- the CW MR jet reflects the pressure difference between the LV and LA during systole
- in mild MR = the pressure gradient between LV and LA remains fairly high throughout systole
- in severe MR the volume of blood leaking back into the LA raises the LA pressure dramatically thus lowering the pressure gradient between the 2 chambers
- this is why severe MR takes on a more triangular parabolic shape
3 main quantitative ways of assessing MR
- regurgitant volume
- regurgitant fraction
- effective regurgitant orifice area (PISA)
is regurgitant volume encouraged for use in MR
- not recommended
total stroke volume definition
- the amount of blood the left ventricle pumps out on a single beat
- includes blood ejected into the aorta and backward in to the MV
forward stoke volume definition
- the amount of blood that actually passes the AV and enters systemic circulation
regurgitant stoke volume
- the amount of blood that back flows across the abnormal valve
what 4 things do you need for stroke volume method for MR
- LVOT diamteter
- LVOT VTI
- MV diameter
- MV VTI
Pisa method to assess MR - principle
- flow proximal to a narrowed orifice must be equal to flow through it
what 3 things are needed to asses MR Pisa method
- pisa radius
- velocity at radius (which is number that color baseline is lowered too)
- peak velocity of the MR jet
regurgitant volume from Pisa method
- RV = ERO x VTI
when should you not use Pisa radius methods
- with eccentric MR jets
regurgitant volume with mild MR
- < 30
regurgitant volume with severe MR
- > /= 60
regurgitant fraction with mild MR
- < 30
regurgitant fraction with severe MR
> /= 50
