C9: Mitral Regurg Flashcards
define MR
backward flow of blood from the LV to the LA during systole
during what time periods does MR occur
IVCT, systole and IVRT
general etiology of MR
leaflet abnormalities - abnorm. that don’t allow for perfect apposition
chordae tendinae abnormalities
pap abnormalities
ischemia
why is perfect apposition of the valve leaflets so important
b/c of the big press difference b/w the LA and LV in systole, if there’s any opening, blood will flow backwards to the LA and take the path w/ least resistance rather than going out the AO
describe the anatomical cause of MV prolapse (MVP)
the fibrosa layer of the valve is thinner and the spongiosa is thicker which makes the leaflet too flexible and unable to deal w/ the high PG…. is buckles into the LA
is MVP genetically determined
MVP prevalence
yes
2-5%
US appearance of MVP
systolic bowing of the belly of the MV leaflet into the LA > 2mm
MVP is associated w/ what other pathologies
MR since leaflet tips no longer coapt
chordal rupture
bacterial endocarditis
arrhythmias
which genetic traits/conditions make you more likely to develop MVP
tall, slender
pectus excavatum (sternum/ribs indent)
Marfan’s or Ehler Danlos syndrome
when can misalignment of the pap muscles occur
when the LV is dilated or hypertrophied
what is the inter-papillary muscle distance (IPMD)
distance b/w the PM and AL pap muscles in PSAX mid level
when will the IPMD be increased
MR
how can ischemia cause MR
if the artery feeding the pap muscle(s) becomes blocked it will not function properly and the LV wall will also be effected
describe the movement of the pap muscle(s) if its supplying artery has become blocked
it will move away from the valve plane as the LV dilates (from the ischemia) which tethers the chordae so the leaflet tips can no longer coapt
1 symptom of MR
other symp
dyspnea/SOBOE - none w/ mild-mod MR unless theres LV dysfunction or arrhythmias
fatigue
palpations
arrhythmias
CHF
why can SV be increase w/ MR
will this occur w/ arrhythmias?
theres extra blood moving through the heart due to the MR which can increase starlings
no, only in norm sinus rhythm
murmur heard w/ MR
soft blowing at apex
how will the heart appear on XRay w/ MR
cardiomegaly and pulmonary venous congestion
common causes of acute MR
large acute MI
trauma
how does the LA appear w/ acute MR
LA is norm size because it hasn’t had time to dilate to compensate (Important)
what will happen to LA press w/ acute MR, what does this cause
markedly increased due to inability to dilate….
pulmonary edema and pulmon HTN
how is EF effected w/ acute MR
usually increased due to increase EDV
how does acute MR effect arterial BP
why
it drops b/c more blood is going back into the LA than to the AO
how does HR change w/ acute MR
tachycardia usually
does MR cause volume overload, or press overload
volume overload
MS causes press overload to the LA
how time, what happens to the LA w/ MR…. long term consequences of this?
dilates
… PV congestion, afib, CHF
With time, what happens to the LV configuration and function w/ MR
eccentric hypertrophy (dilation w/o increased wall thickness).... .... then an irreversible decrease in systolic fx due to remodeling.... ... then LVH and increased dilation w/ CHF
(this is why its important to fix the MV before dilation occurs)
describe the changes seen with chronic MR
dilation and then hypertrophy
2 types of chronic MR
chronic compensatory and chronic decompensatory
describe chronic compensatory MR
- increased LAP leads to LA dilation to accommodate the extra volume at a lower pressure
- this increase in volume will increase total forward SV
- LVEF remains increased for many years (due to starlings) until it starts to fail, and EF decreases
describe chronic decompensatory MR
- prolonged increased LV volume damages the muscle fibres n the LV when it fails and Ef starts to drop
- LVESV increases since less blood is ejected (lower SV)
- this leads to increased LVEDP and LAP
w/ chronic decompensatory MR is EF a good marker of systolic function
why or why not
what do we do instead
no, b/c 30-50% of volume is going back into the LA
Dp/Dt instead for systolic function, more accurate
