C9: Mitral Regurg

Question 1

define MR

Answer 1

backward flow of blood from the LV to the LA during systole

Question 2

during what time periods does MR occur

Answer 2

IVCT, systole and IVRT

Question 3

general etiology of MR

Answer 3

leaflet abnormalities - abnorm. that don’t allow for perfect apposition
chordae tendinae abnormalities
pap abnormalities
ischemia

Question 4

why is perfect apposition of the valve leaflets so important

Answer 4

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

Question 5

describe the anatomical cause of MV prolapse (MVP)

Answer 5

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

Question 6

is MVP genetically determined

MVP prevalence

Answer 6

yes

2-5%

Question 7

US appearance of MVP

Answer 7

systolic bowing of the belly of the MV leaflet into the LA > 2mm

Question 8

MVP is associated w/ what other pathologies

Answer 8

MR since leaflet tips no longer coapt
chordal rupture
bacterial endocarditis
arrhythmias

Question 9

which genetic traits/conditions make you more likely to develop MVP

Answer 9

tall, slender
pectus excavatum (sternum/ribs indent)
Marfan’s or Ehler Danlos syndrome

Question 10

when can misalignment of the pap muscles occur

Answer 10

when the LV is dilated or hypertrophied

Question 11

what is the inter-papillary muscle distance (IPMD)

Answer 11

distance b/w the PM and AL pap muscles in PSAX mid level

Question 12

when will the IPMD be increased

Answer 12

MR

Question 13

how can ischemia cause MR

Answer 13

if the artery feeding the pap muscle(s) becomes blocked it will not function properly and the LV wall will also be effected

Question 14

describe the movement of the pap muscle(s) if its supplying artery has become blocked

Answer 14

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

Question 15

1 symptom of MR

other symp

Answer 15

dyspnea/SOBOE - none w/ mild-mod MR unless theres LV dysfunction or arrhythmias

fatigue
palpations
arrhythmias
CHF

Question 16

why can SV be increase w/ MR

will this occur w/ arrhythmias?

Answer 16

theres extra blood moving through the heart due to the MR which can increase starlings

no, only in norm sinus rhythm

Question 17

murmur heard w/ MR

Answer 17

soft blowing at apex

Question 18

how will the heart appear on XRay w/ MR

Answer 18

cardiomegaly and pulmonary venous congestion

Question 19

common causes of acute MR

Answer 19

large acute MI

trauma

Question 20

how does the LA appear w/ acute MR

Answer 20

LA is norm size because it hasn’t had time to dilate to compensate (Important)

Question 21

what will happen to LA press w/ acute MR, what does this cause

Answer 21

markedly increased due to inability to dilate….

pulmonary edema and pulmon HTN

Question 22

how is EF effected w/ acute MR

Answer 22

usually increased due to increase EDV

Question 23

how does acute MR effect arterial BP

why

Answer 23

it drops b/c more blood is going back into the LA than to the AO

Question 24

how does HR change w/ acute MR

Answer 24

tachycardia usually

Question 25

does MR cause volume overload, or press overload

Answer 25

volume overload MS causes press overload to the LA

Question 26

how time, what happens to the LA w/ MR.... long term consequences of this?

Answer 26

dilates ... PV congestion, afib, CHF

Question 27

With time, what happens to the LV configuration and function w/ MR

Answer 27

``` 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)

Question 28

describe the changes seen with chronic MR

Answer 28

dilation and then hypertrophy

Question 29

2 types of chronic MR

Answer 29

chronic compensatory and chronic decompensatory

Question 30

describe chronic compensatory MR

Answer 30

- 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

Question 31

describe chronic decompensatory MR

Answer 31

- 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

Question 32

w/ chronic decompensatory MR is EF a good marker of systolic function why or why not what do we do instead

Answer 32

no, b/c 30-50% of volume is going back into the LA Dp/Dt instead for systolic function, more accurate