week 4 Mitral Stenosis Flashcards
Mitral Stenosis
restricted opening of MV leaflets during diastole
Mitral Annulus
D shaped ring that supports the leaflets
AMVL vs PMVL - shape
AMVL - shorter and wider; attaches to 1/3 of annulus
PMVL - longer and narrower; attaches to 2/3 of annulus
AMVL and PMVL have about the same area
Commissures
where the AMVL and PMVL meet
PM commissure and AL commissure
chordae tendineae
string like fibers that attach MV leaflets to paps
prevent prolapse of leaflets into LA during systole
NOT false tendons (false tendons do not attach to MV apparatus)
Pap muscles - which wall are they on and which coronary arteries supply them?
AL pap - Ant Lat wall - LAD and Cx
PM pap - Inferior wall - PDA (more likely to be damaged post MI)
Etiology of MS?
Congenital = rare, usually diagnosed in peds, often associated with other heart problems
- Annular hypoplasia
- Commissural fusion
- Parachute MV
Acquired
- Rheumatic*
- MAC
Causes of LVOT obstruction, which is hemodynamically similar to MS…
- MV endocarditis
- LA myxoma
- Cor-triatriatum
- supravalvular ring
What is the most common cause of MS?
Rheumatic (99%)
(and MAC is the 2nd most common)
Annular hypoplasia
A congenital cause of MS
under development of MV (severe MS)
Commissural fusion
A congenital cause of MS
MV opening is too small
Parachute MV
A congenital cause of MS
only a single pap muscle and all chordae go to it
Rheumatic MS
An acquired cause of MS - most common, severe
occurs many years after rheumatic fever from untreated strep throat
AMVL looks like hockey stick (diastolic doming of leaflets)
PMVL is thick / not moving
commissural fusion
thick leaflets and thick/short chordae
calcification (later in disease)
In what order does rheumatic fever damage valves?
- MV
- AoV
- TV
- PV - rare
MAC
An acquired cause of MS
elderly often have mild MAC, only causes MS if mod-severe MAC (and MS is usually less severe than MS caused by rheumatic)
Ca build up on valve; starts at annulus and with time builds out
What are the risk factors for MAC?
elderly (*usually just mild MAC in old ppl)
HT
diabetes
hypercalcemia
renal dialysis
marfans
Rheumatic vs MAC - how to tell them apart
Rheumatic - hockey shaped AMVL, uniform brightness and annulus is same brightness as leaflets
MAC - chunky brightness and annulus is brighter than leaflets
MV endocarditis
Can cause an LVOT inflow obstruction, but more likely to cause MR
vegetation (bacteria) growing on valve
usually patient has history of fever (post surgery) or IV drug use = exposed to bacteria
LA myxoma
Causes LVOT inflow obstruction
Primary tumor of the heart, benign but blocks inflow and risk of embolism. Need open heart surgery to remove
Looks like large ball in LA, attached by one point to IAS. Swings in and out of MV as it opens
Emergency - tell doctor before patient leaves
Cor-triatriatum
Causes LVOT inflow obstruction
Membrane across LA with one or more holes in it
Supravalvular ring
Causes LVOT inflow obstruction - rare
narrowing of LA right before MV (btw LAA and MV)
Cor-triatriatum vs supravalvular ring
Cor-triatriatum - membrane across LA, more superior
supravalvular ring - narrowing in LA, right before MV
Hemodynamic consequences of MS
MS = smaller MV opening in diastole
= incr LA press, which causes
- LA dilates = incr risk A-fib and thrombus formation
- As disease progresses… get Pulm HT = RV dilation and tricuspid annulus dilation = TR = high RAP, therefore blood gets stuck in body (causes incr jugular venous press, liver congestion, ascites, pedal edema)….right heart failure
Signs and symptoms of MS
Dyspnea (SOB) and decr exercise tolerance
if severe:
Dyspnea at rest
Pulm vein congestion
low CO
A fib
right heart failure / jugular venous distention
Ortner syndrome (recurrent laryngeal nerve paralysis)
when would you hear a MS murmur?
in diastole (valve is open) - hear turbulent flow?
Treatment options for MS
Meds - manage symptoms
Percutaneous
- balloon valvuloplasty - use balloon to stretch MV open
- commissurotomy - scrape off excess Ca and cut commissures open
- trans-catheter valves
Surgical
- valve replacement (mechanical or prosthetic)
Role of Echo in MS
- Presence of MS?
2D
colour on - candle flame?
M-mode - flat EF slope? - Determine etiology: Rheumatic (99%), MAC, other
- Assess LA size and presence/absence of thrombus
- measure LA diam, LA vol indexed - Identify associated lesions
- MR
- AS
- A-fib - Assess severity of MS
- ADDED STEP: CW through MV - trace to get mean PG (and VTI)
- PHT to get MVA
(- MV planimetry to get MVA)
- PAP
- continuity eqn to get MVA
(- PISA)
If patient has MS, what will M-mode look like? (vs. normal)
M-mode
Normal - steep EF slope
MS - flat EF slope bc it takes longer for blood to go from LA to LV and equalize pressure (reach diastasis); also thickened leaflets
For MS, what is the ONE extra step you need to add to echo while patient is there?
Ap 4ch - CW through MV
Assessing severity of MS: mean gradient
Ap 4 ch - CW through MV
*must get parallel to flow
trace the waveform, end before systole/QRS = get mean gradient (and VTI)
report mean gradient is _ at HR _ (HR affects slopes)
mild <5
mod 5-10 mmHg
severe >10
Assessing severity of MS: PHT
PHT is time for initial gradient to drop to half of its original value
Use CW through MV and measure PHT on the second waveform - follow the EF slope
Machine will calculate MVA = 220/PHT
MS (vs normal) = blood flows slowly through MV = Pressures equalize slowly = flatter EF slope = longer PHT
Formula to get MVA from PHT?
MVA = 220/PHT
When is PHT not valid?
Tachycardia (shortens diastole)
Significant AI (incr LV press)
Changes in diastole (diastolic dysf)
Any prosthetic valve
How do you measure EF slope if trace is bimodal?
bimodal - E wave has steep deceleration at early diastole, then flatter deceleration
Measure deceleration slope at mid diastole
Assessing severity of MS: 2D valve planimetry
SAX
- store image at smallest MV opening (tips of leaflets
- freeze and find largest MV opening - trace
Assessing severity of MS: PAP
Determine PAP the usual way:
PASP = PG (from TR) + RAP (from IVC)
Expect patients with MS to have pulmonary HT
Assessing severity of MS: Continuity Eqn
hard to do on MV bc of shape… so compare flow entering LV to flow leaving LV
SV (MV) = SV (LVOT)
VTI (MV) * CSA (MV) = VTI (LVOT) * CSA (LVOT)
VTI (MV) - from trace of CW through MV
CSA (MV) - ?
VTI (LVOT) - from trace of PW at LVOT
CSA (LVOT) - from 2D meas
Assessing severity of MS: PISA
PISA
… bigger PISA radius means worse MS
What complications might require you to tailer your MS echo?
significant MR
A-fib
If patient has MS and significant MR, how do you change your MS echo procedure?
Continuity eqn is not valid bc incr SV through MV due to MR and therefore incr velocity
only use PHT (planimetry) to calculate MVA
If patient has MS and A-fib, how do you change your MS echo procedure?
measure 3-5 beats and average
What do you do if patient has thrombus?
Emergency - finish exam but get doctor before patient leaves
