Floppy MV, MV Prolapse, Mitral Regurgitation (M/A)

Floppy MV, MVP, MR (MA47)

-Floppy MV, MVP, and MV Regurg diagnoses were merged bc

-FMV --> MVP --> MVR & so a new category of MV dysfx was made

-There is much history to the origins of this, and prior thinking about MVR prior to the 2nd half of the 20th century...

Path:

-interchordal hooding of the leaflets, doming leaflets twod LA, incr leaflet thickness and surf area, annular dilation (esp if MR) and long/thin cords (+/- rupture)

-Pars Fibrosa of leaflets is disrupted, and dense collagenous fibrosa replaced w loose myomatous CT w too much mucopolysacharides, same thing occurs w cords

-Fibrillin, Elastin, Collagen abNl'ies is being looked into

-Continuous P and stress fr LV systole on the floppy leaflets and cords --> progression of histologic changes

Epi:

-controversial- prior data may rep only echo MVP, but not full FMV/MVP spectrum...

...

Assoc w Other Abnormalities:

-Marfan, Sticklers, EDS, PCKD in adults

-#1 CT dz... ? 2.4% of gen population

Molecular Genetics:

-auto dom x3 genes, X linked x1 found for FMV/MVP

Dx:

-check FHx, pedigree

-check for asthenic habitus, hypomastia, skeletal abNlies, but might not fit criteria for a specific CT dz

-usually thinner than Nl, w ht:wt ratio > Nl, arm span >ht

-2/3pt w FMV/MVP have skel abNlies - chest/spine scoliosis, narrow AP diam, straight back, pectuc excavatum, pectus carinatum

-high arched/cathedral palate also common

-crowding teeth

-adolescent ideopathic scoliosis (F>M)

-check for arachnodactyly, dolichostenomelia (long limbs relative to trunk), jt hypermobility

Auscultation

-Nl S1 and S2.

-MVP --> accentuated S1 if in early systole bc it is the summation of the Nl S1 components with a superimposed mitral systolic click

-multiple nonejection syst clicks can be present if the prolapse of diff leaflet scallops occur at diff times in ventric systole (!)

-Nonejection systolic click(s) +/- late mitral syst murmur = criteria for FMV/MVP

-multiple syst clicks can sound like a pericardial rub or sound like scratching of sandpaper on wood

-High pitched id to late syst murmur of MR often has a click just in before it.

-When post MV leaflet prolapses, the regurg flow can be directed ant'ly twd Ao root, causing the MR murmur to be heard at the apex, and radiate along LSB to Ao area, mimicking an LVOTO

-When ant MV leaflet prolapses, the regurg flow might radiate to the axilla and spine

-If signif MR--> holosyst murmur even when supine, and you might not be able to hear the click

-Dynamic Auscultation

-Upright posture--> click moves closer to S1, and can merge w it; syst MR murmur can become longer and louder, and become holosyst if HR increases

-sometimes MVR murmur only heard while upright

-rarely, hear a syst precordial honk/whoop sound fr the MR murmur

-Squatting fr standing position--> syst click and murmur move to late systole

-Here big changes when pt moves from squat to stand --> murmur/click goes from late syst to early position as HR increases... (But you must be listening constantly thru it...)

-Changes occur bc of LV vol changes, myocardial contractibilty, and HR

-Upright--> decr LV vol, but incr w supine; when pt stands upright, there is a reflex tachycardia that occurs --> further reduce LV vol; decr LV vol--> shorten the mitral annular-papillary muscle distance --> MV leaflets will prolapse earlier in ventric systole, and MVR will occur earlier and the murmur longer and louder

-Prompt squatting --> incr venous return--> incr LV vol--> syst click and murmur becomes late syst; but squat also --> incr SVR/AL--> incr tension on the MV apparatus--> preferential Q into LA rather than periph circ--> late systolic click and murmur louder w squat

ECG:

-Most have Nl ECG, but can have nonspecific ST, T wave changes and T wave inversion ,esp inf'ly

-this improves w exercise and beta blockers

CXR:

-Nl heart and lung, but might see skeletal xx

Echo:

-check leaflet thick, redundancy, incr surf area, annular dilation, long cords

-check amt of MR

-can have negative echo w +exam, likely bc of position pt is in during echo...

MRI:

-same like echo but from all planes..., more precise...

Severity of MV Abnormalities with FMV/MVP:

-FMV/MVP Syndrome = Sx due to neuroendocrine or autonomoci dysfx that can't be explained by the valve abNly alone

FMV/MVP/MVR Sx/Presentation:

-chest pain- nonexertional at L chest and intermittent, palpitations, dyspnea, syncope, but all pts reached predicted work level on exercise test; CVA, migraine headache

Cardiac Arrhythmias

-anatomic substrate and autonomic nervous system role --> xx

-ventricular stretch--> membrane depol'n w stretch activated membrane channels in ventric myocardium, and can cause ectopy

-ventric arrhythmias can also be related to endocardial friction lesions fr cords rubbing against LV myocardium.

MVR Progression

-Sx and xx -infective endocarditis, thromboembolic xx, arrhythmia, sudden death, incr MVR, ruptured cords, CHF; but slowly progressive so no signif MR till 30-40s

High risk pts:

-thick valve leaflets, arterial htn, >50yo are at highest risk

-syst mitral murmur --> incr risk

-LV dilation, LAE are good predictors of subsequent need for surgery

-if no murmur, no thick MV, and no change in LV, LA size --> low risk