Mitral Insufficiency (M/A)

Mitral Insufficiency (MA46)

ISOLATED CONGENITAL MITRAL INSUFFICIENCY

-usually assoc w other CHD, CT dz, metab d/o

-2y/acquired MR seen p ischemia, trauma, CM, CHF, inflmy xx (myocarditis, rh fev, endocarditis, Kawsk)

Physiology:

-In ventric systole, leaflet coaptation--> seal the inlet, prevent reflux

-Mild MR --> only small part of LV SV reflux into LA, so no signif LAE or htn, good antegrade CO

-Mod-Sev MR--> larger reflux to LA--> incr LAP and LA vol and decr fwd LV CO

-Acute MR--> rapid incr LAP and pulm edema

-Ch/gradual MR--> very compliant LA so gets bigger, and venous htn, & resistance to LV ejection goes DOWN (bc easily flows backward to LA)--> early increased LV Ejection

-Big LA--> atrial thrombi & arrhythmias

-Vol return fr pulm vn and regurg vol --> incr LV EDV & ventric and annular dilation --> worsen MR

-Initially LVH to compensate, so syst fx still good

-LV becomes hyperdynamic and tachycardic to maint enough fwd CO

-THEN, latent ventric syst dysfx is masked by the reduced systemic ventric AL and low resistance MR Q, but POSTOP you will see this dysfx once you fix the MR...

-Ch MR eventually--> decr CO and LV syst dysfx, atrial/ventric arrhythmias worsening things, sometimes to the pt that LV won't recover.

Sx/Si:

-Severity d/o age & other CHD

-Adults can handle signif MR for long pd, but infant/kids get CHF Sx sooner- w/in 3yrs of Dx

--> FTT, diaphoresis, pallor, tachypnea, pna, wheeze ("cardiac asthma") bc of bronchial vns congestion --> compress small airways and big LA--> compress LMSB

-Rales bc of inspy re-expansion of collapsed alveoli is rare & ominous!

-PE:

-inc precordial activity, diffuse apical impulse

-quiet S1

-loud P2, narrowly split - if phtn

-Murmur varies

-high freq, plateau blowing or a harsh holosys murmur at apex w rad to axilla/back

-Sometimes, maximal at LSB if ant leaflet is cleft

-Low freq, apical diast murmur and S3 if worse/sev MR

-tachycardia common w Nl SBP

-if severe w low CO, then incr RR w chest hyperexpansion, wheeze bc pulm vn congestion....., & atalectasis if LMSB compression

-poor cap refill, cool limbs if incr sympathetic tone

Mitral Valve Prolapse

-Unsure of cause if isolated MVP

-?abNl myxomatous matrix of the leaflet or collagenous structure of the cords, or ? dvp abNly similar dvpl xx of Ebstein's for TV bc MV has redundant tissue and long cords

-Isolated MVP- rare cause of MR @ <1yo;

-Seen w some Marfan pt's w myxomatous leaflet changes

Dilated or Distorted Mitral Annulus

-Uncommon to have annulus dilation/distortion w/o a CT dz (Marfan/EDS)

--> thick, redundant leaflets w long cords

-Can be assoc w ch ventric enlargement- CM, big L-->R shunt; or it can be distorted bc of RV vol OD/dilation

Cleft MV Leaflet

-Rare; defect of ant leaflet

-AV septum is intact, and no LVOT elongation

-Cleft divides ant leaflet into 2 parts- partial or goes to the base of the valve; edges are thick/rolled

-cleft is directed ant'ly twd outflow septum or Ao root, unlike an AVSD

-Cleft is more post'ly directed twd the inlet septum, and located in a small common leaflet that bridges the septum

-If isolated Cleft MV, paps are usually Nl, but in some complete cleft pts, there are no accessory cords, and ant leaflet usually flails and is grossly insufficient

-Assoc w LVOTO bc of the accessory cords

-Assoc VSD is common, also ASD and TGA

-Annulus often dilated

-Less common: post leaflet xx (aka partial leaflet agenesis)- w clefts fr edge to annulus

Anomalous Mitral Arcade or Hammock Valve

-Free margins of MV are thick and rolled, and may insert directly into pap muscle

-AbNl band of fibrous tissue extends along the free margin of the leaflets--> constrains pap muscles

--> restricted leflet motion--> MR

-If it has cords, they're often fused/short and attach directly to post ventric wall

-leaflet edge can connect directly w pap muscles

-pap muscles often AbNl, small, multiple

-Leaflets are often tethered w poor coaptation

-can also have MS

Surgery for MR w Deficient MV Leaflet

-Cleft MV w MR

-Suture the cleft edge, +/- pericardial patch to augment the leaflet

-may also need annuloplasty

-can sometimes create a 3 leaflet MV bc of cleft, assoc w AVS

Surgery for MR w AbNl Chordal/Papillary Muscle

-May need commissurotomy if they are fused or stenotic

-Restrictive Leaflet motion: if short cords, looks like rh hrt dz, w limited mitral leaflet motion, but unliike w rh hrt dz, the cords are well delineated. Pap muscle hypertrophy adds to narrowed interchordal spaces, w subvalvar AS. Surgeon can fenestrate they paps to increase the spaces, and reimplant the cords or replace them w synthetic cords to improve leaflet mobility

-Excessive Leaflet motion: prolapse, mising cords, long cords/paps

-if absent cords--> do a rectangular leaflet resection if redundant, or replace/reconstruct the cords w teflon sutures

-fix elongated cords by spliting the pap muscle and bring the long cord into the pap muscle w sutures