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VSD (MA32)
VSD (MA32)
Epi:
-#2 type of CHD (after bicuspid Ao vlv)
-20% of CHD have VSD alone
-Incidence: 5-50/1000
-F>M
-common w tri 13, 18, 21, but usually (95% of time) no assoc chrom xx
Path:
-Ventric Septum has 4 parts:
-Inlet Septum = separate MV and TV
-post and inf to perimembranous defects
-behind TV septal leaflet; inf to the pap muscle of the conus
-sometimes called an AVSD, but this is incorrect bc no MV or TV xx, and the AV bundle passes above it, not beneath it (as w true AVSDs)
-Trabecular Septum = fr TV leaf attchmts to apex & upward to crista supraventricularis
(=parietal+conal septum)
-Central = mid-muscular, +/- multiple channels on RV side that coalesc to single os on LV side
-posterior to trabec septomarginalis (septal band of the crista)
-often partly hidden by the trabeculae fr RV view
-Apical = +/- multiple chnnl on RV side, coalesc to single on LV side, small and tortuous
-Marginal - along RV septal jct
-Swiss Cheese - large number of muscular defects, may combine w nonmuscular defects
-aka muscular VSD
-Infundibular Septum (smooth walled outlet) = fr crista supraventric to pulm valve
-just beneath pulm valve
-aka outlet, supracristal, conal, subPulm, doubly committed subarterial
-Membranous septum =small area usually divided into 2 parts by septal leaflet of TV
-most common, usually w extension to other areas
-fr RV side, see it beneath supraventricularis and post to pap muscle of the conus
-may see some TV xx bc of L-->R shunting - extra septal leaflet/pouch that can obstruct VSD
-these pouches ("aneurysm") are assoc w spont VSD closure
-may have varying amt of anterior malalignment bn infundib septum and the ant IVS--> Ao override somewhat; at times post malalign-> subAo AS
-may have an LV-->RA shunt if there's defic at septal commissure of TV, where it is supposed to atach to the AV membranous septum. Assoc w both LV-RV and LV-RA shunting
-Gerbode's defect (Rare)- at atrioventric septum--> isolated LV-RA shunt
-aka infracristal, perimembranous (perimem if +extension into other areas)
-Outlet & Perimemb VSD may--> Ao vlv cusp prolapse into the VSD
-Outlet VSD pt often has a muscular/fibrous support below Ao vlv, w herniation of the R cor leaflet thru the VSD. Ao commissure is Nl, though.
-Prememb VSD pt w AI have herniation of the R or even noncoronary cusp, often w abNl Ao commissure (espec R/non), and may also have assoc infundib pulm stenosis
-The Ao leaflet prolapse can obstruct the VSD to limit Q across, espec if perimembranous
-The AI increases w age
-AV Conduction pathway is important
-Perimembranous- His bundle is in a subendocard position, going along the post-inf (behind/under)
-Inlet- HIs bundle goes ant-sup (above and infront) of teh VSD
-Muscular & Outlet- little danger of hrt block bc the conduction tissue is far removed...
Physiology:
-Sx d/o VSD size
-PVR determines amt of L-->R as an infant
-PVR drop is delayed if there's a large VSD, so the incr PVR prevents massive shunting to lungs
-"incr LAP (pulm venous P) is important in maintaining pulmonary vasc constriction..."
-Small Defect = <1/3 size of Ao root; --> high resistance to Q, so large diff bn RV and LV P during sys
-so, small L-->R, but Nl RVPsys, thus ~Nl
-Q across relates to size of the VSD
-usually no change in PVR
-while there may be continuous Q thru the VSD, the majority is during systole (ejection)
-outflow and perimemb VSDs will send Q to both RV and PA, not just RV
-some pts- stop L-->R at end of isovolumic relaxn bc there's a brief time in early diast when LVP<RVP
-Moderate Defect = large enough to --> mod-large Q across, but small enough to still resist flow
-diameter usually about 1/2 Ao diamter
-pk sys P grad is usually >20mmHg hihger in LV than RV
-very unusual for these pts to have much incr PVR
-most have mod-large L-->R, w vol OD to LA and LV and thus LVH
-RV systolic work and muscle mass are usually only mildly increased
-Mod-Large Defects:
-when the RVP reaches 70-85% of systemic P, the Q across the VSD changes fr like a small VSD (as above), to:
-L to R grad is 15-30mmHg throughout ventricular ejection
-LVP increases quicker w systole than does RVP, so a gradient is maintained throughout syst, into the initial part of isovol relax'n. But, LVP also decreases quicker w diastole than does RVP, so there is transient R-->L during isovol relax'n (Q fr R-->L goes to Ao in outlet VSDs). Then, as diastole starts, LVP again becomes >RVP, so Q gores L-->R again, and the bld that went R-->L goes back to the RV (so never gets to systemic circulation, thus no desaturation)
-In infants, may have large L-->R w/o much incr RVP (it is still restrictive, though much Q thru it), but as the kid gets bigger and the VSD stays the same size, the relative amt of Q thru the VSD decreases...
-Large Defect = ~same size as Ao; are nonrestrictive so the pulm circ get's the full ejectile force of both RV and LV; large L-->R w systemic P in RV and LV, and a small R-->L
-Nonrestrictive VSD = RVP=LVP
-Gradual decr PVR occurs within first few months of life--> worse L-->R
-Incr volume at LA--> Incr LAP, and pulm vn htn
-Incr vol at LA--> big LA and LV, and LVH --> CHF by 2-8weeks old
-Infant compensates w the Frank-Starling effect, incr sympathetic cardiac stim, hypertrophy
-the rapid hypertrophy is why the pt can compensate for the large VSD
-Too much Qp--> vessel injury; ch injury --> thick adventitia, medial hypertrophy, intimal injury
--> pulm bn obst dz
Si/Sx:
-murmur at 1-6 week old
-ASx initially if small VSD; only has endocarditis risk (rare before 2yo)
-Nl precordial activity, but may have thrill at LLSB
-holoystolic murmur (gr 4-6), cresc. or cresc-decresc; often envelops A2 & extends slightly beyond
-it's holosyst bc of cont P grad during systole (and thus shows RVP>LVP); no murmur at diastole bc Q isn't turbulent bc only small amt of Q across in diast
-muscular defects often have softer, short murmurs that stop in midsyst bc of closure of VSD...
-heard better w diaphragm bc it's a high frequency
-if there's ejection across outflow tract of RV, you can hear murmr more cephalad at L parasternal area
-w outlet defect, murmur and thrill is max at 2nd L IS or suprasternal notch
-unlike an innocent vibratory murmur, this murmur is holosyst, at LSB, accentuted w diaphragm bc it's high-freq.
-small VSD valve closure sounds are usually Nl, but some have wide S2 split bc excess Qp
-if +PS or MR then hear a syst murmur tranmsitted to LUSB or apex, respectively...
-Mod-Large VSD-->
-Sx as early as 2wks old - incr RR, incr WOB, diaphoresis bc incr symp tone, tire w feeds
-earlier Sx if premie
-Sx often preceded by resp infection, so hard to tell if WOB is bc of resp xx or hrt failure
-otherwise, the tachypnea is prob bc pulm edema and decr lung compliance
-incr predcordial activity at RV (parasternal) and LV (apical) areas, poor weight gain
-L ant thorax bulges outward in large shunt by 4-6mo
-murmur of mod defect usually has thrill, and is harsh; duration d/o gradiant
-prominent S3 w a short early middiastolic rumble common at apex if Qp is 2x Qs or more
-like w small VSD, murmur loudest at RV area- LLSB
-widely split S2, slightly varied w respiration
-P2 Nl to slightly incr
-murmur of large defect- max at LSB, descresc, disappears at last 1/3 of syst before Ao vlv closes bc there's no more P grad across VSD
-Loud P2, narrow split
-+/- LUSB bc of ejection thru PA
-some w early faint diast decresc murmur--> c/s AI
-prominent S3 & diastolic rumble at apex common
-Some infants have sustained incr PVR so mainly ASx, but at risk for pulm vasc obst dz w reversal of shunting
-if h/o cyanosis not seen on exam- hard to evaluate
-cyanosis during 1st 3 weeks of life is often transient and often only ocurs at times of stress/illness
-persistent cyanosis since birth = more complex CHD, but does reflect a reversal to R-->L, ?bc of phtn
c/s phtn or signif infundib pulm stenosis
-if large VSD w very incr PVR, look ok as kid; if mod-large R-->L then cyanotic at rest, rare as infant, sometimes seen at 2-3yo, but mainly not till teen/young adult
-prominent RV lift, max at xiphoid
-short or no syst murmur fr the VSD
-+/- pulm ejection murmur at LUSB
-loud, harsh S1 w holosyst murmur at RLSB = TR
-many have early diast murmur fr PR
-loud S2, palpable, w single/closely split S2
-no diastolic rumble at apex
-S3 at LSB fr RV
ECG
-Small VSD- Nl ECG, some w rsR' at V1 and V4R
-LAD w AVSD, but also w some small VSD
-Mod VSD- if vol OD on LV--> LVH
-if mild-mod incr RVP--> RVH -see at V4R and V1 w rsR' (R' amp d/o incr RVP)
-Large VSD- infant- counterclockwise QRS vector loop at frontal plane shows how much LVH
-if incr RVP see RVH
-if incr Qp, see LAE w biphasic P waves- best seen at leads I, aVR, V6
-if BVH, see RVH at lead V1 w QRS showing rsR' or rR'
-if much incr PVR, then no LVH or LA; instead see RVH w QRS patterin at V1 w slurred upstroke of R wave and absent/small S wave, and V6 shows Nl R wave and often deep S wave
CXR
-if mod VSD, see enlarged silhouette, incr pulm vasc markings (central & periph), prominent MPA
-see downard and L elongation of silhouette fr big LV
-if sev LA enlarge, see widened tracheal bifurcation w elevated LMSB
-if very incr PVR- ~Nl sized hearts, but see RVH w cardiac apex rotated slightly upward to L and postly
Echo
-check size, but remember defects aren't circular
-c/s size of defect relative to Ao root
-small = <1/3, mod =1/3-2/3; <2mm = tiny/very small
-PSLA- see larger perimemb VSD, check if occluded by aneurysmal tissue, see subAo defect like w TOF, and see defects in the ant trabec or muscular septum; see subpulm defects at outlet
-PSSA- (Ao root)- 1 o'clock see outlet defect, look for Ao cusp prolapse closing it
- 11-12 o'clock- defects at subAo septum
- 10-11 o'clock- perimembranous defects
-at MV leaflet tips level- 12-1 o'clock see anterior part of trabec septum
- 9-12 o'clock midportion of trabec VSD
-7-9 o'clock inlet septum defects
-AP4C/SC4C- see inlet VSDs posteriorly
- see perimembranous and SubAo more ant'ly,
- can't see outlet well enough here, but can be seen on subcostal sagital views
-check Doppler P gradients...
-may show VSD closing- perimemb can close w saccular pouch/aneurysm on RV side ?fr septal leaflet of TV, while muscular defects close by tissue growth at site...
-check AV valve straddling etc
Cath
-can show # of defects, amt of shunting, PVR, workload of ea ventricles, etc
-best in infants w suspected VSD w evidence of large L-->R shunt or hrt failure, and in pts w Si of incr PVR w mod=small L-->R shunts
-simultaneous PA and Ao or periph art P are obtained, and a PCWP or RA P to estimate PVR and SVR
-can calculate LVEDV, LV EF, LV systemic output...
Tx:
Medical Tx
-if Si of CHF, Tx w Rx- Lasix xx of ch use is hyperCa and renal xx, elec xx; Spiro for K sparing PRN
-incr calorie intake
-c/s systemic AL reduction w Enalapril (o.1mg/kg/DAY DIVIDED BID) w incr to effect...
-many have given Digoxin for infant w CHF assoc w VSD and incr Qp
-?effective as studies show the contractile force of LV is Nl/high, but it is known that Sx do improve
-c/s if Lasix/Enalapril fail
Surgical Tx
-<3% surgical mortality for single VSD and VSD w AI 5% if multiple VSD repair (????really???, seems high)
-Close as infant if:
-CHF, FTT, recurrent resp infections,
-if Large, then repair at <2yo even if ASx
-if ASx and small-mod then wait for Qp:Qs to be >2:1
-c/s repair sooner if signif LV dilation, or if AI espec if w Ao cusp prolapse
-Fix most perimemb/inlet VSD w transatrial approach (may need to detach septal TV leaflet to get to it)
-Fix outlet VSD via trans pulm valve approach
-Hard to fix multiple musc defects, espec if near apex, so may c/s PA band initially; some approach via a L ventriculotomy to patch at apex
-transcath VSD closure still uncommon
Postop Sequelae
-often hear residual VSD murmur postop--> check echo
-RBBB common and maybe due to ventriculotomy or direct injury of RBB, though it occurs even p transarterial repair. complete heart block is rare
NHx/Px:
-good long term survival, espec if small VSD, but some risk of endocarditis, AI, late arrhythmia
-many VSDs (75-80%) close w/o intervention by 2yo
-Mod VSD- main risk is heart failure by 1-6mo, usually able to manage medically
-most never need operation, and shunting decreases as an infant, though at risk for signif infundibular PS, which can progress in severity over time and require surgery
-15-20% of these pts have a large L-->R shunt even after 1yo, so go to OR (by2yo) if still Si of large shunting; though in the 1nd Natural Hx of CHD study, 94% of pt w trivial/mild/mod VSD Tx w Rx were NYHA I still at 15yr p Dx
-Large VSD
-CHF can cause mortality at <1yo, and can cause fixed incr PVR, so need Tx by 1yo
-Limited postop long term data, but most do well at OR
-Phtn rare (4%) long term, SA nd dysfx rare long term(4%), but progressive AI is common (16%) even if no AI before OR
-M/A: in large institutions w experience, infants w large defects had same mortality as older pts so c/s doing it earlier if +Sx...
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