Pulmonary Atresia with VSD (M/A)

Pulmonary Atresia with VSD (MA42)

PA+VSD = most sev form of TOF

-PA+VSD is usually more complex than TOF

-more likely to have hypoplastic PA's, periph arborization, syst-pulm collaterals

=2% of all CHD, a common cause of neonatal cyanosis

=20% of all TOF

R/F:

-Infant of diabetic mom, maternal PKU, maternal retinoic acid or trimethadione use --> conotruncal xx

-IDM has 10x risk for PA-VSD, 20x if insulin dependent mom!

Genetics:

-can cluster in families; recurrence risk variable,

-8% have a chrom xx, 12% are syndromic, 7% had other single organ defect

-Only 75% have isolated PA-VSD

-8-23% of TOF have 22q11del

-22q11.2del --> DiGeorge/Celocardiofacial syndrome

-CHD, palate xx, hypoCa, imm'defic, speech/learning disabled, renal xx, psych xx, abNl facies

-very variable phenotype

-10% of 22q11del pts have PA-VSD (more freq w PA-VSD than w TOF)

-other CHD: AP collats, RAoAr, aberrant subclavian also more common w PA-VSD than TOF

-the branch PA stenosis is worse w 22q11del

-Px is worse w 22q11del

Embryology:

-RV is in discontinuity with PA

--> Qp supply is variable. Lungs dvp from foregut so their nutrient blood supply is initially from the paired dorsal Ao's, but by day 27 the art branches of 6th Ao Ar anastomose with pulm vascular plexus --> lungs now have dual supply of blood. W time--> 6th Ao Arch branches enlarge and those from the desc Tx Ao get smaller. The larger vessels--> PA's and delivery Q to alveoli/caps that were derived from the pulm vasc plexus. The smaller vessels--> bronchial arteries.

-Bronchopulmonary anastomoses persist but are of small caliber and disappear postnatally.

-With Pulm Atresia, Qp is from either:

-DA

-bronchial arts

-other syst-pulm collateral arts

Path:

-Extent of atresia varies

-Atretic arterial segment can be just a solid elastic cord in 3/4 pts, and in other pts just unidentifiable

-Most often, pulm valve and prox pulm trunk are atretic

-Rare- only pulm valve is imperf

-Central (=external to lung) RPA and LPA and/or segmental PA's can be confluent or nonconfuent

-Qp is entirely from systemic circulation

-DA, sys-pulm collats, coronary arts (uncommon), bronchial or pleural artery plexuses

-DA and collateral supply can occur together but usually in separate lungs.

-Unifocal Blood Supply- single system arterial source of Qp

-Multifocal Blood Supply- multiple sources of Qp

-Central PA size is realted to amt of Qp

-When DA/collats connect proximally to the central PA's or their lobar branches==> good size PA

-When DA/collats connect distally at segmental/subsegmental PA level==> very small PA's

-Intrapulmonary arteries vary by the type of supply

-If DA supplies a confluent central PA, then intrapulm arts are going to be Nl

-If DA supplies a one nonconfluent PA, then the lung getting this Qp will have Nl arts, but the other lung will have a multifocal supply w fragmented arterial distribution = arborization abnormality.

-If both lungs have multifocal Qp, the both will have arborized arts, and the DA is absent.

-DA is usually unilateral, and assoc w confluent PA's (80% pts)

-Bilat DA (Rare) w nonconfluent PA's does occur

-DA's usually < tortuous than collats, and doesn't branch b4 meeting PA's. and bc the DA is wide open as fetus, the PA's are likely Nl size by birth.

-However, DA will close postnatally--> distal stenosis in 1/3-1/2 of pts.--> decr Qp and the relative PA hypoplasia becomes worse as patient grows.

-Collaterals-

-usually fr Desc thoracic Ao

-also fr subclav sometimes

-Rare fr abd Ao/branches or fr coronaries

-Can have up 6 collats, w diam 1-20mm

-60% have stenoses, often near Ao or intrapulmonary anast.

-discrete or segmental; congen or acquired

-Anast bn central PA's or their branches are seen in 40% pts. Occur at hilum or within lung.

-Other 60% of pts have collaterals entering the hilum and travel with bronchi as a pulm art, and supply variable number of bronchopulm segments

-2/3 pt have confluent central PA's, but they only supply a portion of each lung bc there are also many collaterals and arborization abNlies...

-Small arterial plexuses follow the bronchi or spread over the pleural surfaces. seen on angio

-arise fr Ao and Thoracic branches or fr systemic collats

-These vssls get bigger and prolif postnatally as regional Qp is reduced

-If DA is what supplies the PA's it can close postnatally --> need surgery sooner

-But, collaterals, while more stable Qp, dvp progressively and may be inadequate as pt grows

-Pt can get a range of pulm xx- pulm vasc dz, stasis thrombosis..., bc of areas of hyper or hypoQ

-VSD- membranous or infundibular

-There is a malalignment defect with an overriding Ao, so the VSD is larger than w isolated membranous/infundib defects.

-VSD may rarely be obstructed partly by tricuspid valve tissue

-Ao usually mainly from the RV.

-Asc Ao usually dilated, w dextroposition less than that of TOF

-AI seen bc of annular dilation or infective endocarditis

-R Ao Arch in 1/4-1/2 of pts

-RA dilation/hypertrophy; LA Nl

-ASD or PFO in 1/2 pts

-Tri Vlv usually Nl size, +/- minor leaflet abNl

-Mitral Vlv usually Nl/mildly hypOplastic

-RVH- mod-sev, w infundibulum ending blindly (can be Nl or short)

-The infundibulum is displaced and can fuse to RV wall

-LV wall usually Nl thickness, w Nl size or somewhat small

-Older pts can have LVH & LV dilation

-Most pts, coronary origin/distrib is Nl

-But usually prominent Conus Artery

-xx: coronary ostia, cor-to-pulm art fistulas, RCA origin fr L ant Ao sinus coursing across RV infundib

-Sinus Node- Nl

-AV nd- in Nl position in Koch Triangle

-Nonbranching prox part of His bundle penetrates teh central fibrous body, lies along LV aspect of post-inf rim of the VSD.

-His bundle is closely related to the rim of be membranous VSD, but w infundib VSD is relatively far from the border

-LBB (sheetlike) spreads along the VSD endocardium Nl'y

-RBB (cordlike) must go thru septal musculature to get to its subendocard position along teh septal band. It can be bifid or form aberrant branches.

Other assoc xx-

- Persistent LSVC to CS, CS xx, partial/TAPVR, TS/Tri Atresia, Complete AVSD, d- or l- TGA, dextrocardia, heterotaxia

Sx/Si:

-Cyanotic Newborn

-+/-ASx for a few days until PDA closes--> cyanosis incr/lethal

-PGE must be started ASAP after birth

-Some don't have severe hypoxemia- bc DA open or +enough collats for Qp

-eventually they'll outgrow current supply and get cyanotic

-+/- Heart Failure and signs of incr Qp (Rare)

-usually at WOL 4-6, as pulm arterioles involute

-incr Qp bc the pDA may be large, or there's much Qp from the collats.

-hard to Tx w Rx, so may need surgery

-if large PDA, then PA's usually well dvp'd, allowing for early complete repair

-if large collateral Qp, then PA's usually hypoplastic w abNl arborization, so hard to correct

-22q11del pts tend to have worse dz w more complex collaterals and pulm anatomy

-absent or sev hypoplastic central PA's w multiple collats makes successful biventric repair unlikely

Late Sx

-pts may get recurrent cyanosis as they outgrow shunts.

-PA's may get stenotic or distorted, pulm vasc obstructive dz may dvp

-xx are common esp with:

-Waterstpm (Asc Ao to RPA connection) (therefore not done anymore)

-Potts (Desc Ao to LPA connection) ( " " " " )

-Initial Tx now is w BTS to MPA, or RV to PA nonvalved conduit, which --> more rapid enlargement of central PA than the syst-to-periph PA shunts, and --> less distortion of the periph PA's.

-But, in pts w/o enough distal distribution fr central confluence or if pt has signif periph stenosis, then the large central connections may--> segmental pulm htn.

Exam-

-Neonate <-- profound cyanosis- mild right after birth in some, but then worse as PDA closes, and it can fluctuate much in first few days as DA constricts/relaxes, then after neonatal pd it increases as pt outgrows the DA/collats

-FTT in some, but only if Qp and Qs is too low. If +FTT, c/s 22q11del

-Nl periph pulses and BP, even w PDA, until after 4-6 weeks as PVR drops bc of runoff thru PDA/collats/shunt

-PMI at LLSB

-Nl hrt size

-Nl S1, single loud S2

- +SEM at LLSB 3/6 or less

-unlike TOF, there's no separate loud SEM at LUSB bc it's PA

+continuous murmur if +PDA or +collats (collat murmurs can be multiple and most prominent at back bc they come fr desc Ao)

ECG:

-RVH, RAD

-if pt has incr Qp (rare), then see BVH and LAE

-DDx PA+IVS which has RV hypOplasia and small ant QRS forces w LV preponderance

CXR:

-Boot shaped heart

-bc of levorotation bc of a prominent w upturned cardiac apex, and 2y RVH

-and a concavity at MPA region bc subpulm infundibulum is underdeveloped,

-R Ao Arch in 1/4-1/2 pts, (only 1/4 in TOF)

-Heterogenous reticular pulm vasc markings

-Collats fr syst circ are large, supply PA's

-if small systemic collats, then lung fields may have decr vasc markings

-if large PDA w Nl central PA's, then CXR shows big central PA w incr pulm vascularity

Echo:

-Cath often needed if u can't see pulmonary supply well

-Similar to TOF

-PSLA

-large Ao vlv that ovrrides a malaligned VSD

-infundibular part of IVS is ant'ly malpositioned

-DDx TOF- TOF has a patent, hypoplastic RVOT ant to the infundib septum. This outflow tract is in continuity with the MPA.

-w PA+VSD, the infundib septum is fused with the free wall , and there's no separate Q fr RV

-w PA+VSD, all the RV stroke volume enters the overriding Ao

-DDx Truncus Arteriosus- PA's arise directly fr the post-lat side of truncal root

-Suprasternal notch & high Parasternal windows

-Demonstrate size/status of prox PA's

-Check if PA's are confluent - if so, then if pt has ductal dependent Qp he can get BTS/RVPA conduit w/o cath first

-If nonconfluent or very hypoplastic, it can be hard to see them well, try using color flow... but pt will need cath for angio of pulm tree

-Check for collaterals if possible

-Check for assoc xx

-position of malalignment VSD - membranous or infundib

-ASDs and other muscular VSDs

-PSSA/subcostal

-check coronary abNlies

Cath:

-Get cath if small central PA's or multiple Qp sources

-Must determine true pulmonary arts, and figure out how much collateral Qp there is

-RA P - Nl unless +TR

-No O2 step up in RA unless +ASD

-RV P = LV P bc +large VSD

-can't access PA's bc of pulm atresia, but can get to Ao via VSD

-Ao P is Nl

-PP wide if signif runoff thru PDA or a shunt

-systemic art SaO2 will be desaturated, d/o amt of Qp

-PA P usually not Nl

-if large PDA, or large communicatoin bn systemic collats and the PA's, or a large fistula bn coronaries and PA's, or a shunt that is too large (seen w Waterston and Potts) ==> incr PA P

--> incr risk for pulm vasc obstructive dz

-in these pts, it's easy to enter PA's thru the comm'n to check the P and estimate Qp & PVR

-Angios:

-check for multiple VSDs, coronary anatomy

-check ventriculography w camera in L ant oblique and cranial angulation to see middle part and most of the upper intraventric septum tangentially (see pic)--> see sup malaligned VSD

-Check Qp anatomy

-Check for a central pulm art confluence

-check for collaterals - do they connect to a confluence? via a periph branch?

-check w aortogram

-check size/anatomy of PA's

-check for communication bn adjacent areas of the periph pulm art tree