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Pulmonary Atresia with Intact Ventricular Septum (MA41)
Pulmonary Atresia with Intact Ventricular Septum (MA41)
Epi:
-.04-0.8 of all live births; not common but one of the more common cyanotic heart diseases
-if florid TR as fetus, they likely won't survive to birth, due to RH failure w pleural/pericardial effusions, ascites, pulm hypoplasia.
-sev TR is mutally exclusive with high P RV (which is assoc w coronary fistulas). Both bad TR and high P RV w coronary fistulas that depend on the high P are predictors of poor outcome...
Definition:
-usually--> Levocardia, usual atrial arrangement, concordant AV connection, concordant VA connection.
-RVOT is imperforate - membranous or bc of muscular atresia
-fx'ly intact VS
-Get Qp via PDA; AP collaterals fr desc Ao as sole Qp is rare
-Nonconfluent PA's (each via a PDA) have been seen, but uncommon
Morph:
-Some propose that PA+VSD occurs earlier than PA+IVS, in embryogenesis (w partitioning of truncoconal part of heart, before closure of the VS) bc it has bigger MPA diam, mophologic pulm valve, and moprh/topography of DA.
-They feel PA+IVS occurs after cardiac septation
-This may be true for pt w Nl sized RV, imperf tricuspid pulm vlv w completely fused commissures
-Some think it is a prenatal inflmy disease, and not a true congenital malformation
Path/Physiology:
-Heart size can be only mildly big or massively big w huge dilatd RA in much of R thorax, and can compress the lungs--> lung hypoplasia
-If only mild cardiac enlargement, ant desc coronary art in the ant interventric sulcus outlines a smaller than Nl RV
-RA is somewhat enlarged, RV may be very thinned
-On external inspection, may see coronary xx:
-thickened, nodular coronaries
-may connect to pulm trunk (rare)
-Dimples on epicard surface are assoc w subepicardial coronary arts, and = the external sign of ventriculocoronary connections
-In patients w well formed infundibulum, --> imperf pulm valve has 3 cusps w complete commiss fusion
-Relationship bn a persistent R venous valve, ventric-coronary connections, and PA+IVS
-???
-R to L atrial shunting bc of the PA+IVS--> PFO or true 2nd ASD.
-premature PFO closure--> Fetal death
-Rarely, if no PFO/ASD, then pt gets alt R-->L via coronary sinus to LA fenestration
-If ASD is restrictive, the septum primum may show "aneurysmal proportions" and herniate thru MV
-Tricuspid Valve
-usually abnormal- extreme TS through extreme TR
-TS--> +/- hypoplastic obstructive annulus, muscularized with abNl valve apparatus w thickened free valve margin, shortened dysplastic chordae, and pap muscle abNlies.
-TR--> dilated annulus, w profound displacement- looks Ebstein-like, and dysplastic
-some--> valve not displaced but is dysplastic
-rare--> unguarded valve orifice, similar to Ebstein's
-The valve is most sev. stenotic w an underdeveloped RV, while pts w bad TR occur w large RV
-the bad TR w big RV has poor Px, tough to manage
-RV
-Many diff attempts to classify RV size. Latest is the Congen Heart Surgeons Study (CHSS), using tricuspid diameter Z value = TV diam normalized to BSA. It correlates w RV cavity size.
-Others use RV morph- is it tripartite in structure? (inlet, apical trabecular, and outlet), but it is hard to decide how much the the apical & outlet part contributes to the RV hypertr'phy... (thus how dvpd they are)
-This is very important bc if you relieve the RVOTO/PR, the heart will remodel and RVH improve causing improved RV growth.
-LA, LV, Ao Vlv
-Usually Nl pulmonary venous return
-+/-LVH, esp after infancy
-Small & very hypertensive RV--> more convex IVS at outlet portion--> sev LVOTO--> death after making a cavopulmonary connection, bc of an ufavorable change in LVMass to End diast volume
-Ao valve stenosis sometimes seen, can even be critical AS
-Arch is usually L sided
-Pulmonary Circulation
-W Confluent PA's, they get Q via L sided PDA
-W nonconfluent PA's (rare) they get Q via bilat PDA
-MPA ~always there
-PA diameter doesn't usually contribute to outcome (unlike PA+VSD)
-Beware of CoArc at LPA where PDA inserts
-Myocardial Abnormalities
-ischemia, fibrosis, infarct, myocardial rupture all have been seen
-spongy myocardium, myocardial disarray, ventric endocard fibroelastosis
-more enodcard fibroelastosis --> less likely to have ventric-coronary fistulas
-endocard fibroelastosis is more common w HLHS at LV and ventric-coronaries less common...
-Coronary Arteries
-anomalies are due to myointimal hyperplasia
-wide spectrum of intra and extracardiac xx:
-mild intimal and medial thickening w internal elastic lamina and good lumen, through dz w loss of Nl art wall morph, and replace art wall w fibrocellular tissue w irregular unorganized elastin strands and sev stenosis, or obliteration of art lumen. aka fibroelastosis of cor arts., but really its a myointimal hyperplasia (it's not that there's too much elastin/collagin seen w fibroelast.)
--> distort Nl architecture, --> endothelial irregularity, stenosis, interruption,
-Cor changes happen only if there's a ventric-coronary connection (and thus w RV htn), likely bc of the exposure to high P RV w systolic turbulent Q. The intramural and extramural coronaries away from the ventric-cor connection don't have these findings.
-Ventric-coronary connections don't occur in thin walled, low P RV
-Some Coronary xx have big surgical impact:
-Absence of prox Ao-coronary connection bn noe or both cor arts
-Cor art stenosis/interruption
-Cor-cameral fistula w major fistula bn R and L cor art and RV
-Rarely, you can get arts coming off Desc Ao or gastric arts.
-RV Dependent Coronary Artery Circulation
-Nly, it's the diastolic Ao P that drives Qcor, so Qcor is reduced w reduced Ao diast P or shortened diast
-Ventric-cor art connections--> promotes cor art stenosis/interruption, and Ao diastolic P may not be enough to drive against this to ensure enough Qcor.
-Also, PGE, AP shunts, and tachycardia can all reduce diast P in Ao --> decr Qcor
--> Retrograde Q fr the hypertensive RV during systole (via ventric-cor connections) may be needed to ensure adequate perfusion. This process of RV blood getting into coronaries can worsen coronary artery distortion. SO, if you reduced RV P, then you may decr Qcor and myocardial perfusion...
-Patients w smaller RV's have incr risk for ventric-cor connections, and so more likely to see them in "unipartite" or "bipartite" RV's. , or in pts w negative Z score for TV diam have incr risk...
-in 1 study, 9% of coronaries w ventric-cor connection were RV dependent
-the ventric-cor connections may involute after RV decompression (more in neonates).
-After reducing RVP, it is possible that Qcor to RV might start/increase
Sx/Si:
-cyanotic and hypoxemic as PDA closes
-if the intraatrial comm'n is restrictive (rare) --> CO affected too...
-cyanosis within hours of birth
-tachypnea seen, but no noticeable dyspnea unless bad acidosis, w reduced CO, or bc pulm hypoplasia
-if LV is big, then feel forceful impulse at apex
-Single S1 & S2
-Pansystolic murmur @LLSB = TR, even w a thrill if sev TR, w diastolic rumble at tricuspid
-PDA murmur @ L 2-3rd IS, espec w PGE
-Nl arterial pulses, unless sev restricted ASD/PFO w decr CO
-No hepatomegaly unless the TR is sev or PFO/ASD restrictive
-Hypoxemia refractive to incr FiO2 (!!), mild hypocarbia bc of tachypnea
-If signif metabilic acidosis, = progressive hypoxic cellular damage ==> imminent death w/o Tx!!!
CXR
-heart either mildly enlarged w reduced pulm vasc markings (check lat film to confirm--> sparse hilar markings), or fills entire chest bc bad CM, so hard to define pulm parench to eval lung markings
-DDx of Extreme Cardiomegaly at birth:
-PA +Ebstein's
-Ebstein's + Fx'l PA
-Ao Atresia, AV & VA discordance (l-TGA), and sev L AV vlv regurg
-Fxl Ao Atresia, AV&VA discordance, and sev L AV vlv regurg
-Intraepicardial teratoma
ECG
-NSR, QRS +30 to +90, paucity of RV forces, LV dominance/LVH, and RAE
-often ST-T changes, w subendocard ischemia
-DDx of the ECG
-PA+IVS
-Tricusp Atresia
-DILV
DDx of Blue Baby w soft syst murmur, mild CM, oligemic lungs:
-PA+IVS
-Critical PS
-TOF
-PA+VSD
-Tri Atresia + PA
-Complex univentric AV connection and PA
-RA isomerism and PA or PS
Echo
-Echo can make the Dx, but u still need cath to decide Tx, to check for RV-cor connections and RV dependent coronary Q, esp if you're going to decompress RV w a connection bn RV and PA's
-Echo can't reliably tell if there's coronary stenosis or interruption
-All pts will need echo bc even when they have a Nl sized RV, they may have abNl coronaries
-Check Atrial Septum status, bc pt has obligate R-->L at atria for CO
-Subcostal approach w Doppler
-Septum may be aneurysmal, may herniate thru MV (Rare)
-Check TV size/morph
-May not see Q thru TV if very stenotic/osbtructive
-Check is patent best by TR seen, if no TR by Doppler then c/s it may be tri atresia
-Check Tricuspid annulus to assess RV size (good correlation)
-Subcostal + Precordial views
-Check for TV hypoplasia, ?tripartite...
-Check for pulmonary infundibular and valvar atresia
-Hard to DDx atresia fr severe stenosis- Doppler doesn't always help because PDA Q may mask a small jet of fw flow
-DDx anatomic from Fxl pulm atresia:
-Anatomic PA- pulm valve is imperf.
-Fxl- lack of fw Q bc of high PAP w poor RV fx or sev TR. Here usually pulm vlv morph is Nl but stays closed.
-Doppler can help DDx- if u see a systolic regurg of the pulm valve, caused by jetting effect of PDA, it is a fxl atresia, but not an anatomic atresia (bc that is truly closed...)
-Also w doppler, w Pos Pressure Vent'n, --> transient opening of pulm valve w fwd Doppler Q
-Attempt to document coronary art connections fr RV (hard to do)
Cath:
-Need full HD check before decompressing RV to check cor Q...
-Check for ventric-cor connections, cor stenosis/interruption
-Z score of TV < -2.5 has signif predictive for cor art abNlies w RV dependence for Qmyocardial
-Systemic SaO2 reflects amt of Qp
-Pulm vn SaO2 usually ~Nl unless +lung dz,
-PGE will increase systemic SaO2 bc of incr Qp...
-See RV htn w RVP > or = LVP, or w pt w massive cardiac enlargement, see RVP much much <LVP
-If atrial comm'n is NOT restrictive, the atrial mean P will be LA = RA, but w a small a-wave gradient fr RA to LA.
-If + restriction, then RAP>LAP
--> c/s strongly a balloon atrial septostomy to avoid low CO
-espec if you don't plan on doing RV decompression surg later...
-->RVP >=Systemic P, and End Diast P may be abNly high, c/w noncompliant ventricle
-RV:LV P ratio may be<1 - seen w globally disadvantaged RV- thinned, sev TR, w the TR suggesting an Ebstein abNly or sev TV dysplasia, or rarely an unguarded TV
-Angiography
-RV angio in AP and lat
-coronary angiograms
Tx:
Medical
-PGE asap for PDA; BAS urgently if restrictive AS
-balance Qp and Qs...
-low Pdiast w low CO --> renal/splanch hypoperfusion, acidosis, shock..., and poor DO2 to coronaries
Surgical
-Different d/o if pt has massive CM and RV:LV P <1, (worse Px) vs pt w small RV and ventric-cor connections
-Most pts w PA+IVS wil have some degree of RV hypoplasa/RV htn. Must consider:
-Will pt be candidate for biventric repair in the future ("one and 1/2 ventricle)? vs univentric total cavopulmonary palliation (Glenn/Fontan)
-Pt have ventriculocoronary connections? if yes, is RV cor perfusion dependent on RV?
-Does pt have infundibulum? Is there an MPA trunk in continuity w imperf pulm vlv?
-Is LV fx good?
-1) try to get a biventric repair. Initial surg should include an RV decompression w some form of RVOT reconstruction- surgical pulm valvotomy, outflow tract patch, or cath PV perf.
-If there are ventric-coronary connections that are mostly RV dependent, then pt must get univentric repair, assuming LV fx is ok.
-2)Some data shows that if RV is decompressed enough, it will grow, but no institution has enough pts treated lately to --> consistent recs for Tx. Conventional wisdom--> if RVOT still atretic, then RV is unlikely to grow, so not likely to be able to get biventric repair.
-3)Small TV diam, sev RV dep cor Q, birth wt, date and type of initial surg procedures were R/F for time-related death.
-in one study w overall 81% survival 1 month after 1st surg and 64% at 4yrs post, 18% had univentric repair, 32% biventric repair, and 50% had still incompletely separated pulm/syst circs.
-The syst to PA shunt has low initial surgical mortality, but doesn't promote RV growth
-Valvotomy alone would be dieal, but if pt has small RV and TV, they may need a systemic shunt as well, even many pts treated w an initial transannular pulm outflow tract repair
-Some pts will need a combo of transannular RVOT patch and an arterial shunt initially to survive.
-Some of these pts will later successfuly get the interatrial comm'n and the shunt closed (-->2ventric repair).
-In other pts, the RV won't grow, so in addition to the RVOT patch repair, pt will need a cavopulm connection +/- replace pulm vlv.
-Try to balloon occlude the ASD temporarily and check CO and RA P pre/post, to see if the patient can handle closing the ASD. Then c/s cath closure of the ASD and the syst to PA shunt
-Some pts need 1and1/2 Repair- Glenn to unload the small RV and potentially obstructive TV, and the repair of the pulm valve...
-Decompressing the RV htn- via removing TV doing a pulm valvotomy
-TV avulsion can be done in cath lab, as can pulm valvotomy w radiofrequency
-Review of 408pts w PA+IVS
Survival: 77% @ 1mo, 70%@6mo, 60%@5y, 58%@15yr
-At 15yrs, 33% had biventric repair, 20% univentric Fontan, 5% one and 1/2, 2% transplant, 38% died before getting a definitive repair/palliation
-End stage depended on the RV structures, degree of abNl cor circ, low BW, degree of TR
-Survival has improved fr 49% in '87, to 63% in 92, to 79% in '97.
Mgt of Pt w Mainly RV Dependent Coronary Circulation
-Not a good idea to decompress RV if Qcor d/o it--> myocardial ischemia...
(e.g. pulmonary valvotomy, RVOT reconstruction, TV excision or cath avulsion, or RV thromboexclus'n)
-Instead, do a systemic to pulm art shunt initially, with Balloon Atrial Septostomy if needed, with plan to get a Glenn/Fontan
-Doing a Fontan will let pulmonary veinous Q get to TV then to coronaries via RV (via ASD w L-->R), but many still need cardiac transplant if bad coronary vasculature...
Extreme Ebstein/Dysplastic TV & Organic Pulmonary Atresia
-prior attempts to repair or replace the TV and pulm vlv (after a pulm valvotomy) have had bad Px
-Now, we do either transplant or systemic to PA shunt and later cavopulm palliation...
Transcatheter Techniques in Mgt of PA+IVS
-Ideally, a pt set to get biventric or 1.5 repair will need tripartite RV w near Nl size, with valvar PA and well dvpd pulm art circulation, without signif RV dependent coronaries
-Now via cath we can perf the atretic pulm valve and do a balloon dilation, instead of surgical valvotomy, now mainly w RF energy to --> coagulatoin necrosis.
-Cath avoids bypass, but long term outcome unknown for the most part, though >80% have early success
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