Development of PA
• MPA -septation of the truncus and aortic sac.
• Intrapericardial RPA and LPA -sixth aortic arches with
contribution from the aortic sac.
• intraparenchymal pulmonary arteries - vascular
plexuses of the lung buds.
• Vascular plexuses =intersegmental arteries (ISAs) in the
early embryonic period.
• cephalad malalignment of the infundibular septum=
anatomic obstruction of RVOT and a malalignment-type
• aorta overrides VSD and is rotated in a counter-
• Pulmonary ostium becomses atretic much
earlier in development , shortly after
truncoconal partitioning but before closure of
▫ PUL CIRCULATION is so heterogenous and
highly variable with MAPCAS
• PA-IVS-- PA Occurs much later after cardiac
▫ PDA, MPA, Confluent BPA, are well developed. No
• 1.4% of CHD
• 0.07 per 100 live births.
• 26% - chromosomal abnormality/syndrome/single
DiGeorge syndrome and associated with Chromosome
• 10% -PA-VSD .
• Right aortic arch, or aberrant subclavian artery -MC
• Branch pulmonary arteries are smaller
• depends on the adequacy of pulmonary blood flow
• duct-mediated pulmonary circulation -early mortality
due ductal constriction and closure.
• Half = die by 6 months
• 90% die by 1 year of age
Adequate pulmonary blood flow - greater longevity
Survival in to the sixth decade = multiple
median age at death = 11 months(9 days to 30 years)
• 66% -alive at age 6 months
• 50% alive by 1 year
• 8% alive at age 10 years.
Pulmonary blood supply
• RVOT-Infundibular atresia/ annular atresia
• Extent of MPA atresia
• Native pulmonary arteries
• Source of pul blood
▫ Aquired collaterals
▫ AP window
• Distal pulmonary vascular arborization
• Anular aresia- thick fibrous membrane (analog
of the pulmonary valve)
• Extent of pulmonary valve atresia varies from
only a plate-like atresia of the pulmonary valve
to absence of both valve and a variable length of
• Extension of MPA atresia to its bifurcation
results in non-confluent central pulmonary
Right and Left Pulmonary Arteries
• Presence or absence of confluent PAs =
influences surgical outcome.
• 20% to 30% == nonconfluent RPAs and LPAs.
• Absence of the central portion of one or both of
• Confluent RPA and LPA - patent or atretic PT
Stenoses of Origins of Pulmonary Arteries
• confluence of the BPA and normal
arborization of pulmonary arteries- 10% have
stenosis of RPA, and 20% have stenosis of the
• Stenoses are MC at the origin of PA on the side
• juxtaductal stenoses (pulmonary artery
coarctations) - 65%
Stenoses beyond the origins of PA
• small percentage
• Localized areas of non compliance
• May not present as stenoses until after a
procedure that increases PBF
Arborization of Pulmonary Arteries
• frequent failure of the pulmonary arteries to
distribute to all 20 pulmonary vascular
• Effected by
▫ Confluent central portions of pul arteries.
▫ Presence or absence of a PDA.
• Pulmonary arterial segments that are not
connected to a central pulmonary artery usually
receive large AP collateral arteries.
complete vascular distribution from native pulmonary arteries to 18
lung segments (considered to be complete arborization
inverse correlation between the number of lung segments supplied by collaterals and those
supplied by the native PA.
Alternative Source of pulmonary blood
▫ Aquired collaterals
▫ AP window
• undersurface of the arch -67%
• undersurface of the innominate artery=33%
• PDA = S shaped, long and arises at an acute angle from
• Unilateral PDA =confluent Pas
• PDA bilateral -- non-confluent PAs
• When PDA is present, PAs are confluent in 80% of cases.
• PDA is absent in 1/3 of cases and is associated
with absent central PAs.
Aortopulmonary collaterals (APCs)
• differentiate them from the bronchial arteries
• muscular arteries until they enter the lung parenchyma,
the muscular layer is gradually replaced by elastic lamina
that resembles true pulmonary arteries.
• 30 – 65%
• 2 – 6 in number.
Large Aortopulmonary Collateral Arteries
• “large” -embryologic rather than acquired origin
of the collaterals.
• join an interlobar or intra-lobar pulmonary
artery that arborizes normally within a pul-
monary lobe or segment
origin of APCs include
▫ upper or mid-descending thoracic aorta= MC
▫ subclavian arteries
▫ abdominal aorta
▫ coronary arteries.
Three types of SCAs
• Type I: Bronchial artery branches- from normal
• Type II: Direct aortic branches- descending thoracic
• Type III. Indirect aortic branches- from branches of the
aorta other than bronchial artery-subclavian, IMA and
Morphology of Pulmonary Arterial Supply
• If all intrapulmonary arteries are connected to
unobstructed and confluent intrapericardial
• confluence typically supplies all of both lungs
• persistent PDA that provides unifocal PBF
• rare for confluent pulmonary arteries feeding all
of both lungs to be supplied by a solitary
systemic-to-pulmonary collateral artery.
• rare cases- APW , or via a fistula from the
• different parts of one lung are supplied from
more than one source,
• clinical complexity
• multiple vessels feeding the pulmonary
parenchyma - systemic-to-pulmonary collateral
• hardly ever feed a lung that also receives supply
via the PDA.
Various patterns of pulmonary arterial
anatomy and source of blood supply
• PDA -- less reliable source beyond the first few days of
life due to its tendency to close.
• APCs are also prone for stenosis over a period of weeks
to months but are more reliable than PDA
PDA VS MAPCAS PDA MAPCA’s
ORGIN Opposite to LSCA DTA
COURSE STRAIGHT TORTOUS/RETRO
BRANCHING NO BRANCHING
STENOSIS PA end AORTIC END
DESTINY CENTRAL PA JOIN PA at HILUM /
Congenital Heart Surgeons Society Classification
• Type A: Native PAs present, pulmonary vascular
supply through PDA and no APCs.
• Type B: Native PAs and APCs present
• Type C: No native PAs, pulmonary blood supply
through APCs only.
• origin and distribution = normal
• Conus artery =prominent.
▫ high origin of the coronary ostia,
▫ coronary-to-pulmonary artery fistulas,
▫ origin of the RCA from the left anterior aortic
sinus, coursing across RV infundibulum
• cyanotic newborn
• becomes increasingly hypoxemic as the ductus
• If the ductus arteriosus remains patent or because
systemic collateral vessels are sufficiently developed to
provide adequate PBF -not severely hypoxemic.
• Hypoxemia and cyanosis increase as the patient
“outgrows” the relatively fixed sources of PBF
• If growth is delayed- 22q11.2 microdeletion.
(growth failure due to heart failure caused by excessive
pulmonary blood flow is uncommon)
Modes of presentation
Cyanosis - 50%
Murmur with mild cyanosis – 25%
• normal in the neonatal period(even with a PDA)
• Beyond the first 4 to 6 weeks of age - if pulmonary
blood flow is through a PDA or collaterals ,the pulses are
bounding, and only minimal cyanosis is present.
• normal S1
• single S2
• systolic murmur – LLSB
• not more than grade 3/6 in intensity
• RVOT is atretic- no separate loud systolic ejection
murmur at the upper left sternal border -
• PDA -continuous murmur after the first 4 to 6 weeks of
• If MAPCA are present, continuous murmurs -multiple
and prominent over the back
(originate from the descending aorta)
• Increased PBF---Bi BVHand left LAE
• coeur en sabot
▫ levorotation of the heart, a prominent upturned
cardiac apex, secondary to RVH
▫ concavity in the region of the MPA
• right-sided aortic arch -(26% to 50% of these patients)
;TOF (20% to 25%).
• Pulmonary vascular markings - reticular pattern when
there are multiple collaterals supplying the lungs.
• Extent of pulmonary vascular markings will depend on
the extent of PBF
• PLAX-- large aortic valve that overrides a malaligned
• infundibular portion of the ventricular septum is
• TOF - patent, although hypoplastic, RVOT anterior to
the infundibular septum with continuity with the main
• infundibular septum is fused with the free wall
• Truncus arteriosus - resembles PA-VSD
(in truncus arteriosus, the pulmonary arteries arise
directly from the posterolateral aspect of the truncal root
prior to the arch.)
• Suprasternal notch and high parasternal windows - size
and status of the proximal PA.
• malalignment VSD-membranous or infundibular
• ASDs and additional muscular VSDs
• Short-axis parasternal and subcostal views- coronary
artery abnormalities .
• Color flow -right ventricular to pulmonary artery
Cardiac Catheterization and Angiography
• size and distribution of the true pulmonary arteries
• extent of collateral blood supply
• large VSD- RV pressure is equal to LV pressure.
• RVOT is atretic - catheter will not enter the pulmonary
arteries from RV (manipulated from RV through the
VSD into the aorta.)
• Widened pulse pressure -large runoff into the lungs
through a PDA or a previously constructed shunt.
• Ventricular and aortic root angiography
• LV Ventriculography -LAXO view= middle portion and
most of the upper interventricular septum tangentially.
• Coronary artery anatomy -aortic root angiocardiogram
and a 70-degree left anterior oblique view (with 20
degrees of cranial angulation).
Surgical importance - origin of the left anterior
descending coronary artery from the right coronary
artery=5% of patients
• Selective injections in the systemic-to-pulmonary
collateral arteries -
▫ extent of the pulmonary arterial tree supplied by each
▫ type of pulmonary artery connection
• Evanescent negative washout pattern -stream of
unopacified blood from a connecting pulmonary artery
flowing into an area of opacified pulmonary arterial
tree(may be the only indication of an existing
• If the central native PAs were not identified on
• simultaneous contrast injection into the
proximal stump of the pulmonary artery and the
pulmonary vein wedge injection - length of
discontinuity that need to be “bridged” surgically
CT / MR angiography
RVOT, MPA, branch PAs and APCs
Needs lesser contrast.
Evaluation of adequacy of
• Complexity of pulmonary blood supply determines the
extent of surgical exploration necessary to perform
• Eligibility for complete repair - RV-PA conduit needs to
be placed to the vessel which is connected to maximum
possible pulmonary vascular bed
• Closing the VSD at the time of placement of RV – PA
conduit needs to be determined.
• Adequacy of the pulmonary vascular bed
• pulmonary vascular resistance
▫ determinants of postoperative RV pressure =
• dividing the sum of the diameters of RPA (at the level of
crossing the lateral margin of vertebral column on
angiogram) and LPA (just proximal to its upper lobe
branch), divided by the diameter of aorta at the level
above the diaphragm
[D RPA + D LPA] / D TAO
• average value of 2.1 is normal
• Ratio above 1.2 -acceptable postoperative RV systolic
• Ratio below 0.8 - inadequate for complete repair of PA
• diameter of PAs measured immediately proximal to the
origin of upper lobe branches of the respective branch
• The sum of the cross sectional area (CSA) divided by the
body surface area of
• CSA of RPA (mm2)+ CSA of LPA (mm2)/ BSA (m2)
• >150 mm2/m2 =complete
repair without prior palliative shunt.
• Nakata index = widely used in preoperative assessment
of adequacy of pulmonary vascular bed
• Not useful in patients with multifocal pulmonary blood
supply, who are evaluated for single-stage repair of PA -
• Nakata index= no provision for the additional vascular
bed that will be added by unifocalization
Total Neo-pulmonary artery index (TNPAI)
• APCs index
• addition of CSA of all significant APCs divided by the
• CSA of each APC is calculated from diameter of the
respective vessels measured on preoperative
• sum of total APC index and PA index =TNPAI.
• TNPAI index >200 mm2/m2 = low postoperative RV/LV
pressure ratio and identified patients who were
candidates for VSD closure at the time of single-stage
• limited value since they are based on the size of the
proximal vessels only.
• nature of the distal pulmonary vascular bed and
pulmonary vascular resistance are not expressed in these
Intraoperative method to assess the adequacy of
pulmonary vascular bed
General principles of surgical
therapy of PA-VSD
• Connect as many lung segments as possible to the blood
flow from RV during early infancy - to avoid significant
histologic changes occurs in pulmonary vasculature
• ultimate goal - complete repair
• closure of all septal defects,
• interruption of all extracardiac sources of pulmonary
arterial blood flow
• incorporation of at least 14 pulmonary arterial segments
in a connection to RV
• central pulmonary artery size should be at least 50% of
• At the end of operation, RVSP should be <70%
that measured in LV
• If higher, the ventricular septal defect is
• Complete repair - within weeks to months during
• Therapeutic catheterization - balloon angioplasty help to
rehabilitate pulmonary arteries with stenosis.
Components of surgical repair
Unifocalization of APCs
Placement of RV – PA conduit
performed in one-stage/different operations depending
on the anatomy and institutional policy.
RV – PA conduit placement
• Cadaveric, cryopreserved homograft - right ventricle to
available central pulmonary arteries.
• complex cases, where a central pulmonary artery is
absent or the pulmonary blood flow is multifocal-
unifocalization of the diminutive native pulmonary
arteries and APCs will be performed before RV – PA
conduit is placed
Unifocalization of APCs
Unifocalize significant APCs during the first 3 months of
• Median sternotomy - single stage repair
• multi stage surgical approach- unifocalization is done
through lateral thoracotomies.
• unifocalization- APCs are ligated at the origin and
mobilized to maximize their length .
• Anastomosed in the mediastinum and connected to RV-
Aortic arch angiogram before (A) and main pulmonary
arteriogram (B)after 1-stage complete unifocalization
• at the time of initial repair / If any concerns about the
adequacy of the pulmonary vascular bed- - -defer VSD
• Unrepaired VSD avoids supra-systemic RV pressure in
the immediate postoperative period
Intraoperative method to assess the adequacy of
pulmonary vascular bed
• After completion of unifocalization and distal
anastamosis of RV - PA conduit
• perfusion cannula and a PA catheter are
inserted from the proximal end of the conduit
and left atrial vent is placed.
• conduit is connected to the bypass machine.
• bypass machine is run at increasing flow rates to
2.5 L/min/m2 and the PA pressure is monitored.
• VSD is closed if the mean conduit pressure is
< 25 mmHg, and left open if it is higher.
• < 25mmhg - Predict PRV/LV <0.5 following
• Alternative strategy - closing VSD with a fenestrated
• fenestration =closed later either by surgery or
• VSD closure is deferred at initial repair- surgically
closed after 6 – 12 months- when left to right shunt is
established via the VSD with Qp/Qs exceeding 2:1 by
catheter evaluation .
dependent on :
▫ Nature of PAs (small vs good size)
▫ Duct-dependent or collateral-dependent PBF
▫ Status of APCs
▫ Availability of surgical skills and results of the
• Traditional approach
• palliative shunt in patients with good size, confluent
central PA during neonatal period or early infancy to
relieve cyanosis and allow for growth of distal pulmonary
• diminutive PAs, RV – PA continuity is established by
placing a RV – PA conduit
• VSD is typically left open at this first stage.
• Unifocalization of APCs
• subsequent surgery -
▫ VSD closure
▫ Relieve any residual RVOT obstruction
▫ Placement of a valved conduit.
• APCs unifocalization and cardiac repair
• median sternotomy
Comparison of outcome between
multi and single-stage repair
• Early 1-stage complete unifocalization ->90% of patients
with pulmonary atresia and MAPCAs, and yields good
• Complete repair during the same operation - two thirds
• survival 3 years after surgery - 80%, and but there is a
significant rate of reintervention.
Circulation. 2000; 101: 1826-1832
Outcome of surgical repair
• Early mortality - 4.5%
• Late mortality - 16%
• Ten- and 20-year survival - 86% and 75%
• Freedom from reoperation of 55%.
Incremental Risk Factors for Death
• PA Abnormalities
• Age - > 5 to 8 years
• Higher postrepair PRV/LV
• Duration of CPB
Complementary role of
• Dilation of Distal stenosis within lung parenchyma
(inaccessible to the surgeon. )
• Coil occlusion of APCs
• Stent placement in RVOT
• Palliative stenting of stenotic APC’S
Long term sequelae
• palliative shunts- progressive cyanosis and
• Deterioration of conduit and valve function -- loss of
luminal diameter, calcification, peel formation
• PR -- worsens with RV dilatation and dysfunction
Pulmonary venous wedge angiogram
• TRUE PA in which there is low or no
demonstrable prograde flow like PA
• End hole catheter is advanced from LA into
pulmonary vein wedged forcefully, into distal
• Shows pr wave of arterial contour.
• 0.3-0.4 cc/kg body weight of contrast material
injected over a two second period.
• forcefull hand injection/ by under pressure (less
than 100 PSI).
• Fallowed by 15ml of fush.
• Progressive more force.
• Until PA are visulized.
• Some times contrast extravasates into
sarrounding tissue including bronchus
• Pt may develop hemoptysis- self limiting
• caliber of the parenchymal pulmonary arteries
• sizes at the hilum of the lung
• presence or absence of a mediastinal confluence
of pulmonary arteries.
• Pr of PA(Aproximate).