PA/IVS is a rare congenital cardiac defect that consists of atresia of the pulmonary valve resulting in an absent connection between the right ventricular outflow tract (RVOT) and pulmonary arteries, and an intact ventricular septum that allows no connection between the right and left ventricles

1. PA IVS
Diagnosis
Dr. Sweta Mohanty
Consultant Pediatric Cardiologist
RxDx Healthcare, Rainbow Hospital,
Bangalore
Image: Plasticsurgerykey.org

2. What is the diagnosis? Modified PLAX view

3. Diagnosis- PA IVS
Is the Diagnosis Complete?
Image: doctorlib
Modified PLAX view

4. CASE EXAMPLE

5. History
• 4 days old Term baby
• Bluish discoloration noticed at 2 days
• Progressive increase in cyanosis
• Mild fast breathing noted
Note: Cyanosis coincident with ductal closure
Dyspnea with severe acidosis, reduced C.O. or pulmonary hypoplasia

6. PHYSICAL EXAM

7. Physical exam
• S2 single
• TR- PSM ± thrill at LLSB, MDM
• PDA- murmur in 2nd or 3rd LICS
• If TR severe or ASD restrictive 
hepatomegaly
• If ASD restrictive compromising C.O.
peripheral pulses feeble

8. Blood gas
• Hypoxemia refractory to increased O2
• Hypocarbia from tachypnea
• Metabolic acidosis in severe cases

9. CXR

10. Massive cardiomegaly in a newborn
may be seen in all except:
A] Ebstein’s anomaly and functional
pulmonary atresia
B] Pulmonary atresia and Ebstein’s anomaly
C] ccTGA, severe left AVVR and functional
aortic atresia
D] Intrapericardial teratoma
E] None of the above

11. Image: Radiopedia
CXR

12. CXR in PA IVS
• Mildly enlarged heart with reduced
pulmonary vascular markings & concave
MPA segment
Or
• Gigantic cardiomegaly

13. Image: Thoracickey
ECG

14. Image: Thoracickey
ECG
QRS axis of +30 to +90
LV dominance, lack of RV forces
RA enlargement
ST-T abnormalities (subendocardial ischemia)

15. D.D. of Paucity of RV forces and LV
dominance/ LVH on ECG

16. D.D. of Paucity of RV forces and LV
dominance/ LVH on ECG
•PA IVS
•Tricuspid atresia
•DILV

17. ECHOCARDIOGRAM

18. Role of Echo: To determine
• Size of atrial communication
• Size and morphology of tricuspid valve
• RV morphology & inflow and outflow dimensions
• Anatomical vs functional pulmonary atresia
• Branch PA size and continuity
• Presence of pulmonary blood flow from PDA
• Coronary artery anatomy & connections with RV

19. INTER-ATRIAL SEPTUM

20. Atrial septum
Associations:
• PFO or OS ASD with
obligatory R to L
shunt
• If ASD restrictive,
septum primum may
become aneurysmal
& herniate through
mitral valve
Subcostal view: IAS with
aneurysmal flap, R-L shunt
Image: pedcards.com

21. Atrial septum
• Shunting at the atrial
level is bidirectional
but primarily R-to-L
• Oxygenated pulmonary
venous blood shunts L-
to-R across TV 
perfuses the
myocardium (via the
RV-coronary fistulae)
• Nonrestrictive flow is
essential
Image: Thoracickey

22. Coronary sinus
Associations with PA IVS:
• Stenosis/ atresia of coronary sinus ostium
with decompression through unroofed
coronary sinus
• If atrial septum intact, coronary sinus-LA
fenestration may be seen

23. TRICUSPID VALVE

24. Tricuspid valve
1) Extreme stenosis ≈
Underdeveloped RV
 Hypoplastic
obstructive annulus
 Thick free margin,
short dysplastic
chordae, abnormal
papillary muscles
TV annulus hypoplastic,
hypoplastic RV
Image: doctorlib

25. Tricuspid valve
2) Profound
regurgitation
≈ Large thin-walled RV
 Dilated annulus
 Ebstein-like anomaly/
Not displaced but
dysplastic
Image: doctorlib
A4C view: Ebstein anomaly,
severe TR

26. RIGHT VENTRICLE
Image: Anesthesia and analgesia

27. Right ventricle
• Heterogeneity in RV
size, inlet, TV
competency and RV
function
• Z value of tricuspid
annulus correlates
with RV cavity size
• May be described as
tripartite (with inlet,
apical trabecular &
outlet components) or
underdeveloped
Image: JACC

28. Myocardium
• Ischemia, Fibrosis,
Infarction, Rupture
• Myocardial disarray,
spongy myocardium
• Endocardial
fibroelastosis (inverse
relation with
ventriculo-coronary
communications)
Image: doctorlib.info

29. LVOT
• May be obstructed
by bulge in outlet
septum in small and
high-pressure RV
• LVOTO worsens after
Fontan
Image: pedcards.com
PSAX view:
IVS bowing into LVOT

30. NATURE OF PULMONARY ATRESIA
Image: doctorlib

31. Precordial SAX view with slight clockwise rotation
Image: pedcards.com
Membranous PA

32. Nature of pulmonary atresia
Typically pulmonary valve morphology
correlates with character of RV:
• Well formed RV  Membranous atresia
likely: 3 semilunar cusps with complete fusion
of commissures + well-formed infundibulum
• Diminutive RV  Muscular atresia likely:
Primitive pulmonary valve + severely narrow/
atretic infundibulum

33. PULMONARY ARTERIES

34. Pulmonary arteries
• Usually MPA is present; pulmonary arteries
are confluent & fed by left-sided PDA
• If non-confluent PAs, bilateral PDAs or
MAPCAs seen
• LPA coarctation may occur at site of PDA
insertion

35. CORONARY ARTERIES
Image: doctorlib

36. Coronary arteries
Associated abnormalities of coronaries:
Subepicardial coronaries develop
sinusoidal or fistulous connections with RV
Absence of proximal aorto-coronary
connection
Coronary artery stenosis or interruption
Coronary cameral fistula between RCA/
LMCA and RV

37. Ventriculocoronary connections & RV
Ventriculocoronary connection correlates with:
• Negative tricuspid valve Z value (Z score < -2.5)
• RV classified as unipartite or bipartite
Hypertensive RV with myointimal hyperplasia,
background of glycosaminoglycans, endothelial
irregularity, obliteration of lumen

38. Image: doctorlib
A4C view of posterior RV and LV at level of Coronary sinus:
Multiple coronary sinusoidal channels within RV myocardium

39. Ventriculocoronary connections
• Ventriculocoronary connections may promote
coronary stenosis
• Normal aortic diastolic pressure may be
insufficient to drive coronary blood flow if
obstructive lesions present
• If palliative measures like PGE1 or BT shunt
further lower diastolic pressure, aortic
diastolic pressure insufficient for coronary
perfusion

40. Image: doctorlib
PSAX view: Dilated proximal
RCA with retrograde filling
Ventriculocoronary connections
• Myocardial perfusion
sustained by
retrograde coronary
flow from
hypertensive RV
during systole
• Systemic or
suprasystemic RVSP 
Further coronary
distortion
• Any decrease in RV
blood flow or RVSP 
coronary ischemia

41. Image: Giglia et al, Circulation
Potential of adverse outcome after
RV decompression:
RV to coronary
Fistula without
coronary stenosis
Potential RV steal
phenomenon
RV to coronary Fistula
with proximal ± distal
coronary stenosis
Potential RV steal/
ischemia
RV to coronary Fistula
with Coronary
occlusion/ atresia
Potential Isolation
and MI

42. This superior view demonstrates an atretic pulmonary artery (PA) with a LCA to RV fistula

43. Hypoplastic RV (HRV) with RCA to RV fistula.
Ebstein-like malformation of the septal leaflet of TV

44. RV dependent coronary circulation
(RVDCC)
Coronary artery abnormalities requiring RV
systolic events:
• Absent aorto-coronary connections
• Coronary artery interruption or stenosis
• Profound coronary cameral steal or fistula

45. CARDIAC CATH

46. Role of Cardiac cath.
• Coronary artery abnormalities (Color doppler
cannot image obstructions to the coronary
arteries with the precision of angiogram)
• BAS if PFO restrictive
• RV pressure- If low, suggests functional rather
than anatomical PA Or global RV dysfunction
• RV Angiogram- RV morphology & for
ventriculocoronary connections
• Aortography- PDA, pulmonary arteries

47. Tripartite RV Bipartite RV Monopartite RV
Image: Circulation

48. Angiographic criteria for diagnosis of RVDCC
Stenosis of ≥ 2 major coronary arteries (LMCA, LAD,
circumflex or RCA)
Or
Atresia of the coronary ostia
And
Myocardium distal to the obstruction receiving blood
supply via fistulous connections from RV
Evidence of myocardial ischemia on surface ECG following
catheter placement in RV is suspicious for RVDCC
(Decompression of RV from catheter-related TR)

49. Angiographic diagnosis of RVDCC
Angiographic techniques (Galindo et al):
• RV angiogram
• Aortogram
• Aortogram with balloon occlusion of the aorta
• Selective coronary angiograms

50. RV injection:
Fistula to mid LAD with stenosis proximal to fistulous insertion
LAD irregular proximally with additional proximal stenosis
RCA fills from collaterals to LAD

51. Image: Sakurai, JTCVS, 2018
Lateral view Aortography: No
coronaries arising from aorta
Right ventriculogram:
Proximal RCA, distal RCA &
LCA arising from RV

52. PRENATAL DIAGNOSIS

53. In utero development of coronary a.
abnormalities
Lack of blood-egress
from RV
Elevated RV pressure
Blood forced
retrograde through
thebesian veins
Coronary
sinusoids
(enlarged
thebesian veins)
Fistulae (enlarged
thebesian veins
communicating
with epicardial
coronary arteries)
Image: Thoracickey.com

54. In utero development of coronary a.
abnormalities
High pressure
retrograde flow
through epicardial
coronaries
Endothelial
damage
Coronary
stenoses

55. Fetal echo findings
• TV orifice proportional to
RV size
• TV often dysplastic TR
or TS
• Dilated RA common
• Increased R-L shunt
through PFO  Dilated LV
• Foraminal flap may be
redundant
Small, hypertrophied RV; small PE
28 weeks fetal echo
Image: contemporaryobgyn.net

56. Fetal echo findings
• MPA may be
normal caliber
• Ductal flow
reversal
essential
finding
Retrograde blood flow through
the ductus
Image: contemporaryobgyn.net
28 weeks fetal echo

57. Fetal echo associations
Cardiac:
• ASD
• Tricuspid atresia
• Proximal pulmonary artery atresia
• RA dilatation
• Aortic stenosis
• Ebstein anomaly of the tricuspid leaflets
Extracardiac:
• None

58. Role of Fetal Echo
Predictors for the postnatal surgical pathway:
• Combination of z-scores of fetal cardiac
measurements and tricuspid/mitral valve
(TV/MV) ratios
• Presence of coronary fistulae (usually predicts a
single ventricle route)
• RA pressure based on PFO (normal or
restrictive), TV dimension and competency,
ductus venosus Doppler (abnormal if end-
diastolic flow absent or reversed)

59. Predictors of Biventricular repair
• Fetal echo can predict biventricular circulation
(at 26 weeks gestation) with 92% specificity
• Best predictive scores for specific gestations:
PV z-score (23 weeks)
Median TV z-score (26 weeks)
Combination of median PV z-score and TV/MV
ratio (26 to 31 weeks)
Combination of median TV z-score and TV/MV
ratio (31 weeks)

60. Predictors of poor outcome
• Fetal TV z score ≤ of −4 beyond 23 weeks of
gestation
• Fetal TV annulus of ≤ 5 mm beyond 30 weeks of
gestation
• RV:LV length or width < 0.5
• Absence of TR
Peterson RE, et al.J Am Soc Echocardiogr. 2006.

61. Take-home messages
Diagnosis of PA IVS should include:
• 1) Adequacy of PDA to sustain adequate pulmonary blood flow;
adequacy of ASD for decompression of systemic venous return
to LA
• 2) Size of RV; presence or absence of inlet, trabecular and/or
infundibular portions
• 3) Evaluation of RVOT, anatomic nature of pulmonary valve
(muscular/ membranous)
• 4) Any evidence of opening in a membranous pulmonary valve,
esp. if presence of PR
• 5) Evaluation of TV annulus diameter, any sign of Ebstein’s
anomaly, related chordal attachment abnormalities
• 6) Identification of coronary artery abnormalities and/or RVDCC

62. References
• Nykanen DG. Pulmonary atresia and intact ventricular septum. In Ed.
Allen HD, Driscoll DJ, Shaddy RE, Feltes TF. Moss and Adam’s Heart
Disease in infants, children and adolescents. Seventh ed. Philadelphia,
Lippincott Williams and Wilkins
• Peterson RE, Levi DS, Williams RJ, et al. Echocardiographic predictors of
outcome in fetuses with pulmonary atresia with intact ventricular
septum.J Am Soc Echocardiogr. 2006;19:1393-1400.
• Liu L, Wang H, Cui C, et al. Prenatal echocardiographic classification and
prognostic evaluation strategy in fetal pulmonary atresia with intact
ventricular septum. Medicine (Baltimore). 2019;98:e17492.
• Giglia TM, Mandell VS, Connor AR, et al. Diagnosis and management of
right ventricle-dependent coronary circulation in pulmonary atresia
with intact ventricular septum. Circulation. 1992;86:1516-1528.