Pulmonary Atresia with Intact Ventricular Septum (PA/IVS)

Date
October 20, 2025
URL
https://x.com/WithAScalpel/status/1980243164213456994
Categories
PAIVSIntensive Care

Pulmonary Atresia with Intact Ventricular Septum (PA/IVS)

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Definition and Core Anatomy

PA/IVS is a cyanotic congenital heart defect with an imperforate pulmonary valve, no RV–PA continuity, and an intact ventricular septum. A tricuspid valve (TV) is present—often hypoplastic or dysplastic—and systemic venous return egresses via right-to-left shunting at a PFO/ASD. Pulmonary blood flow (PBF) is ductus arteriosus–dependent in the neonatal period. Multimodality imaging—echo as the primary tool, supplemented by CT/MRI or catheterization when coronary anatomy is uncertain—supports early decision-making [1].

Key anatomic variables that drive strategy

  • Level of atresia: thin membranous/valvar vs muscular/infundibular [1].
  • RV morphology/size: uni-, bi-, or tripartite; RV cavity volume and compliance determine recruitability [1].
  • Tricuspid valve: annular Z-score, leaflet morphology, and degree of TR guide the likelihood of biventricular (BiV) vs univentricular pathways [1].
  • RV–coronary connections: ventriculocoronary fistulae and, critically, RV-dependent coronary circulation (RVDCC)—where proximal coronary stenosis/atresia makes coronary perfusion contingent on high RV pressure [2].

Pathophysiology

Pulmonary valvar occlusion creates a blind RV outflow and systemic-level RV pressure. The hypertrophied, noncompliant RV raises RVEDP, driving:

  • Atrial decompression via right-to-left flow across the PFO/ASD to maintain venous egress.
  • Ductal dependence of PBF; ductal constriction precipitates abrupt hypoxemia.
  • Ventricular interaction, with septal distortion impairing LV filling and potentiating TR.
  • Coronary coupling: in RVDCC, high RV pressure sustains coronary flow through sinusoids; abrupt RV decompression can collapse coronary driving pressure and trigger ischemia or infarction—especially when both right and left systems are obstructed [2].

Clinical Presentation

Neonates present with central cyanosis (often a single S2). As the ductus constricts, rapid desaturation and acidosis ensue. Hepatomegaly and a prominent RV impulse are common; murmurs at the pulmonary area may be soft or absent.

Diagnostic Evaluation

Echocardiography confirms atresia and the absence of antegrade PA flow, defines RV tripartite status, TV Z-score, TR severity, ASD patency, and branch PA size; color Doppler may show to-and-fro sinusoidal flow. CT/MR angiography and catheterization refine coronary mapping and quantify RV pressure when RVDCC is suspected [1].

Initial Stabilization

  • Prostaglandin E1 to maintain ductal patency.
  • Balanced ventilation/oxygenation; avoid excessive systemic vasodilation that could jeopardize coronary perfusion.
  • Balloon atrial septostomy if atrial egress is restrictive.
  • Early multidisciplinary planning with explicit assessment of coronary risk.

Management Pathways

Therapy balances RV recruitment potential with coronary safety and overall anatomy.

1) Biventricular Repair (recruitable RV/TV and no RVDCC)

Most appropriate for membranous/valvar atresia with ≥ bipartite RV and acceptable TV size.

  • Catheter or surgical valvotomy/valvuloplasty to establish antegrade flow; RVOT patch as needed.
  • Temporary PBF support (systemic–PA shunt or ductal stent) may be used during RV rehabilitation.
  • Goal: normalize RV pressure and stroke volume with staged shunt reduction.

Contemporary institutional series show that BiV was the intended pathway in ~54% of patients; overall survival at 1, 3, and 10 years for the cohort was 82.4%, 80.6%, and 79.8%, respectively [3].

2) One-and-a-Half Ventricle (borderline RV/TV, no RVDCC)

When the RV cannot sustain full PBF but contributes meaningfully:

  • Bidirectional Glenn unloads SVC return while preserving RV contribution via a rehabilitated RVOT.
  • Often follows initial palliation (ductal stent/shunt ± valvotomy) after interval growth.

3) Single-Ventricle Pathway (unfavorable RV/TV or RVDCC)

  • Avoid RV decompression in proven RVDCC because coronary flow may be RV-pressure-dependent [2].
  • Provide PBF by systemic–PA shunt or ductal stent, proceed to Glenn and ultimately Fontan when criteria are met.
  • Transplantation is reserved for severe ventricular dysfunction, refractory ischemia, or complex proximal coronary atresia.

Special Considerations: RVDCC

  • Identify it unequivocally. Angiography/advanced imaging should define fistulae and any proximal coronary stenosis/atresia [1,2].
  • Risk gradient by lesion location. Proximal/bilateral coronary obstruction carries the greatest hazard and is a key branch point in management; decompression may be reasonable with isolated fistulae or single-vessel distal disease but is contraindicated when both right and left systems are obstructed [2,5].
  • In RVDCC cohorts, mortality is markedly higher (≈42% vs 7% without RVDCC) and shapes pathway selection toward single-ventricle palliation [3].

Outcomes and Long-Term Issues

  • Pathway completion matters. In a multi-institutional registry, overall 20-year survival was 66%, but among patients discharged after their definitive end-state, survival approached 98% for BiV, ~91% for one-and-a-half, and ~98% for Fontan (reflecting survival conditional on reaching completion) [4].
  • Contemporary multicenter data show mid-term cumulative risks of death of ~11%, 16%, 17%, and 19% at 1, 6 months, 1, and 5 years, respectively; smaller TV Z-score and coronary atresia independently worsen transplant-free survival [6].
  • Late concerns across pathways include residual TR, RV diastolic dysfunction, arrhythmias, coronary ischemia in patients with ventriculocoronary connections, and—after Fontan—exercise limitation, lymphatic complications, arrhythmia, and hepatic sequelae.

Practical Algorithm (condensed)

  1. Stabilize with PGE1; ensure atrial decompression if restrictive.
  2. Define anatomy (RV size/morphology, TV Z-score, atresia type, PA size) and interrogate the coronaries for RVDCC [1,2].
  3. Choose pathway:
  • No RVDCC + recruitable RV/TV → valvotomy ± RVOT patch; temporary PBF support as needed; plan for BiV [3].
  • No RVDCC + borderline RV/TV → staged recruitment with later Glenn (1.5-ventricle).
  • RVDCC or unipartite/very small RV/TV → single-ventricle palliation; avoid RV decompression [2,3].

References

[1] Chikkabyrappa SM, Loomba RS, Tretter JT. Pulmonary Atresia With an Intact Ventricular Septum: Preoperative Physiology, Imaging, and Management. Semin Cardiothorac Vasc Anesth. 2018;22(3):245-255. PubMed

[2] Giglia TM, Mandell VS, Connor AR, Mayer JE Jr, Lock JE. Diagnosis and management of right ventricle-dependent coronary circulation in pulmonary atresia with intact ventricular septum. Circulation. 1992;86(5):1516-1528. PubMed

[3] Sukhavasi A, McHugh-Grant S, Glatz AC, et al. Pulmonary atresia with intact ventricular septum: Intended strategies. J Thorac Cardiovasc Surg. 2022;164(5):1277-1288. PubMed

[4] Wright LK, Knight JH, Thomas AS, et al. Long-term outcomes after intervention for pulmonary atresia with intact ventricular septum. Heart. 2019;105(13):1007-1013. PubMed

[5] Spigel ZA, Kelleman M, Hatef E, et al. Right Ventricle-Dependent Coronary Circulation: Impact of Obstruction Location on Outcomes in Pulmonary Atresia With Intact Ventricular Septum. Ann Thorac Surg. 2020;110(2):608-616. PubMed+1

[6] Iliopoulos I, Mastropietro CW, Flores S, et al. Pulmonary Atresia with Intact Ventricular Septum: Midterm Outcomes from a Multicenter Cohort. Pediatr Cardiol. 2024;45(4):847-857. PubMed