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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Pediatric Cardiology

The Three-Stage Surgical Pathway

At a Glance

Children with univentricular heart conditions often undergo a series of operations: a Norwood or Hybrid procedure soon after birth, a Glenn in infancy, and a Fontan later. Timing depends on lung pressure, heart function, valve health, anatomy, and growth.

Because a single ventricle cannot be “fixed” to function like a two-ventricle heart, surgeons often use a series of three operations to reroute how blood flows through the body. This process is called staged palliation [1]. The goal is to move from a “parallel” circulation (where the one ventricle has to pump to both the lungs and the body at the same time) to a “series” circulation (where blood flows to the lungs first and then is pumped to the body) [2][3].

Note: While this three-stage pathway is the standard approach for many children, some children with diagnoses such as pulmonary atresia with intact ventricular septum (PA/IVS) or unbalanced AVSD may be candidates for a biventricular (two-ventricle) or 1.5-ventricle repair, depending on their specific anatomy.

Why Must the Surgeries Be Staged?

You might wonder why doctors cannot do everything at once. The timing is dictated by your child’s biology [4]:

  • Lung Development: A newborn’s lungs have very high pressure (pulmonary vascular resistance). The later surgeries rely on blood flowing “passively” into the lungs without a pump. This can only happen once the lung pressure naturally drops over the first few months of life [2][5].
  • Heart Strength: The single ventricle needs time to adjust to its workload. Doing too much too soon can overwhelm the heart muscle [6].

Stage 1: The Foundation (Typically Birth to 2 Weeks)

The first surgery is the most complex and occurs shortly after birth. Depending on institutional strategy and your child’s specific anatomy, the surgeon may perform a Norwood procedure or a Hybrid procedure [7][8].

  • The Goal: To ensure the single ventricle can safely pump blood to the entire body while also sending a controlled amount of blood to the lungs [9].
  • What Happens: In a Norwood procedure, surgeons typically build a new, larger aorta (the main pipe to the body) and create a small “shunt” or “conduit” to act as a temporary blood supply to the lungs [7]. Alternatively, a Hybrid approach generally uses stents and bands rather than a large open-heart reconstruction.
  • The Result: Your child will still have “mixed” blood (a mix of red and blue), so their skin may still look slightly dusky or blue. This is expected at this stage [9].

Stage 2: The Glenn (Typically 3 to 6 Months)

As the lung pressures drop and the baby grows, they generally become ready for the Bidirectional Glenn (or “Hemi-Fontan”) [10].

  • The Goal: To reduce the workload on the single ventricle. Instead of the heart pumping blood to the lungs, the large vein from the upper body (superior vena cava) is connected directly to the lung arteries [11].
  • The Result: “Blue” blood from the head and arms now flows directly into the lungs without needing the heart to pump it there [12]. This “unloads” the ventricle, allowing it to focus more on pumping blood to the body [2].

Stage 3: The Fontan (Typically 2 to 4 Years)

The final stage of the planned pathway is the Fontan procedure [13].

  • The Goal: To separate the “red” and “blue” blood to the greatest extent possible.
  • What Happens: The surgeon connects the large vein from the lower body (inferior vena cava) to the lung arteries [5].
  • The Result: Now, the “blue” blood from the body flows passively into the lungs to get oxygen, supported by breathing and muscle movement. The single ventricle is largely responsible only for pumping oxygen-rich blood to the body [11]. After this stage, oxygen levels usually improve substantially, but they may remain below normal. Fontan pathways may include a fenestration (an intentional small hole) or venovenous collaterals, meaning some mixing of blood still occurs [14].

Is My Child Ready for the Next Stage?

Before moving from one surgery to the next, the cardiology team performs a comprehensive assessment. This often includes an echocardiogram (ultrasound) and sometimes a cardiac catheterization (a procedure to measure pressures inside the heart) [15][16]. The team evaluates a complex matrix of factors; this is a center-specific assessment rather than a universal checklist. Key considerations include:

  1. Low Lung Pressure: The pressure in the lung arteries (pulmonary vascular resistance) must be low enough for blood to flow through them passively [17][16].
  2. Strong Ventricle Function: The single ventricle must be squeezing well. Significant weakness can increase the risk of the next surgery [18][19].
  3. Healthy Valves: The valves (the heart’s “doors”) must not be leaking significantly (regurgitation). A leaky valve makes the heart work harder [15][20].
  4. Anatomy and Growth: Doctors evaluate the size of the pulmonary arteries, the presence of collateral vessels, heart rhythm, and the child’s overall growth [15].

If a child does not have favorable anatomy or pressures for the next stage, the team may use medications, perform a minor procedure (like a stent), or explore alternative pathways [21][16].

Common questions in this guide

What are the three stages of surgery for a univentricular heart?
The pathway usually starts with a Norwood or Hybrid procedure soon after birth, followed by a bidirectional Glenn in infancy and a Fontan later in childhood. Each operation changes blood flow so the single ventricle can focus more on pumping oxygen-rich blood to the body. The exact operation and timing depend on the child's anatomy and health.
Why are the operations done at different ages?
Newborn lungs have high pressure in their blood vessels, so they are not ready for blood to flow passively into the lungs. Lung pressure usually falls over the first few months, while the single ventricle also needs time to adapt. Staging helps avoid placing too much strain on the heart at once.
How do doctors know when a child is ready for the Glenn or Fontan?
The cardiology team commonly uses an echocardiogram and sometimes cardiac catheterization to measure heart and lung pressures. They also review pumping strength, valve leakage, pulmonary artery size, heart rhythm, and growth. There is no single schedule that fits every child.
What happens during the Glenn procedure?
During a bidirectional Glenn, the vein that returns blood from the upper body is connected directly to the pulmonary arteries. This lets oxygen-poor blood reach the lungs without being pumped there by the ventricle. The change reduces the ventricle's workload.
What happens during the Fontan procedure?
The Fontan connects the vein returning blood from the lower body to the pulmonary arteries, allowing blood to move to the lungs mainly through passive flow. The single ventricle then does most of the pumping for oxygen-rich blood going to the body. Oxygen levels usually improve, but they may remain below normal.
What if my child cannot proceed to the next surgery?
The team may use medicines, place a stent or perform another smaller procedure, or consider a different surgical pathway. The choice depends on lung pressures, heart function, valve health, anatomy, and growth. A child who is not ready at the usual age may need a more individualized plan.

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Which Stage 1 approach (Norwood, Hybrid, or shunt) do you recommend for my child's specific anatomy, and why?
  2. 2.What are my child's current pulmonary artery pressures and resistance, and how do they compare to the targets for the next stage?
  3. 3.How is my child’s 'working' ventricle performing, and are the valves showing any signs of leaking (regurgitation)?
  4. 4.What specific milestones in growth or weight gain are you looking for before we schedule the Stage 2 (Glenn) surgery?
  5. 5.If my child is not a candidate for the Fontan at the usual age, what alternative pathways or treatments would we explore?

References

References (21)
  1. 1

    The Lymphatic System in the Fontan Patient-Pathophysiology, Imaging, and Interventions: What the Anesthesiologist Should Know.

    RochéRodríguez M, DiNardo JA

    Journal of cardiothoracic and vascular anesthesia 2022; (36(8 Pt A)):2669-2678 doi:10.1053/j.jvca.2021.07.049.

    PMID: 34446325
  2. 2

    Total vascular resistance increases during volume-unloading in asymptomatic single ventricle patients.

    Vaiyani D, Matsuo K, Kanaan U, et al.

    American heart journal 2021; (236()):69-79 doi:10.1016/j.ahj.2021.02.019.

    PMID: 33640333
  3. 3

    Balancing a single-ventricle circulation: 'physiology to therapy'.

    Magoon R, Makhija N, Jangid SK

    Indian journal of thoracic and cardiovascular surgery 2020; (36(2)):159-162 doi:10.1007/s12055-019-00889-w.

    PMID: 33061117
  4. 4

    The Superior Cavopulmonary Connection: History and Current Perspectives.

    Herrmann JL, Brown JW

    World journal for pediatric & congenital heart surgery 2019; (10(2)):216-222 doi:10.1177/2150135119825560.

    PMID: 30841835
  5. 5

    Cardiac Imaging in Patients After Fontan Palliation: Which Test and When?

    Ciliberti P, Ciancarella P, Bruno P, et al.

    Frontiers in pediatrics 2022; (10()):876742 doi:10.3389/fped.2022.876742.

    PMID: 35652057
  6. 6

    Hypoplastic Left Heart Syndrome: Definition, Morphology, and Classification.

    Jacobs JP

    World journal for pediatric & congenital heart surgery 2022; (13(5)):559-564 doi:10.1177/21501351221114770.

    PMID: 36053108
  7. 7

    Risk Factors for Reintervention Following Treatment for Aortic Coarctation With or Without Aortic Arch Hypoplasia in Sweden: From Isolated Coarctation to Complex Bi- and Univentricular Congenital Heart Disease.

    Hlebowicz J, Floberg Cardenas W, Jeremiasen I, et al.

    Journal of the American Heart Association 2025; (14(20)):e040253 doi:10.1161/JAHA.124.040253.

    PMID: 41085210
  8. 8

    Is a hybrid strategy a lower-risk alternative to stage 1 Norwood operation?

    Wilder TJ, McCrindle BW, Hickey EJ, et al.

    The Journal of thoracic and cardiovascular surgery 2017; (153(1)):163-172.e6 doi:10.1016/j.jtcvs.2016.08.021.

    PMID: 27671550
  9. 9

    Current Therapy for Hypoplastic Left Heart Syndrome and Related Single Ventricle Lesions.

    Ohye RG, Schranz D, D'Udekem Y

    Circulation 2016; (134(17)):1265-1279 doi:10.1161/CIRCULATIONAHA.116.022816.

    PMID: 27777296
  10. 10

    The Optimal Timing of Stage-2-Palliation After the Norwood Operation.

    Meza JM, Hickey E, McCrindle B, et al.

    The Annals of thoracic surgery 2018; (105(1)):193-199 doi:10.1016/j.athoracsur.2017.05.041.

    PMID: 28847537
  11. 11

    Role of imaging in the evaluation of single ventricle with the Fontan palliation.

    Kutty S, Rathod RH, Danford DA, Celermajer DS

    Heart (British Cardiac Society) 2016; (102(3)):174-83 doi:10.1136/heartjnl-2015-308298.

    PMID: 26567230
  12. 12

    Echocardiographic Identification of Pulmonary Artery Flow Reversal: An Indicator of Adverse Outcomes in Single Ventricle Physiology.

    Spearman AD, Ginde S, Goot BH, et al.

    Pediatric cardiology 2020; (41(8)):1632-1638 doi:10.1007/s00246-020-02421-z.

    PMID: 32710282
  13. 13

    Predictors of Human Milk Feeding and Direct Breastfeeding for Infants with Single Ventricle Congenital Heart Disease: Machine Learning Analysis of the National Pediatric Cardiology Quality Improvement Collaborative Registry.

    Elgersma KM, Wolfson J, Fulkerson JA, et al.

    The Journal of pediatrics 2023; (261()):113562 doi:10.1016/j.jpeds.2023.113562.

    PMID: 37329981
  14. 14

    Predictors of protein losing enteropathy after Fontan completion: An 8-year retrospective study at Sheikh Khalifa Medical City.

    AbdelMassih AF, Kiraly L, Badaoui HE, et al.

    Global cardiology science & practice 2023; (2023(3)):e202317 doi:10.21542/gcsp.2023.17.

    PMID: 37575289
  15. 15

    Optimizing outcomes for patients undergoing superior cavopulmonary connection procedure: what we know.

    Sabati A, Alaeddine M, Quinones-Carrasquillo S, et al.

    Future cardiology 2025; (21(12)):1177-1185 doi:10.1080/14796678.2025.2598218.

    PMID: 41346285
  16. 16

    Utility of Balloon Occlusion Testing in Determining Fontan Suitability Among Patients with Elevated Pulmonary Artery Pressure and Additional Antegrade Pulmonary Blood Flow.

    Demir IH, Celebi A, Ozdemir DM, et al.

    Pediatric cardiology 2024; (45(3)):632-639 doi:10.1007/s00246-023-03380-x.

    PMID: 38182891
  17. 17

    Elevated Pulmonary Artery Pressure, Not Pulmonary Vascular Resistance, is an Independent Predictor of Short-Term Morbidity Following Bidirectional Cavopulmonary Connection.

    Tran S, Sullivan PM, Cleveland J, et al.

    Pediatric cardiology 2018; (39(8)):1572-1580 doi:10.1007/s00246-018-1932-6.

    PMID: 29948033
  18. 18

    Preoperative single ventricle function determines early outcome after second-stage palliation of single ventricle heart.

    Pająk J, Buczyński M, Stanek P, et al.

    Cardiovascular ultrasound 2017; (15(1)):21 doi:10.1186/s12947-017-0114-7.

    PMID: 28893257
  19. 19

    The Bilateral Bidirectional Glenn Operation as a Risk Factor Prior to Fontan Completion in Complex Congenital Heart Disease Patients.

    Keizman E, Tejman-Yarden S, Mishali D, et al.

    World journal for pediatric & congenital heart surgery 2019; (10(2)):174-181 doi:10.1177/2150135118819997.

    PMID: 30841839
  20. 20

    A 10-year single-centre report on Fontan attrition and non-Fontan candidacy.

    Adamson ME, West Z, John M, et al.

    Cardiology in the young 2026; 1-7 doi:10.1017/S1047951126111354.

    PMID: 41878897
  21. 21

    Peripheral Pulmonary Artery Stenosis Is Not a Contraindication to a Single-ventricle Pathway.

    Al-Khaldi A, Alsahari A, Alotay A, et al.

    The Annals of thoracic surgery 2022; (113(5)):1563-1568 doi:10.1016/j.athoracsur.2021.03.059.

    PMID: 33811885

This page explains staged surgery for children with univentricular heart conditions for informational purposes only and does not constitute medical advice. Your child's pediatric cardiology and congenital heart surgery team should interpret test results and recommend the best timing and pathway for each operation.