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PubMed This is a summary of 26 peer-reviewed journal articles Updated
Pediatric Cardiology

The Three-Stage Surgical Journey

At a Glance

Treatment for Hypoplastic Left Heart Syndrome (HLHS) involves a three-stage surgical journey: the Norwood, Glenn, and Fontan procedures. These surgeries do not fix the left side of the heart but re-route blood flow so the healthy right side can pump blood to the entire body.

The medical management of Hypoplastic Left Heart Syndrome (HLHS) is a structured, lifelong journey. Because the left side of the heart cannot be “fixed” to function normally, the goal of treatment is palliation—a series of surgeries designed to allow the right side of the heart to do the work for the whole body [1][2]. We strongly encourage asking your surgeon or cardiologist to draw a diagram of these surgeries during your visit, as visual aids are immensely helpful for understanding the “re-plumbing.”

Immediate Stabilization: The Lifeline

Before any surgery can happen, your baby must be stabilized. At birth, the medical team will start a continuous intravenous (IV) drip of Alprostadil (Prostaglandin E1 or PGE1) [3].

  • Purpose: This medication keeps the ductus arteriosus (a fetal blood vessel) open. This vessel is the only way oxygen-rich blood can reach your baby’s body before surgery [3][4].
  • Side Effects: You may notice your baby becomes sleepy or has “apnea” (brief pauses in breathing), which is a common side effect of the medication [5][6].

The Three-Stage Surgical Path

This sequence of surgeries “re-plumbs” the heart so that the right ventricle becomes the main pump for the body [2][7].

Stage Name Typical Timing Goal Survival Considerations
Stage 1 Norwood Procedure First 1–2 weeks of life Reconstruct the aorta and create a controlled way for blood to reach the lungs [7][8]. This is the highest risk stage. In top specialized centers, 1-year survival after the Norwood is approximately 90% [9].
Stage 2 Bidirectional Glenn 4–6 months of age Direct blood from the upper body straight to the lungs, reducing the workload on the heart [10][11]. Survival is generally higher once a child safely navigates the Norwood and interstage periods [11].
Stage 3 Fontan Procedure 2–4 years of age Direct blood from the lower body straight to the lungs, completing the “re-plumbing” [2][12]. Long-term survival to adulthood for Fontan patients is approximately 75% or higher [13][14].

Understanding the Norwood Shunt Options

During the Norwood, the surgeon must create a small tube (shunt) to get blood to the lungs. There are two main types:

  • Modified Blalock-Taussig (mBT) Shunt: A tube connecting the aorta to the lung artery [7].
  • Sano (RVPAS) Shunt: A tube connecting the right ventricle directly to the lung artery [15].
  • Which is better? Research shows no significant difference in long-term survival between the two [16][17]. The Sano shunt may offer more stability early on, while the mBT shunt may require fewer follow-up procedures on the lung arteries [18][17].

The “Interstage” Period

The time between the Norwood (Stage 1) and the Glenn (Stage 2) is often considered the most fragile time for a baby with HLHS [19]. Many hospitals have specialized “Home Monitoring Programs” where parents track the baby’s oxygen levels and weight daily to catch any small changes early [20].

Alternative Paths

While the three-stage path is the standard, it is not the only option:

  • Hybrid Procedure: A less invasive first step that uses a combination of a small surgery and a stent. This is sometimes preferred for very small or high-risk infants, though it may carry higher early mortality risks than the standard Norwood [21][22].
  • Heart Transplantation: In some cases—such as if the right ventricle is very weak—a transplant may be considered, though it is often used as a “rescue” if surgeries aren’t working well [23][24].
  • Compassionate (Comfort) Care: For some families, the focus may shift from intensive surgery to ensuring the baby is comfortable and spends their time with family. This is a deeply personal decision made with the support of a multidisciplinary team, and it is a completely valid choice [25][26].

Common questions in this guide

What is the purpose of the three-stage surgery for HLHS?
The surgeries do not fix the underdeveloped left side of the heart. Instead, they re-plumb the heart's connections so the healthy right ventricle can take over pumping oxygen-rich blood to the entire body.
What is the difference between an mBT shunt and a Sano shunt?
Both shunts deliver blood to the lungs during the Norwood procedure. The mBT shunt connects the aorta to the lung artery, while the Sano shunt connects the right ventricle directly to the lung artery. Research shows similar long-term survival rates for both options.
Why does my baby need Alprostadil (PGE1) before surgery?
Alprostadil is an intravenous medication given at birth to keep a fetal blood vessel called the ductus arteriosus open. This ensures oxygen-rich blood can reach your baby's body safely before the first surgery can be performed.
What is the interstage period for HLHS?
The interstage period is the time between the first surgery (Norwood) and the second surgery (Glenn). This is a highly fragile time for an infant, and parents typically participate in a home monitoring program to track the baby's oxygen levels and weight daily.
Are there alternatives to the standard three-stage surgical path?
Yes, depending on the baby's specific anatomy and health. Alternatives include a less invasive Hybrid procedure, a heart transplant if the right ventricle is too weak, or compassionate comfort care focused on quality time with family.

Questions for Your Doctor

5 questions

  • •Based on my baby's specific anatomy, which shunt (mBT or Sano) do you recommend for the Norwood procedure, and why?
  • •Could you draw a quick diagram of how my baby's heart will be 're-plumbed' during the Norwood?
  • •Is my baby a candidate for the 'Hybrid' approach instead of the traditional Norwood procedure?
  • •How does my baby's right ventricular function and tricuspid valve look, and how does that affect their surgical risk?
  • •What are the specific criteria at this hospital for recommending a heart transplant over the three-stage surgical path?

Questions for You

2 questions

  • •How do I feel about the balance between the risks of surgery and the potential quality of life for my child?
  • •Do I have the support system in place to manage the intense monitoring required during the 'interstage' period at home?

References

References (26)
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    Outcomes in Hypoplastic Left Heart Syndrome.

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    Pediatric clinics of North America 2020; (67(5)):945-962 doi:10.1016/j.pcl.2020.06.008.

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    A milestone in congenital cardiac surgery: Four decades of the Norwood procedure.

    Mazurak M, Kusa J

    Journal of cardiac surgery 2021; (36(8)):2919-2923 doi:10.1111/jocs.15657.

    PMID: 34002897
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    Hybridizing the hybrid: a "serendipitous bridge" to heart transplantation in a child with hypoplastic left heart syndrome.

    Rawtani S, Reis M, Gandhi SK

    Indian journal of thoracic and cardiovascular surgery 2021; (37(3)):345-347 doi:10.1007/s12055-020-01088-8.

    PMID: 33967429
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    Unusual presentation of anomalous origin of the right pulmonary artery from the ascending aorta: case report.

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    Low-dose prostaglandin E1 is safe and effective for critical congenital heart disease: is it time to revisit the dosing guidelines?

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    Prostaglandin E1 overdose in a term neonate with congenital heart disease.

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    Technical Aspects and Common Pitfalls of Norwood With Modified Blalock Taussig Shunt.

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    Surgical Palliation for Hypoplastic Left Heart Syndrome: For Now, Just Keep Doing What You Do Best.

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    A Comprehensive Approach to the Management of Patients With HLHS and Related Malformations: An Analysis of 83 Patients (2015-2021).

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    Attrition between the superior cavopulmonary connection and the Fontan procedure in hypoplastic left heart syndrome.

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This page explains the surgical treatment path for Hypoplastic Left Heart Syndrome (HLHS) for educational purposes. Always consult your pediatric cardiologist and surgical team to determine the safest and most appropriate treatment plan for your child.

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