Pediatric Cardiology · Pulmonary Atresia with Intact Ventricular Septum

Treatment Pathways: Biventricular vs. Single Ventricle

At a Glance

Treatment for Pulmonary Atresia with Intact Ventricular Septum follows a biventricular or single-ventricle surgical pathway. The safest route depends on the baby's right ventricle size and whether they have right ventricle-dependent coronary circulation (RVDCC).

Choosing the right surgical pathway for a baby with Pulmonary Atresia with Intact Ventricular Septum (PA-IVS) is not about choosing a “better” or “worse” option—it is about identifying the specific “map” that will allow your child’s heart to function most effectively ^[1].

The decision is driven by the heart’s unique anatomy, specifically the size of the right ventricle (RV) and the way the heart muscle receives its blood supply ^[2]^[3].

The Two Main Pathways

Treatment for PA-IVS generally follows one of two distinct routes based on the initial imaging results ^[3].

1. The Biventricular (Two-Ventricle) Pathway

This pathway is the goal when the right ventricle is large enough to pump blood to the lungs on its own ^[2].

Requirements: A Tricuspid Valve Z-score typically closer to normal (e.g., -2 or higher) and the absence of Right Ventricle-Dependent Coronary Circulation (RVDCC) ^[4]^[5].
The Goal: To use both the left and right sides of the heart as nature intended. While this route may involve multiple procedures to help the right ventricle grow, the final result is a heart with two functioning pumps ^[1]^[6].

2. The Single-Ventricle (Fontan) Pathway

In many cases of PA-IVS, the right ventricle is too small to handle the job of pumping blood, or the heart muscle relies on the right ventricle for its blood supply (RVDCC) ^[7]. In these instances, the single-ventricle pathway is not a “failure” of treatment—it is a life-saving rerouting of the circulatory system ^[8].

Why RVDCC requires this path: If RVDCC is present, the right ventricle cannot be “decompressed” (opened up) to pump blood to the lungs. Doing so would drop the pressure needed to push blood into the coronary arteries, potentially causing a fatal heart attack ^[7]^[3].
The Stages: This pathway is a journey in three stages:
1. Stage 1 (Neonatal): A BT Shunt or PDA Stent to ensure immediate blood flow to the lungs ^[9]^[10].
2. Stage 2 (4–6 months): The Glenn Procedure, which connects the large vein from the upper body directly to the lung arteries ^[11].
3. Stage 3 (2–4 years): The Fontan Procedure, the final step that allows the single working ventricle to pump oxygen-rich blood to the body while oxygen-poor blood flows passively to the lungs ^[12]^[13].

The “Interstage” Reality

For children on the single-ventricle pathway, the time between Stage 1 (neonatal) and Stage 2 (4-6 months) is known as the “Interstage” period ^[8]. This is a highly vulnerable time that requires intense monitoring at home. Before you leave the hospital, you will be rigorously trained to use a pulse oximeter, perform strict daily weight checks, and watch for subtle signs of heart failure or feeding difficulties ^[8].

The Middle Ground: The 1.5 Ventricle Repair

For some children, the right ventricle is “borderline”—too small to do the whole job, but too large to ignore ^[14]. In a 1.5 ventricle repair, the right ventricle is used to pump some blood to the lungs, while a “Glenn” connection helps by sending blood from the upper body directly to the lungs as well ^[15]. This hybrid approach can provide a stable, long-term solution for children with specific anatomy ^[14].

Heart Transplant

In rare cases, if a child has severe RVDCC along with major narrowings (stenosis) or blockages in the coronary arteries, neither the biventricular nor single-ventricle pathway is safe ^[16]. Decompressing the ventricle is impossible, and relying on the damaged coronaries is too high a risk. For these children, a Heart Transplant becomes the necessary pathway to provide a healthy, functioning heart ^[16].

Decision Summary Table

Feature	Biventricular (2-V)	Single-Ventricle (Fontan)
TV Z-Score	Closer to normal (e.g., $\geq$ -2) ^[4]	Often < -3 ^[2]
RVDCC	Must be Absent ^[3]	Present or Absent ^[7]
Primary Goal	Use RV as a pump	Bypass the RV
Survival	Excellent into adulthood ^[17]	Excellent into adulthood ^[8]

Regardless of the pathway, the long-term goal is the same: a stable circulation that allows your child to grow, play, and thrive ^[17]^[8]. Your cardiology team will use every piece of imaging data to ensure they choose the safest possible route for your baby’s specific heart ^[18].

Common questions in this guide

How do doctors choose between the biventricular and single-ventricle pathways for PA-IVS?

Doctors choose a surgical pathway based on your baby's specific heart anatomy. They primarily look at the size of the right ventricle, often measured by a Tricuspid Valve Z-score, and whether the heart muscle relies on the right ventricle for its blood supply.

If my baby has RVDCC, does that mean a two-ventricle repair is ruled out?

Yes, if your baby has Right Ventricle-Dependent Coronary Circulation (RVDCC), a biventricular repair is generally not safe. Opening the right ventricle would drop the pressure needed to supply blood to the heart muscle, so the single-ventricle pathway is used instead.

What is a 1.5 ventricle repair for PA-IVS?

A 1.5 ventricle repair is a middle-ground approach used when the right ventricle is too small to pump all the blood to the lungs on its own, but large enough to help. It uses the right ventricle for some blood flow while redirecting upper body blood directly to the lungs.

What is the Interstage period in the single-ventricle pathway?

The Interstage period is the highly vulnerable time between the first neonatal surgery and the second surgery at four to six months old. During this time, babies require intense at-home monitoring for weight, oxygen levels, feeding difficulties, and signs of heart failure.

When might a baby with PA-IVS need a heart transplant?

A heart transplant may be necessary if a child has severe RVDCC along with major blockages or narrowings in their coronary arteries. In these rare cases, neither the biventricular nor single-ventricle pathways are safe options.

Curated prompts to bring to your next appointment.

1.Based on my baby's TV Z-score and RV size, which pathway is currently the recommendation?
2.If RVDCC was found, does that mean a two-ventricle repair is permanently ruled out?
3.How does a 1.5-ventricle repair differ from a full biventricular repair for my child's future?
4.If we follow the single-ventricle pathway, what specific monitoring will be done between the first and second surgeries?
5.Are there any signs of coronary stenosis that would elevate our child's risk profile to necessitate a heart transplant?

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References (18)

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3
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4
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5
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PMID: 30238627
6
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Petit CJ, Glatz AC, Qureshi AM, et al.
Circulation. Cardiovascular interventions 2017; (10(5)) doi:10.1161/CIRCINTERVENTIONS.116.004428.
PMID: 28500137
7
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Sukhavasi A, McHugh-Grant S, Glatz AC, et al.
The Journal of thoracic and cardiovascular surgery 2022; (164(5)):1277-1288 doi:10.1016/j.jtcvs.2021.11.104.
PMID: 35414413
8
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Elias P, Poh CL, du Plessis K, et al.
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PMID: 29444216
9
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10
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11
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12
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14
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15
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16
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17
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18
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This page explains surgical treatment pathways for PA-IVS for educational purposes only. Your pediatric cardiologist and surgical team are the best sources for determining the safest approach for your baby's specific heart anatomy.

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