Glenn Procedure

Introduction

If your child has been diagnosed with a single-ventricle heart defect, the road ahead is usually a planned series of operations rather than one single repair. The Glenn procedure is the second of these operations for most children. It is a major step, but it is also a stabilising one — many families notice that after recovery, their child breathes more easily, feeds better, grows more steadily, and needs fewer hospital visits.

This guide is written for parents and families whose child has already been diagnosed and is being prepared for the Glenn procedure, or who are learning what comes next after an earlier neonatal heart surgery. It explains what the operation is, why it is done at this point in the pathway, how the surgical team prepares for it, what happens during the surgery, what to expect in the intensive care unit (ICU) and on the ward, what recovery looks like at home, the risks involved, and how the Glenn fits into the longer journey toward the Fontan procedure.

The information here is general. Every child is different, and the specifics of your child’s anatomy, earlier surgery, and current heart function will shape the plan their team puts together. Use this guide to feel more prepared for the conversations ahead, not as a substitute for them.

What Is the Glenn Procedure?

The Glenn procedure is an open-heart operation performed on infants born with certain complex congenital heart defects in which only one of the heart’s two pumping chambers (ventricles) works well enough to support normal circulation. These are called single-ventricle heart defects.

The formal medical name for the modern version of the operation is the bidirectional Glenn shunt (sometimes abbreviated as BDG). During the surgery, the surgeon disconnects the superior vena cava — the large vein that carries oxygen-poor blood from the head, arms, and upper body back toward the heart — and connects it directly to the pulmonary artery, the vessel that carries blood to the lungs. After this connection, blood from the upper body flows passively into the lungs without first passing through the heart.

The Glenn procedure is not a cure and is not a final repair. It is a palliative operation: it improves the way blood circulates and reduces the strain on the single working ventricle, but the child’s heart will still have an unusual circulation. The Glenn is typically the second of three planned operations in the single-ventricle pathway, sitting between an initial newborn operation (such as the Norwood procedure or a systemic-to-pulmonary shunt) and the later Fontan procedure.

How It Changes the Circulation

In a healthy heart, the right ventricle pumps oxygen-poor blood to the lungs, and the left ventricle pumps oxygen-rich blood to the body. In a child with a single working ventricle, that one chamber has to do both jobs at once. It pumps a mixed stream of blood — some heading to the lungs, some to the body — and this puts the heart under significant strain, while oxygen levels in the body remain lower than normal.

The Glenn procedure takes the blood returning from the upper half of the body and routes it directly into the lungs, bypassing the heart entirely on that side. The single ventricle is then responsible mainly for pumping the oxygen-rich blood that has already come back from the lungs out to the body. This:

• Reduces the volume of blood the single ventricle must pump
• Improves the mix of oxygen in the blood reaching the body
• Eases symptoms such as breathlessness and poor feeding
• Sets up the circulation for the Fontan operation later in childhood

Why the Glenn Procedure Is Performed

The Glenn is part of a planned, staged surgical pathway for children with single-ventricle physiology. The reason it is staged — rather than performed as a single corrective operation — is that the lungs and blood vessels of a newborn baby are not ready to receive blood passively from the body. The lungs need to mature, and the pressure in the lung blood vessels needs to fall to a low enough level for passive flow to work. This typically happens during the first few months of life.

The Three-Stage Pathway

1. Stage 1 — Newborn surgery. Performed in the first days or weeks of life. Depending on the defect, this may be a Norwood procedure (for hypoplastic left heart syndrome), a Blalock–Thomas–Taussig shunt, or a pulmonary artery band. The aim is to stabilise circulation and protect the lungs.
2. Stage 2 — The Glenn procedure. Performed at around 4 to 6 months of age, sometimes a little earlier or later. The superior vena cava is connected to the pulmonary artery.
3. Stage 3 — The Fontan procedure. Performed at around 2 to 4 years of age. The inferior vena cava (which brings oxygen-poor blood from the lower body) is also routed to the lungs, completing the separation of oxygen-poor and oxygen-rich blood.

Conditions That Lead to the Glenn Procedure

The Glenn procedure is used for children with a range of single-ventricle and functionally single-ventricle anatomies, including:

• Hypoplastic left heart syndrome (HLHS)
• Tricuspid atresia
• Pulmonary atresia with intact ventricular septum
• Double inlet left ventricle
• Unbalanced atrioventricular septal defect
• Severe Ebstein anomaly in certain situations
• Other complex defects where biventricular repair is not possible

Your child’s specific diagnosis will have been confirmed by echocardiography (ultrasound of the heart), and often by cardiac catheterisation and other imaging before the Glenn.

Who Is a Candidate?

Not every child with a single-ventricle defect is ready for the Glenn at the same time. The decision about when to operate is made by the pediatric cardiac team based on several factors. These include:

• Pulmonary artery pressure. The pressure inside the lung blood vessels must be low enough that blood will flow into them passively, without being actively pumped by the heart. This is the single most important factor, and it is measured during a cardiac catheterisation before surgery.
• Function of the single ventricle. The pumping chamber must be working well enough to support the circulation after surgery.
• Atrioventricular valve function. The valve between the upper and lower chambers should not be leaking significantly.
• The condition of the pulmonary arteries. They need to be of adequate size and without significant narrowing.
• The child’s growth and overall condition. Children need to have reached a certain weight and to be free of active infection.
• Oxygen levels. Most children at this stage have lower-than-normal oxygen saturations, often in the 75–85% range. The Glenn is timed before these levels fall further.

If the pulmonary pressures are too high, or if other anatomical issues are present, the surgical team may delay the Glenn, perform additional preparatory procedures, or in some cases adjust the long-term plan.

The Hemi-Fontan: A Related Technical Approach

In some centres, a slightly different technical operation called the hemi-Fontan is performed instead of the bidirectional Glenn at this stage. The hemi-Fontan achieves the same physiological goal — routing upper-body blood directly to the lungs — but does so using a different surgical configuration that some teams prefer because it can simplify the later Fontan operation.

From a parent’s perspective, the recovery, the hospital course, and the long-term plan are very similar. Whether your child has a bidirectional Glenn or a hemi-Fontan is a decision made by the surgical team based on the child’s anatomy and the centre’s usual practice.

Preparing for the Glenn Procedure

Preparation for the Glenn procedure usually unfolds over several weeks. Your child’s team will want a clear picture of their anatomy, lung pressures, and overall health before going ahead.

Tests Before Surgery

Typical investigations include:

• Echocardiography. A detailed ultrasound to assess the heart structure, ventricular function, and valve function.
• Cardiac catheterisation. A thin tube is passed through a blood vessel into the heart to measure pressures inside the lung arteries and check the anatomy. This is one of the most important tests before the Glenn.
• Chest X-ray. To assess the lungs and the size of the heart.
• Blood tests. Including a full blood count, kidney and liver function tests, clotting studies, and blood typing in preparation for possible transfusion.
• Growth and nutrition assessment. Children who are well-nourished tolerate surgery and recover better.
• Dental and infection screening. Active infections will usually delay surgery.

In the Days Before Admission

The surgical and anaesthetic teams will meet with you to discuss the operation, the risks, the expected hospital course, and what recovery looks like. They will go through consent in detail and answer your questions. It is helpful to write your questions down beforehand — many parents find it hard to remember everything in the moment.

Practical preparation often includes:

• Stopping certain medications as advised
• Following fasting instructions before anaesthesia
• Bathing the child with prescribed antiseptic soap if requested
• Arranging support at home for siblings and other family responsibilities
• Packing for an extended hospital stay, including comfort items for the child

Preparing Yourself

Sending an infant for open-heart surgery is one of the hardest things a parent can do. Many families find it helpful to talk to the hospital’s social worker, child-life specialist, or a counsellor before the day of surgery. Speaking with other families whose children have been through the Glenn can also be reassuring, where the hospital offers that connection.

What Happens During the Glenn Procedure

The Glenn procedure is performed under general anaesthesia. The operation usually takes about three to five hours, although the total time your child is in the operating room (including anaesthesia, preparation, and waking up) is longer.

Step by Step

1. Anaesthesia and monitoring. The child is given general anaesthesia and a breathing tube is placed. Lines are inserted into blood vessels for monitoring blood pressure, giving fluids, and taking blood samples.
2. Chest opening. The surgeon makes an incision down the middle of the chest and divides the breastbone (sternum) to access the heart and great vessels.
3. Cardiopulmonary bypass. The child is placed on a heart-lung machine, which takes over the work of the heart and lungs during the operation. The Glenn can sometimes be performed without the heart being stopped — the team will decide based on anatomy.
4. Disconnecting the superior vena cava. The surgeon separates the superior vena cava from the right atrium of the heart.
5. Connecting to the pulmonary artery. The surgeon then sews the superior vena cava directly to the right pulmonary artery, creating a new pathway for blood from the upper body to flow into the lungs.
6. Closing other shunts. If a shunt was placed during the earlier newborn surgery (such as a Blalock–Thomas–Taussig shunt), it is usually taken down at this point because it is no longer needed.
7. Coming off bypass. The heart resumes its work, and the team carefully monitors how the new circulation is performing.
8. Chest closure. Drainage tubes are placed to remove fluid and air from the chest cavity, and the breastbone is closed with wires. The skin is closed with stitches or surgical glue.

Throughout the operation, a member of the team will keep the family updated. After surgery, your child will be transferred to the pediatric cardiac intensive care unit (PCICU) before you can see them.

The Hospital Stay

The hospital stay after the Glenn procedure usually lasts between one and two weeks, though it can be longer if complications occur. The stay generally has two parts: the intensive care unit phase and the ward phase.

In the Intensive Care Unit

When you first see your child in the ICU, they will look different from how you are used to seeing them. They will usually have:

• A breathing tube and ventilator support
• Several lines in the neck, arms, or legs for monitoring and medications
• Chest drainage tubes
• A urinary catheter
• Wires connected to monitors
• Possibly some swelling around the face and eyes

Key goals in the ICU include:

• Stabilising the new circulation. Doctors will watch oxygen levels, blood pressure, and blood flow to the lungs closely.
• Weaning from the ventilator. Most children come off the breathing tube within the first day or two, though some need longer support.
• Managing fluid balance. Children sometimes develop fluid around the lungs (pleural effusions) after the Glenn, and the team works to manage this with medications and chest drains.
• Pain management. Children are kept comfortable with appropriate pain medication.
• Restarting feeding. Feeding is usually paused at first and then gradually resumed, sometimes through a feeding tube before bottle or breastfeeding restarts.

The typical ICU stay is two to four days, but this varies widely.

On the Cardiac Ward

Once your child is stable and off most of the lines and tubes, they will move to a cardiac step-down unit or the general cardiac ward. Here, the focus shifts to:

• Continuing to remove chest drains as drainage decreases
• Adjusting medications
• Re-establishing full feeding and weight gain
• Monitoring for any late complications
• Teaching parents how to care for the child at home

Before discharge, the team will make sure you are comfortable with the medications, wound care, feeding plan, and the signs to watch for at home. They will arrange the first follow-up appointments with the pediatric cardiologist.

Recovery and Healing at Home

The first weeks at home after the Glenn procedure are a period of steady, gradual healing. Most parents notice that within a few weeks their child looks pinker, feeds more easily, sleeps better, and has more energy. Some changes happen quickly, while others unfold over months.

The First Few Weeks

During the first four to six weeks after discharge, you can expect:

• Improved oxygen saturation. Levels typically rise into the 80–85% range, sometimes higher. They are still lower than a child without heart disease but are an improvement on pre-surgery levels.
• Healing of the chest incision. Keep the wound clean and dry as advised. Watch for redness, swelling, discharge, or fever, which can be signs of infection.
• Sternum precautions. The breastbone takes about six weeks to heal. Avoid lifting your child under the arms; instead, scoop them up supporting the head and bottom.
• Feeding and weight gain. Many children feed more easily after the Glenn because they are less breathless. Some still need extra calories or tube feeding for a while.
• Tiredness and irritability. Recovery is hard work for a small body. Sleep patterns may take time to settle.

Medications at Home

Most children go home on a small number of medications, which may include a low-dose blood thinner such as aspirin (to reduce the risk of clotting in the new Glenn connection), a diuretic for a short period to help with fluid balance, and sometimes other heart medications. Give all medications exactly as prescribed and ask the team before stopping or changing any.

Follow-up Appointments

Your child will have regular follow-up with the pediatric cardiologist, often starting one to two weeks after discharge, then at increasing intervals as recovery progresses. These visits typically include an examination, oxygen saturation check, and an echocardiogram to confirm the Glenn is working well.

When to Call the Team

Contact your cardiac team promptly if your child has:

• Fever or signs of infection
• Redness, swelling, or discharge from the incision
• Worsening breathing or unusually fast breathing
• Poor feeding or vomiting that does not settle
• Significant drop in oxygen levels (if you have a home pulse oximeter)
• Unusual sleepiness or floppiness
• Swelling of the face, neck, or upper body that develops or worsens

Swelling of the upper body, sometimes called SVC syndrome, can occur if the new Glenn connection becomes narrowed or blocked. It is uncommon, but worth knowing about.

Risks and Complications

The Glenn procedure is a major operation, and even with excellent surgical care, there are risks. Survival after the Glenn has improved substantially over the past two decades, and in experienced pediatric cardiac centres outcomes are generally good. Your child’s team can discuss centre-specific outcomes and the particular risks for your child based on their anatomy and earlier surgery.

Possible Complications

• Bleeding. Sometimes requiring transfusion or, occasionally, return to the operating room.
• Pleural effusions. Fluid collecting around the lungs is one of the more common issues and may need extended chest drainage.
• Low oxygen levels. If pulmonary pressures are higher than expected, oxygen saturations may be lower than hoped.
• Arrhythmias. Disturbances of heart rhythm can occur, sometimes needing medication or temporary pacing.
• Blood clots. Clots can form in the Glenn pathway, which is why aspirin or another anticoagulant is often given.
• Infection. Of the wound, the chest, or the bloodstream.
• Stroke or neurological injury. Uncommon but a recognised risk of complex cardiac surgery.
• SVC syndrome. Narrowing or obstruction of the new Glenn connection, causing swelling of the upper body.
• Need for further intervention. Some children develop additional vessels (collaterals) over time that may need to be closed in the cardiac catheterisation laboratory.
• Pulmonary arteriovenous malformations. Abnormal connections in the lung blood vessels that can develop in the years after a Glenn and lower oxygen saturation. These are typically addressed at the time of the Fontan.

Long-term, children with Glenn circulation are monitored closely for changes in heart function, oxygen levels, and growth as they move toward the Fontan operation.

Life After the Glenn Procedure

For many families, the months after recovery from the Glenn are the calmest period in the single-ventricle pathway so far. Symptoms are usually milder than before, hospital visits are less frequent, and the child has more energy for play, feeding, and development.

Growth and Development

Most children grow and develop well after the Glenn, although some take time to catch up. The cardiology team will track weight, length, and developmental milestones. Some children benefit from input from a dietitian, a physiotherapist, or an early-intervention developmental service, particularly if they had a long ICU stay or feeding difficulties earlier on.

Activity and Play

Once the sternum has healed (around six weeks), normal infant and toddler activities are usually fine. As children grow, they may have some limits on the most strenuous activities, but most can play, attend nursery or school, and take part in everyday life. The cardiology team will give specific guidance as your child gets older.

Routine Childhood Care

Standard childhood immunisations are encouraged. The team may add the influenza vaccine and the RSV preventive antibody during the at-risk seasons, and good dental hygiene becomes important from an early age because of the risk of infection of the inner heart lining (endocarditis). Discuss any new medications, dental work, or surgery with the cardiology team in advance.

Looking Toward the Fontan

The Glenn is the second stage. The third stage, the Fontan procedure, is usually performed when the child is between about two and four years old, depending on their growth, oxygen levels, and overall progress. Before the Fontan, the team will usually repeat a cardiac catheterisation to reassess pressures and anatomy.

In the years between the Glenn and the Fontan, the cardiology team watches for:

• Falling oxygen saturations
• Increased symptoms during exertion
• Changes in heart function
• Development of additional blood vessels (collaterals)
• Adequate growth

Emotional Support for Families

The single-ventricle journey is long, and the period around each surgery is emotionally demanding. It is normal to feel anxious, exhausted, or overwhelmed. Many parents describe a mixture of relief and worry after the Glenn — relief that another major step is behind them, and worry about the operations and decisions still ahead.

Things that can help:

• Connecting with other families on the same pathway, either at the hospital or through patient-family support groups
• Accepting practical help from family and friends for meals, childcare for siblings, or transport
• Talking with a counsellor, psychologist, or social worker, especially if you notice signs of depression, anxiety, or post-traumatic stress
• Pacing yourself: the journey is a marathon, not a sprint
• Keeping a simple log of your child’s medications, oxygen levels, weight, and questions for the next clinic visit

Siblings can also be affected by long hospital stays and parental absence. Child-life specialists at the hospital can help explain what is happening in age-appropriate ways.

Frequently Asked Questions

Is the Glenn procedure a cure for my child’s heart defect?

No. The Glenn is a palliative operation that improves the circulation and reduces the strain on the single working ventricle. It is the second step in a three-stage pathway. The third stage, the Fontan procedure, completes the separation of oxygen-poor and oxygen-rich blood. Even after the Fontan, children with single-ventricle hearts need lifelong specialist cardiac follow-up.

When will my child have the Fontan?

Most children have the Fontan between two and four years of age, depending on growth, oxygen levels, pulmonary artery pressures, and ventricular function. The team will plan the timing based on your child’s progress and a cardiac catheterisation before the operation.

Will my child’s oxygen levels be normal after the Glenn?

Oxygen saturations usually improve after the Glenn but typically remain lower than the 95–100% seen in children without heart disease. Levels in the 80–85% range are common after the Glenn, often a little higher. Saturations may drift down gradually over the months and years before the Fontan, which is one of the reasons the Fontan is eventually planned.

How long does the surgery take?

The Glenn operation itself typically takes three to five hours. The total time your child is away from you in the operating area, including anaesthesia setup and waking up, is longer.

How long will my child stay in the hospital?

Most children stay in hospital for about 7 to 14 days after the Glenn, with a few days in the intensive care unit followed by time on the cardiac ward. Children with complications, ongoing pleural effusions, or feeding difficulties may stay longer.

Will my child have a scar?

Yes. The Glenn is performed through an incision down the middle of the chest, and your child will have a vertical scar on the front of the chest. There may also be smaller scars where chest drains and lines were placed. Scars fade significantly over time, particularly in young children.

Can my child take part in normal activities after recovery?

After the sternum has healed and the cardiology team gives clearance (usually around six weeks), most children return to normal infant and toddler activities. As they grow, most can attend nursery, school, and participate in play and many sports. Strenuous competitive sports may be restricted later, and the cardiology team will guide you on what is appropriate at each stage.

Are there any vaccines or medications to avoid?

Standard childhood vaccines are encouraged. The team will usually recommend additional protection against respiratory infections such as influenza and RSV in season. Before any new medication, vaccine, or dental procedure, check with your pediatric cardiologist, as some can interact with heart medications or carry a risk of infection of the heart lining.

What happens if the Glenn does not work as expected?

If the new Glenn pathway becomes narrowed, oxygen levels fall, or other issues arise, the team may consider additional procedures — most often through the cardiac catheterisation laboratory rather than further open-heart surgery. The Fontan plan may also be adjusted. Close follow-up is in place precisely so that any problems are caught and managed early.

Will my child need lifelong follow-up?

Yes. Children with single-ventricle hearts need lifelong specialist follow-up, transitioning from pediatric cardiology to adult congenital heart disease services in their late teens. This is the case even after a successful Fontan operation and into adulthood.

Conclusion

The Glenn procedure is a defining step in the staged surgical pathway for children with single-ventricle congenital heart defects. It does not provide a final repair, but it does something important: it eases the work the single ventricle has to do, improves oxygen levels, and gives children the strength to grow and develop while preparing the circulation for the Fontan operation later in childhood.

For families, the Glenn often marks a shift from a fragile first year of life into a more stable, more manageable phase. Recovery is not always straightforward, and the journey ahead still has important milestones, but with experienced pediatric cardiac care, close follow-up, and family support, most children come through the Glenn and continue to grow, learn, and thrive on the path to their next stage of treatment.