Glenn Procedure: A Critical Milestone in Congenital Heart Surgery
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is the Glenn procedure?
The Glenn procedure is heart surgery for infants, typically at 3 to 6 months, to treat single ventricle heart defects [1]. It connects the superior vena cava to the pulmonary arteries so upper-body blood gets oxygen without passing through the heart [1]. It is a second-stage operation; reported early survival is 96% to 99%, depending on the center and the child's condition.
What the research says
Most babies survive the Glenn procedure. A study of 259 patients operated on between 2002 and 2020 reported a mortality of 3.86% after the procedure and a median hospital stay of 12 days (Yousef et al., Egypt Heart J, 2023) [2].
Keeping some extra blood flow to the lungs during the Glenn did not change early survival. A meta-analysis of 17 studies with 2,504 patients found no significant difference in 30-day mortality between the two Glenn techniques (odds ratio 1.11), while oxygen levels before the Fontan stage were higher with the pulsatile technique (Yasa et al., Ann Thorac Cardiovasc Surg, 2025) [3].
Purpose and Mechanism
The primary goal of the Glenn procedure is to optimize how blood moves through a heart that is effectively missing one of its pumping chambers. In a healthy heart, two ventricles work in tandem to pump blood to the lungs and the rest of the body. In cases of single ventricle defects, only one chamber is capable of this work. The Glenn surgery creates a "shortcut" for blood returning from the upper body, sending it directly to the pulmonary arteries [1]. This reduces the workload on the single functioning ventricle and helps maintain stable oxygen levels in the bloodstream.
Feature | Standard Circulation | Post-Glenn Circulation |
Upper Body Return | Returns to right atrium | Flows to pulmonary arteries |
Heart Workload | Shared by two ventricles | Relieved for single ventricle |
Oxygenation Path | Through heart to lungs | Bypasses heart to lungs |
Ventricle Status | Two active chambers | One primary pumping chamber |
Conditions Treated by the Glenn Procedure
This surgery is specifically indicated for complex heart conditions where the heart's internal structure is incomplete or improperly connected. These defects often involve valves that did not form correctly or ventricles that are too small to pump blood effectively. By addressing these structural issues early in life, the Glenn procedure provides a foundation for the heart to grow and adapt as the child develops.
Hypoplastic Left Heart Syndrome (HLHS): A condition where the left side of the heart is severely underdeveloped.
Tricuspid Atresia: The absence of a tricuspid valve, preventing blood flow between heart chambers [1].
Pulmonary Atresia: A defect where the pulmonary valve does not form, blocking blood flow to the lungs.
Double Inlet Ventricle: A rare defect where both upper chambers of the heart pump into a single lower chamber.
The Surgical Journey and Recovery
The Glenn procedure is typically the second stage in a three-part surgical series. It often follows a neonatal procedure like a Blalock-Taussig (BT) shunt and precedes the Fontan procedure, which is usually performed when the child is older and more active [1]. The surgery itself takes approximately four hours and is performed under general anesthesia [1]. Following the operation, infants usually spend about three days in the Intensive Care Unit (ICU) for close monitoring before transitioning to a regular hospital room [1].
Long-Term Outlook and Benefits
The success of the Glenn procedure has dramatically changed the outlook for children with single ventricle defects. With reported early survival of about 96% to 99%, it is considered a highly effective and reliable intervention [1]. Beyond immediate survival, the procedure prevents the single ventricle from becoming overworked and enlarged [1], which is crucial for long-term heart health. It also simplifies the next stage of surgery, making the final Fontan procedure safer and more likely to succeed.
Conclusion
The Glenn procedure is a cornerstone of modern pediatric heart surgery, providing a life-saving transition for infants with complex heart defects. By elegantly redirecting blood flow, it protects the heart and prepares children for a lifetime of growth. For families facing these challenges, the high success rate and proven benefits of the Glenn procedure offer a beacon of hope and a clear path toward a healthier future for their children.
For more information on pediatric cardiac care and support for families navigating congenital heart defects, please consult our dedicated library of heart health resources. We are committed to providing the guidance and information you need to care for your child's heart.
Frequently Asked Questions
What is the survival rate for the Glenn procedure?
The survival rate for the bidirectional Glenn procedure is high, with reported early survival of about 96% to 99% depending on the center and the child's condition.
How long does the surgery take?
A Glenn procedure typically takes about four hours, though the exact duration can vary based on the child's specific anatomy and surgical needs.
At what age is the Glenn procedure usually performed?
Surgeons generally perform the procedure when a child is between 3 and 6 months old, and rarely before the age of 2 months.
Why is it called a "bidirectional" Glenn?
The Glenn procedure is called bidirectional because the connection allows blood to flow to both the right and left pulmonary arteries simultaneously.
Does my child need a heart-lung machine during surgery?
While some children require a cardiopulmonary bypass machine to support their heart and lungs during the procedure, it is not always necessary for every patient.
How long is the hospital stay after the Glenn procedure?
Children typically spend about three days in the ICU and several additional days in a regular hospital room before they are ready to go home.
What is the next surgery after the Glenn procedure?
The next stage is usually the Fontan procedure, which is typically performed when the child is between 2 and 4 years old and has become more active.
Can the Glenn procedure be a permanent solution?
For some patients who cannot have or do not need a Fontan procedure, the Glenn procedure can serve as a long-term solution for their circulation.
What are the most common complications?
Complications can occur in about 30% of cases and may include low oxygen levels, fluid around the lungs (pleural effusion), or high blood pressure.
When should I call the doctor after we go home?
You should contact your child's cardiologist immediately if they develop a fever, fluid from the incision, difficulty feeding, or trouble gaining weight.
Related Reading
Understanding the Norwood Procedure for HLHS explains the first-stage surgery that comes before the Glenn.
Fontan Procedure: How It Works, Stages, Risks, and Long-Term Outlook covers the final stage that usually follows the Glenn.
Hypoplastic Left Heart Syndrome (HLHS): What It Is, Symptoms, Surgery Stages, and Lifelong Care explains a heart defect treated with staged surgery.
Hypoplastic Right Heart Syndrome: Symptoms, Causes, and Surgical Treatment covers an underdeveloped right heart and its surgical repair.
References
Cleveland Clinic. Glenn Procedure. Cleveland Clinic. October 12, 2022. https://my.clevelandclinic.org/health/treatments/24290-glenn-procedure
Yousef AA, Elmahrouk AF, Hamouda TE, et al. Factors affecting the outcomes after bidirectional Glenn shunt: two decades of experience from a tertiary referral center. Egypt Heart J. 2023;75(1):53. PMID 37378691. https://doi.org/10.1186/s43044-023-00381-2
Yasa KP, Sudarma IW, Harta IKAP, et al. Impact of Pulsatile Bidirectional Cavopulmonary Shunt on Pre-Fontan Hemodynamics in Single Ventricle Physiology: A Meta-Analysis Reveals Favorable Outcomes. Ann Thorac Cardiovasc Surg. 2025;31(1):ra.24-00170. PMID 40010718. https://doi.org/10.5761/atcs.ra.24-00170
Medical disclaimer
This article is for general education only and does not replace advice from a qualified healthcare professional. Talk to your doctor about your own diagnosis and treatment, and seek emergency care right away for severe or sudden symptoms.
Comments