Univentricular Palliations: New Hope for Congenital Heart Patients?
"Heart transplantation offers a solution for children with complex congenital heart defects that require univentricular palliation, but it comes with significant challenges."
Congenital heart defects (CHDs) are structural abnormalities present at birth, affecting the heart's normal function. In severe cases, where a child is born with a single functional ventricle (univentricular heart), a series of palliative surgeries known as univentricular palliation are performed. These procedures, such as the Fontan procedure, aim to improve blood flow and oxygenation but are not curative.
While univentricular palliation can extend a child's life and improve their quality of life, it is associated with long-term complications, including heart failure, liver dysfunction, and protein-losing enteropathy. In some cases, heart transplantation becomes the only viable option for survival.
Orthotopic heart transplantation, where a diseased heart is replaced with a healthy donor heart, presents a unique set of challenges in patients who have undergone previous univentricular palliation. The altered anatomy and prior surgeries complicate the transplantation procedure and require specialized expertise.
Tracking Congenital Heart Defects
Congenital cardiovascular defects are structural problems in the heart or blood vessels that are present at birth, and they are among the most common birth defects worldwide. The CDC reports that the prevalence of heart defects, including critical defects, varies by state and by defect type. Birth-defect tracking programs collect information about affected babies, helping researchers determine where and when these conditions occur and whom they affect. These data also support research into factors that may increase or decrease the risk of heart defects.
Complexity of Transplant Planning
Heart transplantation for congenital heart disease requires detailed, individualized preoperative planning. Important considerations include atrial situs, abnormalities of systemic venous return, great-artery anomalies, and problems created by previous catheter-based palliations. Failed single-ventricle palliation has become the most common indication for transplantation within the congenital heart disease group. Limited donor-heart availability and the broad anatomical variation in congenital disease continue to make pediatric transplantation a surgical challenge.
Building Modern Cardiac Transplantation
Heart transplantation developed through decades of research and surgical innovation addressing immunology, organ preservation, and patient care. Key breakthroughs included vascular anastomosis, cardiopulmonary bypass, and the discovery of cyclosporine A. Norman Shumway is widely regarded as the father of heart transplantation. Earlier advances in heart-lung machines, aortic aneurysm surgery, and congenital heart repair also helped establish techniques that later supported transplantation.
Heart Transplantation After Univentricular Palliation: Addressing the Challenges
A study published in the Journal of Cardiothoracic Surgery in 2015 investigated the outcomes of orthotopic heart transplantation in patients who had previously undergone univentricular palliation. The study, led by María-Teresa González-López and colleagues, reviewed the surgical techniques and results in a cohort of 23 congenital cardiac patients who underwent heart transplantation between 2013 and 2014.
- Surgical Techniques: The researchers employed various surgical techniques to address the challenges posed by the altered anatomy and prior surgeries. These included hemiarch repair, pulmonary artery (PA) branches plasty, hilum-to-hilum PA reconstruction, superior venae cavae reconstruction, stent removal from PA, and inferior venae cavae reconstruction.
- Outcomes: The average cardiopulmonary-bypass time was 257.6 minutes, and the average total-ischemia-time was 220.7 minutes. One patient required ECMO (extracorporeal membrane oxygenation), a life-support machine that oxygenates the blood outside of the body. Four patients underwent delayed sternal closure, and two patients underwent diaphragm plication, a surgical procedure to correct diaphragmatic paralysis. One patient experienced subacute-humoral-rejection, a type of immune response that can damage the transplanted heart, and was treated with plasmapheresis, a procedure to remove antibodies from the blood. The in-hospital stay averaged 44 days.
- Follow-Up: At a follow-up of 14.4 months, the freedom from percutaneous procedures, such as angioplasty or stenting, was 83.3%. There was no 30-day mortality or follow-up mortality. All patients remained with an optimal functional class, indicating that they were able to perform their daily activities without significant limitations.
Transplantation in Congenital Heart Disease
A review of technical considerations in congenital heart transplantation reports that congenital heart disease accounts for 10% of overall transplants. The available case literature also illustrates how transplantation may follow complex staged treatment for associated disease. In one reported case, a patient underwent planned staged left pneumonectomy for recurrent pneumonias caused by bronchomalacia before orthotopic heart transplantation. These reports emphasize the individualized technical demands of transplantation in congenital patients.
Persistent Heart-Failure Risks
Evidence on cardiac-transplant outcomes in some congenital heart disease groups remains limited. As more infants with congenital heart disease survive into adulthood, heart failure has become the leading cause of death in the growing adult cohort. Congenital patients may present with distinctive forms of heart failure that make diagnosis more difficult and can limit responses to guideline-directed heart-failure strategies. Long-term risk may lead to death, heart transplantation, or ventricular assist device placement after congenital heart surgery.
Palliation Versus Early Transplantation
The CDC estimates that just over 1,000 babies are born annually with hypoplastic left heart syndrome. This complex defect generally requires stepwise palliative surgeries and carries a moderate to high risk of definitive heart transplantation at some point during young adulthood. Upfront neonatal transplantation is described as an alternative strategy. However, its use is limited by the availability of donor hearts.
Hope and the Future
Heart transplantation following univentricular palliation offers hope for children with complex congenital heart defects. While the procedure is technically challenging, advancements in surgical techniques and immunosuppression have improved outcomes. Further research and long-term follow-up are needed to optimize the management of these patients and ensure the best possible quality of life.
Expanding Adult Congenital Transplantation
A growing number of children with congenital heart disease are surviving to adulthood and later requiring heart transplantation. Recent work evaluates trends and outcomes in cardiothoracic transplantation for adults with congenital heart disease using three decades of institutional experience. Patients with complex native anatomy or previous procedures such as the Fontan operation may require additional procedures during donor-heart transplantation. These developments point toward increasingly specialized transplant strategies for adult congenital patients.
Referral and Anatomical Complexity
A report on orthotopic heart transplantation after univentricular palliation documented 23 congenital cardiac patients undergoing heart transplantation during 2013-2014. Late referral remains common among patients with congenital heart disease and is associated with worse outcomes. Effective care requires an in-depth understanding of each congenital defect, whether it remains unrepaired or has been repaired into biventricular or single-ventricle physiology. These anatomical and timing challenges complicate transplant decision-making.
Experience From Transplant Centers
A University of Florida study reviewed management and outcomes for 112 patients with congenital heart disease who underwent cardiac transplantation from January 2011 through January 2022. The study also evaluated the impact of using a pretransplant ventricular assist device. Separate research from a high-volume transplant center examined outcomes after heart transplantation in adults with congenital heart disease. Together, these studies reflect efforts to understand how transplant strategies affect patients across complex congenital presentations.