A first-of-its-kind partial heart transplant in a neonate delivered valves that continue to grow and function beyond 1 year of age, researchers said.
The surgery was performed on the 18th day of life of a 5-pound newborn boy diagnosed prenatally with persistent truncus arteriosus and severe truncal valve dysfunction. The procedure involved transplantation of the part of the heart containing the aorta and pulmonary valves from an infant donor upon cardiac death.
The standard of care for neonatal heart valve implants are cadaver grafts. But these grafts are not viable and can’t grow or self-repair. Therefore, recipient neonates need to undergo repeated implant-exchange surgeries until an adult-sized heart valve can fit. Clinical outcomes generally are poor.
“We have learned that these partial heart transplant valves, when procured fresh and the [recipient] baby is placed on low-dose antirejection medicine, can grow with the child and function completely normally,” Joseph W. Turek, MD, PhD, MBA of Duke University Medical Center in Durham, North Carolina, told theheart.org | Medscape Cardiology.
“This represents a new field in heart surgery that could dramatically change the way we care for children with poorly functioning heart valves by allowing valve implants that grow with them.”
A case report describing the novel intervention was published online on January 2, 2024, in JAMA.
‘Expected to Last a Lifetime’
The donor was a 2-day-old female weighing 8 pounds. Delivery had been complicated by hypoxic ischemic brain injury, but echocardiography showed structurally normal, functioning outflow heart valves. The heart was donated after cardiac death and procured using standard surgical techniques.
The recipient infant’s operation involved sternotomy, cardiopulmonary bypass, and cardioplegic arrest of the heart. The pulmonary artery ostia and coronary artery buttons were dissected, and the infant’s irreparable truncal valve was excised.
The donor aortic root was transplanted first, using donor tissue to close the ventricular septal defect. Then, the coronary artery buttons were reimplanted; the right ventricular outflow tract was enlarged; and the pulmonary root was transplanted. Postoperative immunosuppression followed.
On the follow-up at age 14 months, the transplanted valves showed no obstruction or insufficiency on echocardiography. Now, almost 21 months later, the recipient is doing well, Turek said. “His family has shared his many milestones with me, including eating his first birthday cake, videos of his first steps, and his newfound oral appetite (he was largely g-tube fed for a while).”
“The rationale for partial heart transplant is that pediatric heart transplants grow,” Turek and coauthors wrote. “Moreover, failure of heart transplant outflow valves is exceedingly rare. While heart transplant long-term outcomes are limited by inevitable ventricular dysfunction, partial heart transplants spare the native ventricles and are therefore expected to last a lifetime.”
“While this particular baby had truncus arteriosus, this operation should prove to be beneficial for a host of congenital heart conditions with valves that are either too small or poorly functioning,” Turek said. “We have performed subsequent partial heart operations for babies with aortic stenosis, tetralogy of Fallot with pulmonary atresia, and biventricular outflow tract obstruction.”
The challenge is organ availability, he noted. “While this procedure does make use of hearts that would be otherwise unusable for full heart transplant, such as hearts with poor ventricular function or hearts removed from recipients of full heart transplants (aka domino hearts), the availability is still low compared to the need.”
With domino hearts, “you could potentially double the number of hearts that are used for the benefit of children with heart disease,” Turek said in a Duke communication released with the paper. In a domino heart procedure, a patient who has healthy valves but needs stronger heart muscle receives a full heart transplant, and the healthy valves are then donated to another patient in need, creating a domino effect.
Since this breakthrough procedure in 2022, partial heart transplants have been performed 13 times at four centers, including nine at Duke, three of which used the domino technique.
For now, Turek told theheart.org | Medscape Cardiology, “we are hoping to receive funds for a clinical trial that will evaluate these partial heart transplant valves on a larger basis and determine an optimal antirejection dose necessary to maintain viability.”
Preclinical research leading to this case report was supported by the Brett Boyer Foundation. Turek reported no conflicts of interest.