Study Demonstrates Revolutionary Technique Enabling Heart Repairs to Expand with Growing Children
Medical breakthrough: A groundbreaking procedure allows heart repairs to grow with children, as demonstrated by a historic case study For the first time ever, doctors have successfully grown tissue to fix a baby's heart, marking a significant milestone in the field
At just 18 days old, Owen Monroe entered the history books as the youngest person to ever undergo a partial heart transplant. His groundbreaking surgery, which took place in 2022, gained widespread attention, even inspiring Hollywood scriptwriters to feature his story in a recent episode of the popular medical drama "Grey's Anatomy."
The doctors published a study in the journal JAMA on Tuesday, documenting a significant milestone: the tissue used to repair Owen's heart has finally grown, a goal that has been sought after for a long time in this type of repair.
When Owen had his first operation, his heart was the size of a strawberry. Now, at 20 months old, it's about the size of an apricot. The new valves and blood vessels have kept up with his growth, suggesting that unlike most children with the same defect, he may not need to undergo more risky heart surgeries in the future.
Scientists have been striving to develop heart valves through tissue engineering, cultivating them from cells in a laboratory. While this method has been successful in animals, it has not yet yielded the same results in humans.
Dr. Kathleen Fenton, the head of the Advanced Technologies and Surgery Branch of the National Heart, Lung, and Blood Institute, commended this development as a significant breakthrough. She recently penned an editorial on the potential of partial heart transplants, although she was not directly involved in this research.
At 20 months of age, Owen Monroe's heart repair is growing with him.
Nick and Tayler Monroe
Fenton expressed the need for thorough research, especially since it involves only one child. He emphasized the importance of following these children in the long term to understand the true outcomes. Despite the challenges, Fenton remains hopeful that this will be a significant advancement for a group of children who have limited treatment options.
The procedure has gained rapid popularity. Following Owen's surgery, 12 additional partial heart transplants have been carried out in children, with nine being performed at Duke Health, the hospital that pioneered the operation.
Furthermore, the technique has facilitated "domino transplants" and split-root transplants, which make it possible for a single donor heart to save the lives of two severely ill infants.
The first child, born with a weak heart muscle that cannot pump blood adequately, receives a donated heart, while the second baby receives the healthy blood vessels and valves from the first infant. In a split-root transplant, the working parts of a heart are donated to two infants.
"The significant advancement is the potential to utilize donor parts that were previously unusable," stated Fenton.
Dr. Joseph Turek, lead author of the new study and chief of pediatric heart surgery at Duke Health, anticipates that the partial heart transplant he developed could potentially benefit hundreds of children annually in the US. "Ultimately, its success may be constrained by the availability of donors," he stated.
In this country, we perform 500 pediatric heart transplants annually, and for most of those children, their old hearts are available. We can utilize their valves, which could potentially benefit over a thousand kids each year, hopefully," he explained.
During an in-depth ultrasound exam at 20 weeks, Nick and Taylor Monroe discovered that their son Owen had a rare and serious heart defect known as truncus arteriosis.
Usually, individuals have two main blood vessels emerging from the tops of their hearts. The pulmonary artery transports deoxygenated blue blood to the lungs to absorb more oxygen, while the aorta carries oxygen-rich red blood to nourish the rest of the body.
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Owen Monroe shortly before having a procedure to fix his heart in 2022.
Nick and Tayler Monroe
Truncus arteriosis affects approximately 250 newborns in the US annually, causing the fusion of two vessels and resulting in the mixing of oxygenated and deoxygenated blood. Additionally, the condition is characterized by the absence of a necessary valve to prevent blood from flowing backward, often leading to the presence of a hole between the heart's lower pumping chambers in those affected.
Newborns with truncus arteriosis often experience distress shortly after birth, as an excessive amount of blood flows into their lungs, putting strain on the small air sacs. Due to poorly oxygenated blood, they may appear blue in color and struggle to breathe.
"We knew he would need open-heart surgery at a very young age, followed by several more surgeries before his teenage years, and a few more throughout his life," shared Nick Monroe.
However, Owens' case was even more severe, Turek added.
Normally, in cases of truncus arteriosis, surgeons typically only need to replace the missing pulmonary heart valve in a child. The existing valve can often be used as the aortic valve. However, in Owen's case, the sole valve he had was not functioning properly. After his initial post-birth ultrasound, a doctor believed that Owen would require a complete heart transplant.
The following day, Turek spoke to Owens' parents and offered an alternative: he had been developing a new technique that could replace only the defective parts of Owen's heart with living vessels and valves from a recently deceased donor. Owen's mother, Tayler Monroe, inquired about the doctor's experience with this procedure.
"He said, Ive done it five times - on piglets, " Nick Monroe said.
Making the decision to be first
Turek assured them that if the procedure was successful, Owen would not require any additional open-heart surgeries. However, using frozen valves from cadavers meant their son had only a 50% chance of survival.
Monroe acknowledged the risks involved, but they understood that it was their son's best hope for survival. With Owen already in heart failure, the hospital was unable to provide the life-saving ECMO bypass due to his compromised heart function.
Monroe explained that they were unable to provide any additional emergency care for him. "People always say it must have been a tough decision, but when you're in a desperate situation and the surgeon offers a lifeline, you take it," he said. "We saw it as the best chance for our son to survive."
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Owen Monroe
Nick and Tayler Monroe
They agreed to try the partial transplant, and then they waited.
"Every day, he appeared more jaundiced, and the tension in the room was palpable during our rounds. It was taking a toll on everyone," Monroe explained. "The entire team in that unit - the nurses, fellows, and doctors - would express the same sentiment every time: no improvement, no positive news."
Owens's mother works as a pediatric ICU nurse and was familiar with the situation. According to Monroe, she handled it by keeping her emotions separate from her clinical understanding.
"When we were at the hospital, she was in nurse mode, very analytical and logical, familiar with all the equipment and unafraid to ask the doctors questions," Monroe said.
But once back at the Ronald McDonald House at night, Monroe said he could hear her crying in the shower "because it's so emotionally draining and you can only distance yourself so much."
More than two weeks later, a glimmer of hope finally arrived: The hospital had located a compatible heart. Although the donor's heart muscle was not appropriate for transplantation, the valves and blood vessels could potentially assist Owen. The hopeful news was communicated to the staff on the morning of April 22, 2022, and by 3 p.m., Owen was undergoing surgery.
"We were simply sitting in the waiting room for the intensive care unit, hours passing by without much to do," Monroe explained. "We were just staring off into space, waiting for the next phone call."
Then, around midnight, Turek emerged to inform them that the procedure had been completed and everything had gone smoothly.
Ever since then, Owen has been unstoppable, now a joyful and energetic young child, successfully achieving his developmental goals. "The most incredible part of this journey is that it's as if his body was prepared and just needed his heart fixed before he could thrive," Monroe shared.
Weighing the risks
Partial heart transplants come with their own set of tradeoffs. While Owen still requires medication to prevent rejection of the transplanted portions of his heart, the dosage needed is significantly lower.
Usually, when the immune system views a donor heart as foreign, it is specifically rejecting the heart muscle. There are fewer markers in the tissue that forms the blood vessels and valves, so it is not as reactive.
"Turek explained that regular heart transplant recipients take two medications to address their rejection concerns. Owen is currently taking one of those two medications, but at a reduced dosage," Turek clarified.
Turek is currently conducting research on how the body reacts to this particular transplant in order to potentially improve the treatment regimen.
While immune-suppressing drugs can be life-saving, they also increase the risk of infections and cancer. The ultimate goal is to find a permanent solution that does not rely on these medications.
Another child whos gotten a partial heart transplant hasnt needed any anti-rejection medication and is doing well.
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"Turek noted that he is not on any immunosuppression and his valve is continuing to grow very well. I believe that his donor was a very good match for him," Turek said.
The Monroes are thankful for the opportunity to assist Owen and other children as well. According to Nick Monroe, if Owen had received the older heart repair procedure, they would already be planning his third surgery.
He explained, "Our focus was solely on what would benefit our son. However, in the end, we are proud to have paved the way for improved treatment and the betterment of the lives of other children with congenital heart disease."
