Research and Clinical Trials

Heart Transplant Research and Investigative Studies

At Seattle Children’s Heart Center, your child is cared for by doctors who are international leaders in advancing pediatric heart transplantation. Our doctors are well-trained specialists with significant experience transplanting hearts and in treating children with heart failure. Because patient care and research go hand in hand, we continually improve our performance, techniques and patient outcomes. In doing so, we make possible a better future for our young patients.

Survival rates for children who get heart transplants at Seattle Children’s are among the best in the nation. Seattle Children’s doctors take part in multicenter research studies to improve care for children who need heart transplants. What we learn can let us successfully transplant children who would be turned down by other centers. Our patients benefit from promising new treatments we are exploring today.

Keeping Hearts Going Before, During and After Transplant

Ongoing research helps our team refine and improve treatment using extracorporeal life support (ECLS) while a child waits for, receives and heals from a heart transplant. The ECLS we provide includes heart-lung bypass (ECMO, or extracorporeal membrane oxygenation), mechanical heart pumps (VADs, or ventricular assist devices) and total artificial heart.

Seattle Children’s is 1 of 2 sites on the West Coast that will take part in the Pumps for Kids, Infants, and Neonates (PumpKIN) trial. The study aims to find the best device for infants and young children who weigh as little as 7 pounds. It is funded by the National Heart, Lung, and Blood Institute. Dr. Michael McMullan, Seattle Children’s surgical director of heart transplant, will lead Seattle Children’s part of the trial.

Helping More Children Get Transplants

Seattle Children’s offers innovative treatments that help make transplants available to more children.

ABO-incompatible transplants

In ABO-incompatible transplants, a child receives a heart from a donor who is not a blood-type match. In collaboration with our blood bank, we carefully prepare our patients so they are able to receive an ABO-incompatible transplant. Our methods minimize the number of antibodies that might attack a new heart that is ABO incompatible. Being able to transplant a heart from a mismatched donor means children don’t have to wait as long for a heart transplant. After a decade of performing ABO-incompatible transplants, our patient outcomes are as excellent as ABO-compatible transplant outcomes.

Transplants for patients who are highly sensitized to HLA

Patients whose immune systems are highly sensitized often face longer wait times for a heart and are at higher risk for rejecting their new organ. “Highly sensitized” means the person has developed antibodies to certain human leukocyte antigens (HLAs). HLAs help determine whether an organ is a good match for a patient. If a patient already has antibodies, they are likely to quickly attack any donor organ that contains those HLAs. We use state-of-the art tissue typing, blood banking and a variety of immune system treatments so highly sensitized children can be successfully transplanted. For a very ill child, shortening the wait time may save their life.

Overcoming Immune System Challenges

Today’s improved antirejection medicines are the result of research to better understand children’s immune systems. We continue to fine-tune treatment after transplant so a child does not reject their new heart and also keeps a strong enough immune system to fight infection and disease. This is called immunosuppression.

Better measures of medicine levels

Our researchers have made it easier to measure medicine levels in heart transplant patients’ blood so doctors know what dose of immunosuppressants to use. We want to make such testing as easy as checking glucose levels for people with diabetes. The new test lets patients prick their finger (or have their parents do it) at home and put a few drops of blood on a special paper strip. The paper containing the blood sample is mailed to Seattle Children’s for lab work.

This method is as accurate as traditional testing. It was developed by Dr. Jane Dickerson. This method will make it easier for doctors to monitor immunosuppression levels.

Understanding allergies to reduce rejection

Allergies occur when the immune system overreacts to something foreign in the body. Yet patients with cellular markers of allergies are less likely to reject transplanted hearts than patients without allergic cellular markers. Learning why may be a step toward using information about an individual patient’s immune system to pinpoint which medicines they need and the right dose.

Gender and heart transplant rejection

Dr. Mariska Kemna and colleagues are studying whether patients who receive hearts from donors of the same gender (such as boys who receive hearts from boys) have a lower chance of rejecting their new hearts. This won’t change how we do things now. There are too few donor hearts to let doctors match the patient’s and donor’s genders. But this finding can serve as a clue to why some patients reject transplanted hearts or struggle to survive with them.

Effect of HLA matching on organ rejection

Human leukocyte antigen (HLA) is like a chemical bar code that identifies people. No two people have the same HLA codes, except identical twins. Drs. Yuk Law and Paul Warner are studying whether heart transplant patients live longer when their HLA is similar to their donor’s HLA. We have also identified a potentially more accurate way to determine HLA matching/mismatching. This will help doctors and researchers better understand the HLA system in heart transplantation. We expect this will lead to better care for our patients because HLA differences between the donor and recipient are the root cause of rejection.

Our researchers are also investigating whether patients with high levels of HLA antibodies – which attack donated tissue – are more likely to reject transplanted hearts or suffer coronary artery disease after transplant. This could help doctors identify patients who are at high risk of rejection. It could also help determine how much medicine those patients need to prevent rejection of their new heart.

International Partnerships Improve Heart Transplants for Children

Seattle Children’s heart doctors hold leadership positions in international groups working to improve heart transplantation. In this way, we share our expertise and learn from the experience of pediatric heart transplant centers around the world. Sharing information helps us know more quickly what works and what does not. We also take part in multicenter studies that give our patients access to new treatment options.

Seattle Children’s doctors are actively involved in the Pediatric Heart Transplant Study (PHTS), which keeps an international database related to heart transplantation in children. The PHTS collects and analyzes information from more than 50 heart transplant centers to increase knowledge and improve treatments for children undergoing transplant.

Dr. Yuk Law serves on the PHTS Steering and Scientific Committees. He also leads the Pediatric Heart Failure Committees of the International Society for Heart and Lung Transplantation (ISHLT) and the American Heart Association (AHA).

Dr. Michael McMullan is a member of the United Network for Organ Sharing (UNOS) Pediatric Transplantation Committee.

Seattle Children’s has been named a Center of Excellence by the Extracorporeal Life Support Organization (ELSO). This group of healthcare professionals and scientists from around the world works to improve care for children needing heart and lung support. McMullan is a member of the ELSO board of directors. He and Dr. Thomas Brogan are members of the ELSO Steering Committee.

Reducing the Need for Heart Transplantation

Some of our research gives us a better understanding of heart failure and heart disease. This helps us improve treatments so in the future some children may avoid the need for transplant.

Read more about Seattle Children’s Heart Center research. Learn about participating in transplant research.