Kidney Function in Pediatric Heart Retransplant Patients

How can a standard kidney evaluation improve outcomes for heart retransplant patients?

Immunosuppressive medications play a vital role in helping heart transplant recipients’ bodies accept their new organs. However, some drugs that ensure the success of a new heart — including tacrolimus and cyclosporine — can have lasting damage on a patient’s kidney function. These adverse effects are worse in children, who are exposed to the drugs for longer periods of time and who will likely require a heart retransplant later in life. Children’s Hospital Colorado nephrology fellow Melvin Chan, MD, is researching how kidney function in heart transplant patients changes over time, with the goal of helping prevent kidney failure.

Determining kidney function in heart retransplant patients 

Measuring creatinine, a waste product, is a standard blood test which shows how well a patient’s kidneys are working. In pediatric nephrology, there are various equations that incorporate creatinine levels to estimate a person’s kidney function, known as an estimated glomerular filtration rate (eGFR). However, other disciplines usually do not know the strengths and weaknesses of these tests to evaluate kidney function, despite their patients often taking medications damaging to their kidneys. 

But what if there was stronger knowledge-sharing between nephrology and cardiology? 

That’s the question that drove Dr. Chan to his recent study that evaluated changes in renal function over the first year in children following a repeat heart transplant. He wanted to help cardiologists better understand their patients’ kidney risk before it becomes problematic. 

“Over time, we were able to show that there's a difference [in kidney function] between people with first time heart transplants versus those who needed a second heart transplant,” Dr. Chan says. 

Those who needed a second heart transplant had worse kidney function and were at higher risk of kidney failure than first-time recipients — some may need to be listed for both a second heart transplant and a kidney.  

These results give Dr. Chan a platform from which to advocate for the kidney health of heart patients and begin bridging gaps in understanding between the two disciplines. “I think it's really important to have champions in different departments, so in my department for instance, Dr. Bock is the urology champion,” he says.

Improving outcomes for transplant patients

Dr. Chan plans to use his team’s findings to create standard protocols for screening those at risk for kidney disease, which could foster earlier interventions. "Previously, some [heart transplant] patients would have only their urine tested prior to transplant, so we are creating a protocol where every year they'll get screened for these specialized kidney function tests through blood draws, as well as urine tests,” Dr. Chan says. “That way we can screen them over time and know when they should be referred to a kidney doctor.” 

His intention is for this research to expand to all areas of medicine where children are at risk for kidney disease (such as bone marrow transplants), making multidisciplinary collaboration essential. “At Children's, our collaboration is unique because a lot of times specialists at other institutions work in their silos and don’t really talk to each other,” Dr. Chan says. “This project is novel in that we’re talking to each other and we're trying to figure out the best way of caring for these really high-risk patients.”

Dr. Chan also hopes to understand which risk factors, beyond taking certain immunosuppressants, can lead to decreased kidney function. Then, his team will use a scoring calculator to assess those most at risk of developing severe kidney disease.

Pushing this next phase of research across the finish line requires that his team pool data from other large academic centers. "This research requires us to collaborate with other centers because while we have great patient data, we need more people,” Dr. Chan says. “We only have about 60 patients who've undergone second heart transplants; we need hundreds.”

The same sentiment threads through Dr. Chan’s research: Sometimes, collaborating in new ways is the best approach to solving old problems.

1. Chan M, Silveira L, Patterson DJ, et al. Changes in estimated glomerular filtration rate over the first year following repeat heart transplant in children and young adults. Pediatric Transplantation. 2024; 28:e14651. doi:10.1111/petr.14651