Her heart (research) is in the right place

Lily LinAt barely a week old, Annie* underwent the first of three open heart surgeries she would face before the age of five.

Born with hypoplastic left heart syndrome (HLHS), the left side of Annie’s heart was critically underdeveloped and couldn’t effectively pump blood to her body. Instead, the right side of her heart is responsible for pumping blood to the lungs and to the rest of her body.

The surgeries aren’t a cure—they’ll change her blood circulation—and there’s a 30 per cent chance that Annie won’t reach her 10th birthday.

Although HLHS is only found in two to three cases per 10,000 live births, it’s something that Lily Lin—a pediatric cardiologist and master’s student—sees more than she’d like at the Stollery Children’s Hospital.  

Children with HLHS only have the pump on the right side of the heart working, leaving the underpowered tricuspid valve, which acts like a one-way door to ensure blood flows in the correct direction, responsible for all the pumping in what is a high-pressure and high-volume circulation system. Lin explains it’s imperative that the blood continues in the right direction but sometimes the tricuspid valve leaks, which can cause huge problems.

“One of the major factors of mortality and morbidity in children with HLHS is how well the tricuspid valve works,” says Lin.

But if you follow the children throughout their three surgeries, she says about 25-30 per cent develop leakage of the tricuspid valve—like Annie did—and the heart becomes less efficient. Over time, more volume on the heart puts stress on this single pump.

Fortunately, Lin explains, when the cells in the heart valve are plastic—that is, when under certain stressors and exposed to certain chemicals, they are able to adapt the structure of the valve.

Lin, who received a WCHRI graduate studentship for this research, and her team developed a new model simulating the HLHS environment to try to understand how those cells adapt.

The team is just finishing up the first set of seven experiments, and even without full data analysis, they’ve observed differences between the experimental and control groups.

“When compared to the control group, we’ve noticed that tricuspid valves in the experimental group have a more ring-shaped top portion, they look more tethered and the leaflets are larger,” notes Lin. “Our next step is to look closely at those architectural changes under a microscope and search for the cells responsible for these changes.”

The current management strategies for a leaky tricuspid valve in HLHS have a fairly modest success rate.

“By teasing out the differences we’re seeing in our experiments, we hope to come up with innovative ways to correct the leaks in the tricuspid valve,” says Lin, “and help patients like Annie and her family.”

*names have been changed

Lily Lin’s graduate studentship is funded by the Stollery Children’s Hospital Foundation through the Women and Children’s Health Research Institute. Her co-supervisors are pediatric cardiologist Nee Khoo and cardiac surgeon Darren Freed.

Stollery Children's Hospital Foundation

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