2024 Children's of Alabama/UAB Annual Report

life-sustaining, leads to increased venous pressure throughout the body, particularly in the abdomen and legs.

“The pie in the sky for these patients is getting some sort of pump into them to better push the blood to the lungs,” Hebson said. “There’s all sorts of ideas out there of how to do that, like mechanical implantations and valves. But human beings have our own intrinsic pump that we can maximize: the skeletal muscle pump in our legs, which pushes venous blood out of the legs back up toward the lungs.” People who don’t exercise a lot have weak skeletal muscle pumps, he said, which increases the blood pooling and pressure on vital organs, resulting in complications and early mortality. “People who have the strongest legs, the most physically fit legs, the best muscle tone are going to actuate their skeletal muscle pump as much as possible,” he added.

Camden Hebson, M.D.

Yet, families and medical teams have traditionally taken a protective approach with these children and limited physical activity, Hebson said. “In some ways, that’s actually a negative, because then these kids are less active than the other kids their age,” he explained. “They exercise less, and then it actually makes the problems of the physiology more likely to occur in their 20s and 30s.” Hampton Gray, M.D.

The link between exercise and better outcomes comes from studies on long-lived Fontan patients called “Super-Fontans.” While the exact reasons for their success aren’t fully understood, physical fitness appears to play a crucial role.

To better understand the effects of exercise on the cardiovascular system of Fontan patients, Hebson and his team use metabolic exercise testing to track heart rate and blood flow during physical activity. This not only helps identify potential treatment targets and provide reassurance about exercise safety but serves as an early warning sign for complications. For instance, it can reveal issues that aren’t usually apparent at rest, such as the need for stenting the Fontan conduit based on limitations shown in exercise capacity.

2024 Academic Annual Report

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