Our birthdays record how long we have lived. They say nothing about how our bodies are actually aging. Biological age is a different measurement entirely, one that reflects the condition and function of our cells and tissues, shaped by genetics, lifestyle, environment and disease. That distinction is now driving a new line of research at the Stanford Cardiovascular Institute, where scientists are asking whether the pace of cellular aging can help explain the long-term health of people born with severe heart defects.
The question matters because researchers have repeatedly observed signs of aging arriving earlier than expected in people with chronic conditions. Cancer, kidney disease and heart disease have all been linked to this phenomenon, known as accelerated biological aging. In cardiovascular disease specifically, the gap between a person's birthday and the biological wear on their body may carry real consequences: accelerated biological aging has been associated with worse outcomes in adults living with heart failure.
Why Congenital Heart Defects Raise a New Question
Adults with heart failure are one population in which biological aging appears to matter. But people born with heart defects may also face a heightened risk of age-related health problems, a possibility that raises a straightforward yet largely unexplored question: could measuring biological aging give researchers a better window into the long-term health of people living with complex heart conditions?
One group for whom that question is especially relevant is people living with a Fontan circulation.
What Fontan Circulation Means for the Body
Some children are born with severe heart defects that leave them with only one functioning pumping chamber, or ventricle, instead of two. To keep blood moving, a series of surgeries performed in early childhood constructs an entirely new route for circulation.
- Blood returning from the body travels directly to the lungs rather than being pumped there by a dedicated ventricle.
- No second pumping chamber drives blood into the lungs.
- The single working ventricle pumps oxygen-rich blood out to the rest of the body.
The resulting arrangement, known as Fontan circulation, leaves patients living with a fundamentally different system for moving blood through the heart, lungs and body. That difference is permanent, which makes this population a compelling group in which to study how the cardiovascular system ages over a lifetime.
Inside the Stanford Study
To explore biological aging in this population, a Stanford Cardiovascular Institute team led by senior author Sushma Reddy compared 90 children and adults with a Fontan circulation against 59 people with normal heart structure and function. Most of the participants were adolescents. The work was published in the Journal of the American Heart Association and includes co-first authors Jennifer Woo and Annabelle Grace Binti Vincent.
Telomeres as a Measure of Cellular Wear
The researchers focused their attention on telomeres, the protective caps found at the ends of chromosomes. These structures are a common focus in research on biological aging because they offer a measurable signal of how cells and tissues are holding up over time, separate from how many birthdays a person has accumulated.
Studying a marker of this kind in a congenital heart population is a departure from the usual approach, which tends to focus on structural function, surgical outcomes and exercise capacity rather than the underlying biology of aging.
Shorter Telomeres Even at Young Ages
One of the study's notable findings concerned timing. Evidence of shorter telomeres appeared even at young ages in the Fontan group, a pattern that points toward the same phenomenon documented in other chronic diseases: biological aging that runs ahead of the calendar.
Most participants were adolescents, a stage of life when such signals would ordinarily be far less pronounced. Finding them in a comparatively young cohort suggests that the altered circulation created by Fontan surgery may leave a measurable imprint on how quickly cells age, though the study's design means it identifies an association rather than proving a cause.
What This Could Mean for Patients
The practical promise of this line of work lies in what it might eventually allow clinicians to do. If biological aging can be reliably measured in people with Fontan circulation, it could become a tool for anticipating which patients face the greatest risk of age-related complications and for timing care accordingly.
That would be a meaningful shift. Fontan patients already require lifelong cardiovascular follow-up, and a marker that captures biological rather than chronological age could add a new dimension to those assessments, complementing imaging, blood work and functional testing.
It also reframes how the Fontan population is understood. Rather than viewing these patients solely through the lens of the surgical repair they received as children, researchers can examine how a rewired circulatory system interacts with the biology of aging across decades.
Questions That Remain Open
The Stanford comparison is a snapshot, and it leaves several threads for future investigation:
- How telomere length and other aging markers change over time in the same patients.
- Whether the observed differences translate into measurable differences in clinical outcomes later in life.
- Which factors, from genetics to lifestyle to the specifics of a patient's circulation, drive the accelerated aging signal.
- Whether any intervention could slow the process, or whether it is an unavoidable consequence of the Fontan arrangement.
Answering those questions would require long-term follow-up and larger cohorts, but the current findings give researchers a reason to pursue them.
The Broader Picture
Accelerated biological aging has already reshaped thinking in oncology, nephrology and adult cardiology. Extending that framework to congenital heart disease is a logical next step, and the Fontan population is a natural starting point because its circulatory physiology is so distinct.
For families navigating Fontan care, the immediate takeaway is not a change in treatment but a widening of the research lens. Scientists are beginning to look past the mechanics of blood flow and ask how the body's cells keep time. If biological age can be measured early and tracked reliably, it may one day help explain why some Fontan patients fare better than others over the long haul, and it may point toward ways to close that gap.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
