What started as a simple conversation about wearable technology has evolved into a new research study aimed at revolutionising how we monitor patients with congenital heart disease (CHD)*.
At its core lies a key question: can wrist-worn wearables accurately estimate peak VO₂ (oxygen) levels as patients go about their everyday activities? And, crucially, could this kind of monitoring enable safer, earlier interventions for patients whose health may be starting to deteriorate?
Adults with CHD often need regular monitoring to track their heart health - typically through hospital-based exercise tests that measure peak VO₂.
“This is a key fitness marker which shows how well the body uses oxygen during intense activity,” explains senior clinical respiratory physiologist Holly Le Winton.
“A decline in VO₂ max can be an early warning sign that something’s wrong and might mean a patient needs surgery or a change in treatment.”
A conversation that sparked a PhD
The idea to use wearables to measure patients’ peak VO₂ came up during a discussion between Holly and lead research respiratory physiologist Ben Knox-Brown.
“We were bouncing around ideas, and the thought came up - what if we could use standard wearables to estimate peak VO₂ and compare that to exercise stress test results?” reflects Holly.
“Could we monitor our CHD patients as they go about their daily lives? And could that data help us to spot early signs of deterioration without patients needing to come into the hospital?”
Keen to turn the idea into a PhD, the pair realised a pilot study was necessary to find out if it was even feasible to home monitor CHD patients. And that’s when they discovered the Innovation Fund, supported by Royal Papworth Charity.
Holly Le Winton and Ben Knox-Brown holding the wrist-worn and chest-worn research-grade wearables
Innovation in action
Open to all Royal Papworth Hospital employees, the fund supports our strategic aim to ‘research and innovate’ by backing both clinical and non-clinical research initiatives. As part of a competitive selection process, Holly was delighted to learn their application had been successful and they’d been awarded £18,383.
“Without that funding, the PhD wouldn’t have been possible as it’s enabled us to purchase six wrist-worn and six chest-worn research-grade wearables,” she explains.
“The research and development team were amazing; they helped refine the concept and guide me through the application process.”
In January 2025, Holly embarked on her five-year part-time PhD project.
“Essentially, the PhD is a feasibility study to assess whether peak VO₂ can be reliably estimated in CHD patients using wearables, and whether this kind of remote tracking can flag declines in CHD patients early enough to act,” she explains.
“The data will be compared to traditional VO₂ tests to develop an algorithm that estimates patients’ heart fitness using wearable-collected data, eliminating the need for hospital visits.”
Once ethics approval is complete, around 60 CHD patients will be recruited from all over the country to wear both a wrist and chest device over several days. Higher-risk patients, such as those with internal defibrillators, will be excluded from the study to ensure safety.
The wrist-worn and chest-worn wearables
A new era of heart care
The research has the potential to significantly transform how CHD patients are monitored and aligns with the three key shifts in the Government’s new 10-year health plan: from hospital to community; from analogue to digital; and from sickness to prevention.
Although home monitoring may not entirely replace hospital-based exercise tests, it could reduce the need for frequent hospital visits - particularly for stable patients who can be safely monitored from a distance. It could also help to reduce health inequalities by extending care to people who face challenges travelling to the hospital.
For Holly, one of the most valuable long-term goals is to help reduce the fear many CHD patients have around physical activity as she explains: “These are people who’ve lived their whole lives with a heart condition, and often there’s anxiety about pushing themselves physically.
“If we can use data to reassure them and detect any real decline early then we’re empowering people to live fuller, healthier lives.”
Over time, the study could pave the way for personalised exercise prescriptions for CHD patients, encouraging safe and consistent physical activity. However, while that vision is still on the horizon, the potential impact is profound.
“If exercise could be bottled, it would be the most powerful medicine,” adds Holly.
“This is a way of encouraging people to stay active but safely.”
Listening to patients, shaping the future
As the study moves forward, patient involvement will be key. Participants will be asked for feedback about their experience - whether they feel reassured by it, how easy it is to use, and whether they’d prefer it over traditional in-clinic testing.
“We want this to work not just for clinicians but for our patients. Their voices are essential if this is going to make a real difference,” says Holly.
*Congenital heart disease refers to a range of conditions present from birth that affect the heart’s structure and function. Though many adults with CHD live full, active lives, they often require lifelong specialist care and are at increased risk of complications. That’s why ongoing monitoring is essential and why this kind of innovation could be life-changing.