May 8, 2025 | The stethoscope, despite being more than 200 years old, is not an easily retired diagnostic device. It remains symbolic of the medical profession, even if many physicians no longer wear them and those that do are not particularly good at using them, according to Anurag Agarwal, Ph.D., professor in acoustics and biomedical technology at the University of Cambridge (UK).
Nostalgia for the stethoscope is not in and of itself problematic, but a failure to adopt newer, more accessible alternative technologies powered by artificial intelligence comes at a cost in terms of both human lives and the cost of care, he says. This is especially true when it comes to the early detection of heart valve disease, which has a prognosis worse than many cancers because up to half of patients are not diagnosed until the disease is more advanced and deadly.
Cases go undiagnosed for a combination of reasons, says Agarwal. For starters, heart valve disease is a degenerative condition often considered a natural consequence of aging, typically developing irrespective of lifestyle habits. The first line of diagnosis is physicians using a stethoscope, an examination reportedly done in only 38% of patients who visit their general practitioner with symptoms of the condition.
Two of the typical symptoms of heart valve disease, breathlessness and fatigue, are often confused with respiratory diseases or dismissed as a byproduct of aging, he adds. And if people believe they’re tired simply because they’re getting older, they tend to make minor adjustments to their lifestyle such as trying to avoid stairs or walking to a grocery store one block from home rather than two. “It is very easy to miss these things.”
Moreover, using a stethoscope correctly for the diagnosis of heart valve disease requires clinical training and, even then, is difficult to use because nothing about it is automated. “You have to rely on doctors’ experience and hearing, and, for heart disease, they have to carefully place [the stethoscope] at four anatomical locations,” Agarwal says.
Patients must undress, since the chest piece needs to touch their bare skin, he continues. Doctors also must interpret the sounds they hear.
Electronic stethoscopes offer some advantages over traditional acoustic stethoscopes, notably sound amplification and recording and analyzing heart and lung sounds. But the placement challenge remains, says Agarwal. The electronic versions have also faced some adoption barriers related to their higher cost, needed training, and clinician preference for the experience of listening to internal body sounds (a process known as “auscultation”) with the older technology.
His answer to this diagnostic dilemma was to work alongside his Cambridge peers to develop a “better stethoscope” that is affordable and easy to use even for lay people without any medical training, opening the possibility of population-based screening for heart valve disease. Results of a validation study demonstrating the effectiveness of the flexible, multi-sensor device for handheld sensing of heart sounds were published recently in the IEEE Journal of Biomedical and Health Informatics (DOI: 10.1109/JBHI.2025.3551882).
The new “Biophonics” device, as it is currently being termed, is the size of a rice cake and features six sensors (versus one with a traditional stethoscope) with a gel between them to absorb vibrations so the sensors don’t interfere with each other, says Agarwal. It works well even when it’s not placed precisely on the chest or is used over clothing.
Heart recordings can be saved on the device, which incorporates a machine learning algorithm that detects signs of valve disease automatically, he adds.
The project started serendipitously when he became interested in the physics of blood flow through a diseased valve, Agarwal explains, which naturally segued into how to better interpret the sounds that signaled heart valve disease without the need for specialized training. Better data collection, in combination with machine learning to automatically take and record sound measurements, provided an answer to making auscultation more accessible and thereby bringing down the burden of disease.
In the UK, both the National Health Service and the National Institute for Health and Care Excellence have identified early detection of heart valve disease as a key goal to improve the quality of life for patients and decrease costs. For American insurers, the financial consequences of detecting the condition late are estimated to be an extra $2 billion in expenditures annually, he says, based on results of a 2016 study (ClinicoEconomics and Outcomes Research, DOI: 10.2147/CEOR.S112691).
When detected late, heart valve disease can lead to severe complications, including heart failure and death, says Agarwal. The gold standard test—an echocardiogram—needs to be done in a hospital and, at least in the UK, waiting lists are lengthy. In any geography, getting to a location offering echocardiograms can also involve considerable travel, he adds. “Also, how do you know you need one? You need the first line of inquiry.”
In the latest study, the Biophonics device recorded the heart sounds of healthy participants with various body types. The next step, Agarwal says, is to evaluate the device in a clinical setting against results from an echocardiogram.
The goal is approval by regulatory authorities in the UK and U.S. “It is still early days,” says Agarwal, noting that the technology still resides with the university. But in another study currently under review that focuses on the machine learning component, the device outperformed general practitioners in detecting heart valve disease, he notes.
In the UK, the first use case for the multi-sensor device will be to triage patients who are waiting for an echocardiogram. In the U.S., population screening would be the focus, specifically older people on Medicare who get a cardiovascular disease screening every five years. The Biophonics device could become part of that checkup to determine when an echocardiogram is needed. The device might also find utility in the hands of staff members or nurses at wellness centers based in retail pharmacies and physician practices.
Admittedly, it will not be easy. Mainstay diagnostic devices, including acoustic stethoscopes as well as blood pressure cuffs and body weight scales, remain “very primitive” despite significant technological advancements. People may wonder why the likes of the fictitious tricorder, first featured on the Star Trek television series back in 1966, has yet to materialize, says Agarwal. One of the reasons is that securing payer reimbursement for any new diagnostic approach is a significant challenge globally.