Researchers from the University of Glasgow have led in the development of a new system which uses radar to track patients’ heart sounds like a doctor uses a stethoscope.

According to the team behind the tech, the new health monitoring tool uses radar to ‘listen’ to patients’ heart sounds with remarkable accuracy, and could lead to a new generation of contactless medical monitoring equipment.

In a paper published in the IEEE Journal of Biomedical and Health Informatics, the team demonstrated the use of advanced signal processing techniques to isolate and measure the heart sounds of human volunteers, and saw significant improvements on previous methods of measuring heart rates using radar waves, which take readings from measurements of patients’ chest movements.

Using a 24Ghz continuous-wave radar system, electromagnetic waves were bounced off volunteers’ bodies. The reflections of the waves allowed the team to measure not just the movement of their chests but also the sounds their hearts produced as valves opened and closed – a method similar to the way doctors use stethoscopes to hear how patients’ hearts are beating.

Sophisticated filters were then used to remove signal noise and other interference, allowing a clear pulse signal to calculate patients’ heart rate.

At the same time, the researchers also monitored the volunteers’ hearts using an electrocardiogram (ECG) machine, the current ‘gold standard’ for clinical measurements of heart rate.

The team found that the new system was capable of measuring heart sounds across all intensities with nearly 99% accuracy – with their readings differing from the simultaneous ECG measurements by less than one beat per minute.

The previous technique using chest movement to measure heart rates was found to fall short of the ECG measurements by between eight and 50 beats depending on the intensity of the volunteers’ heart beat, evidence that the new method offers substantial improvement.

Dr. Hasan Abbas, senior lecturer at the James Watt School of Engineering, and one of the paper’s authors, said: “Unlike camera-based patient monitoring technologies, radar preserves patient privacy by collecting only their vital signs and no information about their movements or activities.

“The system we’ve developed could form the basis of a game-changing user-friendly healthcare technology in the future.”

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It’s hoped that by increasing the accuracy of contactless heart sound detection the full potential of the technology could be realised in clinical settings, allowing for the continuous monitoring of vital signs in critical situations. 

In the future, the technique could even be used to help diagnose heart disease, among Scotland’s leading causes of premature deaths, and the team are already considering how to pair heart rate monitoring with breathing rates and blood pressure readings for a fully-featured commercial design.