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Optical monitor checks heart rhythm

08 Oct 2008

The developers of a product that takes just a few seconds to monitor how rhythmically a patient's heart is beating are looking for companies to commercialise their idea.

A UK company called Melys AFS has unveiled a non-invasive and low-cost way of screening for atrial fibrillation (AF), a condition that goes largely undetected. People suffering from AF have an irregular heartbeat and to date the monitor has screened over 500 patients producing no false negatives and just seven false positives.

"This is a more objective way of measuring how rhythmically your heart beats," Dawood Parker, a director of Melys, told optics.org. "The incidence of AF in the elderly is high and often it is found entirely accidentally. Our monitor pinpoints a condition that would otherwise go undetected."

The prevalence of AF increases with age, and so do the associated risks. For example, AF accounts for 33% of strokes in the elderly so it is a problem that adds a significant burden to the health service. Despite this, screening for AF is not a routine procedure.

"In a GPs surgery, a trained nurse would feel for your pulse and decide whether or not it was rhythmical," explained Parker. "This is a subjective measurement whereas our device is entirely electronic. Our monitor offers a guide as to whether the patient requires an electrocardiogram (ECG), which would then confirm the existence of AF."

The Melys monitor is very simple to use. The patient places their finger in a clip containing an LED and a detector. Visible light then shines through the finger and the detector collects a waveform that represents the heart beat. The monitor compares the patient's waveform with a template and judges the variance from a regular rhythm.

"We use Fourier analysis and derive the spectrum for a perfect sinusoidal waveform and use that as the template," explained Parker. "If your heartbeat was in sinus rhythm, then your variance from that template would be zero. What we have found through clinical trials is that there is a threshold above which you are very likely to be an AF sufferer. It is not possible to derive this threshold theoretically."

Parker and his colleagues have performed clinical trials at both Singleton Hospital in Swansea, UK, where over 300 patients were examined, and Connecticut Heart Group in the US, where over 200 patients participated. During the trials, the predictions made by the Melys monitor were compared with ECGs.

"We don't need any more clinical proof," said Parker. "We have a pre-production prototype and are now looking for companies who are willing to take the technology on and launch it. We would like GPs to use the instrument to give it credibility. After that, it could be placed in pharmacies or used in the home by people on medication such as Warfarin, which is used to thin the blood and restore a normal heartbeat. If this instrument were produced in large volumes, the price would be very low indeed."

If you would like more information on the AF monitor, please contact Dawood Parker directly via email on

Author
Jacqueline Hewett is editor of Optics & Laser Europe magazine.

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