Web cam used to detect abnormal heart rhythm
Web cam used to detect abnormal heart rhythm
23 hours ago
By Madeline Kennedy
NEW YORK (Reuters Health) - With a regular laptop camera
and sophisticated software, researchers may be able to detect atrial fibrillation
about as accurately as with a standard electrocardiogram (ECG), according to a
new pilot study.
The technology records and analyzes video footage of a
person’s face and detects subtle shifts in skin color that indicate changes in
blood flow.
“Existing ECG-based technologies are used only for
patients who had symptoms,” said the Jean-Phillipe Couderc of the University of
Rochester Medical Center in New York, who led the study.
But there are “approximately 3.2 million people with AF
in the U.S., and an estimated 30 million people in the world,” he told Reuters
Health, and currently there’s no way to diagnose the condition without
consulting a doctor.
In atrial fibrillation (AF), the upper and lower chambers
of the heart beat out of sync with each other. Although that can cause symptoms
like heart palpitations or dizziness, often the condition has no signs.
An estimated 30 percent of people with AF do not know
they have it, according to past research.
The long-term implications are serious, as AF is
progressive and can lead to stroke or heart failure.
Couderc said the video-based system, developed with
colleagues at Xerox Research Center in Webster, New York, is the first
diagnostic tool to measure the electrical activity of the heart without physical
contact with skin.
He envisions the face scan being used one day to diagnose
patients without symptoms and monitor their progress as they receive treatment.
For the pilot study, Couderc and his team enrolled 11
patients with diagnosed atrial fibrillation who were scheduled to undergo ECG
at the university’s hospital. The researchers set up a standard web camera to
capture video of the person’s face in 15-second increments at the same time as
the ECG was being performed.
The scan focuses on the face because its skin is
particularly thin, making blood running through the veins more easily visible.
In particular, the program looks for the color of the blood as it reflects or
absorbs green light.
The experiment demonstrated that the observed color changes
corresponded with the subject’s heart rate, the study team reports in the
journal Heart Rhythm.
The scan correctly identified the presence or absence of
atrial fibrillation 80 percent of the time, with an error rate of 20 percent.
That was similar to the automated ECG measurements, which were wrong between 17
percent and 29 percent of the time.
This new technology could one day be used by anyone with
a tablet or laptop, Couderc said, though he cautioned that the small study is
only a proof of concept and “we need to evaluate the technology in a large
prospective clinical trial,” to test how accurately it works and how easy it is
to use.
Dr. Steven Swiryn of Northwestern University in Chicago,
who studies atrial fibrillation, agreed that the small study is “quite
preliminary, and though interesting, has a number of major limitations.”
One, is that patients need to be absolutely still for the
scan, an issue that excluded one participant in the study. Another participant
was excluded because she was wearing makeup, which obstructed the camera’s
ability to see blood flow. Finally, Swiryn noted, the study only included
Caucasians and the technology needs to be tested on people of color as well.
While it may not be possible to diagnose atrial
fibrillation without a doctor, the condition can also “be strongly suspected by
taking the pulse,” Swiryn said in an email. (See Reuters Health article of July
23, 2014, here: http://reut.rs/YqvCTe).
However, Swiryn added, if the new technique’s methods
were refined and applied to a larger and more diverse group, it would be worth
pursuing with more research and “might prove a useful and inexpensive screening
method.”
SOURCE: bit.ly/W84G9h Heart Rhythm, online August 29,
2014.
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