Videoplethysmography: a webcam for the diagnosis of atrial fibrillation
Upon careful examination, a person's face provides a huge amount of information about what is happening in his body. The latest joint development of the University of Rochester and Xerox allows using a webcam and software to diagnose atrial fibrillation by minor changes in the complexion of a person - a treatable, but potentially life–threatening condition.
Atrial fibrillation is manifested by irregular and, in some cases, rapid heartbeat, accompanied by impaired blood supply to the body. The reason for such cardiac rhythm failures is the desynchronization of atrial and ventricular contractions due to disturbances in the electrical activity of the myocardium.
This condition is easily diagnosed, but in many cases it has a hidden form due to the transient nature and non-specificity of symptoms, manifested by weakness and fatigue. According to experts, about 30% of people with atrial fibrillation are unaware of their disease.
Moreover, despite the fact that atrial fibrillation is amenable to both medical and surgical treatment, in many patients this disease recurs over time. In the absence of adequate treatment, it is associated with a significantly increased risk of blood vessel thrombosis and stroke.
A new diagnostic technology – videoplethysmography – uses an algorithm developed by Xerox specialists that scans a person's face and detects indistinguishable changes in the color of the skin with the naked eye. To do this, a person must remain motionless for only 15 seconds.
Digital camera sensors are configured to register three colors: red, green and blue. The protein hemoglobin, which provides blood coloring, absorbs mainly the waves of the green part of the spectrum, which makes the blood visible to the camera sensor. Moreover, the small thickness of the facial skin and the proximity of blood vessels to its surface allows you to register even minor changes in the concentration of hemoglobin.
Eleven participants in the pilot study of the effectiveness of the new development were simultaneously scanned with an electrocardiogram, which made it possible to compare the results obtained with the camera with the electrical activity of the heart in real time.
Processing of the data obtained showed that the changes in complexion recorded during video monitoring fully correspond to the changes on the cardiogram. At the same time, irregular electrical activity of the heart in people with atrial fibrillation was manifested by visual pulsation of the facial veins. According to the researchers, the probability of error during videoplethysmography is 20%, which is comparable to the probability of error during automatic cardiac monitoring, which is 17-29%. They are currently evaluating the effectiveness of the technology in a larger study involving both patients and healthy people.
The developers believe that the new technology can be used for diagnostics, as well as for monitoring the condition of people at risk for the development of atrial fibrillation. Contactless technology, as well as the widespread use of webcams, will allow you to run the program in the background and monitor during daily work at the computer.
Article by Jean-Philippe Couderc et al. Detection of Atrial Fibrillation Using Contactless Facial Video Monitoring is published in the journal Heart Rhythm.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Rochester:
“Face Time” for the Heart Diagnoses Cardiac Disease.
09.09.2014