Validation of a smartphone based photoplethysmographic beat detection algorithm for normal and ectopic complexes

Background: To date little or no smartphone apps exist to differentiate between a normal heart beat and a premature ectopic beat. Aim: To develop and validate a smartphone based acquisition and processing algorithm based on photopletyhsmographic (PPG) data collected in a controlled hospital environment. Methods: A smartphone camera application was developed to record PPG data in synchronization with a reference electrocardiogram. Subjects were recorded while undergoing an electrophysiological examination. The PPG data acquisition was validated on 28 volunteers with sinus rhythm. After signal analysis an algorithm was developed for detection of ectopic beats. To characterize arrhythmias, supraventricular extrasystoles were induced every 10, 5 or 3 beats after 500 ms by applying a pacing train to the right atrium. The coupling interval was also examined by altering the intermediary time by 400, 500 or 600 ms. Results: After signal conditioning, an accurate ectopic beat detection was obtained from the PPG signal. Premature atrial ectopic beats could be differentiated based on the interpeak distance at different coupling intervals. Conclusion: By acquiring a PPG signal with the camera, the smartphone is not only capable of determining a regular sinus rhythm, but it also has the power to identify ectopic beats.