Arrhythmia Detection based on Photoplethysmography

The purpose of this work is to create an embedded system, acting as a Body Area Network. The device should allow real-time arrhythmias detection and be able to store and download the detected alarms, in order to send them to a specialist, who provides for a more accurate analysis and decides if further investigations are needed. This is possible thanks to the Bio2Bit Move, a prototype of wearable device developed by STMicroelectonics. The board is plugged in an adjustable wrist strap, which acquires and transmits signals and alarms via Bluetooth Low Energy. The analysis for the arrhythmia detection is carried out using the photoplethysmographic signal at green wavelength, under reflectance mode. This allows to make non-invasive monitoring in almost any part of the body, enabling in this way, the continuous monitoring of the cardiac condition over a long period of time, as opposed to the devices currently used in clinic for arrhythmia’s diagnosis (ECG, Holter Monitor, Event Monitor). Since the photoplethysmografic set-up requires only a few opto-electronic components, it is possible to reduce the costs of the device compared to those equipped with ECG electrodes. The board is also capable of acquiring, among other signals, photoplethysmography at red wavelength and accelerometer data, which enable to evaluate the impact of noise on the measure, and allow to filter the artifact or otherwise, to assess the estimation's reliability. The arrhythmia analysis is focused on finding Premature Ventricular Beats (PVBs). They are very common among the population and, although they are usually benign, when their frequency is high, multiform premature contraction occurs or under some other conditions, it is necessary to better evaluate the clinical situation. Since PVBs are sporadic in most patients, a continuous long-term monitoring by means of the Bio2Bit Move, would be more suitable than the methods currently used and would allow the doctor to determine, if necessary, the best clinical investigations to be carried out. The PVBs detection is performed using the morphology of the signal: this allows to discriminate beats with different shapes and to establish if the ectopic beats recur following a specific pattern or not. The design of a comfortable, low-cost and accessible device, allows therefore to perform an arrhythmia telescreening on a large part of the population. In this way, everyone will access to an appropriate clinical evaluation and it will be possible to establish the real need for further medical examinations. This is important not only for reducing the number of unnecessary visits, but also because it will be easier to establish the most suitable diagnostic and treatment path for each patient.