Usability of Wireless ECG Body Sensor for Cardiac Function Monitoring During Field Testing

Today's lifestyle presents high risk for cardiovascular diseases, which is a leading cause of death worldwide. Previous studies have targeted various risk factors for development of cardiovascular diseases, such as high blood pressure, smoking, type 2 diabetes, obesity, psychological stress and physical inactivity.

Increased level of physical activity has numerous beneficial long-term effects on cardiovascular system, and might decrease relative risk of sudden cardiac death. However, the risk of unexpected cardiovascular events is increased during, and immediately after intense exercise. Two studies conducted in France, reported a daily incidence of three sudden deaths and four myocardial infarctions during regular physical activity in the general population. Twelve-year longitudinal study showed that average age of young recreational athletes in Switzerland who died during physical activity was 27.6 years, with the incidence of 0.52/100.000 per year. Some studies reported dramatic increase of unexpected cardiovascular events in a middle age group of recreational population, which was at the level of 6.5/100.000 per year. Furthermore, several studies reported higher incidence of sports related cardiovascular events between general population in comparison with professional athletes. Males are more affected, and the most affected age group is middle-aged between 35 and 59 years.

Previous studies noticed that the key challenge is identification of structural heart disease and inheritable conditions that increase incidence for lethal arrhythmias during exercise, because sudden cardiac events often occurs without any warning or prediction. Therefore, early detection of persons with higher risk for sudden cardiac death is of crucial importance. In this regard, numerous European countries have introduced a mandatory medical examination for all persons registered in sports clubs or associations. Exercise stress test (EST) which includes electrocardiographic (ECG) monitoring is an important part of examination. However, the problem arises from the fact that EST is especially sensitive for testing individuals with previous known symptoms of cardiac disease, while the positive predictive value of an EST in asymptomatic subjects is relatively low. On the other hand, it was proven that long term ECG monitoring during regular daily activities can be very useful in detection of heart disease in people who had normal 12-lead ECG, and negative Master two-step tests. Also, it was proven that it is possible to detect atrial fibrillation in asymptomatic people with long-term one-channel ECG monitoring.

Recent studies showed that the wireless body ECG sensor is a feasible solution for reliable and accurate long-term heart rhythm monitoring, but the sensor placement and fixation is an important factor which can influence the signal quality and needs to be taken into consideration. In accordance with previously said, our main goal was to determine whether it is possible to measure quality electrocardiographic report using ECG body-sensor during standardized outdoor tests. Additional aim was to determine whether different types of sensors' fixation affect quality of the ECG signal during submaximal and maximal running settings.

Twenty-three were included, 13 males and 10 females, age between 19 and 23 years (Age = 20.56±1.19 years; Body height = 177.28±9.76 cm; Body mass = 70.11±7.68 kg). All participants were physically active non-athletes, with daily involvement (3-5 times per week, 30 to 60 minutes of moderate to high intensity) in various physical activities (team sports, cyclic activities, resistance training). To meet the criteria for participation in the study, participants had to confirm they were healthy, and without known previous cardiac problems. In accordance with the Declaration of Helsinki participants gave the signed consent for participation in the study. Prior to the tests, the purpose and protocols of the study were explained in details to each participant. Ethics approval for the study was obtained from the Institutional Ethical committee (Approval no. 02-1359/18-2).