A system to study the evolution of cardiac arrhythmias at home

Abstract

The aim of this paper is to discuss the main features of a system to follow-up cardiac arrhythmias without people being hospitalized. Patients are registered in the system during their first visit to the physician. A battery-powered device was developed to digitize a one-lead ECG up to three minutes; physician should indicate the frequency to make the tests. The digital ECG is transmitted, using a Bluetooth connection, to an Android telephone running a mobile application developed by the authors. The incoming ECG is processed to detect and classify QRS complexes as an essential step for measuring RR intervals. Identification of bigeminism, trigeminy, asystole and compatible signals with atrial fibrillation is based on the measurements made. This data is uploaded to a web site using the HTTP protocol and a GSM/GPRS network as support; a web application stores this data in a SQL database. Physicians can log in this application to study the evolution of their patients using trend charts and others graphical tools. This operation mode allows medical treatment can be adjusted as soon as it is necessary. An alternative telephonic device is being developed by the authors to provide a low-cost solution for poor countries. Algorithms for ECG processing were tested with annotated database and voluntaries. Sensitivity in QRS complex detection was 98.77% using the MIT-BIH database as reference. The Bluetooth communication between the ECG device and several mobile telephone models was reliable, without data loss or data corruption. The same result was obtained testing the upload process with more than 600 ECG files. The ECG device was evaluated according to the IEC 60601-2-47 standard; results for all safety and parametric tests never exceed the permissible limits.