Electrocardiogram compression technique for global system of mobile-based offline telecardiology application for rural clinics in india

Compression of Electrocardiographic (ECG) data is an important requirement to develop an efficient telecardiology application. This study describes an offline compression technique, which is implemented for ECG transmission in a global system of mobile (GSM) network for preliminary level evaluation of patient´s cardiac condition in a non-critical condition. A short-duration (5-6 beats) ECG data from Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) arrhythmia database is used for the trial. The compression algorithm is based on direct processing of ECG samples in four major steps: viz., down-sampling of dataset, normalising inter-sample differences, grouping for sign and magnitude encoding, zero element compression and finally, conversion of bytes into corresponding 8 bit American standard code for information interchange (ASCII) characters. The developed software at the patient side computer also converts the compressed data file into formatted sequence of short text messages (SMSs). Using a dedicated GSM module these message are delivered to the mobile phone of the remote cardiologist. The received SMSs are to be downloaded at the authors computer for concatenation and decompression to obtain back the original ECG for visual or automated investigation. An average percentage root-meansquared difference and compression ratio values of 43.54 and 1.73 are obtained, respectively, with MIT-BIH arrhythmia data. The proposed technique is useful for rural clinics in India for preliminary level cardiac investigation.