International Journal of Engineering Research and Development ISSN: 2278-067X, Volume 1, Issue 7 (June 2012), PP.38-41 www.ijerd.com 38 A Survey on Ambulatory ECG and Identification of Motion Artifact Deepak Vala 1, Dr. Tanmay Pawar 2 Department of Electronics Engineering, BVM Engineering College, Vallabh Vidyanagar, Gujarat, India Abstract—Ambulatory ECG monitoring (AECG) is increasingly for the patients suffering from cardiac disorders. Ambulatory monitoring has an advantage over the indoor monitoring that the patients can perform their daily routine activities. The major difficulty with ambulatory ECG monitoring is that the ECG signals are contaminated by motion artifact introduced due to physical activity (PA) of the patient. The AECG during commonplace PA is presumed to be an additive mix of signals due to cardiac activities, motion artifacts. Based on this fact, AECG is analysed to yield some information regarding the PA. This can be used for accurate interpretation of the AECG and hence can increase the utility of ambulatory cardiac monitoring. Here in this paper a brief introduction to the recent research activities for detecting and recognizing the PA related information from analysis of the ambulatory ECG signals is presented. Keywords— AECG, physical activity (PA), Wearable Device (WD), Motion Artifact, QRS, wavelet transform (WT) I. INTRODUCTION Cardiovascular disease is the leading cause of death in many regions. Considering the fact that a majority of such deaths due to cardiac arrest occur before the patient can get the needed medical care, the patient should be continuously monitored for real time detection of the events of cardiac arrest. In recent years ambulatory ECG monitoring (AECG) devices become popular for long term cardiac monitoring because they are convenient to use and serve as an option to the hospitalization. A surface ECG is a time-series cardiac signal of the heart that is easily recorded from the skin surface of the chest using Ag-Cl electrodes. ECG signal has the following important segments: P-wave, QRS-complex and T- wave occurring in a sequence as depicted in Fig. 1. The ECG-waves represents the following cardiac activities of the heart: P wave - atrial depolarization (contraction), QRS-complex - ventricular depolarization and T wave – ventricular repolarization (relaxation). For a normal heart the cardiac cycle repeats continuously in the same ordered manner and time of repetition of the cardiac cycle determines the heart-rate, which is variable due to many different physiological aspects. A medical expert visually investigates the abnormalities in the ECG signal for primary diagnosis of cardiac disease. 10 20 30 40 50 60 70 80 90 -1 -0.5 0 0.5 1 1.5 2 2.5 time amplitude R P Q S T Fig. 1 A cardiac beat of ECG signal recorded in ambulatory conditions. The signal is contaminated by motion artifacts due to the patient’s physical activity. With an AECG device the ECG signal can be recorded or monitored in ambulatory conditions where the patient can perform all the routine activity. However, the effectiveness of AECG can be significantly impaired by motion artifacts which contaminates the signal and that can lead to errors in estimation of cardiac parameters and trigger false alarms. Skin stretching due to body or limb movement or physical activity (PA) is a main cause of motion artifacts in AECG signals. The motion artifact induced due PA has a spectral overlap with ECG signal in 1-10 Hz [16]. Many important cardiac features of ECG signal like P and T wave has significant energy content in this overlapping band of 1-10Hz. So it is very difficult to separate or eliminate motion artifact completely without affecting these cardiac features in AECG [16]. Therefore researchers have developed various techniques to provide PA information for AECG to prevent their wrong interpretation in presence of PA [16, 13, and 14]