R-Wave Detection in the Presence of Muscle Artifacts

Ambulatory electrocardiogram (ECG) recordings from patients undergoing severe physical stress are corrupted by large muscle artifacts (EMG) and other noise sources, such as baseline drifts and currents induced by motion artifacts and electromechanical devices. A simple and reliable QRS filter and R-wave detectot unit, for use under moderate to low QRS signal-to-noise ratio conditions, is described. It is found that a narrow bandpass sampled data filter design with a center frequency and bandwidth equal to 4 Hz maximizes the QRS signal-to-noise ratio under such conditions. The detector includes automatic gain control and a differencing integrator for improved R-wave detection.