Beat-to-beat detection of ventricular late potentials and His potential using the adaptive orthogonal projection

Noninvasive techniques to record the activation wave of His potential and ventricular late potentials have so far depended largely on signal averaging. Although this approach produces representative signals, any beat-to-beat variations are removed by the averaging process. These beat-to-beat variations are important in the diagnosis of many heart anomalies, particularly arrhythmias. The paper describes an experimental system which can detect His potential and ventricular late potentials at the body surface while preserving beat-to-beat variations. The system uses a number of different techniques, but an important feature is the use of blind separation sources using higher order statistics for the removal of mains interference and multidimensional adaptive orthogonal projection succeeded by an adaptive filtering to cancel random noises such as electrode noise, electronic noise, motion artefacts and electromyographic (EMG) signals. This technique was evaluated by using real cardiac signals recorded on four channels, by an array of four small surface electrode pairs.