Virtual leads for the ambulatory ECG monitoring: Remarks on the persistency of their direction

Abstract

We attempt to improve the performances of the algorithms devoted to the computer-based detection of arrhythmias by improving the quality of the tracings they have in input. This aim is pursued by building virtual tracings mathematically derived from the original ones. In this paper we describe the persistency in the time domain of the direction of some virtual leads. Such a persistency will tell us how often in a subject we must recalculate the virtual lead. They have been defined starting from the original tracings of the two leads belonging to the BIH MIT Arrhythmia Database. We considered the width of the time window just more than the cycle duration: i.e., a severe experimental condition. We found there is no persistency and we have to recalculate continuously the direction of the virtual lead. The set consisting of only two original leads and the short windowmay have had a major influence on our results. About the specific contribution that the virtual leads take to the improving of the tracings quality, we have several examples where, in respect to the original tracings, the virtual tracings show a positive increase of the differences between normal and abnormal beats.