Non-invasive Laplacian ECG detection using active concentric ring sensors

It is important to be able to detect spatially distributed cardiac electrical activity from body surface electrical recordings noninvasively and with spatial and temporal accuracy. Standard electrocardiographic (ECG) monitoring techniques provide limited spatial information regarding cardiac electrical activity. A new body surface active ECG sensor has been pursued to provide high fidelity spatial resolution of cardiac electrical activity.The fundamental innovation is the measurement of the moment of activation (MOA) with tripolar concentric ring sensors from the body surface. The concentric ring sensor was shown to be able to detect multiple spatially separate cardiac bioelectric sources. By combining the tripolar concentric ring sensor with a signal processing circuit that is directly mounted over the electrodes, real-time MOA at specific electrode locations can be detected non-invasively without time consuming digital signal processing. These high quality, low-noise, and site-specific signals from the active sensors were fed from several surface sites simultaneously to a portable computer system that was configured as a data acquisition system. Signal averaging yielded numerical delays of the MOAs for each site with respect to an automatically detected time reference. This reference was the peak of the R-wave in the standard Lead 2 surface ECG. From such delays the spatial pattern of rhythmic electrical depolarization sequences of the heart can be determined. By comparing time delays between the MOAs from multiple sensors, from numerous human subjects, using the R-wave of the standard Lead II ECG as the time reference, these patterns were identified with specific rhythm disturbances including atrial flutter, left and right bundle branch block, ventricular tachycardia, etc. The results from the simultaneous recordings of LECGs from multiple sites with active sensors and in combination with a portable computer and some specific software, promising applications have been identified for this technology both in cardiology and in other health related areas