Abstract: The present invention is directed to an electrode for use in measuring low level signals amidst competing noise signals. The electrode includes an electrically non-conductive substrate having a closed loop of electrical conductive and adhesive material carried by the substrate which defines therein an open area on the substrate. A first electrically conductive terminal is embedded within the closed loop of electrically conductive and adhesive material. Within the open area is an inner mass of electrically conductive and adhesive material. The inner mass of electrically conductive and adhesive material is spaced from the closed loop. The electrode also includes a second electrically conductive terminal which is embedded with the inner mass of electrically conductive and adhesive material. The electrode includes a first contact device for making electrical contact with the first terminal and a second contact device for making electrical contact with the second terminal.

Abstract: An electronic test instrument for rapid comprehensive verification of correct operation of medical pacers. This portable microprocessor-based test instrument includes a device for measuring and displaying pacer characteristics including pacing rate, pulse duration, pulse amplitude, sensitivity, sensed refractory interval, stimulus refractory interval, atrio-ventricular delay, D.C. leakage, susceptibility to A.C. interference, frequency response and battery drain. The test instrument includes a device for selecting each test and entering associated parameters, a device to convert the analog pacer pulses to digital values for detection and measurement, a device to generate variable amplitude test waveforms and apply them to a medical pacer at a specified rate or at a specified delay from a previous pacer pulse or with a specified delay between two test waveforms and a device for displaying test results.

Abstract: An apparatus and method for detecting low level bioelectric signals on the surface of a patient. The bioelectric signals are enhanced by filtering out noise through a particular adaptive filtering technique. In detecting His signals at the chest of a patient, surface ECG's are acquired at a plurality of external locations, the acquired data is digitized and stored. One of the ECG signals is selected as a reference channel and the remaining ECG signals are used as input channels. With the use of a feedback coefficient, each data point of interest in each cycle is adaptively filtered to remove the noise and the filtered signal is displayed. The adaptive filtering involves performing two pre-updates of a weight matrix associated with each sample point of each input channel based on the measured samples before and after a sample point, calculating an output signal based on the weight matrix and the input channel, and updating the weight matrices based on the calculated output signal.