Noninvasive recording of the his-purkinje system electrical activity by a digital system design.

The atrioventricular conduction pathways which are composed of the atrioventricular node and the His-Purkinje system (HPS) form a specialized conduction system in the heart that participates in the control of the ventricular conduction. His bundle recordings require cardiac catheterization in the diagnosis of abnormalities within the HPS. These recordings have limitations that include discomfort, a slight morbidity risk, and limited recording area within the heart. This report outlines a noninvasive technique that utilizes high gain, wide band filtering and coherent signals averaging to extract the electrical activity of the HPS at the body surface. We have designed a portable instrument which enables: (i) a high gain, very low noise, optically isolated differential amplifier, (ii) an online digital QRS detector based on the principle of contour limiting which detects the desired QRS complexes and generates a very accurate trigger for the coherent signal averaging; (iii) a digital memory averager. This instrument can be used as an automatic clinical tool or as a data acquisition and preprocessing system for high frequency ECG and many other low level electrophysiological signals.