Surface recording of His-Purkinje activity on an every-beat basis without digital averaging

Efforts to record evidence of electrical activity from the body surface originating in the His bundle or bundle branches have been reported since 1973. Almost exclusively, these techniques have required digital averaging of 50-100 sequential cardiac cycles. For immediate diagnostic, therapeutic and prognostic application, recording on an every-beat basis is highly desirable. This is especially important in instances of changing atrioventricular conduction, arrhythmias or less-than-constant RR intervals. Our object has been to develop a system for more nearly optimal noise reduction, to avoid the disadvantages of serial signal averaging, and to be able to record His-Purkinje activity in man on an every-beat basis. Using multiple parallel inputs wih linear amplification, additional logarithmic amplification, some bandpass filtering, and a logic circuit that ultimately examines and accepts or rejects a deflection as "true" signal, we can record, in most instances, on a beat-by-beat basis, this very valuable component of the cardiac electrical cycle.