Electrocardiography of arrhythmias: from deductive analysis to laboratory confirmation--twenty-five years of progress.

Before the advent of the microelectrode, His bundle recording and direct cardiac pacing, electrocardiographic interpretation of arrhythmias in human beings was based on presumed mechanisms derived by deductive analysis. This indirect approach was forced by the fact that the surface electrocardiogram does not directly record the behavior of the specialized tissue that is the site of origin of most arrhythmias. In the past 25 years it has become possible to record directly from the specialized tissue. The result has been experimental confirmation of several underlying concepts of the electrocardiographic interpretation of arrhythmias and progress evidenced by the conversion of concept to fact.