Foreword to His-bundle pacing supplement: Everything that is old will be new again.

Physiological pacing has been a term that has been used to describe many phenomena. It was used over 30 years ago to describe the advent of AV synchronous or dual chamber pacing, later the addition of the rate-responsive mode to pacing, and even more recently to describe biventricular pacing. In the last several years, there has been a resurgence of interest in pacing the conduction system: selective His-bundle pacing and non-selective His-bundle pacing. Despite the widespread use of this term, I believe “selective His-bundle pacing” is the true embodiment of physiologic pacing. In order to better understand the phenomenon, the Journal of Electrocardiology has produced a truly scholarly review of this field. Papers included in this seminar will review the anatomy and pathology of the conduction system, the mechanics and phenomenology of pacing the conduction system as well as the basic science behind understanding the phenomenon of pacing the conduction system. This symposium covers this subject material in a comprehensive