Cardiac Conduction
In order to objectively define cardiac conduction in a cohort, we
identified 181 patients who had invasive electrophysiologic measure of
the His-Purkinje system (i.e. H-V interval measurement in ms) as well as
a surface EKG measuring QRS duration (in ms). Repolarization via the
surface EKG was also measured (maximum QT interval in ms). HV was
measured via standard electrophysiologic lab
practices12. During electrophysiologic study, patients
were classified as having dual atrioventricular (AV) node physiology or
not having dual AV node physiology from the presence or absence ofdiscontinuous antegrade AV nodal conduction in response to atrial
programmed electrical premature stimulation using an abrupt increase in
AV nodal conduction time of ≥50 ms in response to a decrement of 10 ms
as the definition of dual AV nodal pathway physiology.