Measurement of Human Ventricular Effective Refractory Periods: Effect of Incremental Versus Decremental Extrastimulation

Incremental Versus Decremental Extrastimulation for Refractoriness. Measurement of ventricular refractoriness is performed routinely at electrophysiological study but methods of refractory period determination have not been standardized. This study compared the difference between refractory period measurements hy incremental and decremental extrastimulns techniques. Twenty‐six patients were included and a > 5‐msec increase in incremental compared to decremental ventricular effective refractory period (V ERP) was found in all (hysteresis interval). There was no significant effect of order of extrastimulus protocol, right ventricular site, or current strength on the hysteresis interval. There was an effect of longer duration of drive to increase hysteresis interval. When incremental extrastimulation was performed first, there was an increased hysteresis interval at shorter cycle lengths of drive, whereas when decremental extrastimulation was performed first, there was an increased hysteresis interval in sinus rhythm. We conclude that decremental extrastimulation yields shorter refractory periods tban incremental extrastimulation, as a combined effect of cycle length shortening and duration of pacing. A standard method for determining ventricular refractoriness should he considered. (J Cardiovasc Electrophysiol, Vol. 1, No. 6, pp. 506–511 December 1990)