The Dispersion of Ventricular Repolarization During Programmed Extra Stimulation in Patients Without Structural Heart Disease.

In order to study the mechanism of ventricular tachyarrhythmia (VTA) genesis during programmed extra stimulation(PES),monophasic action potentials(MAP) were recorded in 10 patients without structural heart disease.Dispersions of repolarization were calculated in condition of sinus rhythm,pacing and PES.Results:Dispersion of action potential duration(APDd) during S 1S 1 pacing(500 ms) was not different from that during sinus rhythm(34±10 ms vs 38±9 ms,P0.05).Action potential duration (APD) decreased relatively along with S 1S 2 duration shortening and activation time (AT)、dispersion of AT (ATd)、APDd and repolarization time (dispersion RTd) increased gradually.After S 1S 2 duration was less than effective refractory period (ERP)+30 ms,APDd and RTd were larger than that during sinus rhythm or S 1S 1 pacing,but ATd was an exception.The average value of effective refractory period dispersion(ERPd)and ERP/APD were 31±14 ms and 0.89 ±0.08 respectively.We conclude that PES can make repolarization dispersion increase,but dispersion of AT is not increased by means of PES,VTA is not easily developed in normal subjects.[Chinese Journal of Cardiac Pacing and Electrophysiology,2000,14(2):79～81] Programmed extra stimulation Ventricular repolarization dispersion Monophasic action potential