A preliminary study on the dispersion of ventricular repolarization in normal adults

Objective Values of the ventricular repolarization dispersion in people with normal heart structure were determined to provide a reference for further studies. The mechanisms of electrophysiological stability in normal ventricle were also discussed. Methods Multipoint endocardium monophasic action potentials (MAP) were recorded in 19 persons without structural heart disease. The activation time (AT), MAP duration at 90% repolarization (APD 90) and repolarization time (RT) during sinus rhythm, APD during S 1S 1 stimulation (APD S1), effective refractory period (ERP) and ERP/APD S1 at every recorded site were measured and their dispersions, defined as the difference between the maximum and minimum of each parameter, were calculated. Results A close negative correlation between the average AT and APD 90 was revealed in this normal group (LV:r=-0.91, RV:r=-0.94, P0.01). Dispersions of AT(ATd), APD(APDd) and RT (RTd) during sinus rhythm were (28±8) ms, (40±12)ms and (27±6) ms, respectively, without any difference between males and females (P0.05). RTd was significantly less than APDd(P0.01). APDd during sinus rhythm was not distinctly different from that during S 1S 1 pacing (APD S1d) in 10 who received programmed stimulation [(38±9) ms vs (34±10) ms, P0.05]. Dispersion of ERP(ERPd), ERP/ APD S1 and dispersion of ERP/ APD S1 (ERP/ APD S1d) were (31±14) ms, 0.89±0.08 and 0.10±0.07, respectively. Conclusions MAP mapping is a relatively direct method to assess the myocardial repolarization course. Repolarization dispersion and electrophysiological stability exist in normal ventricular myocardia simultaneously.