Temporal and spatial dispersion of repolarization during premature impulsepropagation in human intact ventricular muscle - Comparison between singlevs double premature stimulation

Aims This study was performed to determine whether or not the kinetics of a ction potential duration restitution during double premature stimuli (S-3) differ from that during single premature stimuli (S-2) in the human intact right ventricle. Methods and Results A monophasic action potential (MAP) was simultaneously recorded from the right ventricular apex (RVA) and outflow tract (RVOT) dur ing programmed ventricular pacing in II patients with symptomatic bradyarrh ythmias (five males, six females, mean age 58 years). In the five most rece nt patients, the RV pressure and its dp/dt were also obtained during the pr otocol. A substantial difference in the restitution of the MAP duration (MA PD) between S-2 and S-3 was observed at short diastolic intervals (<100 ms) , that is, the restitution curve of S-2 showed an early biphasic pattern (u pward hump), while such a phenomenon was not seen during the restitution of S-3. All the quantitative parameters of MAPD restitution representing its kinetics were significantly greater in S-3 than S-2. Maximum attainable dis persion of repolarization between the two MAPs was significantly greater du ring S-3 than S-2 (76 +/- 17 vs 59 +/- 17 ms, P<0.05) and was mainly caused by the difference in the MAPD difference, thus by the difference in the re stitution kinetics of S-2 and S-3. The dp/dt of the RV pressure was signifi cantly greater during S-2 than S-3 for all diastolic intervals tested. Conclusion It was concluded that similar to previously reported canine expe rimental studies, the APD restitution of S-3 is substantially different fro m that of S-2 in the human intact ventricle (endocardium). (Europace 2000; 2: 201-206) (C) 2000 The European Society of Cardiology.