© 2000 by European Society of Cardiology
Temporal and spatial dispersion of repolarization during premature impulse propagation in human intact ventricular muscle
Comparison between single vs double premature stimulation
First Department of Internal Medicine, Nippon Medical School Tokyo, Japan
AIMS: This study was performed to determine whether or not the kinetics of action potential duration restitution during double premature stimuli (S3) differ from that during single premature stimuli (S2) 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) during programmed ventricular pacing in 11 patients with symptomatic bradyarrhythmias (five males, six females, mean age 58 years). In the five most recent patients, the RV pressure and its dp/dt were also obtained during the protocol. A substantial difference in the restitution of the MAP duration (MAPD) between S2and S3was observed at short diastolic intervals (<100 ms), that is, the restitution curve of S2showed an early biphasic pattern (upward hump), while such a phenomenon was not seen during the restitution of S3. All the quantitative parameters of MAPD restitution representing its kinetics were significantly greater in S3than S2. Maximum attainable dispersion of repolarization between the two MAPs was significantly greater during S3than S2(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 restitution kinetics of S2and S3. The dp/dt of the RV pressure was significantly greater during S3than S2for all diastolic intervals tested.
CONCLUSION: It was concluded that similar to previously reported canine experimental studies, the APD restitution of S3is substantially different from that of S2in the human intact ventricle (endocardium).
Key Words: Monophasic action potential, restitution, single premature stimulus, double premature stimuli, dispersion of repolarization, right ventricular pressure
Correspondence: Yoshinori Kobayashi, MD, First Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan.