Rosenheck S, Schmaltz S, Kadish A H, Summitt J, Morady F
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109.
Am Heart J. 1991 Feb;121(2 Pt 1):512-7. doi: 10.1016/0002-8703(91)90719-x.
The purpose of this study was to determine the effects of quinidine and mexiletine on the adaptation of ventricular refractoriness to a change in heart rate. The ventricular effective refractory period was measured at a basic drive cycle length of 500 msec with basic drive train durations of two beats, eight beats, 20 beats and 3 minutes. The ventricular refractory periods were measured in the baseline state and after oral treatment with quinidine or mexiletine in 20 subjects each. In the baseline state, there was progressive shortening of the ventricular refractory period as the drive train duration increased from two beats to 3 minutes. Quinidine prolonged refractoriness by 5% (p less than 0.001) at each drive train duration. Mexiletine did not affect the ventricular effective refractory period at any of the drive train durations. In a control group of 20 subjects, there were no significant differences between two determinations of refractoriness at each basic drive train duration. In conclusion, neither quinidine nor mexiletine affect the adaptation of ventricular refractoriness to an increase in rate. Although the ventricular effective refractory period measured with a conventional basic drive train duration of eight beats is often more than 20 msec longer than the actual ventricular effective refractory period measured with a drive train duration of 3 minutes, the effects of quinidine and mexiletine on the conventionally measured ventricular effective refractory period accurately reflect the effects of these drugs on the actual ventricular effective refractory period.
本研究的目的是确定奎尼丁和美西律对心室不应期适应心率变化的影响。在基础驱动周期长度为500毫秒、基础驱动序列持续时间分别为两个搏动、八个搏动、20个搏动和3分钟的情况下测量心室有效不应期。在20名受试者中，分别在基线状态以及口服奎尼丁或美西律后测量心室不应期。在基线状态下，随着驱动序列持续时间从两个搏动增加到3分钟，心室不应期逐渐缩短。在每个驱动序列持续时间下，奎尼丁使不应期延长5%（p<0.001）。在任何驱动序列持续时间下，美西律均不影响心室有效不应期。在一个由20名受试者组成的对照组中，在每个基础驱动序列持续时间下的两次不应期测定之间无显著差异。总之，奎尼丁和美西律均不影响心室不应期对心率增加的适应性。尽管采用传统的八个搏动的基础驱动序列持续时间测量的心室有效不应期通常比采用3分钟的驱动序列持续时间测量的实际心室有效不应期长20毫秒以上，但奎尼丁和美西律对传统测量的心室有效不应期的影响准确反映了这些药物对实际心室有效不应期的影响。
