Sakai R, Inoue D, Ishibashi K, Inoue M, Omori I, Yamahara Y, Asayama J, Nakagawa M
Second Department of Medicine, Kyoto Prefectural University of Medicine.
Kokyu To Junkan. 1993 Oct;41(10):987-91.
To investigate frequency dependent conduction slowing by mexiletine in the human atrium, we examined inter-atrial conduction time (IACT) at different stimulation frequencies (100/min to 220/min) in 13 patients with paroxysmal atrial fibrillation (Paf) and 7 patients without Paf. IACT was prolonged as the stimulation frequency was increased, and either before or after mexiletine administration IACT was longer in the Paf group (max 114 +/- 9 msec, p < 0.01, mean +/- SD) at any stimulation frequency than in the non-Paf group (max 100 +/- 8 msec). The change in IACT induced by mexiletine administration (% delta IACT) was larger in the Paf group (max 14.8 +/- 5.4%, p < 0.05) than in the non-Paf group (max 5.5 +/- 2.2%) at stimulation frequency over 140/min. Effective refractory period measured at the high right atrium was slightly decreased due to mexiletine in both the non-Paf and the Paf group. In conclusion, mexiletine showed frequency dependent suppression of conduction in the human atrial myocardium especially in patients with Paf.
为研究美西律对人体心房频率依赖性传导减慢的作用，我们检测了13例阵发性心房颤动（Paf）患者和7例非Paf患者在不同刺激频率（100次/分钟至220次/分钟）下的心房内传导时间（IACT）。随着刺激频率增加，IACT延长，且在任何刺激频率下，无论美西律给药前后，Paf组的IACT（最大值114±9毫秒，p<0.01，均值±标准差）均长于非Paf组（最大值100±8毫秒）。在刺激频率超过140次/分钟时，美西律给药引起的IACT变化（IACT变化百分比）在Paf组（最大值14.8±5.4%，p<0.05）大于非Paf组（最大值5.5±2.2%）。在非Paf组和Paf组中，美西律均使高位右心房测得的有效不应期略有缩短。总之，美西律对人体心房肌传导具有频率依赖性抑制作用，尤其是在Paf患者中。
