正常心肌与肥厚心肌跨室壁不应期离散度实验研究

目的：探讨在体犬正常心室肌以及肥厚心室肌三层之章否存在跨室壁的不应期离散。方法：采用特制电极直接测量在体三层心肌的不应期。结果：正常心肌三层之间的不应期呈均一性,没有显的不应期离散。同正常心肌相比,肥厚心肌三层不应期均有延长,而中层心肌延长的幅度最大,使得跨室壁的不应期离散度增大。采用突然的循环长度改变可使跨室壁的不应期离散度增大更加明显。结论：正常犬三层心肌之间不存在跨室壁的不应期梯度,而肥厚心肌中存在跨室壁的不应期离散。采用长－短间期和短－长间期刺激可使跨室壁的不应期离散度增大。

Experimental Study of ERP-Dispersion among myocardial layers in the intact normal and hypertrophic

Objective To investigate whether the in vivo Canine heart exhibits transmural dispersion of effective refractory periods(ERPs) among three myocardial layers. Methods The specially designed plunge-needle electrodes(10 mm long,4 bipolar electrodes,interelectrode distance 2 mm) were inserted into the ventricular wall in 10 dogs. Effective refractory periods of epimyocardium,midmyocardium and endomyocardium were determined by the extrastimulus technique. Results In normal canine heart,ERPs were uniform in all muscle layers.There was no significant ERPs-dispersion among the three myocardial layers; in contrast to normal heart,ERPs of all three myocardial layers were prolonged in hypertrophic heart,but the ERPs of midmyocardium were significantly prolonged, and thus caused a significant transmural ERP-dispersion throughout the canine hypertrophic ventricle.The programmed extrastimulus technique with "long-short"and "short-long"interval increased this transmural ERPs-dispersion. Conclusion No local gradients of refractoriness are found among the three myocardial layers in normal canine heart; but a significant transmural ERPs-dispersion is present in hypertrophic myocardium.