Opthof T, Coronel R, Vermeulen J T, Verberne H J, van Capelle F J, Janse M J
Department of Clinical and Experimental Cardiology, University of Amsterdam, The Netherlands.
Cardiovasc Res. 1993 Nov;27(11):1954-60. doi: 10.1093/cvr/27.11.1954.
Dispersion in refractoriness is considered a major factor in induction and persistence of cardiac arrhythmias. The sympathetic nervous system is known to modulate refractoriness. An index of refractoriness has therefore been assessed in normal and ischaemic myocardium simultaneously at multiple sites, with and without sympathetic stimulation.
In six dogs on total cardiopulmonary bypass the average interval between local activations was measured during artificially induced ventricular fibrillation from extracellular electrograms simultaneously recorded from 32 ventricular sites. These local ventricular fibrillation intervals may be used as an index of local refractoriness.
During regional ischaemia, ventricular fibrillation intervals of ischaemic sites could prolong by up to 60% after 3 min following coronary occlusion. Left stellate ganglion stimulation during ischaemia produced either no response or prolonged the ventricular fibrillation intervals even further at ischaemic sites, whereas ventricular fibrillation intervals at non-ischaemic sites shortened. Dispersion in refractoriness across the ischaemic border increased by 14-59% in individual hearts following sympathetic stimulation during acute, regional ischaemia.
Due to opposite effects on normal and ischaemic myocardium, sympathetic stimulation increases the difference in refractoriness over the ischaemic border. This may enhance the chance for regional conduction block and the propensity to re-entrant arrhythmias.
不应期离散被认为是心律失常诱发和持续的主要因素。已知交感神经系统可调节不应期。因此，在有或没有交感神经刺激的情况下，在正常和缺血心肌的多个部位同时评估不应期指标。
在六只接受全心肺转流的犬中，在人工诱发心室颤动期间，从32个心室部位同时记录的细胞外电图测量局部激活之间的平均间隔。这些局部心室颤动间隔可用作局部不应期的指标。
在局部缺血期间，冠状动脉闭塞后3分钟，缺血部位的心室颤动间隔可延长多达60%。缺血期间刺激左星状神经节，缺血部位要么无反应，要么心室颤动间隔进一步延长，而非缺血部位的心室颤动间隔缩短。在急性局部缺血期间交感神经刺激后，各个心脏缺血边界处的不应期离散增加了14% - 59%。
由于对正常和缺血心肌的相反作用，交感神经刺激增加了缺血边界处不应期的差异。这可能增加局部传导阻滞的机会和折返性心律失常的倾向。
