心肌缺血阈与冠心病相关性研究

目的:探讨无痛性心肌缺血发生机制及规律。方法:采用24h动态心电图记录结合患者生活日志分析诊断。结果:172%无痛性心肌缺血ST段下移发生于轻体力和脑力劳动时,发作高峰位于上午6:00～12:00时(P<0.01),90.7%ST段压低时心率加快(P<0.01),缺血发作的最高心率与24h内最高心率差距很小,与ST段压低相平行(P<0.01)。2无痛性心肌缺血ST段弓背抬高幅度及阵次以夜间为著,发作高峰位于1:00～6:00(P<0.01),心率减慢时ST段弓背抬高(P<0.01),夜间心肌缺血阈变异性增高、心率变异性低频/高频比值降低、ST段下移和ST段抬高持续时间延长(P<0.01),缺血发作的最低心率发生于夜间,与ST段弓背抬高相平行(P<0.01)。结论:缺血阵次、ST段移位幅度、缺血持续时间、心肌缺血阈、心肌缺血阈变异性、心率变异性低频/高频比值可了解心肌缺血时耗氧水平、交感神经系统活性、冠状动脉张力的高低,是冠心病患者和各种治疗疗效的有价值的指标。交感神经兴奋致耗氧量增加为缺血发作的重要机制,主张给β受体阻滞剂。冠状动脉张力增加与副交感神经张力异常引起相对冠状动脉供血不足,主张给钙离子拮抗剂和硝酸类药物。

The relationship between myocardial ischemia threshold and coronar-y heart disease

Objective：To study the mechanisms and rules of painless myocardial ischemia （SMI）. Methods： Analysis was conducted on the records of 24-hour Holter and Life log. Results： ①72% Painless myocardial lack of ST-segment depression occurred in light physical work and Mental work ,and the attack peak emerged between 6 am to 12 at noon（P〈0. 01）. 90. 70% ST-segment depression attacked when the heart rate speeding up （P〈0. 01）. The gap was very small between maximum heartrate at the time of ischemic attack and a maximum heart rate within 24 hours, and ischemic attack paralleled ST segment depression. ②The degree and duration of ST-segment evaluation for SMI myocardial ischemia were obvious at night, and the attack peak emerged between 1 am to 6 am（P〈0. 01）. ST-segment elevated when heart rate decreased （P〈0.01）. Isehemia variability threshold at night（IV）increased and the ratio of low frequency and high frequeney（LF/HF）of heart rate decreased. The duration of ST-segment depression and ST-segment elevation extended. The lowest heart rate occurred at night when ischemic attack, and paralleled with ST elevation（P〈0. 01）. Conclusion： Ischemic attack times, the duration of ischemia, myocardial ischemia threshold variability, heart rate variability low frequency/high frequency ratio of myocardial ischemia can predict the level of oxygen consumption, the sympathetic nervous system activity and the tension of the coronary artery and they are the valuable indicators for various treatment measures in patients with coronary heart disease. Excited sympathetic nerve-induced increase in oxygen consumption can be viewed as an important mechanism of ischemic attack. Increase tension of coronary artery related with the coronary relative insufficiency caused by the abnormal parasympathetic tension, so we advocate for nitric acid and calcium antagonist drugs.