CIRCADIAN VARIATION IN ISCHEMIC THRESHOLD AND VASCULAR RESISTANCE IN CAD

缺血性心脏病的发生频率存在昼夜变化， 冠状动脉疾病患者中的发作。 心率 这些事件中缺血发作前的阈值也 在白天变化。 确定负责以下方面的机制： 这些变化，我们测量缺血阈值在跑步机 运动试验和最小前臂血管阻力，作为指标 最小冠状动脉血管阻力，在不同的时间， 冠状动脉疾病患者的日常生活。 缺血阈 定义为ST段压低开始时的心率 在运动和最小前臂血管阻力是 在缺血5分钟后测量。 在研究的15名患者中， 前臂最小血管阻力和缺血性 阈值，因此，在一天中的时间，当前臂血管 阻力最低，缺血阈值最高，反之亦然 亦然 此外，在整个组中，缺血阈值 晨、夜血压较低，血管阻力较高 相比中午和晚上。 因此，冠状动脉患者 疾病具有缺血阈值昼夜变化，其可 是由冠状动脉血管的逆昼夜变化引起的， 阻力 这些变化可以解释昼夜节律 短暂性脑缺血发作的变化及其变量 冠状动脉疾病患者的阈值。 的机制 负责昼夜变化的血管阻力需要， 进一步调查。

There is a circadian variation in the frequency of ischemic episodes in patients with coronary artery disease. The heart rate threshold before the onset of ischemia in these episodes also varies during the day. To define the mechanisms responsible for these variations, we measured ischemic threshold during treadmill exercise tests and minimum forearm vascular resistance, as an index of minimum coronary vascular resistance, at different times of the day in patients with coronary artery disease. Ischemic threshold was defined as the heart rate at the onset of ST segment depression during exercise and minimum forearm vascular resistance was measured after 5 minutes of ischemia. In 15 patients studied, there was a strong inverse correlation between the minimum forearm vascular resistance and ischemic threshold, so that at the time of day when forearm vascular resistance was lowest, ischemic threshold was highest and vice versa. Furthermore, in the group as a whole, ischemic threshold was lower and vascular resistance higher in the morning and night compared to noon and evening. Thus, patients with coronary artery disease have a circadian variation in ischemic threshold which may be caused by an inverse circadian variation in coronary vascular resistance. These variations may account for the circadian variations in transient ischemic episodes and their variable threshold in patients with coronary artery disease. The mechanisms responsible for circadian variation in vascular resistance need to be further investigated.