CIRCADIAN VARIATION IN ISCHEMIC THRESHOLD AND VASCULAR RESISTANCE IN CAD

缺血的频率存在昼夜节律变化。 冠状动脉疾病患者的发作。心率 在这些发作中，缺血发作前的阈值也 白天变化很大。定义负责以下方面的机制 在这些变化中，我们测量了在跑步机上的缺血阈值 运动试验和前臂最小血管阻力作为一项指标 最小冠脉阻力，在不同的时间 冠心病患者的一天。缺血阈值 被定义为ST段压低开始时的心率 在运动和最小前臂血管阻力是 缺血5分钟后测量。 在15名被研究的患者中，有很强的负相关性。 前臂最小血管阻力与脑缺血 阈值，以便在一天中的时间当前臂血管 阻力最低，缺血阈值最高，最低 反过来说。此外，在整个组中，缺血阈值 早晚较低，血管阻力较高 与中午和晚上相比。因此，冠状动脉疾病患者 疾病的缺血阈值有昼夜变化，这可能 是由冠状动脉血管的反昼夜节律变化引起的 抵抗。这些变化可能解释了昼夜节律 短暂性脑缺血发作的变化及其变量 冠心病患者的临界值。其作用机制 负责昼夜节律变化的血管阻力需要 有待进一步调查。

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.