Camici P G, Marraccini P, Lorenzoni R, Buzzigoli G, Pecori N, Perissinotto A, Ferrannini E, L'Abbate A, Marzilli M
C.N.R. Institute of Clinical Physiology, University of Pisa, Italy.
J Am Coll Cardiol. 1991 Jun;17(7):1461-70. doi: 10.1016/0735-1097(91)90632-j.
Coronary hemodynamics, myocardial metabolism and left ventricular function at rest and after incremental atrial pacing were evaluated in 12 patients with stress-induced angina and ST segment depression, angiographically normal coronary arteries and no evidence of spasm, generally labeled as syndrome X, and in 10 normal subjects. At baseline study, great cardiac vein flow was comparable in patients and control subjects. During pacing, an equivalent rate-pressure product was reached in the two groups, but the slope of the relation between rate-pressure product and great cardiac vein flow was significantly less steep in patients than in normal subjects (0.0027 vs. 0.0054 ml/mm Hg.beat, p less than 0.001). Nevertheless, the left ventricular ejection fraction was comparable in both groups at rest (66 +/- 6% vs. 71 +/- 7%, p = NS) and during pacing (71 +/- 7% vs. 66 +/- 5%, p = NS). At baseline study, myocardial glucose extraction was more efficient in patients with syndrome X (p less than 0.05), but net myocardial exchange of pyruvate and alanine was, respectively, smaller and greater than in control subjects. Lactate was extracted to a similar extent in the two groups and in no instance was net lactate release observed during pacing or recovery. During pacing and recovery, patients with syndrome X showed net pyruvate release, unlike the control subjects in whom net pyruvate exchange was positive. In addition, patients with syndrome X continued to show net myocardial extraction of alanine during spacing and recovery, whereas normal subjects produced alanine throughout the study. Myocardial carbohydrate oxidation increased significantly during maximal pacing in normal subjects but not in patients, in whom it always remained below (p less than 0.01) the concurrent rate of myocardial uptake of carbohydrate equivalents (glucose, lactate, pyruvate, alanine). Myocardial energy expenditure was significantly lower in patients than in control subjects at maximal rate-pressure product levels (p less than 0.01). The metabolic pattern in patients with syndrome X therefore is not consistent with classic ischemia, although differences in the net exchange of circulating substrates (glucose, pyruvate, alanine) can be demonstrated. Thus, in patients with syndrome X, the symptoms, electrocardiographic signs and impairment in the increase in great cardiac vein flow during pacing coexist with preserved global and regional left ventricular function and myocardial energy efficiency.
对12例有应激性心绞痛和ST段压低、冠状动脉造影正常且无痉挛证据（一般称为X综合征）的患者以及10名正常受试者，评估了静息状态下和递增性心房起搏后的冠状动脉血流动力学、心肌代谢及左心室功能。在基础研究中，患者和对照受试者的大心静脉血流量相当。起搏期间，两组达到了相同的心率 - 血压乘积，但患者心率 - 血压乘积与大心静脉血流量之间关系的斜率明显低于正常受试者（0.0027对0.0054 ml/mm Hg·次，p<0.001）。然而，两组静息时左心室射血分数相当（66±6%对71±7%，p = 无显著性差异），起搏时也相当（71±7%对66±5%，p = 无显著性差异）。在基础研究中，X综合征患者的心肌葡萄糖摄取更有效（p<0.05），但丙酮酸和丙氨酸的心肌净交换量分别小于和大于对照受试者。两组乳酸摄取程度相似，起搏或恢复期间均未观察到乳酸净释放。起搏和恢复期间，X综合征患者出现丙酮酸净释放，而对照受试者丙酮酸净交换为正值。此外，X综合征患者在起搏和恢复期间持续出现丙氨酸心肌净摄取，而正常受试者在整个研究过程中产生丙氨酸。正常受试者在最大起搏时心肌碳水化合物氧化显著增加，而患者则无增加，患者的心肌碳水化合物氧化始终低于（p<0.01）同时期心肌摄取碳水化合物当量（葡萄糖、乳酸、丙酮酸、丙氨酸）的速率。在最大心率 - 血压乘积水平时，患者的心肌能量消耗明显低于对照受试者（p<0.01）。因此，X综合征患者的代谢模式与典型缺血不一致，尽管循环底物（葡萄糖、丙酮酸、丙氨酸）的净交换存在差异。所以，在X综合征患者中，症状、心电图表现以及起搏时大心静脉血流量增加受损与整体和局部左心室功能及心肌能量效率保留并存。
