Watanabe T, Harumi K, Akutsu Y, Yamanaka H, Michihata T, Okazaki O, Katagiri T
Third Department of Internal Medicine, Fujigaoka Hospital, Tokyo, Japan.
Am Heart J. 1998 Sep;136(3):533-42. doi: 10.1016/s0002-8703(98)70232-7.
Ischemic ST-segment depression (horizontal or downsloping) is the most common manifestation of exercise-induced myocardial ischemia. The mechanisms responsible for these types of ST-segment depression are largely unknown. We investigated the relation of these 2 types of exercise-induced ST-segment depression to changes in regional myocardial blood flow (RMBF) by using exercise positron emission tomography (PET).
The RMBF was measured with nitrogen-13 ammonia PET both at rest and during low-level supine bicycle exercise in 27 patients with angiographically proven coronary artery disease and in 6 healthy volunteers. ST-segment depression was measured from the isoelectric PR segment 80 ms after the J point. Exercise-induced horizontal ST-segment depression > or =0.1 mV was observed in 9 patients and downsloping depression > or =0.1 mV was observed in 18 patients. Multivessel disease was more frequent and areas of exercise-induced ischemia were larger in patients with downsloping depression than in patients with horizontal depression (P < .02, P < .05). In patients with horizontal ST-segment depression, RMBF in ischemic areas and in surrounding areas increased by a similar amount (31%+/-29% and 32%+/-16%) with exercise. In patients with downsloping ST-segment depression, RMBF was unchanged or decreased in ischemic areas (10%+/-24%) but increased in surrounding areas (46%+/-27%) with exercise. In healthy volunteers, RMBF increased in all areas (56%+/-30%) with exercise.
Compared with horizontal changes in ST-segment morphology, downsloping changes may better indicate severe ischemia and greater differences in the increase of blood flow with exercise in the ischemic myocardium and in the surrounding areas.
缺血性ST段压低（水平型或下斜型）是运动诱发心肌缺血最常见的表现。导致这类ST段压低的机制在很大程度上尚不清楚。我们通过运动正电子发射断层扫描（PET）研究了这两种运动诱发的ST段压低与局部心肌血流（RMBF）变化之间的关系。
在27例经血管造影证实患有冠状动脉疾病的患者和6名健康志愿者中，使用氮-13氨PET在静息状态和低水平仰卧位自行车运动期间测量RMBF。从J点后80毫秒的等电位PR段测量ST段压低。9例患者观察到运动诱发的水平型ST段压低≥0.1mV，18例患者观察到下斜型压低≥0.1mV。下斜型压低患者多支血管病变更常见，运动诱发缺血区域比水平型压低患者更大（P<.02，P<.05）。在水平型ST段压低患者中，缺血区域和周围区域的RMBF在运动时增加量相似（分别为31%±29%和32%±16%）。在下斜型ST段压低患者中，缺血区域的RMBF在运动时无变化或降低（10%±24%），但周围区域增加（46%±27%）。在健康志愿者中，运动时所有区域的RMBF均增加（56%±30%）。
与ST段形态的水平变化相比，下斜型变化可能更好地表明严重缺血以及缺血心肌和周围区域运动时血流增加的更大差异。
