Effects of extra-intracranial arterial bypass on cerebral blood flow and oxygen metabolism in humans.
Effects of extra-intracranial arterial bypass on cerebral blood flow and oxygen metabolism in humans.
复制标题
颅外动脉旁路对人体脑血流量和氧代谢的影响。
作者：
Y. Samson;J. Baron;M. Bousser;A. Rey;J. Derlon;P. David;J. Comoy
12例患者，11例颈动脉阻塞和1例大脑中动脉阻塞，在成功的单侧颅内外动脉旁路（EIAB）之前和之后进行了研究，使用PET和15-0稳态技术测量局部脑血流量（CBF），氧提取分数和氧代谢率（CMRO 2）。在整个患者组中，EIAB后两个大脑半球的CBF和CMRO 2均显着增加，恢复到年龄匹配受试者定义的对照水平。另一方面，平均氧提取分数不受影响。单独地，EIAB出现了三种不同的作用：1）如先前所报道的，缓解长期存在的单侧“痛苦-灌注”状态; 2）双侧CBF和CMRO 2的平行增加，这是由于代谢的血流动力学抑制的改善而出现的，其确切机制仍然不清楚; 3）CBF-CMRO 2偶联中的复杂的、意外的变化再次导致CMRO 2的增加。EIAB在我们的患者中提供的这种代谢改善以前从未报道过;这表明长期血流动力学衰竭可能会诱导代谢抑制，这种代谢抑制仍然可能通过手术血运重建逆转。
Twelve patients, eleven with a carotid obstruction and one with an occlusion of the middle cerebral artery, were studied before and after a successful unilateral extra-intracranial arterial by-pass, (EIAB) using PET and the 15-0 steady-state technique to measure regional cerebral blood flow (CBF), oxygen extraction fraction and oxygen metabolic rate (CMRO2). In the whole group of patients, both CBF and CMRO2 increased significantly on both cerebral hemispheres after EIAB, returning toward control levels defined in age-matched subjects. Mean oxygen extraction fraction, on the other hand, was not affected. Individually, three different effects of EIAB emerged: 1) Alleviation of a state of long standing unilateral "misery-perfusion", as reported earlier; 2) parallel increase of CBF and CMRO2 bilaterally, which appeared due to improvement of a hemodynamic depression of metabolism, the precise mechanism of which remains obscure; 3) Complex, unexpected changes in the CBF-CMRO2 couple again resulting in increases in CMRO2. This metabolic improvement afforded by EIAB in our patients has not been reported before; it suggests that long-standing hemodynamic failure may induce a metabolic depression that is still potentially reversible by surgical revascularization.