Department of Cardiac Surgery, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy.
Eur J Cardiothorac Surg. 2010 Jun;37(6):1322-31. doi: 10.1016/j.ejcts.2009.12.029. Epub 2010 Feb 6.
Antegrade selective cerebral perfusion (ASCP) represents the best method of cerebral protection during surgery of the thoracic aorta. However, brain integrity and metabolism after antegrade cerebral perfusion have not yet been investigated. We assessed cerebral positron emission tomography (PET), diffusion-weighted imaging, proton magnetic resonance spectroscopy and cognitive functions in patients undergoing either ASCP or coronary artery bypass grafting (CABG) to elucidate whether cerebral perfusion was associated with postoperative neuronal alterations, metabolic deficit or cognitive decline.
Seventeen patients undergoing aortic arch surgery using ASCP with moderate hypothermia (26 degrees C) (ASCP group) and 15 patients undergoing elective on-pump CABG (CABG group) were prospectively enrolled in the study. Brain PET, diffusion-weighted imaging, proton magnetic resonance spectroscopy and neuropsychometric testing were performed preoperatively, and at 1 week and 6 months postoperatively (T1, T2 and T3, respectively). Patient data were compared for statistic analysis with a normal database made up of healthy subjects.
One patient in each group was excluded because they refused postoperative evaluation. There were neither strokes nor hospital deaths. Two patients suffered from temporary neurological dysfunction (one in each group). Proton magnetic resonance spectroscopy did not reveal significant alterations in cortical N-acetyl-aspartate (NAA) content within and between the groups at T2 and T3. In the ASCP group, brain diffusion-weighted magnetic resonance showed a significant increase of the apparent diffusion coefficient values, reflecting vasogenic cerebral oedema, at T2, that disappeared at T3. Magnetic resonance detected new focal brain lesions in two CABG group patients. In seven ASCP group patients, PET scan showed glucose hypometabolism in the occipital lobes at T2, which disappeared in five patients at successive examination (T3). Significant cognitive decline was not observed in any patient. Test score changes between and within groups were not significant.
There was no evidence of ischaemic brain injury after ASCP even if some degree of reversible brain oedema secondary to cardiopulmonary bypass (CPB) was present. The cognitive outcomes in patients undergoing ASCP were comparable to patients undergoing coronary artery bypass. The lack of left subclavian artery perfusion during cerebral perfusion leads to temporary glucose hypometabolism in the occipital lobes without neuronal injury.
顺行性选择性脑灌注（ASCP）是胸主动脉手术中脑保护的最佳方法。然而，ASCP 后大脑的完整性和代谢尚未得到研究。我们评估了接受 ASCP 或冠状动脉旁路移植术（CABG）的患者的脑正电子发射断层扫描（PET）、弥散加权成像、质子磁共振波谱和认知功能，以阐明脑灌注是否与术后神经元改变、代谢缺陷或认知能力下降有关。
17 例接受中度低温（26°C）ASCP 的主动脉弓手术患者（ASCP 组）和 15 例接受选择性体外循环 CABG 患者（CABG 组）前瞻性纳入本研究。术前、术后 1 周和 6 个月（分别为 T1、T2 和 T3）进行脑 PET、弥散加权成像、质子磁共振波谱和神经心理测试。患者数据与由健康受试者组成的正常数据库进行统计学分析比较。
每组各有 1 例患者因拒绝术后评估而被排除。两组均无卒中或院内死亡。两组各有 1 例患者出现暂时性神经功能障碍。质子磁共振波谱未显示 T2 和 T3 时两组皮质 N-乙酰天冬氨酸（NAA）含量有显著变化。在 ASCP 组，脑弥散加权磁共振显示 T2 时表观扩散系数值显著增加，反映出血管源性脑水肿，T3 时消失。磁共振在 2 例 CABG 组患者中检测到新的局灶性脑病变。在 7 例 ASCP 组患者中，PET 扫描显示 T2 时枕叶葡萄糖代谢低下，5 例患者在连续检查（T3）时消失。任何患者均未观察到认知能力显著下降。组间和组内的测试评分变化无显著性差异。
即使存在一定程度的心肺转流（CPB）继发的可逆性脑水肿，ASCP 后也没有证据表明发生脑缺血损伤。接受 ASCP 的患者的认知结果与接受冠状动脉旁路移植的患者相当。在脑灌注期间不灌注左锁骨下动脉导致枕叶暂时葡萄糖代谢低下，而无神经元损伤。
