Ye J, Ryner L N, Kozlowski P, Yang L, Del Bigio M R, Sun J, Donnelly M, Summers R, Salerno T A, Somorjai R L, Saunders J K, Deslauriers R
Institute for Biodiagnostics, National Research Council of Canada, Winnipeg, Manitoba, Canada.
Circulation. 1998 Nov 10;98(19 Suppl):II313-8.
In the past few years, although significant efforts have been made to assess flow distribution during retrograde cerebral perfusion with microspheres, dye, or hydrogen clearance, flow distribution in real time is still undefined. We used MR perfusion imaging to monitor flow distribution in the brain during and after deep hypothermic circulatory arrest (DHCA) with antegrade or retrograde cerebral perfusion (ACP or RCP).
Thirteen pigs were divided into 2 groups and exposed to 120 minutes of either RCP (n = 7) or ACP (n = 6) at 15 degrees C, followed by 60 minutes of cardiopulmonary bypass (CPB) at 37 degrees C. During DHCA, the brain was perfused antegradely through the common carotid artery or retrogradely through the superior vena cava at pressures of 60 to 70 mm Hg and 20 to 25 mm Hg in the ACP and RCP groups, respectively. Esophageal temperature was monitored continuously. MR perfusion images were acquired every 30 minutes before, during, and after DHCA. The brain was perfusion-fixed with formaldehyde solution for histopathology at the completion of each experiment. During initial normothermic CPB, MR perfusion imaging showed a nearly uniform distribution of flow in the brain. The same pattern was maintained with a significant increase in regional cerebral blood volume during ACP and reperfusion in the ACP group. RCP provided little or no detectable blood distribution to the brain, resulting in poor reperfusion of many areas of the brain on reflow with CPB at 37 degrees C. The total area suffering poor reperfusion was significantly higher in the RCP group than the ACP group. Histopathology showed no morphological changes in any area of the brain in the ACP group, whereas varying severity of neuronal damage was observed in different regions of the brain in the RCP group.
ACP preserves uniform blood distribution and normal morphology of brain tissue after prolonged DHCA. RCP provides very little blood to the tissue of the brain. A 120-minute period of RCP results in abnormal flow distribution and neuronal damage during reperfusion. The damage resulting from shorter periods of RCP remains to be assessed.
在过去几年中，尽管已做出巨大努力，利用微球、染料或氢清除法来评估逆行性脑灌注期间的血流分布，但实时血流分布仍不明确。我们采用磁共振灌注成像来监测在深低温停循环（DHCA）期间及之后，采用顺行性或逆行性脑灌注（ACP或RCP）时脑内的血流分布。
将13头猪分为2组，在15℃下分别进行120分钟的RCP（n = 7）或ACP（n = 6），随后在37℃下进行60分钟的体外循环（CPB）。在DHCA期间，在ACP组和RCP组中，分别通过颈总动脉顺行灌注或通过上腔静脉逆行灌注脑，压力分别为60至70mmHg和20至25mmHg。持续监测食管温度。在DHCA之前、期间和之后，每隔30分钟采集磁共振灌注图像。在每个实验结束时，用甲醛溶液对脑进行灌注固定以进行组织病理学检查。在初始常温CPB期间，磁共振灌注成像显示脑内血流分布近乎均匀。在ACP组中，ACP期间及再灌注时，区域脑血容量显著增加，维持了相同的模式。RCP几乎未向脑提供可检测到的血流分布，导致在37℃进行CPB复流时，脑的许多区域再灌注不良。RCP组中灌注不良的总面积显著高于ACP组。组织病理学显示，ACP组脑的任何区域均无形态学变化，而RCP组脑的不同区域观察到不同程度的神经元损伤。
延长DHCA后，ACP可保持脑内均匀的血流分布和脑组织的正常形态。RCP向脑组织提供的血流极少。120分钟的RCP会导致再灌注期间血流分布异常和神经元损伤。较短时间RCP造成的损伤仍有待评估。
