Objective Through establishment of brain slice model in rats with perfusion and oxygen glucose deprivation (OGD), we investigated whether this model can replicate the pathophysiology of brain injury in cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) or not and whether perfusion and OGD can induce preoligodendrocytes (preOL) injury or not, to provide cytological evidence for white matter injury after cardiopulmonary bypass. Methods Three to five living brain slices were randomly obtained from each of forty seven-day-old (P7) Sprague-Dawley (SD) rats with a mean weight of 14.7±1.5 g. Brain slices were randomly divided into five groups with 24 slices in each group: control group with normothermic artificial cerebralspinal fluid (aCSF) perfusion (36℃) and DHCA groups: OGD at 15℃, 25℃, 32℃ and 36℃. The perfusion system was established, and the whole process of CPB and DHCA in cardiac surgery was simulated. The degree of oligodendrocyte injury was evaluated by MBP and O4 antibody via application of immunohistochemistry. Results In the OGD group, the mature oligodendrocytes (MBP-positive) cells were significantly damaged, their morphology was greatly changed and fluorescence expression was significantly reduced. The higher the OGD temperature was, the more serious the damage was; preOL (O4-positive) cells showed different levels of fluorescence expression reduce in 36℃, 32℃ and 25℃ groups, and the higher the OGD temperature was, the more obvious decrease in fluorescence expression was. There was no statistically significant difference in the O4-positive cells between the control group and the 15℃ OGD group. Conclusion The perfused brain slice model is effective to replicate the pathophysiology of brain injury in CPB/DHCA which can induce preOL damage that is in critical development stages of oligodendrocyte cell line, and reduce differentiation of oligodendrocyte cells and eventually leads to hypomyelination as well as cerebral white matter injury.
Objective To study the impact of chronic hypoxia on white matter (WM) injury and brain development delay using a neonatal rat model, and to explore its value in simulating chronic hypoxic brain damage in cyanotic congenital heart disease (CHD). Methods Three-day-old Sprague-Dawley (SD) rats were randomly distributed to an experiment group (n=36, FiO2 10.5%±1.0%) and a control group (n=36, FiO2 21.0%±0.0%) and were raised for 12 days. (1) Body weight of SD rats was recorded every day and fresh brain weight was measured on P14. (2) H&E staining was performed on sections of brain tissue to observe pathological changes and ventricular size. (3) Immunohistochemistry (IHC) was applied to reveal alterations of oligodendroglial progenitor cells (OPC), preoligodendrocytes (PreOL) and myelin basic protein (MBP) in brain WM area. (4) Protein was extracted from 50 mg of brain tissue in WM area and expression of MBP was determined using Western blotting. (5) Motor function and coordination of rats (P30) were assessed via rotation experiment. Results (1) Body weight and brain weight were significantly less in the experiment group compared with the control group on P14 (body weight 14.92±1.26 gvs. 30.26±1.81 g, t=7.51, P<0.01; brain weight 0.68± 0.05 gvs.0.97±0.04 g, t=13.26, P<0.01); (2) HE staining: Sections of brain tissue from the experiment group showed ventricular size enlargement with a statistical difference (P<0.01), disordered cell organization, local neuronal death and leukomalacia. (3) The number of OPC and PreOL in the experiment group were significantly less than those in the control group (64.8±6.3vs. 126.2±8.4, t=11.19, P<0.01; 19.1±7.6vs. 46.7±9.5, t=7.28, P<0.01, respectively). MBP distribution was sparse and disorganized in the experiment group. (4) Western blotting: Expression of MBP was less in the experiment group (P<0.01). (5) Behavioral test: Time on rotarod was less in the experiment group with a statistical difference (P<0.01). Conclusion Chronic hypoxia can result in WM injury and brain development delay in neonatal rats, with features comparable to those seen in infants with cyanotic CHD.
ObjectiveTo summarize the experience and lessons of right ventricular decompression in children with pulmonary atresia and intact ventricular septum (PA/IVS) and to reflect on the strategies of right ventricular decompression.MethodsThe clinical data of 12 children with PA/IVS who underwent right ventricular decompression in our hospital from March 2015 to December 2019 were reviewed retrospectively. There were 10 males and 2 females with a median age at the time of surgery was 5 d (range, 1-627 d). Correlation analysis between the pulmonary valve transvalvular pressure gradient and changes in Z score of tricuspid valves after decompression was performed.ResultsOne patient died of refractory hypoxemia due to circulatory shunt postoperatively and family members gave up treatment. There were 2 (16.67%) patients received postoperative intervention. The pulmonary transvalvular gradient after decompression was 31.95±21.75 mm Hg. Mild pulmonary regurgitation was found in 7 patients, moderate in 2 patients, and massive in 1 patient. The median time of mechanical ventilation was 30.50 h (range, 6.00-270.50 h), and the average duration of ICU stay was 164.06±87.74 h. The average postoperative follow-up time was 354.82±331.37 d. At the last follow-up, the average Z score of tricuspid valves was 1.32±0.71, the median pressure gradient between right ventricle and main pulmonary artery was 41.75 mm Hg (range, 21-146 mm Hg) and the average percutaneous oxygen saturation was 92.78%±3.73%. Two children underwent percutaneous balloon pulmonary valvoplasty at 6 and 10 months after surgery, respectively, with the rate of reintervention-free of 81.8%. There was no significant correlation between pulmonary transvalvular gradients after decompression and changes in Z score of tricuspid valves (r=–0.506, P=0.201).ConclusionFor children with PA/IVS, the simple pursuit of adequate decompression during right ventricular decompression may lead to severe pulmonary dysfunction, increase the risk of ineffective circular shunt, and induce refractory hypoxemia. The staged decompression can ensure the safety and effectiveness for initial surgery and reduce the risk of postoperative death.