Senior Researcher, Scientific Laboratory of Optical Coherence Tomography, Research Institute of Experimental Oncology and Biomedical Technologies; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia.
Associate Professor, Leading Researcher, University Clinic; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia.
Sovrem Tekhnologii Med. 2021;13(4):36-45. doi: 10.17691/stm2021.13.4.04. Epub 2021 Aug 28.
was to use multimodal optical coherence tomography (MM OCT) to evaluate microstructure and microcirculation in the proximal and distal sections of the intestine relative to the resected area in acute mesenteric ischemia.
The study was carried out using three groups of male Wistar rats weighing 270-435 g (n=18). Acute occlusive arterial ischemia of the small intestine was initiated in all animals. After 80-90 min, the ischemic non-viable part of the intestine was resected, and the operation was completed by stoma exteriorization (group 1, n=6), by applying purse-string sutures (group 2, obstructive resection, n=6), or by internal drainage of the proximal and distal ends of the small intestine (group 3, bypass, n=6). Relaparotomy and anastomosis formation were performed 2 days later.With the help of MM OCT at each stage of the surgical intervention, images were obtained from the serous membrane side: the intestinal wall microstructure (layers) was viewed using cross-polarization OCT (CP OCT) and the intramural circulation - using optical coherent angiography (OCA). The MM OCT images obtained from the terminal intestine sections immediately after resection and 2 days later (before the anastomosis formation) were compared between the experimental groups, as well as with the pre-ischemic data (norm). All resected sections of the intestine were then histologically examined. The MM OCT data were compared with the histological and intravital macroscopy data.
As a result of studying the intestinal wall microstructure by CP OCT, it was found that during ostomy (group 1) and obstructive resection (group 2), the images showed signs of tissue edema and destructive changes in the mucous membrane that were confirmed histologically, while with bypass surgery (group 3), there were minimal changes as compared with the norm.According to the OCA data, on day 2 of ostomy in the proximal and distal segments of the intestine, there was a noticeable disappearance of small and medium blood vessels; mainly large arteries and veins could be visualized. Following obstructive resection (purse-string suturing) or bypass surgery, the most noticeable changes (a decrease in the number of visualized blood vessels) were observed in the distal part of the intestine. The L index calculated from OCA images and characterizing the total length of the intramural perfused vasculature, showed a statistically significant decrease during ostomy: 12.18 [10.40; 14.20] μm - in the proximal and 10.67 [7.98; 13.05] μm - in the distal section; for comparison, the L index before ischemia was 18.90 [17.98; 19.73] μm and 18.74 [17.46; 19.90] μm, respectively (p=0.0001). In obstructive resection (group 2), statistically significant differences in the L parameter were found only for the distal bowel section: 16.39 [12.37; 18.10] μm compared with 18.74 [17.46; 19.90] μm before ischemia (p=0.041). After bypass surgery (group 3), there were no significant deviations in the L index.
By using MM OCT, we found that in treating the remaining sections of the intestine after its emergency resection for acute mesenteric ischemia, the type of surgical technique determines the tissue structure in the period before the delayed anastomosis is applied.The least pronounced and most balanced changes occur in the proximal and distal segments of the intestine when operated using the bypass technique. However, to recommend this type of surgery, the development of reliable, safe, and effective bypass instruments is needed.
使用多模态光学相干断层扫描（MM OCT）评估急性肠系膜缺血患者肠切除部位的近、远段与切除区域相关的微观结构和微循环。
本研究纳入 3 组雄性 Wistar 大鼠，体重 270-435 g（n=18）。所有动物均发生急性闭塞性小肠动脉缺血。缺血 80-90 min 后，切除不可存活的缺血肠段，手术通过肠外置（第 1 组，n=6）、荷包缝合（第 2 组，梗阻性切除，n=6）或小肠近端和远端的内引流（第 3 组，旁路，n=6）完成。2 天后进行再次剖腹术和吻合术。在手术干预的每个阶段，借助 MM OCT 从浆膜侧获得图像：使用交叉偏振 OCT（CP OCT）观察肠壁微观结构（层），使用光相干血管造影（OCA）观察壁内循环。比较各组动物在肠段切除后即刻和 2 天后（吻合术形成前）获得的末端肠段的 MM OCT 图像与实验前（正常）数据。所有切除的肠段均进行组织学检查。将 MM OCT 数据与组织学和活体宏观数据进行比较。
通过 CP OCT 研究肠壁微观结构，发现肠外置（第 1 组）和梗阻性切除（第 2 组）时，图像显示黏膜组织水肿和破坏性改变的迹象，这些改变在组织学上得到证实，而旁路手术（第 3 组）与正常相比，变化最小。根据 OCA 数据，在肠近端和远端段肠外置第 2 天，可见小血管和中等血管明显消失；主要可以观察到大动脉和静脉。梗阻性切除（荷包缝合）或旁路手术后，在肠的远端观察到最明显的变化（可见血管数量减少）。OCA 图像计算的 L 指数，用于描述壁内灌注血管的总长度，在肠外置时显著下降：近端 12.18 [10.40；14.20] μm，远端 10.67 [7.98；13.05] μm；相比之下，缺血前的 L 指数分别为 18.90 [17.98；19.73] μm 和 18.74 [17.46；19.90] μm（p=0.0001）。在梗阻性切除（第 2 组）中，仅在肠的远端部分发现 L 参数有统计学意义的差异：16.39 [12.37；18.10] μm 与缺血前的 18.74 [17.46；19.90] μm 相比（p=0.041）。旁路手术后（第 3 组），L 指数无明显偏差。
通过使用 MM OCT，我们发现，在治疗急性肠系膜缺血后紧急切除剩余肠段时，手术类型决定了延迟吻合前的组织结构。当使用旁路技术进行手术时，近端和远端肠段的变化最不明显且最平衡。然而，为了推荐这种类型的手术，需要开发可靠、安全和有效的旁路仪器。
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