Amini Afshin, Nagalli Shivaraj
St. Luke's Hospital
Yuma Regional Medical Center
Bowel ischemia can affect a small or large intestine and can occur by any cause, which leads to intestinal blood flow reduction. This is an uncommon medical condition, but it has a high mortality rate. The intestine is mainly supplied by 2 major arteries, which include the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA). The SMA supplies the bowel from the lower part of the duodenum to two-third of the transverse colon. The IMA supplies a large intestine from the distal one-third of the transverse colon to the rectum. The celiac artery also has collaterals to supply the intestine. Bowel ischemia can be classified as small intestine ischemia, which is commonly known as mesenteric ischemia and large intestine ischemia, which generally referred to as colonic ischemia. Two main areas in the colon, including splenic flexure (Griffiths point) and rectosigmoid junction (Sudek's point), are prone to ischemia. These are also known as the 'watershed' areas, which mean the regions in the colon between 2 major arteries that supplying colon. Splenic flexure is the area between SMA and IMA supplies, and the rectosigmoid junction is the region between the IMA and the superior rectal artery supplies.These areas mostly supplied by the marginal artery; however, in 50% of the population, this artery is poorly developed. Watershed areas account for about 70% of ischemic colitis cases. The colon venous drainage is the parallel of arterial supply. The superior mesenteric vein drains the areas supplied by SMA, and an inferior mesenteric vein drains the left side of the colon and the rectum. An acute decrease in mesenteric arterial blood flow accounts for 60% to 70% of patients with mesenteric ischemia. The rest of the causes are related to colonic ischemia and CMI. Abdominal pain is the most common symptom in patients with intestinal ischemia. Some features of a patient can help to distinguish between the acute small bowel and colonic ischemia. Patient's characteristics, such as age over 60 years, not appearing severe ill, mild abdominal pain, tenderness, rectal bleeding, or bloody diarrhea, are the features that are more common in acute colonic ischemia. Generally, an abdominal computed tomography (CT) scan is used in hemodynamically stable patients who present with acute abdominal pain. In patients with high suspicious for intestinal ischemia, CT angiography and MR angiography are the initial tests. Based on acute mesenteric ischemia (AMI) subtypes, different medication treatments have been suggested. Papaverine, through the angiographic catheter with the mechanism of relaxation of vessels vasospasm, can be used for all arterial forms of AMI and nonocclusive mesenteric ischemia.
肠缺血可累及小肠或大肠，可由任何原因引起，导致肠道血流减少。这是一种罕见的病症，但死亡率很高。肠道主要由2条主要动脉供血，包括肠系膜上动脉（SMA）和肠系膜下动脉（IMA）。SMA为从十二指肠下部至横结肠三分之二的肠段供血。IMA为从横结肠远端三分之一至直肠的大肠供血。腹腔动脉也有分支为肠道供血。肠缺血可分为小肠缺血（通常称为肠系膜缺血）和大肠缺血（一般称为结肠缺血）。结肠的两个主要区域，包括脾曲（格里菲斯点）和直肠乙状结肠交界处（苏德克点），容易发生缺血。这些区域也被称为“分水岭”区域，即结肠中两条主要供血动脉之间的区域。脾曲是SMA和IMA供血区域之间的区域，直肠乙状结肠交界处是IMA和直肠上动脉供血区域之间的区域。这些区域大多由边缘动脉供血；然而，在50%的人群中该动脉发育不良。分水岭区域约占缺血性结肠炎病例的70%。结肠静脉引流与动脉供应并行。肠系膜上静脉引流SMA供血的区域，肠系膜下静脉引流结肠左侧和直肠。肠系膜动脉血流急性减少占肠系膜缺血患者的60%至70%。其余病因与结肠缺血和慢性肠系膜缺血（CMI）有关。腹痛是肠缺血患者最常见的症状。患者的一些特征有助于区分急性小肠缺血和结肠缺血。患者特征，如年龄超过60岁、看起来病情不严重、轻度腹痛、压痛、直肠出血或血性腹泻，在急性结肠缺血中更常见。一般来说，腹部计算机断层扫描（CT）用于有急性腹痛表现且血流动力学稳定的患者。对于高度怀疑肠缺血 的患者，CT血管造影和磁共振血管造影是初始检查。根据急性肠系膜缺血（AMI）的亚型，已提出不同的药物治疗方法。罂粟碱通过血管造影导管，以舒张血管痉挛的机制，可用于所有动脉形式 的AMI和非闭塞性肠系膜缺血。
