実験からみた虚血性大腸病変

A Study on Ischemic Lesion of the Large Intestine from the Morphological Viewpoint of the Experimental Ischemic Colitis

要旨　虚血性大腸病変の臨床例では腸管の血流障害を証明することは困難である．そこで，実験的に血流障害を作製し，生じた病変の画像を点（P），線（L），面（A），深さ，更に経過（時間）を考慮して整理し，実験的虚血性大腸病変の画像の“ものさし”を作った．X線像でバリウム付着異常があり，肉眼像で浮腫，びらんがあるものは動脈系の障害の初期像，びらんがないものは静脈系の障害の初期像であった．X線像で管状狭小化がみられ，肉眼像で厚い白苔の付着する潰瘍性病変は，動脈系障害の時間が経過した像であった．X線像で屈曲，捻れがみられ，肉眼像で粘膜ひだ集中を伴う潰瘍を認めるものは，動脈系障害の治癒像で，コイル様外観などのloopの変形は主に腸間膜の病変による像であった．X線像で拡張がみられるものは，広い範囲の血流障害であった．実験で作った虚血性腸病変の“ものさし”を使って，臨床例にみられる虚血性大腸病変の画像を解析し，障害された主な血管および障害からの時間をある程度は推定できると考えられた．

　Ischemic lesion of the large intestine is caused by impairment of blood supply. The impaired site of blood supply can not be identified even by angiographic and histopathologic examinations in many cases. Therefore, we established experimental models of ischemic colitis by several methods (Fig. 1). The impairment of blood supply induced various colonic lesions. The colon with the impaired site of blood supply was surgically resected and examined radiologically and macroscopically. The characteristics of macroscopic and radiologic findings of colonic lesions were studied by the two dimensional analysis proposed by Dr. Shirakabe, the three dimensional analysis which included the depth of lesions, and even the four dimensional analysis which included the time course of lesions. We made the “indicators” from the morphological feature of the experimental ischemic colitis. Abnormal barium coating in the radiologic examination and edema in the macroscopic examination were considered to be the morphological features of venous congestion, and erosions were thought to be signs of acutely impaired arterial blood supply. Tubular narrowing and ulcer with thick slough indicated the late phase of impaired arterial blood supply. Angulation, distortion, multiple shallow and longitudinal ulcers with converging folds were signs of the healing stage of impaired arterial blood supply. A coilshaped deformity of the loop was caused by a mesenteric lesion. Dilatation of the intestinal lumen and a demarcated necrotic pattern were found immediately after the onset of a wide range of impaired blood supply. In conclusion, the impaired region of blood supply and time of onset in each clinical ischemic colitis can be presumed, to some extent, by the morphological features of the “indicators” of the experimental ischemic colitis.