Dobrin P B
Department of Surgery, Loyola University Medical Center, Maywood, Illinois.
Surg Gynecol Obstet. 1991 Jun;172(6):503-8.
Partial narrowing of arteries produces poststenotic dilatation. This appears as a dilation of the vessel wall 1 to 3 centimeters distal to the area of a partial stenosis. When a stenotic band is placed in dogs, poststenotic dilatation develops rapidly, often within eight to ten days. Moderate stenoses that produce a bruit and thrill are effective in eliciting poststenotic dilatation, whereas very tight and very mild stenoses usually are ineffective. Thus, development of poststenotic dilatation requires the presence of flow disturbances sufficient to produce an audible bruit and a palpable thrill. Although the exact flow disturbance is uncertain, statis, increased lateral pressure, cavitation, abnormal shear stresses and turbulence all have been postulated to be the cause of poststenotic dilatation. Of these, experimental studies support abnormal shear stresses and turbulence as the most likely causes. Whatever the flow disturbance, it must make the wall vibrate to produce poststenotic dilatation. Vibrations are thought to produce alterations in wall elastin and possibly in vascular smooth muscle tone. This leads to dilatation of the vessel. If the dilatation is slight, removal of the stenosis may cause reversal of poststenotic dilatation with recovery beginning within hours of correction of the stenosis. If the dilated area is enlarged to twice normal diameter, it may exhibit permanent aneurysmal changes and, therefore, requires resections with reanastomosis. Arteries that are dilated to as little as one-third more than normal size may contain areas of ulceration with overlying thrombus. These vessels also may require resection with reanastomosis.
动脉部分狭窄会导致狭窄后扩张。这表现为在部分狭窄区域远端1至3厘米处的血管壁扩张。当在狗身上放置狭窄带时，狭窄后扩张会迅速发展，通常在八到十天内出现。能产生杂音和震颤的中度狭窄可有效引发狭窄后扩张，而极严重和极轻微的狭窄通常无效。因此，狭窄后扩张的发生需要存在足以产生可闻杂音和可触及震颤的血流紊乱。虽然确切的血流紊乱尚不确定，但已推测血流停滞、侧压力增加、空化、异常剪切应力和湍流都是狭窄后扩张的原因。其中，实验研究支持异常剪切应力和湍流是最可能的原因。无论血流紊乱是什么，它都必须使血管壁振动以产生狭窄后扩张。振动被认为会导致血管壁弹性蛋白发生改变，也可能导致血管平滑肌张力改变。这会导致血管扩张。如果扩张轻微，去除狭窄可能会使狭窄后扩张逆转，在狭窄纠正后的数小时内开始恢复。如果扩张区域扩大到正常直径的两倍，可能会出现永久性动脉瘤样改变，因此需要进行切除并重新吻合。扩张至比正常大小仅大三分之一的动脉可能含有溃疡区域及覆盖其上的血栓。这些血管也可能需要进行切除并重新吻合。
