Hyperdynamic Circulation in portal Hypertension : Pathophysiology and Effects of Vasoactive Substances

1.肝硬变门脉高压高动力循环的病理生理学研究(1)各种血管床的血流动力学特征外周动脉血管扩张主要发生在内脏循环，在高动力循环的启动中起重要作用。胰高血糖素和心钠素参与了这一现象。高动力内脏循环随着肝病的进展而发展。但食道静脉曲张和胃底静脉曲张患者的门静脉流出模式不同。肝肾综合征患者出现的肾血管收缩与内脏动脉循环充盈不足时肾脏的动态平衡反应有关。在肝脏循环中，肝动脉对门脉血流改变的缓冲反应降低。(2)对生理刺激的反应进食后观察到内脏充血。卧位也引起了与ATRI…增加相关的类似变化更多的钠尿肽水平。直立姿势减少了食道静脉曲张的血流量和钝化的餐后内脏充血。因此，进食和卧位似乎是静脉曲张出血的危险因素。此外，时序学检查显示血浆心钠素水平和反映鸟苷环化酶受体激活的环鸟苷一磷酸水平在夜间达到峰值。这一发现可能解释了为什么肝硬化患者往往在夜间出现食道静脉曲张出血。血管活性物质在肝硬变和门脉高压中的血流动力学作用血管加压素和心得安减少内脏流入，导致侧支血流量减少。心得安对门脉压力反应的个体差异被认为是β-2肾上腺素能受体状态的异质性。吸烟减少内脏血流量，导致门脉血流量减少，提示尼古丁具有潜在的门脉压力降低作用。较少

1. Pathophysiology of Hyperdynamic Circulation in Cirrhosis and Portal Hypertension(1) Hemodynamic characteristics in various vascular bedsPeripheral arterial vasodilatation which plays an important role in the initiation of hyperdynamic circulation occurred mainly in the splanchnic circulation. Glucagon and atrial natriuretic peptide contributed to this phenomenon. Hyperdynamic splanchnic circulation developed as liver disease progresses. However, portal outflow pattern was different in patients with esophageal varices and patients with gastric varices. Renovascular constriction seen in patients with hepatorenal syndrome was responsible for kidney's homeostatic response to underfilling of the splanchnic arterial circulation. In liver circulation, hepatic arterial buffer response to altered portal blood flow was reduced.(2) Response to physiological stimuliSplanchnic hyperemia was observed after meal ingestion. Recumbent posture also caused similar change associated with increased atri … More al natriuretic peptide levels. Upright posture reduced esophageal variceal blood flow and blunted postprandial splanchnic hyperemia. Thus, meal ingestion and recumbent posture seemed to be risk factors for variceal bleeding. Furthermore, chronological examination showed that plasma atrial natriuretic peptide levels and cyclic guanosine monophosphate level which reflects activation of the guanylate cyclase receptors by the peptide peaked at night. This finding may explain why patients with cirrhosis tend to have esophageal variceal bleeding episodes at night.2. Hemodynamic Effect of Vasoactive Substances in Cirrhosis and Portal HypertensionVasopressin and propranolol decreased splanchnic inflow, resulting in reduction in collateral blood flow. Individual variability of portal pressure response to propranolol was thought to be heterogeneity of the beta-2 adrenoceptor status. Smoking decreased splanchnic blood flow, resulting in reduction in portal blood flow, suggesting that nicotine has potential portal pressure reducing effect. Less