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

1.肝硬化门脉高压高动力循环的病理生理（1）不同血管床的血流动力学特征外周动脉血管舒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。随着肝病的进展，内脏循环动力增强。但食管静脉曲张患者和胃静脉曲张患者的门静脉流出模式不同。肝肾综合征患者的肾血管收缩是肾脏对内脏动脉循环充盈不足的稳态反应的原因。在肝循环中，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。横卧姿势也引起了类似的变化， ...更多信息 钠尿肽水平。直立姿势可减少食管静脉曲张血流量并减弱餐后内脏充血。因此，进食和卧位似乎是静脉曲张出血的危险因素。此外，时间顺序检查显示，血浆心钠素水平和环磷酸鸟苷水平，反映了鸟苷酸环化酶受体的激活肽在夜间达到高峰。这一发现可以解释为什么肝硬化患者食管静脉曲张出血倾向于在夜间发作。血管活性物质在肝硬化门脉高压症中的血流动力学作用加压素和心得安减少内脏流入，导致侧支血流量减少。门静脉压力对普萘洛尔反应的个体差异被认为是β 2肾上腺素受体状态的异质性。吸烟使内脏血流量减少，导致门静脉血流量减少，提示尼古丁具有潜在的门静脉降压作用。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