Hepatopulmonary syndrome: update on recent advances in pathophysiology, investigation and treatment.
J Gastroenterol Hepatol. 2012 Nov 28;
Authors: Grace JA, Angus PW
Hepatopulmonary syndrome (HPS) is an important cause of dyspnoea and hypoxia in the setting of liver disease, occurring in 10-30% of patients with cirrhosis. It is due to vasodilatation and angiogenesis in the pulmonary vascular bed, which leads to ventilation-perfusion mismatching, diffusion-limitation to oxygen exchange and arteriovenous shunting. There is evidence, primarily from animal studies, that vasodilatation is mediated by a number of endogenous vasoactive molecules, including endothelin-1 (ET-1) and nitric oxide (NO). In experimental HPS, liver injury stimulates release of ET-1, and results in increased expression of ET(B) receptors on pulmonary endothelial cells, leading to upregulation of endothelial NO synthase (eNOS) and subsequent increased production of NO, which causes vasodilatation. In addition, increased phagocytosis of bacterial endotoxin in the lung not only promotes stimulation of inducible NOS, which increases NO production, but also contributes to intrapulmonary accumulation of monocytes, which may stimulate angiogenesis via vascular endothelial growth factor pathway. Despite these insights into the pathogenesis of experimental HPS, there is no established medical therapy and liver transplantation remains the main treatment for symptomatic HPS, although selected patients may benefit from other surgical or radiological interventions. In this review we focus on recent advances in our understanding of the pathophysiology of HPS, and discuss current approaches to the investigation and treatment of this condition.
PMID: 23190201 [PubMed - as supplied by publisher]