Evidence for an Association Between Intrahepatic Vascular Changes and the Development of Hepatopulmonary Syndrome

Background Hepatopulmonary syndrome (HPS) is characterized by an arterial oxygenation defect, defined by an increased alveolar-arterial oxygen gradient, induced by pulmonary vascular dilatations in the context of liver disease. The pathogenesis of HPS is poorly understood. Morphologic changes associated with HPS are unknown. This study aimed at describing imaging and pathology changes associated with HPS. Methods We performed a case-control study in candidates for transplant with suspicion of cirrhosis. Each patient with HPS (Pao 2  ≤ 70 mm Hg) was matched to three control subjects for age, cause, and liver disease severity. Pretransplant thoracic and abdominal imaging and explanted livers were reviewed. Results CT scans and Doppler ultrasounds from 21 patients with HPS were compared with those from 63 control subjects. HPS was associated with a two- to threefold higher prevalence of obstructed intrahepatic portal branches, of slowed or hepatofugal portal blood flow, and of large abdominal portosystemic shunts. Hepatic artery diameter was also larger in patients with HPS. Explanted livers from 19 patients with HPS were compared with those from 57 control subjects. HPS was associated with a fourfold higher prevalence of portal venule thrombosis and a ninefold higher prevalence of extensive vascular proliferation within fibrous septa. Obstruction of centrilobular venules, sinusoidal dilatation, and liver parenchymal extinction were also more common in patients with HPS. Conclusions HPS is associated with intrahepatic vascular changes and with features suggesting severe portal hypertension. These results raise the hypothesis that intrahepatic vascular changes precipitate the development of HPS, opening new therapeutic perspectives for HPS.