Hipertensión portal no cirrótica: presentación de cuatro casos y revisión breve de la literatura / Non-cirrhotic portal hypertension: presentation of four cases and a brief review of the literatura

La hipertensión portal es un síndrome hemodinámico de la circulación venosa portal que condiciona múltiples complicaciones potencialmente mortales, debido a las alteraciones generadas en la circulación esplácnica y sistémica. En las últimas décadas se ha identificado la presencia de hipertensión portal en ausencia de cirrosis con un fenómeno de vasculopatía característico. Esta entidad puede clasificarse como prehepática, hepática y posthepática, según la localización del compromiso, identificado mediante estudios hemodinámicos. Se presentan cuatro casos de pacientes con hipertensión portal no cirrótica secundaria a trombosis portal. Adicionalmente, se realiza una revisión breve de la literatura, haciendo énfasis en las dos causas más frecuentes de hipertensión portal no cirrótica; la trombosis venosa portal crónica y la enfermedad vascular porto-sinusoidal.

Portal hypertension is a hemodynamic syndrome of the portal venous circulation that causes multiple life-threatening complications due to the alterations generated in the splanchnic and systemic circulation. In recent decades, the presence of portal hypertension in the absence of cirrhosis has been identified with a characteristic vasculopathy phenomenon. This condition can be classified as pre-hepatic, hepatic and post-hepatic, according to the location of the involvement, identified by hemodynamic studies. Four case reports of patients with non-cirrhotic portal hypertension secondary to portal thrombosis are presented. Additionally, a brief review of the literature is included, with emphasis in the two most frequent causes of non-cirrhotic portal hypertension; chronic portal venous thrombosis and portosinusoidal vascular disease.

Remodeling of hepatic vascular changes after specific chemotherapy of schistosomal periportal fibrosis

Hepatosplenic schistosomiasis was the first human disease in which the possibility of extensive long standing hepatic fibrosis being degraded and removed has been demonstrated. When such changes occurred, the main signs of portal hypertension (splenomegaly, esophageal varices) progressively disappeared, implying that a profound vascular remodeling was concomitantly occurring. Hepatic vascular alterations associated with advanced schistosomiasis have already been investigated. Obstruction of the intrahepatic portal vein branches, plus marked angiogenesis and compensatory hyperplasia and hypertrophy of the arterial tree are the main changes present. However, there are no data revealing how these vascular changes behave during the process of fibrosis regression. Here the mouse model of pipestem fibrosis was used in an investigation about these vascular alterations during the course of the infection, and also after treatment and cure of the disease. Animals representing the two polar hepatic forms of the infection were included: (1) "isolated granulomas" characterized by isolated periovular granulomas sparsely distributed throughout the hepatica parenchyma; and (2) 'pipestem fibrosis' with periovular granulomas and fibrosis being concentrated within portal spaces, before and after treatment, were studied by means of histological and vascular injection-corrosion techniques. Instances of widespread portal vein obstruction of several types were commonly found in the livers of the untreated animals. These obstructive lesions were soon repaired, and completely disappeared four months following specific treatment of schistosomiasis. Treatment was accomplished by the simultaneous administration of praziquantel and oxamniquine. The most impressive results were revealed by the technique of injection of colored masses into the portal system, followed by corrosion in strong acid. The vascular lesions of non-treated pipestem fibrosis were represented...

Patogénesis de la hipertensión portal / Pathogenesis of portal hypertension

It is now well established that portal hypertension is not a purely mechanical phenomenon. Primary hemodynamic alterations develop in the hepatic and systemic circulatory systems; these alterations in combination with mechanical factors contribute to the development of portal hypertension. In the hepatic circulation, these hemodynamic alterations are characterized by vasoconstriction and impaired hepatic vasodilatory responses, whereas in the systemic circulation, particularly in the splanchnic bed, vessels are hyperemic with increased flow. Thus, an increase in intrahepatic resistance in conjunction with increased portal venous inflow, mediated through splanchnic dilation, contributes to the development of portal hypertension. The ensuing development of elevated flow and transmural pressure through collateral vessels from the hypertensive portal vasculature into the lower pressure systemic venous circulation accounts for many of the complications, such as bleeding esophageal varices, observed with portal hypertension. The importance of the primary vascular origin of portal hypertension is emphasized by the utility of current therapies aimed at reversing these hemodynamic alterations, such as nitrates, which reduce portal pressure through direct intrahepatic vasodilatation, and fi blockers and octreotide, which reduce splanchnic vasodilatation and portal venous inflow. New evidence concerning relevant molecular mechanisms of contractile signaling pathways in hepatic stellate cells and the complex regulatory pathways of vasoactive molecules in liver endothelial cells makes a better understanding of these processes essential for developing further experimental therapies for portal hypertension. This article examines the current concepts relating to cellular mechanism that underlie the hemodynamic alterations that characterize and account for the development of portal hypertension.

Actualmente está bien establecido que la hipertensión portal no es un fenómeno puramente mecánico. En esta entidad se presentan alteraciones hemodinámicas primarias en los sistemas circulatorios hepático y sistémico; estas alteraciones en combinación con factores mecánicos, contribuyen al desarrollo de la hipertensión portal. En la circulación hepática, las alteraciones hemodinámicas se caracterizan por vasoconstricción y una respuesta anómala a la vasodilatación, mientras que en la circulación sistémica, especialmente en el lecho esplácnico, los vasos están congestivos y con un flujo aumentado. Por lo tanto un incremento en las resistencias intrahepáticas asociado a un aumento del flujo venoso portal, mediado a través de la dilatación esplácnica, contribuyen al desarrollo de la hipertensión portal. La consecuencia del flujo y la presión transmural elevada a través de los vasos colaterales a partir de una vasculatura portal hipertensa hacia la circulación venosa sistémica con menor presión, conlleva a muchas de las complicaciones observadas en la hipertensión portal, como la hemorragia por várices esofágicas. La importancia del origen vascular primario de la hipertensión portal se basa en la utilidad de terapias actuales orientadas a revertir estas alteraciones hemodinámicas, como los nitratos que reducen la presión portal, a través de vasodilatación intrahepática directa y los P bloqueadores y octreótida, que reducen la vasodilatación esplácnica y el flujo venoso portal. Además, existen nuevas evidencias en relación con los mecanismos moleculares de vías de señalización contráctil de las células estelares hepáticas y complejas vías de regulación de sustancias vasoactivas en las células endoteliales hepáticas que han ayudado a entender mejor estos procesos esenciales para el desarrollo de terapias experimentales para la hipertensión portal. Este artículo revisa los conceptos actuales relacionados con los mecanismos celulares causales de las alteraciones hemodinámicas que caracterizan y condicionan el desarrollo de la hipertensión portal.