Portal Hypertension in Children
Portal hypertension is defined as an increase of blood pressure in the portal venous bed beyond the physiological values.
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Neil Di Salvo, Michela Maffi, and Mario Lima
27.1
Definition
Portal hypertension is defined as an increase of blood pressure in the portal venous bed beyond the physiological values of 5–10 cm H2O or as an increase of pressure gradient of more than 5 cm H2O between the hepatic veins and the portal circulation (hepatic venous pressure gradient or HVPG) [1–5].
27.2
Classification and Etiology
It is caused by either: • An increase of resistance to the blood flow from the mesenteric venous circulation through or to the liver (which is way more frequent in childhood) • An increase of the blood flow to the portal circulation The increase of resistance is the consequence of an obstruction in the portal system. Depending on the site of this obstruction, we can divide all
N. Di Salvo (*) • M. Maffi • M. Lima Pediatric Surgery, S. Orsola-Malpighi Hospital, Bologna University, Via Massarenti 11, 40138 Bologna, Italy e-mail: [email protected]; [email protected]; [email protected]
causes of portal hypertension into three main categories: • Prehepatic portal hypertension, also known as extrahepatic portal vein obstruction (EHPVO). Unlike in adulthood, this represents the most frequent type of portal hypertension in children (60–75 %). • Intrahepatic portal hypertension, secondary to hepatocellular injury leading to cirrhosis. This is the second most frequent type of portal hypertension in childhood. Among all hepatocellular diseases leading to portal hypertension (Table 27.1), biliary atresia is the most common. • Post-hepatic portal hypertension. It is caused by thrombosis of large or small veins draining blood from the liver into the inferior vena cava (Budd-Chiari syndrome, rare in children). Extrahepatic portal vein obstruction can be caused by: • Thrombosis of the portal vein (Fig. 27.1): instrumentation and cannulation of the umbilical vein at birth including umbilical vein catheters for intravenous access in the first days of life, omphalitis, sepsis, hypovolemic shock and hereditary hypercoagulable states represent risk factors for this condition. Regarding the umbilical cannulation, some authors report a 40 % risk of thrombosis after
© Springer International Publishing Switzerland 2017 M. Lima (ed.), Pediatric Digestive Surgery, DOI 10.1007/978-3-319-40525-4_27
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the catheter is left in place for 48 hours; 100 % if more than 72 hours. Some others believe this risk has been nowadays reduced by the Table 27.1 Hepatocellular diseases leading to portal hypertension Biliary atresia Postinfectious cirrhosis Congenital hepatic fibrosis Congenital disorders of bile acid metabolism Sclerosing cholangitis Autoimmune hepatitis Drug toxicity Metabolic diseases (e.g., alpha-1 antitrypsin deficiency)
improvement of catheters’ materials. However the principle is that this kind of venous line must be taken into consideration only if extremely needed. • Portal vein congenital stenosis/atresia (Fig. 27.2a) or postnatal fibrotic stenosis (Fig. 27.2b). The latter is due to abnormal spr
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