Clinical Features of CHF
Some definitions: Congenital-meaning inherited, predetermined or present at birth, Hepatic-pertaining to the liver (medical management determined by GI specialists/hematologists), and fibrosis- formation of fibrotic tissue or scarring.
CHF is malformation of the bile ducts and surrounding tissue that is also referred to as Ductal Plate Malformation. This malformation is associated with biliary ectasia (bile duct dilatation) and scarring of the liver in the portal tracts (which carry blood to the liver and bile away from the liver). It is uncommon for a person to have CHF without ARPKD. However, if a person has ARPKD they always have some degree of CHF. The inherited genetic defect affecting the kidneys and liver is the same. CHF has a highly variable clinical course and there are no guidelines that predict the prognosis. Symptom presentation and severity varies greatly, from microscopic biopsy detection to severe clinical liver manifestations with complications.
The liver may be normal or enlarged in size. By ultrasound it is usually echogenic or coarse in appearance. Dilated intrahepatic biliary ducts, decreased visualization of peripheral portal veins or hypoplasia of the portal vein may be noted even in the neonate. As fibrosis progresses, hepatosplenomegaly (enlarged liver and spleen) develops along with ultrasound findings of patchy echogenicity.
The portal vein, which carries large amounts of blood to and through the liver, and the bile ducts, which carry bile away from the liver are both part of the “plumbing system”. They normally have unrestricted flow. Usually bile ducts are thin and hair-like in shape. In CHF, it is thought that fetal maturation of the portal tract and bile ducts is incomplete which results in an abnormal, bizarre configuration, hence ductal plate malformation. For some reason these areas fill with scar tissue (fibrosis) creating blood flow resistance and turbulence. This slows blood flow resulting in a “backup pressure” within the vessels that feed the portal vein. This backup pressure results in increased pressure in the portal vein (portal hypertension). When the blood flow obstruction is severe, blood flow may reverse, or may spontaneously by-pass (shunt past) the liver. These shunts manifest as swollen veins in the esophagus (esophageal varices), on the abdominal wall and around the rectum (hemorrhoids). Portal hypertension is different to high blood pressure that can be measured with a blood pressure machine.
Doppler flow studies showing blood flow towards the kidneys (hepatopetal) may exhibit less portal hypertension pressure then the reversal of portal blood flow. Magnetic Resonance Cholangiography (MRC) is an effective non-invasive diagnostic tool for evaluating portal hypertension and the biliary tree.
Liver function tests usually remain normal. Even for symptomatic individuals, synthetic liver function generally is preserved, as the liver usually continues to excrete, synthesize, and regulate hormones and chemicals normally. As a child ages, fibrosis tends to progress. Liver failure and liver transplantation are not common, although severe liver involvement sometimes requires shunting or transplantation.