PORTAL HYPERTENSION

Portal hypertension (PHT) is defined as 'elevation of portal venous pressure gt;12 mm Hg, due to hepatic or extra­hepatic obstruction in portal blood flow'.

Portal vein is formed by joining of splenic and superior mesenteric veins and carries most of the gastrointestinal blood flow to liver for further metabolism of absorbed nutrients.

Etiologically, PHT may be broadly classified as—(a) pre- hepatic or extra-hepatic, (b) hepatic, and (c) post-hepatic or post-sinusoidal obstruction (Table 15.12). Extrahepatic PHT accounts for ~75% cases in Indian children. Umbilical sepsis or cannulation in neonatal period is the commonest cause of extrahepatic PHT.

Pathogenesis: Irrespective of etiology, primary hemo­dynamic abnormality in PHT is the obstruction in portal blood flow, leading to:

a. Development of collateral flow (porto-caval shunts), e.g. esophageal varices, rectal hemorrhoids or periumblical caput medussae.

b. Chronic hepatic ischemia, with compromised liver functions.

TABLE 15.12: Causes of portal hypertension

• Pre-hepatic or extrahepatic

- Umblical sepsis/cannulation in newborns

- Dehydration/septicemia in early infancy

- Acute peritonitis in older children

- Hypercoagulable states: Protein C or S deficiency

- Portal vein malformations, e.g. AV fistula

• Intra-hepatic (Chronic liver disease)

- Congenital hepatic fibrosis

- Chronic viral/autoimmune hepatitis

- Cirrhosis

- Metabolic disorders, e.g. Wilson disease

- Hepatic tumors

- Cholestasis, e.g. total parenteral nutrition

• Post-hepatic or post-sinusoidal

- Budd-Chiari syndrome

- Veno-occlusive disease of liver

- Constrictive pericarditis

c. Cavernous transformation of portal vein (acquired portal cavernoma).

Clinical features of PHT depend on the site of obs­truction, severity of portal pressure and extent of collateral flow.

• Recurrent GIT bleeding as hematemesis or melena is the common, originating from esophageal varices. Hemorrhoids are uncommon in children. Hematemesis may be preceded by mild respiratory infections and cough (increase in intra-abdominal pressure) or drug intake, e.g. salicylates.

• Dilated periumbilical veins (caput medussae) with blood flow away from umbilicus, i.e. reversal of normal direction. Engorged veins with upward flow in abdominal flanks indicate inferior vena cava obstruction in post-hepatic PHT.

• Splenomegaly with/without hypersplenism is invari­ably present, though the size may reduce temporarily after GIT hemorrhage.

• Signs of chronic liver disease, e.g. ascites, icterus, hypo­proteinemic edema and spider nevi, etc. are common in hepatic/post hepatic PHT, but not in extrahepatic PHT.

• Hepatic encephalopathy may develop after severe GIT bleeds due to further compromise of hepatic blood flow, though uncommon in extrahepatic PHT.

• Secondary complications, e.g. anemia, shock are often present, immediately after severe bleeds.

Important clinical differences between various types of PHT are summarized in Table 15.13.

Diagnostic investigations in PHT include:

• Ultrasonography to confirm the site of obstruction, estimate portal vein size, and visualize esophageal varices. Doppler flow studies may demonstrate reversed blood flow in portal circulation.

TABLE 15.13: D/D portal hypertension

investigation

*or umblical cannulation, **S#8725;o Inferior vena caval obstruction.

***in acute cases

• Liver function tests including coagulation profile in all cases, even in absence of clinical signs, to assess baseline liver functions.

• Endoscopic visualization of esophageal varices in all cases at the time of diagnosis, which may ligated at the same time.

• Contrast studies: IVC venogram is indicated in unexplained post hepatic PHT, e.g.

Management of PHT depends on the clinical state at the time of presentation and includes—(a) emergency hemodynamic support, (b) control of active bleeding, and (c) prevention of further bleeding.

• Emergency hemodynamic support includes: (a) fluid and electrolyte correction, (b) blood transfusion in severe anemia, (c) vitamin K supplements, (d) continuous nasogastric drainage to detect and quantify further bleeding, and (e) H₂ receptor antagonists, e.g. ranitidine to reduce gastric bleeding.

• Control of active bleeding with endoscopic ligation of bleeding varices by elastic bands or sclerotherapy is the treatment of choice in active hematemesis, though subsequent endoscopies may be required to ligate#8725; sclerose all varices. Complications include infection, traumatic ulcerations and stricture formation in esophagus.

Following emergency medical measures may be useful, if endoscopic facility is not available:

- Splanchnic vasoconstrictors to reduce portal flow and pressure, with Octreotide, (IV 1-10 #956;g#8725;kg Q12hr) or Vasopressin (IV 0.33 U/kg bolus over 20 min followed by 0.2 U/1.73 m²/min), till bleeding is controlled.

- Sengstaken-Blackmore tube, passed nasogastrically to apply mechanical pressure over bleeding varices. However, re-bleeding after removal and pulmonary aspiration is common.

• Prevention of further bleeding: Ligation of esophageal varices and periodic follow-up is usually enough for most cases. However, selected cases may require portacaval shunts and treatment of primary cause, including liver transplants.

Portacaval shunts, e.g. proximal linorenal shunt, are indicated in severe PHT with recurrent bleeding to reduce portal venous pressure. However, shunt­thrombosis and further hepatic ischemia with acute liver failure are common.

Long-term therapy with-blockers, e.g. propranolol (PO 1-2 mg#8725;kg#8725; d) may also reduce the risk of variceal bleeding and improve survival.

Prognosis is poor in cases with hepatic disease. In extrahepatic PHT, frequency of bleeding often reduces with age due to development of collaterals and most patients can be successfully managed with periodic variceal ligation/sclerotherapy.

Important late complications of PHT include hepatorenal syndrome (Ch 15.8) or Porto-pulmonary syndrome, i.e. pulmonary artrerial hypertension gt; 25 mmHg with severe PHT, usually following cirrhosis.

Budd-Chiari syndrome (BCS) due to occlusion of hepatic veins or suprahepatic inferior vena cava due to intraluminal thrombus or web (primary BCS) or extraluminal pressure, e.g. tumors, is an important cause of post-hepatic PHT.

While most patients have insidious course with hepatomegaly, ascites and PHT, acute BCS presents with abdominal pain, tender hepatomegaly and rapidly progressive liver failure with ascites. Back and flank veins are dilated and tortuous, with flow from below- upward.

Diagnosis may be confirmed by Doppler studies and venography.

Treatment requires restoration of venous patency by stenting or transjugular intrahepatic porto-systemic shunt. Surgery is rarely required, though terminal cases may need liver transplant.

BIBLIOGRAPHY

Ganguli S et al. Viral hepatitis. Standard treatment guidelines. Indian Academy of Pediatrics. 2022.

Yadav SR et al. Hepatitis C: Current state of treatment in children. Pediatr Clin North Am. 2021;68(6):1321.

Poddar U et al. Management of hepatitis C in children - A new paradigm. Indian Pediatr. 2023;60:56.

Mishra S et al. Diagnosis and management of pediatric acute liver failure: ESPGHAN and NASPGHAN 2022 Indian Pediatr. 2022;59:307.

Basavaraja GV et al. Acute gastrointestinal bleed standard treatment guidelines. Indian Academy of Pediatrics. 2022.