Portosystemic shunt

A porto-systemic shunt or porta-systemic shunt (medical subject heading term) (PSS), also known as a liver shunt, is a bypass of the liver by the body's circulatory system. It can be either a congenital (present at birth) or acquired condition and occurs in humans as well as in other species of animals. Congenital PSS are extremely rare in humans but are relatively common in dogs.[1] Thus, a large part of medical and scientific literature on the subject is grounded in veterinary medicine.

Background

In normal condition, the blood leaving the intestines reaches the liver through the portal vein. The liver filters this nutrient –rich blood before it reaches the rest of the body. Congenital portosystemic shunts are vascular malformations, which cause blood to bypass the liver. As a result, blood flows directly to the heart.

Congenital porto-systemic shunts (CPSS) are developmental in origin: they arise in utero. This is in contrast to secondary shunts which develop in the setting or portal hypertension.[2]

Epidemiology and classification

CPSS are thought to affect 1 in 30 000-50 000 live births. While most patients present with a single shunt, complex shunts, which include multiple abnormal vessels, are also reported.[2][3]

Congenital porto-systemic shunts (CPSS) are classified into two categories according to the site of the shunt. Intrahepatic shunts are located between a portal branch and a hepatic vein, while extrahepatic shunts define abnormal connections between mesenteric or portal veins outside the liver and either a systemic vein or the vena cava. The clinical manifestations of intra- and extra- hepatic portal systemic shunts can be similar.

Physiopathology

In physiological conditions, there are no direct communications between the portal and hepatic veins within the liver, nor between the systemic veins and the portal, superior mesenteric or splenic veins.[4] Two distinct systems provide the liver with blood. Oxygen rich blood is sent to the liver from the heart via the hepatic artery, while the portal vein brings nutrient rich (but depleted in oxygen) blood to the liver from the intestines. This blood passes by the network of capillaries before being evacuated by the hepatic veins into the inferior vena cava and subsequently the heart. The division between these two systems helps assure the liver's physiological roles.

A CPSS results in a direct communication between the portal circulation and the systemic circulation. This breaks down the separation between these two systems which is crucial in ensuring normal physiological function. A reduction in the proportion of blood flowing from the digestive system to the liver during the first pass reduces filtration and an accumulation of toxins in the blood circulatory system occurs.[5]

Clinical Manifestations

The size of the liver in patients affected by PSS is typically 45% to 65% of the standard volume for a given age.[2] Liver tumors, hepatopulmonary syndrome, pulmonary hypertension and encephalopathy are common clinical manifestations of CPSS in both adults and children.[2] In adults, the discovery of a CPSS is often fortuitous but can also occur in response to the work up for one of these clinical manifestations. These complications are generally induced by long-term portosystemic derivations and are more commonly observed in children than in adults.[3] Unexplained neurocognitive dysfunction and other behavioral issues linked to hepatic encephalopathy occur in 17% to 30% of cases.[4] In children, CPSS may present as neonatal cholestasis. Several other signs and symptoms have been reported in the setting of CPSS. These include hyperandrogenism, vaginal bleeding, haematuria, GI bleeding, and pancreatitis.[6]

Treatment

Spontaneous closure of CPSS can ocur in some anatomic forms during the first two years of life.[7][8][9] Most commonly spontaneous closure does not occur. Given the risk of severe systemic complications, it is generally agreed amongst specialists that the majority of CPSSs should be closed by radiological or surgical intervention.[5][10] Shunt closure prevents the development of complications in pre-symptomatic subjects and may reverse or stabilize signs and symptoms in symptomatic patients.

On-going research

The International Registry of Porto-Systemic Shunts (IRCPSS) has been developed to further the understanding of CPSS. The primary aim of the registry is to "better identify patients who are at risk of developing complications and to offer them standardized care."  Information for patients and professionals is available at IRCPSS

See also

References
  1. Alonso-Gamarra, Eduardo; Parrón, Manuel; Pérez, Ana; Prieto, Consuelo; Hierro, Loreto; López-Santamaría, Manuel (2011-05-01). "Clinical and Radiologic Manifestations of Congenital Extrahepatic Portosystemic Shunts: A Comprehensive Review". RadioGraphics. 31 (3): 707–722. doi:10.1148/rg.313105070. ISSN 0271-5333. PMID 21571652.
  2. Bernard, O.; Franchi-Abella, S.; Branchereau, S.; Pariente, D.; Gauthier, F.; Jacquemin, E. (November 2012). "Congenital Portosystemic Shunts in Children: Recognition, Evaluation, and Management". Seminars in Liver Disease. 32 (4): 273–287. doi:10.1055/s-0032-1329896. ISSN 0272-8087. PMID 23397528.
  3. Papamichail, M.; Pizanias, M.; Heaton, N. (2018-03-01). "Congenital portosystemic venous shunt". European Journal of Pediatrics. 177 (3): 285–294. doi:10.1007/s00431-017-3058-x. ISSN 1432-1076. PMC 5816775. PMID 29243189.
  4. Stringer, Mark D. (2008). "The clinical anatomy of congenital portosystemic venous shunts". Clinical Anatomy. 21 (2): 147–157. doi:10.1002/ca.20574. ISSN 1098-2353. PMID 18161055. S2CID 42632424.
  5. "Interview d'Amaria Remil, Cheffe de projet du Centre de Référence AVB-CG, et du Pr Stéphanie Franchi-Abella, Responsable du secteur de radiologie interventionnelle pédiatrique (Université Paris-Saclay)". Filfoie: tout savoir sur les maladies rares du foie, recherche, enseignement (in French). 2020-12-17. Retrieved 2021-07-28.
  6. Bahadori, Atessa; Kuhlmann, Beatrice; Debray, Dominique; Franchi-Abella, Stephanie; Wacker, Julie; Beghetti, Maurice; Wildhaber, Barbara E.; McLin, Valérie Anne; On Behalf Of The Ircpss, null (2022-02-11). "Presentation of Congenital Portosystemic Shunts in Children". Children. 9 (2): 243. doi:10.3390/children9020243. ISSN 2227-9067. PMC 8870378. PMID 35204963.
  7. the International Registry of Congenital Portosystemic Shunt members; Franchi-Abella, Stéphanie; Gonzales, Emmanuel; Ackermann, Oanez; Branchereau, Sophie; Pariente, Danièle; Guérin, Florent (August 2018). "Congenital portosystemic shunts: diagnosis and treatment". Abdominal Radiology. 43 (8): 2023–2036. doi:10.1007/s00261-018-1619-8. ISSN 2366-004X. PMID 29730740. S2CID 19116849.
  8. McLin, Valérie; Franchi-Abella, S.; Debray, D.; Korff, S.; Casotti V; Colledan, M.; d'Antiga, L.; de Ville de Goyet, J.; Lurz, E.; Stéphenne, Xavier; Rock, Nathalie (2019). "Congenital porto-systemic shunts in children: preliminary results from the IRCPSS". {{cite journal}}: Cite journal requires |journal= (help)
  9. McLin, Valérie A.; Franchi Abella, Stephanie; Debray, Dominique; Guérin, Florent; Beghetti, Maurice; Savale, Laurent; Wildhaber, Barbara E.; Gonzales, Emmanuel; Members of the International Registry of Congenital Porto-Systemic Shunts (May 2019). "Congenital Portosystemic Shunts: Current Diagnosis and Management". Journal of Pediatric Gastroenterology and Nutrition. 68 (5): 615–622. doi:10.1097/MPG.0000000000002263. ISSN 1536-4801. PMID 30628988.
  10. "Oral Abstracts (Abstracts 1–288)". Hepatology. 70 (S1): 1–187. October 2019. doi:10.1002/hep.30940. ISSN 0270-9139. S2CID 242005271.
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