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Congenital portosystemic shunt: attenuation

ISSN 2398-2950

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Synonym(s): Postosytemic shunt ligation

Introduction

  • Surgery to attenuate congenital portosystemic shunt (CPSS) aims to restore normal blood flow to the liver and hence resolve clinical signs associated with functional hepatic insufficiency.
  • A variety of techniques can be employed to achieve CPSS attenuation:
    • Suture attenuation.
    • Ameroid constrictor placement.
    • Cellophane band.
    • Coil embolization (interventional radiology).
  • Complete attentuation of the CPSS either acutely or using a technique that achieves gradual attenuation is preferable.
    Should not be attempted in practice - refer for surgery.

Uses

Aims of surgery

  • Identify abnormal vessel and confirm diagnosis.
  • Provide acute or gradual attenuation of CPSS to redirect portal blood flow to liver.
  • Resolve clinical signs and hepatic insufficiency.
  • Liver biopsy to confirm diagnosis and rule out concurrent disease processes.

Advantages

  • Attenuation associated with an improvement in or resolution of clinical signs.
  • Successful surgery obviates the need for long term medical management, which is attractive to many owners for reasons of convenience and finance.
  • Surgery likely to provide better overall outcome than medical management alone, although there is little information on long term medical management in the cat.

Disadvantages

  • Complicated surgery - refer to a specialist.
  • Also requires specialist anesthesia and postoperative care.
  • Specialized equipment and facilities often required.
  • Significant postoperative complications can occur.
  • Intrahepatic shunts are more challenging to treat surgically.

Alternative techniques

Medical management

All cats should be stabilized with medical management prior to undergoing surgery.

  • Can be used for long term management if surgery not possible.

Interventional radiology

  • The use of interventional radiology to attenuate a CPSS via coil embolization has been reported in one cat with an intrahepatic shunt.
  • Interventional radiology is minimally invasive and may be particularly useful for intrahepatic CPSS that would be challenging to approach surgically.
  • It is likely that this technique will become more commonly used in cats in the future.

Decision taking

Criteria for choosing test

  • Several techniques have been recommended for the surgical attenuation of CPSS in cats:
    • Partial or complete suture attenuation.
    • Gradual attenuation with an ameroid constrictor Congenital portosystemic shunt: ameroid constrictor .
    • Gradual attenuation with a cellophane band.
  • The evidence base for choosing between treatments in terms of short and long term outcome is very weak in cats. Many surgeons prefer a gradual attenuation technique such as an ameroid constrictor or cellophane band as these typically require less intensive intra-operative and postoperative monitoring and may reduce surgery time.
  • Variation in surgeon preference for different techniques.
  • Suture attenuation:
    • Complete versus partial attenuation of the CPSS is determined on the basis of intra-operative assessment of portal hypertension.
    • Complete attenuation associated with a better long term outcome than partial.
    • Some surgeons recommend repeat surgery 2-3 months following partial attenuation to allow complete attenuation. This is possible in the majority of cats.
    • Suture ligation guarantees complete CPSS attenuation in cats that can tolerate this (rather than relying on a gradual method).
  • Ameroid constrictors:
    • Consist of a ring of casein with a lumen surrounded by a stainless steel collar. The ring is placed around the vessel and closed with a small casein key.
    • The casein gradually absorbs fluid and expands, narrowing the lumen. This narrowing in combination with thrombosis results in gradual occlusion of the CPSS.
    • Constrictors gradually attenuate the CPSS over 2 or more weeks.
  • Cellophane band:
    • Strip of folded cellophane is placed around the CPSS and secured with surgical clips.
    • The band can either be placed loosely or with some degree of attenuation.
    • The cellophane band causes a fibrous reaction and gradual attenuation of the CPSS over a period of weeks.
  • Intrahepatic CPSS:
    • Typically more challenging to approach surgically and may require hepatic dissection.
    • Should be referred to experienced surgeons.
    • In some instances suture attenuation is preferred over ameroid constrictor, cellophane band or hydraulic occluder placement as complex dissection may make these devices hard to place.

Requirements

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Preparation

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Technique

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Cabassu J, Seim H B 3rd, Macphail C M et al (2011) Outcomes of cats undergoing surgical attenuation of congenital extrahepatic portosystemic shunts through cellophane banding: 9 cases (2000-2007). JAVMA 238 (1), 89-93 PubMed.
  • Tivers M & Lipscomb V (2011) Congenital portosystemic shunts in cats. Investigation, diagnosis and stabilisation. J Fel Med Surg 13 (3), 173-184 PubMed.
  • Tivers M & Lipscomb V (2011) Congenital portosystemic shunts in cats. Surgical management and prognosis. J Fel Med Surg 13 (3), 185-194 PubMed.
  • Lipscomb V J, Lee K C, Lamb C R et al (2009) Association of mesenteric portovenographic findings with outcome in cats receiving surgical treatment for single congenital portosystemic shunts. JAVMA 234 (2), 221-228 PubMed.
  • Lipscomb V J, Jones H J & Brockman D J (2007) Complications and long-term outcomes of the ligation of congenital portosystemic shunts in 49 cats. Vet Rec 160 (14), 465-470 PubMed.
  • Hunt G B, Kummeling A, Tisdall P L et al (2004) Outcomes of cellophane banding for congenital portosystemic shunts in 106 dogs and 5 cats. Vet Surg 33 (1), 25-31 PubMed.
  • Havig M & Tobias K M (2002) Outcome of ameroid constrictor occlusion of single congenital extrahepatic portosystemic shunts in cats: 12 cases (1993-2000). JAVMA 220 (3), 337-341 PubMed.
  • Kyles A E, Hardie E M, Mehl M et al (2002) Evaluation of ameroid ring constrictors for the management of single extrahepatic portosystemic shunts in cats: 23 cases (1996-2001). JAVMA 220 (9), 1341-1347 PubMed.
  • Tillson D M & Winkler J T (2002) Diagnosis and treatment of portosystemic shunts in the cat. Vet Clin North Am Small Animal Pract 32 (4), 881-899 PubMed.
  • Weisse C, Schwartz K, Stronger R et al (2002) Transjugular coil embolization of an intrahepatic portosystemic shunt in a cat. JAVMA 221 (9), 1287-1291 PubMed.
  • White R N & Burton C A (2001) Anatomy of the patent ductus venosus in the cat. J Feline Med Surg (4), 229-233 PubMed.
  • Wolschrijn C F, Mahapokai W, Rothuizen J et al (2000) Gauged attenuation of congenital portosystemic shunts: Results in 160 dogs and 15 cats. Vet Q 22 (2), 94-98 PubMed.
  • Vogt J C, Krahwinkel D J Jr., Bright R M et al (1996) Gradual occlusion of extrahepatic portosystemic shunts in dogs and cats using the ameroid constrictor. Vet Surg 25 (6), 495-502 PubMed.
  • White R N, Forster van Hijfte M A, Petrie G et al (1996) Surgical treatment of intrahepatic portosystemic shunts in six cats. Vet Rec 139 (13)314-317 PubMed.
  • VanGundy T E, Boothe H W & Wolf A (1990) Results of Surgical Management of Feline Portosystemic Shunts. JAVMA 26 (1), 55-62 VetMedResource.
  • Blaxter A C, Holt P E, Pearson G R et al (1988) Congenital Portosystemic Shunts in the Cat - a Report of 9 Cases. JSAP 29 (10), 631-645 Wiley Online Library.