Canis ISSN: 2398-2942

Interventional radiology: intrahepatic portosystemic shunt

Synonym(s): IR treatment of portosystemic shunting

Contributor(s): Ivan Doran, Zoe Halfacree

Introduction

  • Interventional radiology (IR) encompasses a range of minimally invasive diagnostic and therapeutic techniques.
  • Access is gained through incision into the vascular system.
  • A combination of guide wires and catheters is used to reach the required location in the body, guided most commonly by fluoroscopic imaging.
  • Contrast agents, medications or embolization devices can then be delivered to the site through these catheters. A range of stents can also be deployed using stent-delivery catheters.

Uses

  • Common non-vascular applications in veterinary medicine include tracheal stent delivery to manage tracheal collapse Trachea: collapse and ureteral stent insertion to address ureteral obstruction. Percutaneous nephrostomy tube placement and subcutaneous ureteral bypass are becoming more common. Stenting of esophageal, colorectal and urethral strictures is also described.
  • Veterinary vascular applications include treatment of patent ductus arteriosus Patent ductus arteriosus and attenuation of portosystemic shunts Congenital portosystemic shunt: attenuation. Embolization of hepatic arteriovenous fistulation is also reported.
  • This article will describe interventional radiological treatment of intrahepatic portosystemic shunts (IHPSS).

Advantages

  • IR treatment of IHPSS offers various advantages over traditional surgical intervention:
    • Heat losses are markedly reduced by avoiding opening a body cavity.
    • The morbidity of a laparotomy Laparotomy: midline incision is obviated and the consequent need for analgesia is similarly minimized.
    • There is a risk of hemorrhage during dissection around the IHPSS with traditional surgical approaches and this is greatly reduced through the use of IR although vessel perforation with a catheter or delayed hemorrhage from the vascular access site can occasionally occur.

Disadvantages

  • IR treatment of IHPSS can carry disadvantages:
    • The equipment is expensive; both the imaging equipment and the consumables.
    • The techniques involved are different from traditional surgical approaches and require the operator to have specific training in IR procedures.
    • Thromboembolization coil delivery is irreversible and the introduction of too many coils results in portal hypertension which may be difficult or impossible to successfully treat (the tension of ligatures or cellophane bands can be more precisely gauged during surgery and adjusted if portal hypertension results).
    • Clotting responses vary between dogs and, whilst coagulation profiles or thromboelastography Thromboelastography (TEG) are typically measured preoperatively, this contributes to the variability in response which individuals exhibit to coil delivery. The differing sizes of IHPSS and the varying capacities of animals' hepatic vascular beds are other factors which promote variability in response between individuals and these considerations are common to both IR and traditional surgical interventions.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Limited data to date. In the largest study reported, 66% of cases were weaned off all medication and prescription diets long term without return of clinical signs. The same study reported 15% of cases with resolution of clinical signs as long as medication and prescription diets were continued and finally 19% with unimproved or worsening clinical signs.
  • Severe post-operative neurologic changes have been reported in 6% of cases following IR attenuation and in 5 -18% of dogs following traditional attenuation methods but no study has directly compared these two methods.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Weisse C, Berent A C, Todd K et al (2014) Endovascular evaluation and treatment of intrahepatic portosystemic shunts in dogs: 100 cases (2001-2011). JAVMA 244 (1), 78-94 PubMed.
  • Hogan D F, Benitez M E, Parnell N K et al (2010) Intravascular occlusion for the correction of extrahepatic portosystemic shunts in dogs. JVIM 24 (5), 1048-1054 PubMed.
  • Bussadori R, Bussadori C, Millán L et al (2008) Transvenous coil embolisation for the treatment of single congenital portosystemic shunts in six dogs. Vet J 176 (2), 221-226 PubMed.
  • Frankel D, Seim H, MacPhail C et al (2006) Evaluation of cellophane banding with and without intraoperative attenuation for treatment of congenital extrahepatic portosystemic shunts in dogs. JAVMA 228 (9), 1355-1360 PubMed.
  • Kummeling A, Teske E, Rothuizen J et al (2006) Coagulation profiles in dogs with congenital portosystemic shunts before and after surgical attenuation. JVIM 20 (6), 1319-1326 PubMed.
  • Asano K, Watari T, Kuwabara M et al (2003) Successful treatment by percutaneous transvenous coil embolization in a small-breed dog with intrahepatic portosystemic shunt. J Vet Med Sci 65 (11), 1269-1272 PubMed.
  • Léveillé R, Johnson S E & Birchard S J (2003) Transvenous coil embolization of portosystemic shunt in dogs. Vet Radiol Ultra 44 (1), 32-36 PubMed.
  • Yool D A, Kirby B M (2003) Neurological dysfunction in three dogs and one cat following attenuation of intrahepatic portosystemic shunts. J Small Anim Pract 43 (4), 171-176 PubMed.
  • Papazoglou L G, Monnet E & Seim H B 3rd (2002) Survival and prognostic indicators for dogs with intrahepatic portosystemic shunts: 32 cases (1990-2000). Vet Surg 31 (6), 561-570 PubMed.
  • Gonzalo-Orden J M, Altónaga J R, Costilla S et al (2000) Transvenous coil embolization of an intrahepatic portosystemic shunt in a dog. Vet Radiol Ultrasound 41 (6), 516-518 PubMed.
  • White R N, Burton C A & McEvoy F J (1998) Surgical treatment of intrahepatic portosystemic shunts in 45 dogs. Vet Rec 142 (14), 358-365 PubMed.
  • Hunt G B, Bellenger C R & Pearson M R (1996) Transportal approach for attenuating intrahepatic portosystemic shunts in dogs. Vet Surg 25 (4), 300-308 PubMed.
  • Hottinger H A, Walshaw R & Hauptman J G (1995) Long-Term Results of Complete and Partial Ligation of Congenital Portosystemic Shunts in Dogs. Vet Surg 24 (4), 331-336 PubMed.
  • Swalec K M & Smeak D D (1990) Partial Versus Complete Attenuation of Single Portosystemic Shunts. Vet Surg 19 (6), 406-411 PubMed.


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