Diagnosis, management & treatment of portosystemic shunts: a team approach


Diagnosis of Portosystemic Shunts

Methods described for the imaging of congenital portosystemic shunts include ultrasonography, magnetic resonance angiography (MRA), computed tomography angiography (CTA), findings on intra-operative mesenteric portovenography (IOMP) direct gross observations at surgery and the examination of corrosion casts made post mortem. Using these imaging techniques it has proved possible to classify congenital portosystemic shunts (PSS) as either intrahepatic (left, right or central divisional) or with further sub-classification of extrahepatic portosystemic shunts dependent on which portal vessel they leave and which systemic vein they enter. The mainstay of imaging shunts (ultrasound) has been largely superseded by CTA. IOMP remains important.

Key learning objective:

1. Choose the most appropriate imaging modality, devise the best approach to imaging and how to best acquire a diagnosis.

Surgical Treatment of Portosystemic Shunts

Congenital portosystemic shunts; being intrahepatic or extrahepatic can be completely or partially ligated with nonabsorbable sutures or gradually attenuated with an ameroid constrictor, thin film banding, or hydraulic occluder. Interventional procedures can also be used especially with intrahepatic portosystemic shunts. Gradual attenuation is preferred to reduce the risk of postoperative complications, which if occur can be life threatening. In the last published papers compering ameroid ring with thin film banding it was concluded that residual shunting and subsequently revision surgery was more common when thin film banding was used, but both treatments achieved favorable long-term outcomes with minimum morbidity and mortality.

Key learning objective:

1. Deciding which treatment option can be a bit confusing as there are many treatment options. The aim is to discuss these options and decide which is the best one for our practice.

Medical and Interventional Management

The diagnosis of a portosystemic shunts relies on recognizing the various clinical signs associated with the condition, detecting the common abnormalities present on routine haematology, biochemistry and urinalysis alongside the interpretation of specific liver function tests. Following the diagnosis of a portosystemic shunt medical management should be instigated prior to considering surgical or interventional approaches. Both emergency management of the acutely encephalopathic patient and the chronic medical management (both dietary and pharmacological) will be debated. Interventional Radiology provides a new, minimally invasive option for treating intrahepatic portosystemic shunts in both dogs and cats. The technique, advantages and disadvantages of these approaches will be discussed and its comparison to traditional surgery debated.

Key learning objectives:

1. Develop a logical approach to the diagnosis of a suspected portosystemic shunt

2. Understand the rational for commonly used medical and dietary management

3. Develop an understating of new, minimally invasive options for treating portosystemic shunts in companion animals

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