Page 597 - WSAVA2018
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and right divisional shunt. The central divisional anomalous vessel is the most difficult to trace due to its short length. Both left and right divisional anomalous vessels are wide and tortuous.
There are many types of extrahepatic anomalous shunt vessel. The most commonly seen are splenoazygus, splenocaval and splenophrenic. Less commonly seen anomalous shunt are splenocaval, right gastric-caval, double right gastric-caval, double right gastric-azygus. The presence of extra blood vessel(s) adjacent to the aorta making splenoazygus shunt readily recognized with both intercostal and subcostal approaches. However, due to the long and tortuous nature of the anomalous vessel, it is not easy to trace the entire vessel back to the splenic vein. Anomalous splenocaval shunt vessel is normally short and could be trace at the region of the portal hepatis. Due to the cranial position of the anomalous splenophrenic shunt vessel adjacent to the diaphragm, this type of shunt vessel is more challenging to visualize due to movement of the diaphragm secondary to respiration.
Acquired shunt is normally secondary to portal hypertension, and multiple shunt vessels or varices are present. Most of the time, these varices are short, small in diameter and tortuous. They are commonly located cranial to the left kidney or at the region of the splenic vein. Esophageal varices has been reported. Whenever, there is suspicious or confirmation of an acquired
shunt, measure of portal blood flow velocity should be performed. Normal portal blood flow velocity is between 10-25 cm/sec. Any patients with portal blood flow velocity of <10cm/sec has higher probability of developing acquired extrahepatic shunts.
Computed tomography has become the imaging modality of choice for most clinician nowadays. This
is because it is not invasive and the detail anatomy of the anomalous blood vessels could be outline with
post procession 3D reconstruction. The information of diameter, length and the actual insertion of the shunt vessel could be acquired from the CT study. Computed tomography normally is fast (less than 10 minutes), and with 64 slice machines, occasionally this study could be performed under heavy sedation. The only disadvantage of this is the intrahepatic portal veins may not be identified.
The ultimate choice of modalities/technique used in the investigation of anomalous vessels is again depending on the patient preparation, available of equipmentsand also the operator experience and preference. Recently, the clinician/surgeon’ preference has become a deciding factor of the choice of the techniques. Some surgeons want to know the distant between the portal hepatis and the anomalous vessel, the size and length of the anomalous vessel and also the exact connection point of the anomalous vessel for surgical planning. A
3 D reconstruction of the anomalous vessel is always requested by surgeons prior to surgical correction.
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