INTRAHEPATIC SHUNTSJames Montgomery, DVM

March 30, 2009

Acc # 111557 & 111556

Acc#: 111557 Madeline 3 month old female basset hound Cystoliths Elevated liver enzymes Elevated bile acids Referred for evaluation of shunt

Acc#: 111557

Acc#: 111556

Acc#: 111557

Portal Vein Formed within the mesentery dorsal to the right

limb of the pancreas Confluence of cranial and caudal mesenteric

portal branches Receives blood from the GI tract and spleen

Mesenteric veins, gastroduodenal, splenic, and gastric veins

As approaches liver, sweeps from right to left and divides into right and left branches Main right branch – right lateral and caudate

process of caudate lobe Main left branch – all other lobes

Intrahepatic Shunts Almost all intrahepatic shunts occur in

large dogs Connect portal vein branches after their

divergence from the portal vein to the hepatic veins or abdominal vena cava, bypassing the hepatic sinusoids

Many intrahepatic shunts result from failure of the ductus venosus to close in infancy 65% are anatomically considered PDV

Divided into right, left, and central divisional shunts

Fetal Circulation

Dyce, Sack & Wensing, Textbook of Veterinary Anatomy, 2nd ed, p. 249.

Intrahepatic Shunts Right divisional shunts

Pass through either the caudate process of the caudate lobe or the right lateral lobe of the liver before entering the vena cava

Central divisional shunts Pass through either the right medial or

quadrate lobes before entering the vena cava Left divisional shunts

Pass through either the papillary process of the caudate lobe, the left lateral lobe or the medial lobe before entering the vena cava

Madeline1 2

3

Madeline

R

Miller’s Anatomy of the Dog, 3rd ed, p. 453.

Acc#: 111557

Treatment Often requires more than one surgery Surgical techniques described

Posthepatic left hepatic vein attenuation – no clinical effect

Posthepatic direct shunt ligation Intrahepatic direct shunt dissection and ligation with

ultrasound guidance Intravascular placement of embolisation coils Intraluminal closure of the shunt via the thoracic vena

cava Transportal closure of the shunt via portal venotomy

Direct attenuation of the PDV before it enters the venous ampulla is technically less demanding

Treatment The significant blood flow through large

intrahepatic shuts cannot be suddenly obstructed Life threatening portal hypertension would

develop Causes of intraoperative death

Intraoperative shock (hemorrhagic and septic), cardiac arrest, and portal hyper- and hypotension

Postoperative survival rates: 75-89% Peritonitis, portal vein thrombosis, and

portal hypertension are most common postoperative causes of death

Prognosis Predictors for postoperative

complications Low body weight (<10 kg) and

hypoproteinemia or hypoalbuminemia Shunt location had no effect on short or

long-term outcome Partially attenuated shunt survival rates

1 year – 60% 2 year – 55%

After 4 months, euthanasia due to failure to show clinical improvement was most common cause of death

References Mathews KG, Bunch SK. Vascular Liver

Diseases. In Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine, 6th ed (St. Louis, MO: Elsevier, 2005) pp. 1453-64.

White RN, Burton CA. Anatomy of the patent ductus venosus in the dog. Veterinary Record (2000) 146, 425-9.

Whiting PG, Peterson SL. Portosystemic shunts. In Slatter D, ed. Textbook of Small Animal Surgery, 2nd ed (Philadelphia, PA: WB Saunders Co., 1993) pp. 660-74.