Rex Shunt for Extrahepatic Portal Vein Obstruction in Children Christopher Harms MD SCH December 5th, 2013

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices HPI 11-year-old generally healthy girl vomited blood at home Repeat hematemesis in ED. EGD revealed variceal bleeding. Controlled with banding and octreotide. Iron deficient and tired. Good appetite.

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices PMH Full-term by normal vaginal delivery. Supernumerary digit attached to right thumb. Little vision in right eye. Congenitally absent right kidney. Historically enlarged spleen. Thrombocytopenia.

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices ROS Negative for jaundice, liver trauma, hypercoagulable disorders. Social/Family history Lives with family in Oregon Active in sports, particularly basketball Healthy 20-year-old sister and 16-year-old brother No family history of thromboembolic disease

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices Allergies Cephalosporins and penecillins: anaphylaxis. Latex Medications Losartan Prilosec Iron sulfate

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices Physical Exam 67.3 kg, 166.8 cm. (>97th percentile) AFVSS. 2/6 systolic ejection murmur at left 2nd intercostal space. No abnormality on ECHO Dec 2012. Mild ascites with shifting dullness. Spelnomegaly 4 cm below costal margin. Palpable liver edge. Electrolytes WNL. AST 25, ALT 21, alk phos 204 total bilirubin 1.6, albumin 3.1 WBC 2.4. HgB 9.3. Platelets 56. Normal factor VIII, homocysteine, positive ANA with negative antismooth muscle antibody, anti-DNA, low IgG. Negative Factor V Leiden. Weight and height unusual for condition!?!

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices Ultrasound 10/21 Cavernous transformation of the main portal vein with multiple collateral vessels. Spelnomegaly (21.9 cm). Moderate ascites. Gastroesophageal varices. CT abdomen with contrast 11/22 Evidence of portal hypertension, varices at the EG junction. Numerous small vessels seen in the expected location of the portal vein, suggesting cavernous transformation. Liver biopsy 11/22/2013 Normal hepatic architecture and connective tissue. Quiescent lobule, all PAS positive. Central veins patent without sclerosis.

Case Report: A.Y. 11-year-old girl with bleeding esophageal varices Impression Long-standing extrahepatic portal vein obstruction (EHPVO) with collateralization and progressive portal hypertension. Potential complications: GI bleeding, bile duct compression, exudative enteropathy, hypersplenism, Plan Meso-Rex shunt Graft options: left internal jugular, inferior mesenteric, gonadal, coronary Contraindication: occlusion of left portal vein Other options: splenorenal shunt, mesocaval shunt Advantages: promotes physiologic hepatopetal flow. Decreases splenomegaly. Portal Venous Hypertension >5mmHg difference between portal venous system and IVC (Bleeding >12 mmHg) Extraheptaic Portal vein obstruction (EHPVO) Forward hepatopetal flow from the SMV, spelnic, and coronary veins is impeded by a relative or complete obstruction of the portal vein Results in cavernous transformation of portal vein Second most common cause of portal hypertension in western world. (MC in asia) Associated with umbilical venous line placement Presents with unanticipated variceal bleeding or increasing splenomegaly With or w/o hypersplenism and thrombocytopenia Well-preserved liver histology and function Mild coag and encephalopathy Secodnary to altered flow??? Other Benefits: enhances liver growth and function, somatic growth, improves encephalopathy Usually traditional shunt distal splenorenal shunt only one kidney = inappropriate mesocaval shunt higher risk of causing hyperammonemia.

Meso-Rex Bypass for extrahepatic portal vein obstruction (EHPVO) Meso-Rex shunt first described in 1992 and used to treat EHPVO in 1996 Insertion of splanchnic vein and the end of the intrahepatic portal vein into the Rex fossa Restores a physiologic portal inflow to the liver avoiding pulmonary hypertension, hepatic encephalopathy, portopulmonary syndrome, and liver nodules Curative in portopumonary syndrome whereas PSS can worsen Operative Steps Operative procedure: Dissection of ligamentum teres proximal to the distal portion of the left portal vein (Rex fossa) Surround portal branches to segments III and IV by slings and temporarily occluded Junction of umbilical remnant and left portal vein opened to assess patency If patent, an internal jugular veing graft or a synthetic polyfluroethylene graft was anastomosed end-to-end to the left portal branch of the Rex fossa Proximal shunt sutured to the SMV, splenic vein pancreaticoduodenal vein, or large vein of the cavernoma Note: Ligamentum teres divides left lobe into medial and lateral sections. Falciform ligament-derivative of ventral mesentery

Meso-Rex Bypass for extrahepatic portal vein obstruction (EHPVO) Rex recess Splanchnic circulation connected to left portal vein Good continuity between right and left lobes Called a shunt but more of a bypass as it restores normal liver physiology Anastomosis occurs at the Rex recess Located between segments III and IV at the adjunction between the round ligament and left portal vein Ideal location as it does not usually involve the many collaterals that occur in EHPVO Several variations exist

69 patients (median age 6.6 (4.0-10.6). Single-center retrospective study that compared Meso-Rex bypass (MRB) to portosystemic surgical shunt (PSS) in children with EHPVO between 1996 and 2010. Success defined as shunt patency after 6 months and free of varices and symptoms. 69 patients (median age 6.6 (4.0-10.6). 24 patients had a neonatal umbilical catheter. 47 patients had an upper GI bleed. Study in 2013 Inclusion criteria for surgery GI bleeding, grade II or III varices, hypersplenism or cholangiopathy caused by the cavernoma Imaging of splanchnic vascularture digital subtraction angiography of celiac and SMA. Difference between 2004 technique delayed imaging prior CTA after Assessment of intrahepatic portal vein done by mesenteric angiogrphy or non-invasive approaches (Doppler and CTA or MRA) ***until 2001!!!! vs wedged hepatic vein portography (2005-2010) EARLY defined as first 6 years Only a previous history of NUC predicted failure on multivariable anaylsis!!!!

60 percent success rate for MRBs versus 100 for PSS (P < 0.001) Of completed MRBs, 11 failed during surgery and four had persistent thrombosis. 60 percent success rate for MRBs versus 100 for PSS (P < 0.001) Lowest success rate in: patients whom had a NUC used (2 of 10 vs 24 of 33 P=0.004) procedures taken early in the series ( 6 of 16 versus 20 of 27 0.020) unfavorable imaging (0 of 5 versus 26 of 38 P = 0.006) ***PSS was performed in patients with non-patent left portal vein branch in the Rex fossa Jugular vein used in 40 out of 43 patients in which an MRB was attempted All 11 failures converted to PSS ___________________________________________ Postoperatively, patients received nonfractionated heparin bolus and 3 weeks of LMWH Patency assessed by ultrasoubnd

Wedged hepatic vein portography The imaging was classified as: Favorable if there was a patent left portal branch in the Rex fossa communicating with the right intraheptatic portal vein branch Unfavorable if patency of the Rex fossa was not seen, doubtful, or left and right intrahepatic branches did not communicate. Some surgeons attempted MRB in the latter group whereas others opted for a PSS procedure**** Of patients with favorable imaging: 8/10 with NUC failed 18/21 without NUC succeeded Wedged hepatic vein portography

Preoperative Imaging Absence of intrinsic liver disease Patent intrahepatic left portal vein measuring at least 2mm Contiguity of the right and left intrahepatic portions of the portal vein An adequate mesenteric vein The Children’s hospital of Philadelphia 2011

Preoperative Imaging - Ultrasound In some cases, an abdominal ultrasound with Doppler may be sufficient Observe the gallbladder closely for biliary tract abnormalities (increased) Best at assessing patency of IJV

Preoperative Imaging - Multidetector CT Best at depicting SMV and splenic vein Obscured by bowel gas on US Picture: White arrowhead – gastric varices Black arrowhead - Patent coronary vein Arrow (white) - Cavernous transformation of portal vein Splenomegaly

Preoperative Imaging – wedged hepatic venous portography Invasive Requires contrast (iodinated or carbon dioxide) Useful if portal system is hypoplastic or obscured by collaterals

Postoperative imaging: Doppler ultrasound Flow increases a few days after surgery Size of collaterals decreases Liver grows 1.3 – 1.7 times baseline one week after surgery Conversely, failure/thrombosis is represented by reappearance of collaterals at hilum, decreased flow, etc. Patent Rex bypass

Retrospective review by two radiologists 20 patients (9 m, 11 f, mean age 26). Includes all patients referred to the center between Nov 1998 and Nov 2008. Images ordered per surgeon discretion Unenhanced CT and MR excluded 57 Preoperative images total (median 3.0; 1.0-5.0) Measured diagnostic capability 2011 USCF study Preoperative imaging criteria: Patent intrahepatic left portal vein Suitable and patent superior mesenteric vein contiguity of the intrahepatic left and right PV (not strict requirement) Claim: no published study on capability prior to this one

Differences between results for PV patency (P = 0.39) “Table 1 summarizes the diagnostic capability, defined as the number of studies resulting in confident diagnosis of patency versus occlusion or contiguity versus non-contiguity divided by the number of studies which did not allow for confident diagnosis, for each modality.” Not all characteristics were evaluated during surgery in all patients * 9 patients received a Rex shunt Differences between results for PV patency (P = 0.39)

“Nine patients ultimately received a Rex shunt; there were no noted discrepancies between findings at surgery and the preoperative imaging findings. However, not all structures assessed with imaging were evaluated during surgery. In particular, PV contiguity was not assessed during surgery. Five underwent distalsplenorenal shunting per the preferences of the liver surgeon. Two patients received a liver transplant. Four patients have not undergone definitive surgical treatment.”

CT arterial portography Contrast-enhanc ed CT However, sometimes a picture is worth a thousand words… 64-year-old s/p liver transplant undergoing evaluation for a possible Rex shunt Contrast-Enhanced CT vs CT arterial portography CT arterial portography

Conclusions Meso-Rex shunt is a bypass that restores physiological hepatopetal flow Successful shunt construction is predicted by preoperative imaging; however, no current consensus exists about which imaging modality to order Though invasive, CT arterial portography may offer the best diagnostic capability Postoperatively, shunt patency may be followed by Doppler ultrasound

Questions?