Chapter 76C Distal splenorenal shunt

Background

The distal splenorenal shunt (DSRS) was developed by Warren and colleagues in 1967 to achieve selective variceal decompression to prevent recurrent variceal bleeding. Selective variceal decompression combines the benefit of a decompressive shunt to control bleeding with maintenance of portal hypertension and portal flow to the cirrhotic liver to help maintain liver function. The original, classic article on selective variceal decompression described the animal work leading up to the initial clinical data on DSRS (Warren et al, 1967). Proof of concept was shown in the animal studies and in the results of the first six patients in whom DSRS was performed. The unique prior experiences of Warren and Zeppa led to the evolution of this concept: Warren had seen that total shunts control variceal bleeding, but at the cost of liver failure, whereas Zeppa had seen devascularization procedures maintain portal perfusion, but at a cost of significant risk of rebleeding.

Over the next 4 decades, DSRS became the most widely used operation to control variceal bleeding, with a worldwide following (Orozco et al, 2007). The technique continued to evolve, with greater degrees of portal azygos disconnection improving its effectiveness (Henderson et al, 1989). However, in the 1990s, the evolution of improved endoscopic therapy with banding (see Chapter 75B), introduction of transjugular intrahepatic portosystemic shunting (TIPS; see Chapter 76E), and coming of age of liver transplantation (see Chapter 97A, Chapter 97B, Chapter 97C, Chapter 97D, Chapter 97E ) left few indications for shunt surgery for variceal bleeding (see Chapter 76A).

Indications for DSRS

The indications for DSRS have markedly diminished in the last decade, as other options have improved, and the available expertise of surgeons facile at performing DSRS has diminished. That said, DSRS remains a good option for the following patients:

• Patients with variceal bleeding refractory to endoscopic and pharmacologic therapy who have well-preserved and stable liver function

• Patients with portal hypertension and normal livers, such as those with portal vein thrombosis, who have refractory bleeding and a patent splenic vein

• Patients in some geographic locations, where there is only one chance to control bleeding, and they cannot return for the multiple visits required for management with endoscopy or TIPS

Patient Evaluation

Patients being considered for DSRS require full evaluation to define 1) gastroesophageal varices as the source of bleeding, 2) the cause of the portal hypertension, 3) status of liver function and damage, and 4) vascular anatomy. Evaluation for possible DSRS is only appropriate in patients on propranolol with documented recurrent variceal bleeding or persistent high-risk varices and who have had adequate endoscopic management. Accurate endoscopic evaluation is therefore the first step. In this context, these patients have had upper diagnostic and therapeutic endoscopy at the time of an acute variceal bleed, and follow-up endoscopy is aimed at therapeutic variceal obliteration. Prior to considering patients for DSRS, endoscopy should confirm persistent varices or portal hypertensive gastropathy.

The cause of portal hypertension for most patients in the United States and Europe with variceal bleeding is cirrhosis. In these patients, the first question to be addressed is whether the patient now or in the future is a candidate for liver transplantation. If the patient is likely to need a transplant in the next 1 to 2 years, surgical shunt is not indicated. If the patient has good liver function and is unlikely to need a transplant in the near future, DSRS may be a good option. Other etiologies of portal hypertension—portal vein thrombosis or noncirrhotic portal fibrosis, in which patients have normal liver function—need to be defined early in the evaluation, because the long-term prognosis depends on best prevention of variceal bleeding. Such patients may be candidates for DSRS earlier in their management.

Liver function is assessed from clinical findings and laboratory studies. Jaundice, ascites, and encephalopathy are the three clinical signs and symptoms of advanced liver disease and indicate that patients are not candidates for surgical decompression. Laboratory measurements of serum bilirubin, albumin, serum creatinine, and prothrombin time prolongation are the most useful studies to assess the status of cirrhosis. Combining the clinical and laboratory parameters to discern the Child-Turcotte-Pugh (CTP) class and/or Model for End-Stage Liver Disease (MELD) score gives an objective assessment of risk (Table 76C.1 and Box 76C.1).

Table 76C.1 Child-Turcotte-Pugh Classification

Box 76C.1 Model for End-Stage Liver Disease Score for Liver Disease Severity

Score = 0.957 × log_e creatinine (mg/dL) + 0.378 × log_e bilirubin (mg/dL) +1.120 log_e INR

INR, international normalized ratio

Imaging for portal venous anatomy helps with diagnosis and treatment planning and should be performed as part of the evaluation of patients after their initial variceal hemorrhage. Doppler ultrasound can usually visualize the splenic, superior mesenteric, and portal veins as well as the hepatic veins for liver outflow. Early identification of thrombosis of the portal and/or splenic veins may alter the whole approach in the management of the patient. Ultrasound also should examine liver morphology, particularly for evidence of focal lesions suggestive of hepatocellular carcinoma. Computed tomography (CT) or magnetic resonance (MR) vascular imaging and morphologic assessment can augment ultrasound studies; usually these are sufficient to make clinical decisions.

Arteriography may sometimes be required for final definition of the veins before surgical intervention. The components of this evaluation can include the following:

1 Hepatic venous pressure gradient (HVPG)

2 Left renal vein anatomy and drainage (this is abnormal in 20% of the population)

3 Superior mesenteric, portal, and splenic vein patency, flow direction, and venous anatomy on the venous phase of the arterial study

4 Major variceal inflow paths on the same study as in number 3 above

This combination of venous and arterial angiographic study can give information not available with ultrasound, CT, or magnetic resonance imaging (MRI).

Candidates for DSRS are CTP class A or B 7 or 8 patients (i.e., their CTP score is 7 or 8 points), usually without ascites, who are considered to have stable liver disease and are unlikely to need liver transplantation in the next 5 years.

Technique for Distal Splenorenal Shunt

Attention to detail in perioperative and postoperative monitoring and management of a patient undergoing DSRS improves outcome. Monitoring requires an arterial line, a central venous catheter, and a urinary catheter. Good venous access should be obtained in the event that rapid transfusion is required.

Blood and blood products should be available: packed red blood cells, fresh frozen plasma, and platelets may be required if there is major intraoperative blood loss or perioperative hemorrhage. A cell saver can be used in higher risk patients and may reduce blood bank requirements.

The patient is positioned on the operating table with the left arm at the side and the left side slightly elevated. Hyperextending the operating table to open the angle between the left lower ribs and iliac crest aids in exposure and access to the tail of the pancreas. The primary operating surgeon is on the patient’s right. The operation is more easily completed when the first assistant (to the left of the table) also has experience with the procedure.

The steps in DSRS are illustrated. The preferred incision is a long left subcostal incision, extended across the right rectus muscle (Fig. 76C.1). Coagulating diathermy should be used extensively in patients with portal hypertension to achieve hemostasis in dividing tissues. If present, ascites should be aspirated and cultured, and a liver biopsy specimen should be obtained to document the status of the liver at the time of the procedure.