Techniques of portasystemic shunting: Selective and nonselective shunts

Introduction

Surgical shunts for portal hypertension and variceal bleeding are rarely undertaken today, making this chapter either irrelevant or more important than ever. I believe the latter. The decline in surgical shunting is generally a consequence of the perceived outcomes with transjugular intrahepatic portosystemic shunt (TIPS) and the concept of TIPS as a bridge to transplantation (see Chapter 85 ). The results with TIPS have been shown in several trials to be inferior to and never better than surgical portal decompression, and its role in bridging to transplantation seems too often an illusion because the bridge is seldom “crossed.” Accelerating the decline in surgical shunting is the loss of shunting in the armamentarium of most surgeons. No longer is surgical shunting “fair game” on the written or oral exams for board certification. No longer are patients with upper gastrointestinal (GI) hemorrhage routinely cared for on surgical services. Rarely are surgeons consulted regarding patients with bleeding varices or gastropathy. Generally, the decision to apply portal decompression for bleeding varices is now made without the involvement of surgeons, but rather using intensivists, hepatologists, interventional radiologists, and gastroenterologists.

To wit, the UK guidelines on the management of variceal hemorrhage in cirrhotic patients state that TIPS be used for patients who rebleed despite combined variceal banding/ligation and noncardioselective β-blocker therapy (or when monotherapy with variceal banding/ligation or noncardioselective β-blocker therapy is used because of intolerance or contraindications to combination therapy) and in selected patients because of patient choice. Where TIPS is not feasible in Child A or B patients, these guidelines suggest that “shunt surgery” can be used where local expertise and resources allow. How can patients knowledgably choose? “Shunt surgery” is excessively broad, reflecting nonsurgeons’ view of and understanding of surgery. Furthermore, patients of Child class C consume fewer resources after operative portal decompression than after TIPS.

The American College of Gastroenterology (ACG) & American Association for the Study of Liver Diseases (AASLD) Joint Clinical Guidelines state that TIPS is indicated in patients in whom hemorrhage from esophageal varices cannot be controlled or in whom bleeding recurs despite combined pharmacologic and endoscopic therapy and should be considered in patients in whom hemorrhage from fundal varices cannot be controlled or in whom bleeding recurs despite combined pharmacologic and endoscopic therapy. Herein, to the detriment of the guidelines, there is no mention of operative shunting.

Others also state the role of operative shunting with silence, denoting their perception of its role. So stated, combined treatment with vasoactive drugs, prophylactic antibiotics, and endoscopic techniques is the recommended standard of care for patients with acute variceal bleeding. To others, surgical shunts are considered only when all other treatment modalities fail.

There is also a belief that the disorder of cirrhosis and bleeding varices or portal gastropathy has changed based on the decreasing number of patients undergoing portal decompression for bleeding varices or portal gastropathy. Whether this decrease is because patients are identified earlier in the course of their disorder, gastroenterologists are better at caring for these patients so that portal decompression is unnecessary, or the care of these patients is so decentralized that their numbers go unrecognized and unreported is unknown (see Chapters 74 and 81 ).

With that preamble, this chapter brings together a summary of the shunt procedures that were the backbone for the control of variceal bleeding for half a century ending early in the 21st century. Even as these surgical shunts evolved with improving outcomes, other therapies—pharmacologic (e.g., beta blockade), endoscopic (e.g., variceal banding/sclerotherapy), and radiologic (e.g., TIPS)—were evolving, generally for the benefit of patients (see Chapters 80 , 81 , and 85 ). It is unfortunate that the role of surgical shunting has diminished to the extent it has because its application is now unreasonably infrequent.

Preoperative assessment

Patient assessment before any shunt procedure is similar and is based on:

• 1.

  Underlying liver disease and its severity

• 2.

  Abdominal venous anatomy and patency

• 3.

  Overall performance status

Clinical and lab assessment with determination of Child class and Model for End-Stage Liver Disease (MELD) score are the best tools for assessment of the severity of liver disease (see Chapter 4 ). Stated better, outcome after shunting is related to hepatic reserve, which is not measured well with conventional “liver function tests,” which, in fact, are not “tests” of liver function at all. Child class, 60 years since its description, is probably the best predictor of outcome after shunting. Vascular imaging is performed with color-flow Doppler ultrasound, computed tomography (CT) venography, or magnetic resonance imaging (MRI) venography (see Chapter 14 ). If venous anatomy is not apparent after these studies, something is wrong. Occlusion versus patency versus recanalization must be resolved and may sometimes require angiography/portal venography.

Overall status is assessed by American Society of Anesthesiologists (ASA) score or Eastern Cooperative Oncology Group (ECOG) score for general performance activities. Detail is beyond the scope of this chapter, but centers managing patients with portal hypertension should have standard approaches to general assessment of these patients.

Options for patients include:

• 1.

  Endoscopic variceal sclerotherapy (EVS) or banding (EVB): For patients amenable to definitive control of esophageal varices. Bleeding gastric varices/gastropathy requires one of the following options (see Chapters 80 and 81 ).

• 2.

  Devascularization operations: Indicated to separate the portal circulation from the gastroesophageal variceal complex. Ascites, among many issues, seem to plague these patients postoperatively (see Chapter 82 ).

• 3.

  TIPS: Not our preferred choice because of high failure rates within the first year (about 50%) and excessive diversion of nutrient hepatic blood flow with dramatic diminution of effective hepatic blood flow and resultant progressive hepatic dysfunction ^, (see Chapter 85 ).

• 4.

  Operative shunting: Our choice when option #1 is not indicated or possible (see Chapter 83 ).

Portacaval shunts

Portacaval shunts decompress the portal system by direct means and are referred to as “central shunts” or “nonselective shunts”; the terms are used interchangeably. They were the only successful therapy in the first three-quarters of the 20th century because of limitations of endoscopy and interventional radiology. There are three variations for portacaval shunts:

• 1.

  End-to-side

• 2.

  Side-to-side (small diameter or large diameter)

• 3.

  Interposition, which may be either large or small in diameter

The exposure and set up of the portal vein (PV) and inferior vena cava (IVC) is similar for all these options, but the anastomoses are different. This section will describe and illustrate the techniques (see Chapter 83 ).

Exposure and dissection

A limited Kocher maneuver is undertaken, using electrocautery generously, from the foramen of Winslow dividing tissue caudally to expose the anterior surface of the IVC. The peritoneal covering to the IVC contains small collateral vessels that can be controlled with cautery, and dissection of the fibroareolar tissue encasing the IVC is carried out (using a conventional plastic sucker with a Russian forceps holding the IVC) caudally to the level of the renal veins ( Fig. 84.1 ); ultimately 100% of the IVC is freed of overlying tissue, unless an interposition shunt is used. Once mobilization is complete, a vessel loop or umbilical tape is placed around the vena cava, which should elevate the IVC toward the PV without difficulty. For an interposition shunt, mobilization of the IVC only needs to involve dissection of the ventral 50% of the IVC.

The hepatoduodenal ligament is then incised posteriorly and laterally with electrocautery, and the PV is identified. The common bile duct and replaced/accessory right hepatic artery (if present) are retracted ventrally and medially with a vein retractor held from the left side of the operating table. Whatever shunt is used, it is important to identify and preserve an accessory or replaced artery to avoid deficiencies in liver blood flow after shunting. The dissection is carried out along the long axis of the PV in a cranial to caudal fashion, gently lifting the fibroareolar tissue away from the vein, which should be grasped with a Russian forceps ( Fig. 84.2 ). Dissection should be circumferential with a vessel loop placed around the PV; the vessel loop is used to retract the vein laterally as it is mobilized to its bifurcation distally (i.e., towards the liver) and to the pancreas proximally.

Adequate mobilization of both IVC and PV is judged by raising the IVC ventrally and retracting the PV posterolateral with their respective vessel loops. Usually, a portion of the caudate lobe requires resection to allow the two vessels to be brought into appropriate propinquity without tension. The caudal tip of the caudate lobe can be grasped with a ringed forceps, retracted caudally, and removed with electrocautery. If bleeding is notable, pressure should be placed on the caudate edge and applied, using a retractor if need be. The bleeding generally stops with this; electrocautery reapplication may be necessary.