Transjugular Intrahepatic Portosystemic Shunt
Transjugular Intrahepatic Portosystemic Shunt
Attempts to devise a less invasive approach to portal decompression led to the development of a nonsurgical shunt, the TIPS. The potential advantages of this technique include avoidance of general anesthesia, decreased procedural morbidity and mortality rates, and avoidance of surgery in the region of the hepatic hilum, which may be important in potential liver transplantation candidates.
A percutaneous method of creating a portosystemic shunt was first conceived in the late 1960s. Although technically successful, the shunts were short-lived, and all thrombosed within a few days. The development of expandable, implantable metallic stents provided a means, albeit imperfect, for maintaining shunt patency and allowed the widespread clinical implementation of this technique. The use of the flexible Wallstent endoprosthesis (Schneider, Minneapolis, MN) and several technical modifications have reduced procedure times to the range of 1 to 3 hours.Although a TIPS can be created successfully in over 95% of patients, considerable operator skill and experience in vascular and hepatobiliary interventional procedures are required.
There are minor variations in the technique among centers, and a variety of stents are in use. In brief, the technique employed at the University of California, San Francisco, is as follows: with the patient under sedation and analgesia, the right internal jugular vein is punctured percutaneously, and a vascular sheath is advanced into the inferior vena cava and then into a hepatic vein. Next, a Colapinto transjugular needle is advanced through the sheath caudally and anteriorly into the liver parenchyma. Portal vein puncture is detected by aspiration of blood and confirmed by injection of contrast medium. The portal pressure is measured after a branch of the portal venous system is entered. Subsequently, a guidewire is introduced and manipulated into the main portal vein. The needle is removed, an angioplasty balloon catheter is advanced over the guidewire, and the tract between the hepatic and portal veins is dilated. An 8- or 10-mm-diameter expandable metallic Wallstent is then deployed across the tract, with care taken to prevent intrusion of the stent into the portal vein or inferior vena cava in a manner that might compromise subsequent liver transplantation surgery. Portal venography is then repeated, and postshunt portal and vena caval pressures are determined.
Ideally, the portal vein inferior vena cava gradient is decreased to less than 12 mm Hg, the threshold below which varices rarely bleed. However, achieving this hemodynamic goal is not always possible with the relatively small stents used in the TIPS procedure. Typically, portal decompression is judged adequate if the gradient falls to 15 mm Hg or lower and varices can no longer be demonstrated radio graphically after injection of contrast medium into the splenic vein. When the gradient remains greater than 15 mm Hg or variceal flow persists, the stent is expanded to 10 or 12 mm in diameter, and, if necessary, a second parallel shunt is placed and the varices embolized with coils or alcohol. Patients are then monitored closely for bleeding for 12 to 24 hours. A Doppler ultrasonographic examination is performed the day after TIPS to assess patency of the shunt.
TIPS should not be performed in patients who have polycystic liver disease or cholangiohepatitis with intrahepatic bile duct dilation because of the high risk of traversing a cyst or bile duct, respectively. Like all portosystemic shunts, TIPS acutely increases right-sided cardiac pressure and therefore should not be performed in patients who have right-sided heart failure or primary pulmonary hypertension. Relative contraindications to TIPS include biliary obstruction, active intrahepatic or systemic infection, severe hepatic encephalopathy, and portal vein thrombosis.
Attempts to devise a less invasive approach to portal decompression led to the development of a nonsurgical shunt, the TIPS. The potential advantages of this technique include avoidance of general anesthesia, decreased procedural morbidity and mortality rates, and avoidance of surgery in the region of the hepatic hilum, which may be important in potential liver transplantation candidates.
A percutaneous method of creating a portosystemic shunt was first conceived in the late 1960s. Although technically successful, the shunts were short-lived, and all thrombosed within a few days. The development of expandable, implantable metallic stents provided a means, albeit imperfect, for maintaining shunt patency and allowed the widespread clinical implementation of this technique. The use of the flexible Wallstent endoprosthesis (Schneider, Minneapolis, MN) and several technical modifications have reduced procedure times to the range of 1 to 3 hours.Although a TIPS can be created successfully in over 95% of patients, considerable operator skill and experience in vascular and hepatobiliary interventional procedures are required.
There are minor variations in the technique among centers, and a variety of stents are in use. In brief, the technique employed at the University of California, San Francisco, is as follows: with the patient under sedation and analgesia, the right internal jugular vein is punctured percutaneously, and a vascular sheath is advanced into the inferior vena cava and then into a hepatic vein. Next, a Colapinto transjugular needle is advanced through the sheath caudally and anteriorly into the liver parenchyma. Portal vein puncture is detected by aspiration of blood and confirmed by injection of contrast medium. The portal pressure is measured after a branch of the portal venous system is entered. Subsequently, a guidewire is introduced and manipulated into the main portal vein. The needle is removed, an angioplasty balloon catheter is advanced over the guidewire, and the tract between the hepatic and portal veins is dilated. An 8- or 10-mm-diameter expandable metallic Wallstent is then deployed across the tract, with care taken to prevent intrusion of the stent into the portal vein or inferior vena cava in a manner that might compromise subsequent liver transplantation surgery. Portal venography is then repeated, and postshunt portal and vena caval pressures are determined.
Ideally, the portal vein inferior vena cava gradient is decreased to less than 12 mm Hg, the threshold below which varices rarely bleed. However, achieving this hemodynamic goal is not always possible with the relatively small stents used in the TIPS procedure. Typically, portal decompression is judged adequate if the gradient falls to 15 mm Hg or lower and varices can no longer be demonstrated radio graphically after injection of contrast medium into the splenic vein. When the gradient remains greater than 15 mm Hg or variceal flow persists, the stent is expanded to 10 or 12 mm in diameter, and, if necessary, a second parallel shunt is placed and the varices embolized with coils or alcohol. Patients are then monitored closely for bleeding for 12 to 24 hours. A Doppler ultrasonographic examination is performed the day after TIPS to assess patency of the shunt.
TIPS should not be performed in patients who have polycystic liver disease or cholangiohepatitis with intrahepatic bile duct dilation because of the high risk of traversing a cyst or bile duct, respectively. Like all portosystemic shunts, TIPS acutely increases right-sided cardiac pressure and therefore should not be performed in patients who have right-sided heart failure or primary pulmonary hypertension. Relative contraindications to TIPS include biliary obstruction, active intrahepatic or systemic infection, severe hepatic encephalopathy, and portal vein thrombosis.
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