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TRANSJUGULAR TRANSHEPATIC PORTOSYSTEMIC SHUNTS IN THE TREATMENT OF PORTAL HYPERTENSION
SUNDEEP J PUNAMIYA*, ZIV J HASKAL**
*Associate Consultant and Head of Department Vascular and Interventional Radiology, Bombay Hospital, Mumbai. **Director, Vascular and Interventional Radiology, New York Presbyterian Hospital, New York.
INTRODUCTION
The management of portal hypertension has undergone significant changes in the last two decades, with advances in medical, endoscopic and interventional radiologic treatment options. Many methods have been incorporated in reducing the portal venous pressure, for treating the serious and life threatening complications of advanced liver disease. Since its introduction over a decade ago, the TIPS has become in fundamental treatment option.
In its most basic form, a TIPS is a percutaneously created shunt spanning the intrahepatic portal and hepatic veins, created within the liver parenchyma using interventional radiological techniques. This conduit behaves just like a surgical portosystemic shunt, with far less morbidity and mortality, and has replaced the surgical shunt in most centres throughout the world.
To date, more than 70,000 TIPS have been created in the last 13 years, a meteoric rise compared with the number of surgical portosystemic shunts performed in that therapy's 60-year history. It is expected that the number will increase as the worldwide incidence of hepatitis C related cirrhosis continues to grow.
INDICATIONS
The concept of TIPS was first described in 1969, by Rosch and Hanafee. Twenty years elapsed until the first TIPS was created in humans, partly until the development and availability of metallic stents. In the early days, high procedural mortalities were reported, partly due to the novel nature of this technically complex procedure and partly due to the mortally ill condition of most patients referred for treatment. It has since been well demonstrated that the preprocedure condition of the patient determines outcome and that appropriate patient selection reduces procedural morbidity to very low levels. Indeed, an uncomplicated elective TIPS can often be created in 1 hour under conscious sedation and the patient discharged the next morning. The minimally invasive nature of the procedure has broadened the indications for portal decompression. To date, over 1100 scientific papers have been published on TIPS in the English language alone.
Based on the available data, accepted indications for TIPS would include:
Acute variceal bleeding refractory to endoscopic and medical therapy
Oesophageal and variceal bleeding are the leading causes of death in patients with portal hypertension. Although most patients are managed well with drug and endoscopic therapy, a fraction have partly or uncontrolled bleeding requiring balloon tamponade catheters. TIPS has been proven highly effective in such patients.[1,2] It is also useful in patients with ectopic varices, including intestinal, anorectal and stomal varices.[3-6]
Recurrent variceal bleeding refractory to endoscopic or medical therapy
TIPS is very useful in the treatment of patients who develop rebleeding despite adequate medical or endoscopic therapy.[1,2] Eleven published randomized trials have compared TIPS with endoscopic therapy for treatment of variceal bleeding indicating significantly lower rebleeding rates in patient treated with TIPS (Table 1).[20-28]
Patients (No.) Sanyal (1997)[20] Cello (1997)[21] Cabrera (1996)[22] Rossle (1997)[23] Merli (1998)[24] Sauer (1997)[25] Jalan (1997)[26] Garcia-Villareal(1999)[27] Pomier-Layrargues (2001)[28]
Refractory ascites
Patients with severe or refractory ascites include ones who are diuretic resistant or intolerant or are receiving increasingly frequent large volume paracenteses. TIPS can effectively control fluid accumulation in a majority of such cases, reducing or obviating the need for repeated paracentesis.[1,7] In one randomized trial, TIPS proved significantly better at controlling fluid and prolonging survival free of transplantation compared with large volume paracentesis.[29]
Hepatic hydrothorax
Hepatic hydrothorax i.e. a cirrhotic pleural effusion, develops in approximately 5% of cirrhotic patients. It may be present with ascites or in its absence. It is believed to represent ascites drawn through small defects within the diaphragm. TIPS has been reported to be helpful in the treatment of this infrequent complication.[1,8]
Budd-Chiari syndrome
The Budd-Chiari syndrome results from obstruction to the venous outflow from the liver, and is a fairly common occurrence in Asian countries, especially India, Korea and China. Most of the cases in India are due to membranous obstruction of the inferior vena cava and/or hepatic veins. These are best managed by interventional techniques, such as angioplasty and stent placement within the occluded vessel. At times, however, the hepatic vein thrombosis is very extensive within the liver, which precluding angioplasty. TIPS is proving to be effective at reducing reversing hepatic congestion and thus, the stimulus to hepatocyte necrosis and development of cirrhosis.[9] A TIPS mimics the decompressive effect of a mesoatrial shunt, because its outflow is always cephalad of the narrowed portion of the inferior vena cava, obviating some of causes of failure of mesocaval shunts that decompress portal blood into the infrahepatic, hypertensive inferior vena cava.
Additional indications have been described in case reports and small case series. These newly described indications include:
1. Hepatorenal syndrome : Type I and Type II hepatorenal syndrome (HRS) represent complication of renal failure seen in patients with advanced liver disease and ascites. Without transplantation the prognosis of patients with this disorder is nearly uniformly poor. TIPS has been used in a small number of patients with HRS, with improvement in their renal function and significant increase in short-term survival.[10,11]
2. Hepatopulmonary syndrome : Hepatopulmonary syndrome is rarely seen in patients with chronic liver disease, manifesting with cyanosis, clubbing and hypoxia due to functional right-to-left shunts in the lungs. TIPS has been used in a few patients with intractable hepatopulmonary syndrome, with excellent clinical results.[12]
3. Mesenteroportal vein thrombosis : Early experience suggests that the combination of TIPS and thrombolysis and thrombectomy of portal system thromboses in hypercoagulable symptomatic patients with abdominal pain can provide valuable clinical benefit.
Contraindications
All forms of portal decompression (surgical or percutaneous) increase right atrial pressure, cardiac output and cardiac index. Similarly, they deprive the liver of a fraction of nutrient portal flow in order to achieve pressure reduction. Portosystemic shunts are contraindicated in patients who cannot tolerate these conditions. These include patients with:
1. Heart failure.
2. Severe pre-existing hepatic encephalopathy.
3. Severe hepatic failure.
Relative technical contraindications include. (Note that TIPS have been created in all these settings):
1. Polycystic liver disease
2. Long-standing portal vein thrombosis with cavernomatous transformation.
3. Extensive primary or metastatic liver malignancy.
4. Unrelieved biliary obstruction.
Technique
TIPS are created performed in the interventional radiology suite, with facilities for high-resolution fluoroscopy, digital subtraction and continuous haemodynamic monitoring. Briefly, the procedure is as follows:
The jugular vein (usually right internal jugular) is catheterised, and a cannula advanced across the inferior vena cava into the hepatic vein (Fig. 1a). Through this cannula, a needle is passed, which punctures the hepatic vein wall and traverses the liver parenchyma into the intrahepatic portal vein (Fig. 1b). The parenchymal tract created by the needle is dilated with a balloon (Fig. 1c) and a stent deployed to maintain its patency (Fig. 1d).
The portal and hepatic vein pressures are measured before and after TIPS creation, and the resultant portosystemic gradient (PSG) calculated. This gradient provides a measure of the degree of portal hypertension and determines the end-point of the procedure. When treating patients with variceal bleeding, it is generally desirable to reduce the PSG to below 12-15 mm Hg. In some cases, lower gradients may be needed (e.g. patients with gastric varices and spontaneous splenogastrorenal shunts).
In patients who are actively bleeding, variceal embolization can be performed as part of TIPS.
RESULTS
Overall Technical Results
The technical success rate is close to 100% in most recent series.[14,15] On an average, the mean PSG is reduced from 23-24 mm Hg, before TIPS to 9.7-11 mm Hg after TIPS.[14,15]
Mortality due to the procedure is less than 1%.[14] The 30-day mortality, ranges from 3.44%, almost entirely attributable to patient selection and their pre-TIPS condition. Most mortality is from worsening liver function, sepsis or multiorgan failure.[14] This rate is minimized by appropriate case selection; elective paitents with compensated liver function response well. Various parameters have been used in predicting mortality following a TIPS, such as the APACHE II score, pre-TIPS bilirubin levels, Mayo end-stage liver disease (MELD) score, and Bonn TIPS early mortality (BOTEM) analysis.[16-19 ,44] Using these scoring systems, it is now possible to identify a sub-group of high-risk cirrhotic patients that are unlikely to have a good outcome from a TIPS procedure.
Control of Bleeding
TIPS can control active or recurrent variceal bleeding in 81-96% of patients. (Fig. 2a-c) In nine randomised clinical trials comparing TIPS to endoscopic therapies (ET), the mean rate of variceal rebleeding after TIPS was 32% lower than that of endoscopic therapy (Table 1).[20-28] Mean rates of rebleeding for TIPS and ET were 17% (range 9-24%) and 49% (range 24-66%), respectively. In a meta-analysis of 586 patients enrolled in randomised TIPS versus endoscopy trials, differences in rebleeding rates proved statistically significant (p < 0.001), strongly favouring TIPS for prevention of rebleeding, while encephalopathy rates were understandably higher in the TIPS group: 33% versus 17% for ET.
Surprisingly, however, post-TIPS and ET encephalopathy rates were considered statistically identical in three of the trials composed largely of Child-Pugh class C patients randomised after their first index bleed. Average mortality at one year proved indistinguishable in both groups (approximately 23%), although one series by Garcia-Villareal demonstrated one- and two-year actuarial survival benefits for TIPS patients.[27] The similarities in late mortality generally speak to the progressive nature of advanced liver disease and the need for liver transplantation evaluation.
Most of the studies did not test TIPS versus ET, but rather, TIPS versus ET with crossover to TIPS. Stated another way, rebleeding or failed endoscopic patients were rescued with TIPS, a phenomenon that occurred in nearly 20% of cases. It could be argued that a survival benefit with primary TIPS might have been more evident if the concomitant morbidity of failed endoscopic patients had not been included in the TIPS groups.
In nearly all cases, rebleeding after TIPS was directly related to shunt stenosis or occlusion. It is conceivable that if the obstacle of TIPS patency was reduced, the rates of TIPS-related rebleeding would be lower, as would patient morbidity from interim episodes of bleeding. Resolving the uncertainty of TIPS patency might expand its clinical use on a number of fronts, including Child class A patients with anticipated long-term survival independent of liver transplantation.
Control of Ascites
The literature evaluation TIPS for the treatment of refractory or recurrent ascites is less well developed, although this has arguably become the predominant indication of TIPS in most hospital practices. An important randomised trial was published by Rossle et al, in which 60 patients underwent repeated large volume paracentesis versus TIPS.[29] 70% of the patients had Child B disease, with mean Child-Pugh scores of 8.9 and mean serum bilirubin levels of 1.8 mg/dL. The duration of follow-up was approximately 44 months in both groups. The primary outcome was sur vival without liver transplantation, and the authors found that this was statistically better in the TIPS group at both one and two years (69% and 58% TIPS versus 52% and 32% paracentesis). At 3 months, 61% of the TIPS patients were free of ascites compared with 18% in the paracentesis group (p=0.006). Interestingly, encephalopathy rates were similar in both groups. Their findings suggest that patients meeting the profiles of those reported should undergo TIPS rather than repeated paracentesis because of better treatment outcomes and survival.
These authors also documented improvements in creatinine in their patients, findings that several groups have previously described in careful analyses of the haemodynamic, physiologic, and hormonal effects of TIPS. It appears that TIPS can profoundly affect the hepatorenal axis by improving renal blood flow, glomerular filtration rates, and sodium handling, and by correcting the hyperaldosteronaemic and hyperadrenergic states in cirrhotic patients with refractory ascites.[10,11,29] Theses finding have, in part, spurred the use of TIPS in patients with type I and II hepatorenal syndrome. While reports are still few, promising findings have been published. In one study, Guevara reported similar corrections of severe metabolic abnormalities in patients with type I HRS and mean survival of 4.7 months at publication, a marked improvement for a condition in which survival is otherwise abysmal.[11]
Budd-Chiari Syndrome
TIPS has also proved invaluable in the treatment of patients with BCS.9 If caught early, these hypercoagulable patients may be spared the development of hepatic fibrosis and cirrhosis due to continued hepatic congestion from impaired hepatic venous outflow, obviating future liver transplantation. In BCS patients, a TIPS mimics a surgical mesoatrial shunt in that it decompresses the portal venous circulation into the suprahepatic cava cephalad of the area that is compressed by the congested liver (Fig. 3 a-d). This overcomes a disadvantage of surgical meso-caval shunts, which may have impaired outflow into an often hypertensive infrahepatic inferior vena cava.
Creating TIPS in BCS patients can be technically challenging because of hepatic vein thromboses, enlarged swollen livers, and hypercoagulability that causes acute shunt thrombus formation. The authors have followed BCS patients with TIPS with shunt venograms, liver function tests, and periodic liver biopsies. We have confirmed maintenance of reduced portal venous pressures, absence of ascites, and most important, durable absence of hepatic congestion and prevention of fibrosis.
Shunt Patency
Despite the adoption of TIPS at academic and community hospitals worldwide, the procedure remains clouded by the need for routine shunt surveillance and periodic revision, due to unpredictable durability of the shunt. Shunt malfunction, secondary to shunt stenosis or occlusion, is the commonest cause of recurrent portal hypertension in patients that have undergone TIPS.30,31 A complex process of pseudointimal proliferation, by which a layer of tissue migrates through the stent interstices and reduces or occludes the shunt lumen, causes shunt stenosis. The mechanism of this proliferation is poorly understood, and is probably related to bile seepage into the TIPS.
Most centres performing TIPS have a surveillance programme for early detection of shunt malfunction, using colour Doppler and/or venography.31 A secondary intervention, such as angioplasty and stent placement, is used to maintain shunt patency when stenosis of the TIPS is detected (Fig. 4 a-c). When revision of the TIPS is not successful, a new, parallel shunt may be created30-32 (Fig. 5 a-c). Overall the primary patency rate for TIPS is 25-66% at 1 year, and 5-32% at 2 years.[14,30,31] The secondary intervention can raise the patency rate to up to 87% at 3 years.[31]
Use of stent-grafts
The poor TIPS patency rates have spurred a lot of research into improving shunt patency. Investigators have applied a variety of semi- and impermeable graft materials and coatings to stents and tested them in swine and, more recently, in humans. Several animal studies and human trials have shown remarkable abilities of polytetrafluorothylene (PTFE) lined stents to prolong TIPS patency, by preventing proliferation of tissue within the stent lumen, and by protecting the shunt from seeping bile.[33-36]
At present, only one such commercially manufactured TIPS device is available (Viatorr, WL Gore and Associates) (Fig. 6). A 15-centre randomised trial is currently underway in the U.S. comparing the device with the most commonly used stent (Wallstent, Boston Scientific Corp) since the last year. The device is already in use in Europe, where prospective 18-month data indicate that the PTFE TIPS grafts provide excellent primary patency rates ranging from 88-100%.[37-40] Shunt malfunction was invariably due to hepatic vein stenosis, when the stent was not seen to reach up to the hepatic vein ostium. Almost none of the stent-grafts that provided coverage to the hepatocaval junction had restenosis.[36] The experience in India is similar, with none of our 15 patients having restenosis at 0.1-14 months follow-up at Bombay Hospital (unpublished data) (Fig. 7a,b).
Complications
Major procedural complications are rare, occurring in less than 1% of cases. These include hepatic laceration, hepatic arterial injury, haemoperitoneum from extrahepatic portal vein puncture, and inadvertent intra-abdominal organ injury.[41]
Complications could also result from portosystemic shunting, and may appear immediately or as a delayed event following TIPS. The important shunt-related complications included liver failure and hepatic encephalopathy.
Liver failure is one of the leading causes of death in patients undergoing TIPS.[19] After TIPS insertion, there is significant portal flow diversion and the liver relies on the hepatic arterial supply for survival. In some cases, the hepatic arterial flow may not be sufficient to provide enough blood to the liver, and hepatic failure ensues. Careful selection of patients for TIPS is critical inavoiding this complication.[16-19]
Hepatic encephalopathy is a fairly common after TIPS, occurring in 3-75% patients (usually 30-40%) in different series.[42] Fortunately, most of them are mild and well controlled with medical management. Refractory encephalopathy can develop in 3-7% of patients, requiring either implantation of a "reducing stent" or alternatively, occlusion of the shunt.[43]
CONCLUSION
Transjugular intrahepatic portosytemic shunts (TIPS), when devised more than a decade ago, were hailed as the ultimate treatment option for management of portal hypertension. Various studies, case reports and series later, much has been learned about this therapeutic procedure. It has assumed an established role for the treatment of some complications of portal hypertension, such as uncontrolled or recurrent variceal bleeding, refractory ascites and hydrothorax, and Budd-Chiari syndrome. TIPS has a much lower morbidity and mortality compared to surgical shunts, and can hence be offered to sicker patients. However, case selection is vital in preventing major shunt-related complications such as liver failure and severe encephalopathy and should be used with caution in patients with advanced liver disease and critical illness. The major disadvantage of TIPS is its poor long-term patency requiring a mandatory surveillance programme. Stent-grafts seem extremely promising in preventing shunt malfunction and enhancing the life of the shunt - thereby reducing the need for shunt surveillance, obviating costly and invasive shunt revisions, reducing patient morbidity and costs from repeat hospitalisations, and providing greater clinician confidence in the procedure.
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