How is patency of a Transjugular Intrahepatic Portosystemic Shunt (TIPS) maintained or assessed?

TIPS Patency Maintenance and Assessment

TIPS patency is maintained by using PTFE-covered stents and assessed primarily through scheduled Doppler ultrasound surveillance at 6-12 month intervals, with invasive venography reserved only for suspected dysfunction based on clinical symptoms or abnormal ultrasound findings. 1

Maintaining TIPS Patency

Stent Selection

• All TIPS procedures must use PTFE-covered stents (8-10mm diameter), which achieve >75% patency at 2 years compared to >50% occlusion rates with bare metal stents. 1, 2, 3
• This represents a strong recommendation with high-level evidence and is the single most important factor for long-term patency. 1

Procedural Targets

• Reduce the portal pressure gradient to <12 mmHg or achieve ≥20% reduction from baseline during initial placement. 1, 3
• This threshold minimizes rebleeding risk while balancing hepatic encephalopathy complications. 1

Assessing TIPS Patency

Early Post-Procedure Assessment

• Early Doppler ultrasound within 7 days is unreliable due to microbubbles obscuring flow in covered stents and should NOT be routinely performed. 1, 2
• However, confirm TIPS flow before discharge specifically in prothrombotic patients (Budd-Chiari syndrome, portal vein thrombosis). 1, 2
• Obtain laboratory assessment (transaminases, bilirubin, coagulation studies, CBC) the day after intervention to detect early complications. 2

Routine Surveillance Schedule

• Perform Doppler ultrasound at 4-6 weeks post-procedure, then every 6-12 months thereafter. 1, 2
• The 6-month interval conveniently aligns with hepatocellular carcinoma screening schedules. 1, 2, 3
• This frequency is justified by the 44% dysfunction rate at 2 years even with covered stents. 2

Doppler Ultrasound Parameters to Monitor

Monitor these specific parameters at each examination: 2

• Maximum flow velocity in the portal vein
• Flow velocity within the stent tract
• Flow direction in intrahepatic portal vein branches
• Flow velocity in upstream portal vein and downstream hepatic vein

Concerning findings suggesting stenosis include: 2

• Increased or decreased flow velocities within the shunt
• Decreased flow velocity in the portal vein trunk
• Reversal of flow direction in portal vein branches
• Peak shunt velocity <90 cm/s 4

When to Proceed to Invasive Venography

Perform TIPS venography and manometry only when: 1, 2

• Doppler ultrasound shows findings suspicious for dysfunction
• Clinical signs of recurrent portal hypertension appear (ascites, variceal rebleeding)
• Patient has prothrombotic conditions requiring more intensive surveillance

Critical caveat: Doppler ultrasound has only 33-95% specificity with 50% false positive rates for detecting TIPS dysfunction. 1, 2 Therefore, clinical context determines whether to act on abnormal ultrasound findings. 1

Clinical Decision Algorithm for Intervention

For patients with TIPS placed for varices: 1

• Any clinical or ultrasound findings suggesting stenosis → proceed to venography and manometry
• Stenosis increases portosystemic gradient and rebleeding risk, requiring prompt intervention

For patients with TIPS placed for ascites/hepatic hydrothorax: 1

• If ascites remains well-controlled despite ultrasound findings → venography may not be necessary
• If ascites recurs → proceed to venography regardless of ultrasound findings

For patients with portal vein thrombosis: 1, 2

• Perform routine scheduled venography within 1-2 months after recanalization
• Assess for residual thrombus, perform additional recanalization if needed
• Embolize competing portosystemic shunts to maintain portal vein patency

Alternative Cross-Sectional Imaging

• Contrast-enhanced portal-venous CT angiography is the optimal method for anatomical visualization of the portal venous system. 2
• Perform CT angiography at 6-12 months to assess portal venous recanalization. 2
• MR angiography is less optimal due to metal artifacts making stenosis quantification difficult. 2

Special Populations Requiring Intensive Surveillance

Prothrombotic conditions (Budd-Chiari syndrome, portal vein thrombosis): 1, 2, 5

• More frequent Doppler ultrasound surveillance beyond standard intervals
• Lower threshold for proceeding to venography
• Consider routine scheduled venography as determined by interventional radiology

Patients with prior TIPS dysfunction and successful revision: 5

• Significantly higher risk of recurrent dysfunction (p=0.001)
• Continue detailed long-term surveillance beyond 2 years

When Surveillance Can Be Reduced

After 2 years of unremarkable follow-up in asymptomatic patients without prothrombotic states, detailed surveillance has minimal therapeutic impact (0.75%) and can be reduced. 5

No TIPS dysfunction occurs more than 4 years after implantation in most patients. 5

Common Pitfalls to Avoid

• Do NOT perform routine invasive venography in the absence of clinical or ultrasound suspicion of dysfunction. 1, 2 This represents unnecessary risk and cost.
• Do NOT rely on early (<7 days) Doppler ultrasound for covered stents as microbubbles obscure interpretation. 1, 2
• Do NOT ignore clinical symptoms even with normal ultrasound, as ultrasound has high false negative rates. 1, 5
• Do NOT continue intensive surveillance indefinitely in low-risk patients with normal function at 2 years. 5