Effect of technical parameters on transjugular intrahepatic portosystemic shunts utilizing stent grafts

Hemodynamic comparisons of different shunt positions and geometrical model simplification strategies in the simulation of transjugular intrahepatic portosystemic shunt (TIPS)

Transjugular intrahepatic portosystemic shunt (TIPS) is a widely used surgery for portal hypertensive patients, whose potential postoperative complications are closely related to the hemodynamic condition of the portal venous system. The selection of shunt position in the surgery may affect the postoperative hemodynamics; however, it is difficult for clinical studies to investigate the influence. Therefore, this study aims to employ the computational model simulating TIPS to compare the hemodynamic differences resulting from different shunt positions, and also to investigate the influences of different geometrical model simplification strategies used in the TIPS simulation. For this purpose, the clinical data of two representative patients were retrospectively collected, based on which, the computational hemodynamic models of the portal venous systems after TIPS were constructed, incorporating three typical shunt positions (i.e. shunt at the left/main/right portal vein) and three types of geometrical model simplification. Results showed that among the models with different shunt positions, the area-averaged flow velocity magnitudes in the shunts were very similar, while the model with shunt at the main portal vein showed the lowest postoperative portal pressure and the smallest area of high wall shear stress near the portal venous bifurcation. Among the models using different geometrical model simplification strategies, the simulated blood pressures at the main portal veins were very similar, but showed marked differences near the shunt inlets. Moreover, the area-averaged flow velocity magnitudes in the shunts were almost the same, while the velocity distributions differed a lot, leading to the different spatial distributions of wall shear stress near the portal venous bifurcations and shunt walls. These results on one hand suggested that placing the shunt at the main portal vein is more beneficial for the patient; on the other hand, they proved the feasibility of utilizing simplified model to save computational cost without losing the accuracy when the pressure at the main portal vein is mainly focused on. These findings would assist clinical decision-making and promote more accurate and efficient TIPS simulations.

Do the stent blind insertion into the main portal vein (MPV) and stent diameter influence the surgical outcome of the transjugular intrahepatic portosystemic shunt (TIPS)?

Transjugular intrahepatic portosystemic shunt (TIPS) surgery is a clinical intervention to treat portal hypertension (PH) by deploying a covered stent to establish a shunt path for the portal vein (PV) system, and proper surgical strategy is of great importance to balance the shunt effect and the risk of complications. To understand the clinical strategies of the stent blind insertion and stent selection in clinic, this study investigated the effects of varying stent insertion positions and diameters on the PV hemodynamics and the shunt effect by computational fluid dynamics (CFD) analysis of five post-TIPS subjects. The results showed that the successful TIPS surgeries of the five PH subjects were confirmed by quantifying their pressure drops. The stent insertion positions at the main portal vein (MPV) slightly affected the clinically concerned hemodynamic indexes (i.e., MPV pressure, stent-outlet velocity) and the shunt index (SI). This indicated that the position of the stent going into the MPV may not need to be deliberately selected. Moreover, the covered stents with 6 mm and 8 mm diameters slightly influenced the hemodynamics as well, but the large-diameter stent better improved the shunt effect compared to the small-diameter one. Despite this, the 6 mm stent was suggested thanks to the higher risk of the hepatic encephalopathy (HE) observed in clinic, which indicated the excessive shunt of the 8 mm stent. The current work revealed the effects of different TIPS strategies on the surgical outcome, and could be useful for potential clinical practices.

Computational hemodynamic analysis for optimal stent position in the transjugular intrahepatic portosystemic shunt procedure

Transjugular intrahepatic portosystemic shunt (TIPS) is an effective treatment for portal hypertension (PH). The current study aimed to investigate the effect of stent position on post-TIPS hemodynamic performance using computational fluid dynamics. Patient-specific pre- and post-TIPS models were reconstructed from CT images of two patients, then virtual TIPS models were created by shifting the portal vein (PV) entry site of the stent. Although there were marginal differences the effects of left-sided and right-sided TIPS on post-TIPS portal pressure and shunting flow, right-sided TIPS resulted in a greater proportion of superior mesenteric vein (SMV) flow diverting to stents compared to that for left-sided TIPS. The results also demonstrated that the nearer the entry site of stent to the portal venous bifurcation, the greater and more stable the shunting blood flow. These results suggest that the entry site of the stent should be as close to the portal vein bifurcation as possible during TIPS. TIPS on the right branch of the portal vein may be more likely to result in post-TIPS hepatic encephalopathy than that on the left branch.

Cranial stent position is independently associated with the development of TIPS dysfunction

Complications of portal hypertension can be treated with transjugular intrahepatic portosystemic shunt (TIPS) in selected patients. TIPS dysfunction is a relevant clinical problem. This study investigated the prognostic value of two-dimensional (2D) TIPS geometry for the development of TIPS dysfunction. Three hundred and seven patients undergoing TIPS procedure between 2014 and 2019 were analyzed in this monocentric retrospective study. 2D angiograms from the patients with and without TIPS dysfunction were reviewed to determine geometric characteristics including insertion and curve angles and the location of the stent. Primary outcome was the development of TIPS dysfunction. A total of 70 patients developed TIPS dysfunction and were compared to the dysfunction-free (n = 237) patients. The position of the cranial stent end in the hepatic vein and the persistence of spontaneous portosystemic shunts were significantly associated with the development of TIPS dysfunction. Among significant parameters in univariable regression analysis (portal vein-pressure after TIPS, Child-Pugh Score before TIPS, MELD before TIPS and white blood cell count before TIPS), multivariable models showed cranial stent position (p = 0.027, HR 2.300, 95% CI 1.101-4.806) and SPSS embolization (p = 0.006, HR 0.319, 95% CI 0.140-0.725) as the only predictors of TIPS dysfunction. This monocentric study demonstrates that the position of the cranial stent end is independently associated with the development of TIPS dysfunction. The distance of the cranial stent end to the IVC at the time of TIPS placement should be less than 1 cm in 2D angiography.

Predicting death or recurrence of portal hypertension symptoms after TIPS procedures

BACKGROUND

Accurate prediction of portal hypertension recurrence after transjugular intrahepatic portosystemic shunt (TIPS) placement will improve clinical decision-making.

PURPOSE

To evaluate if perioperative variables could predict disease-free survival (DFS) in cirrhotic patients with portal hypertension (PHT) treated with TIPS.

MATERIALS AND METHODS

We recruited 206 cirrhotic patients with PHT treated with TIPS, randomly assigned to training (n = 138) and validation (n = 68) sets. We recorded 7 epidemiological, 4 clinical, and 9 radiological variables. TIPS-distal end positioning (TIPS-DEP) measured the distance between the distal end of the stent and the hepatocaval junction on contrast-enhanced CT scans. In the training set, the signature was defined as the random forest for survival algorithm achieving the lowest error rate for the prediction of DFS which was landmarked 4 weeks after the TIPS procedure. In the training set, a simple to use scoring system was derived from variables selected by the signature. The primary endpoint was to assess if TIPS-DEP was associated with DFS. The secondary endpoint was to validate the scoring system in the validation set.

RESULTS

Overall, patients with TIPS-DEP ≥ 6 mm (n = 49) had a median DFS of 24.5 months vs. 72.8 months otherwise (n = 157, p = 0.004). In the training set, the scoring system was calculated by adding age ≥ 60 years old, Child-Pugh B or C, and TIPS-DEP ≥ 6 mm (1 point each) since the signature showed high DFS probability at 6.5 months post-landmark in patients that did not meet these criteria: 86%, 80%, and 78%, respectively. The hazard ratio [95 CI] between patients determined to be low-risk (< 2 points) and high-risk (≥ 2 points) was 2.30 [1.35-3.93] (p = 0.002) in the training set and 2.01 [0.94-4.32] (p = 0.072) in the validation set.

CONCLUSION

TIPS-DEP is an actionable radiological biomarker which can be combined with age and Child-Pugh score to predict death or PHT symptom recurrence after TIPS procedure.

KEY POINTS

• TIPS-DEP measurement was the third most important but only actionable variable for predicting DFS. • TIPS-DEP < 6 mm was associated with a DFS probability of 78% at 6.5 months post-landmark. • A simple scoring system calculated using age, Child-Pugh score, and TIPS-DEP predicted DFS after TIPS.

Impact of PTFE-covered stent position and extension on TIPS patency

PURPOSE

The objectives of this study were to determine the effects of expanded polytetrafluoroethylene (PTFE)-covered stent location and TIPS extension on primary patency.

METHODS

This retrospective cohort study examined patients with PTFE-covered TIPS creation between 07/2002 and 06/2016. Clinical information and patency outcomes at 24 months were extracted. At TIPS creation, extension was performed at the discretion of the operator. Kaplan-Meier curves of primary patency were generated with conditional variables of HVO-HCJ distance, extension status, and covered versus uncovered extensions. Additional logistic regression analyses of distances were performed.

RESULTS

Of 393 patients, 115 patients (29%) underwent stent extension, 79 (20% of total cohort) of which were at the HVO end alone. Primary patency for all TIPS was 75%, 68%, and 54% at 3, 6, and 12 months. The data endpoint were transplant or death in 92 (23%) and 116 (30%). Kaplan-Meier curves showed no statistically significant difference between the variables and primary patency at 12 and 24 months: distance up to versus greater than 10 mm (p = 0.32, 0.81); extension versus no extension (p = 0.83, 0.85); uncovered versus covered extensions (p = 0.58, 0.70). Logistic regression analyses showed a trend toward statistical significance.

CONCLUSION

In the setting of PTFE-covered TIPS creation, extended TIPSs and unextended well-positioned TIPSs have no difference in primary patency rates. Stent position and extension length may have an effect on primary patency, but were likely obscured by "user recognition" effects.

Persistence of gastric or esophageal varices on final angiography increases transjugular intrahepatic portosystemic shunt revision rate after polytetrafluoroethylene-covered stent shunt creation

Background

To assess the association between final polytetrafluoroethylene (PTFE)-covered stent transjugular intrahepatic portosystemic shunt (TIPS) angiographic parameters and free shunt revision survey.

Methods

Series of two comparison groups were generated with persistence of varices or not, the 25^th, 50^th, and 75^th percentile as cutoff for each angle and a 15-mm distance as cutoff for distance D. Kaplan Meier free shunt revision curves were then created and compared with Log Rank test.

Results

Mean follow-up was 455 days. Thirteen (19.4%) patients had shunt revision. Significant free shunt revision survey difference was found between post-procedural angiographic persistent varices group and the group without varices (P=0.0001). Shunt revision rate at 3, 12 and 24 months was respectively 13%, 29%, and 39% in the group with varices versus 0%, 2.7% and 2.7% in the group without. No difference was found between groups for angles A, B, C and distance D.

Conclusions

Persistence of gastric or esophageal varices on final trans-TIPS angiography increases TIPS revision rate after PTFE-covered stent shunt creation whereas geometric parameters have no influence.

Transjugular Intrahepatic Portosystemic Shunt in Patients with Portal Hypertension: Patency Depends on Coverage and Interventionalist's Experience

BACKGROUND AND AIMS

Transjugular intrahepatic portosystemic shunt (TIPS) is the treatment of choice in decompensated portal hypertension. TIPS revision due to thrombosis or stenosis increases morbidity and mortality. Our aim was to investigate patient- and procedure-associated risk factors for TIPS-revision.

PATIENTS AND METHODS

We retrospectively evaluated 189 patients who underwent the TIPS procedure. Only patients who required TIPS revision within 1 year (Group I, 34 patients) and patients who did not require re-intervention within the first year (Group II [control group], 54 patients) were included.

RESULTS

Out of 88 patients, the majority were male (69.3%) and mean age was 56 ± 11 years. Indications for TIPS were refractory ascites (68%), bleeding (24%), and Budd-Chiari syndrome (8%). The most frequent liver disease was alcohol-induced cirrhosis (60%). Forty-three patients (49%) received bare and 45 patients (51%) covered stents, thus resulting in reduction of hepatic venous pressure gradient (HVPG) from 19.0 to 9.0 mm Hg. When comparing patient- and procedure-related factors, the type of stent (p < 0.01) and interventionalist's experience (number of performed TIPS implantations per year; p < 0.05) were the only factors affecting the risk of re-intervention due to stent dysfunction, while age, gender, indication, Child-Pugh, and model of end-stage liver disease score, platelet count, pre- and post-HVPG, additional variceal embolization, stent diameter, and number of stents did not significantly differ.

CONCLUSION

Patients undergoing TIPS procedure should be surveilled closely for shunt dysfunction while covered stents and high-level experience are associated with increased -patency.

Effect of initial stent position on patency of transjugular intrahepatic portosystemic shunt

AIM

To evaluate the effect of initial stent position on transjugular intrahepatic portosystemic shunt (TIPS).

METHODS

We studied 425 patients from January 2004 to January 2015 with refractory ascites or variceal bleeding who required TIPS placement. Patients were randomly divided into group A (stent in hepatic vein, n = 57), group B (stent extended to junction of hepatic vein and inferior vena cava, n = 136), group C (stent in left branch of portal vein, n = 83) and group D (stent in main portal vein, n = 149). Primary unassisted patency was compared using Kaplan-Meier analysis, and incidence of recurrence of bleeding, ascites and hepatic encephalopathy (HE) were analyzed.

RESULTS

The mean primary unassisted patency rate in group B tended to be higher than in group A at 3, 6 and 12 mo (P = 0.001, 0.000 and 0.005), and in group D it tended to be lower than in group C at 3, 6 and 12 mo (P = 0.012, 0.000 and 0.028). The median shunt primary patency time for group A was shorter than for group B (5.2 mo vs 9.1 mo, 95%CI: 4.3-5.6, P = 0.013, log-rank test), while for group C it was longer than for group D (8.3 mo vs 6.9 mo, 95%CI: 6.3-7.6, P = 0.025, log-rank test). Recurrence of bleeding and ascites in group A was higher than in group B at 3 mo (P = 0.014 and 0.020), 6 mo (P = 0.014 and 0.019) and 12 mo (P = 0.024 and 0.034. Recurrence in group D was higher than in group C at 3 mo (P = 0.035 and 0.035), 6 mo (P = 0.038 and 0.022) and 12 mo (P = 0.017 and 0.009). The incidence of HE was not significantly different among any of the groups (P = 0.965).

CONCLUSION

The initial stent position can markedly affect stent patency, which potentially influences the risk of recurrent symptoms associated with shunt stenosis or occlusion.