The study was conducted according to the Standards of Practice Guidelines of the Cardiovascular and Interventional Radiological Society and conducted under an approval by the Institutional Review Board. The study was conducted according to the Declaration of Helsinki and an informed consent to undergo TIPS and to participate in this research was signed by each patient.
We conducted a retrospective study on 101 consecutive patients undergone TIPS procedure February 2016 to August 2018 in our center.
The inclusion criteria was portal hypertension diagnosed by clinical symptoms, laboratory and imaging tests. Uncontrollable or recurrent variceal hemorrhage and refractory ascites were all indications for TIPS implantation. And the exclusion criteria consist of chronic heart, lung, or renal hypofunction, complication of overt hepatic encephalopathy (OHE), extensive primary or metastatic hepatic malignancy before TIPS insertion, follow-up time of less than one year and patients with incomplete data.
According to the actual application of ePTFE covered stents, 101 subjects belonging to two groups were recruited: Viabahn group (n = 64) and Fluency group (n = 37). The baseline characteristics of all patients were displayed in Table 1.
A standardized TIPS technique has been detailed described previously [15–18]. After the catheterization of the right or middle hepatic vein was performed through the right internal jugular vein with a transjugular liver access set (RUPS-100; Cook Inc.), a pressure measurement was obtained. An intrahepatic tract was created by the puncture needle between the hepatic vein and one of the branches of portal vein, and then the guidewire and catheter were advanced into the portal vein. At this time, portography was performed and a pressure measurement was obtained subsequently. After the parenchymal tract was pre-baloon dilated, an 8 mm bare stent (E-Luminexx or Lifestent; Bard Inc.) combined with an ePTFE covered stent (Fluency; Bard Inc. or Viabahn; Gore Inc.) was implanted between the hepatic vein and the portal vein. Portal pressure gradient (PPG) value was obtained then. The length of the covered stent inside the portal vein was less than 1 cm. Cyanoacrylate was utilized to embolize gastric varices via angiography once found.
The angle of deviation of the blood flow at the portal venous inflow (α) and central venous outflow (β) were mesured by two radiologists on portography and CT image, The angles were calculated according to Fig. 1, which has been detailed described previously .
After the procedure, all patients were required to stay in hospital for several days and strict vital signs monitoring was needed. In addition, they received symptomatic treatments, such as analgesia, antibiotic prophylaxis, and routine treatments to improve liver function. Anticoagulation was not routinely recommended except in patients with portal vein thrombosis (PVT) .
After TIPS implantation, laboratory testings (including blood test, liver and kidney function and coagulation function) and imaging examinations (such as ultrasound, CT or MRI) were reexamined at 1, 3, 6, 12 months in the first year and once a year here after. Phone calls were made regularly to keep up with the prognosis and complications of the patients and they were kept in detailed records .
During the follow up, if a maximum shunt flow velocity of ≤ 50 cm/s or ≥ 250 cm/s or an absence of blood signal was found by ultrasonography, or clinical symptoms (such as rebleeding and ascites) relapsed, then there would be a reason to suspect shunt dysfunction [2, 22]. Transjugular-route portal venography was then performed on this kind of patients, and shunt dysfunction was confirmed by a shunt stenosis of > 50%, and stent revision (recanalization, balloon dilation or creation of a parallel shunt) was needed once diagnosis was confirmed [3, 4]. The OHE was evaluated and graded based on the West Haven criteria .
Continuous variables were expressed as mean ± standard deviation and compared using the independent sample t test or paired t test, categorical variables were expressed as frequencies and compared using Fisher exact test or the chi-squared test. Actuarial probabilities were calculated with Kaplan-Meier curves and compared using the log‐rank tests. Independent predictors were identified with Cox regression model. Differences were considered significant at P < 0.05. The statistical analyses were performed with IBM SPSS statistics version 22.0 (IBM, Inc., Chicago, IL, USA).