Embolisation of the parenchymal tract after percutaneous portal vein catheterization: a retrospective comparison of outcomes with different techniques in two centres – CVIR Endovascular

Study design

This is a retrospective cohort study in patients who underwent transhepatic or transplenic PPVC procedures between January 2010 and December 2020 in two tertiary referral centres for liver and pancreatic surgery and transplantation. Patients were identified using case match search words from Institutional radiological records. Written informed consent for the interventional procedures was obtained prior to treatment from all the patients and/or from legal guardians in case of minors. Local Ethical Committees authorized this retrospective study that was conducted in respect of the principles of the Declaration of Helsinki.

Inclusion criteria were:

• a radiological procedure of percutaneous portal vein catheterization, both transhepatic of transplenic;

• availability of procedural technical details in interventional radiology reports;

• availability of periprocedural imaging for review: at least an Ultrasound (US) or Computed Tomography (CT) examination 1 week before and up to 1 month after the interventional procedure;

• availability of 1-month post-procedural clinical data.

Exclusion criteria were:

• PPVC for portal vein embolisation with ipsilateral approach;

• absence of procedural technical details in interventional radiology reports;

• absence of periprocedural imaging and clinical follow-up;

• tract embolisation performed with unusual devices, such as vascular plugs, or a combination of materials.

Early post-procedural imaging was not routinely performed unless upon clinical indication in case of uncontrolled pain, suspected bleeding, or organ dysfunction.

Study endpoints and outcome measures

The primary objective was the technical success of the techniques, defined as the intraoperative evidence of release of embolic materials in parenchymal tract and/or the ability to remove the percutaneous sheath without any signs of bleeding.

The secondary endpoint was a clinical success in terms of the absence of post-procedural bleeding and the absence of non-target embolic complications. Post-procedural imaging bleeding was defined by the development of acute pain, a drop of hemoglobin level, and/or hemodynamic instability from 1 hour to 72-hours after the procedure, confirmed by the evidence of abdominal fluid collections or hematomas at imaging. Non-target embolisation was assessed by any available post-procedural imaging study up to 1 month (or until further interventions were performed) and it was defined as the evidence of embolic material inside the vessel lumen. Intrahepatic portal vein thrombosis detected at post-procedural imaging was also recorded, regardless of evidence of non-target embolisation.

Bleeding, non-target embolisation, and thrombotic events were considered procedure-related complications and were graded according to the CIRSE Quality Assurance Document and Standards for Classification of Complications (Filippiadis et al. 2017).

PPVC technique

All the patients were considered eligible for PPVC if no medical or technical contraindications were present. The procedures were performed electively or deferred where possible depending on clinical urgency. All available procedure data were collected. Coagulopathy (International Normalized Ratio ≥ 2 and platelet count < 50.000) and perihepatic or perisplenic ascites were considered absolute contraindications, unless corrected with transfusions or drained, respectively.

In Centre 1, the main indication for PPVC was portal vein stenosis or thrombosis in liver-transplanted patients. The choice of interventional approach was based on imaging findings, at the discretion of the interventional radiologist based on experience; the primary approach was via a transhepatic route with a transplenic approach used as the second choice if this was not feasible. In Centre 2, the main indication was pancreatic islet transplantation.

All procedures in both centres were performed using fluoroscopy and digital subtraction angiography in the angiographic suite; both centres were equipped with Allura Xper FD20 (Philips Healthcare, Best, the Netherlands). Interventional radiologists had at least 5 years of experience. Conscious sedation with midazolam and fentanyl was used for adults, while general anesthesia was performed by a dedicated anesthesiologist in paediatric patients (after induction with propofol, fentanyl, and rocuronium bromide, general anesthesia was maintained with sevoflurane).

PPVC technique was the same in both centres: a parenchymal branch of the portal vein system was punctured under US guidance with a 22G Chiba needle; the guidewire was then advanced under fluoroscopic guidance and a standard coaxial 4F introducer system (Neff percutaneous access set, Cook Incorporated, Bloomington, IN; AccuStick, Boston Scientific, Marlborough, MA) was pushed over the guide. For pancreatic islet transplantation, cell infusion was performed through the 4F introducer sheath; for all the other procedures that required portal vein navigation up to 7F standard vascular introducer sheaths (Merit Medical System, South Jordan, UT) were used. In case of portal vein stenosis or thrombosis, sodium heparin was transcatheter administered in the portal vein with boluses ranging from 50 to 80 units/kg.

The study population was divided into four groups, regardless of indication, based on the embolisation technique selected by the interventional radiologist during the procedure:

• Group 1: cyanoacrylate and ethiodized oil (Glubran 2, GEM, Viareggio, Italy; Lipiodol, Guerbet, Villepinte, France);

• Group 2: coils 2–3 mm of diameter × 30 mm of length (MReye, Cook Incorporated, Bloomington, IN);

• Group 3: gelfoam torpedoes (Johnson & Johnson Medical N.V., Belgium);

• Group 4: no tract embolisation performed.

Tract embolisation with glue and gelfoam was performed through the introducer sheath during its retraction (Saad and Madoff 2012); coil embolisation was performed through standard hydrophilic 4F catheters (Terumo Corporation, Tokyo, Japan; Cordis Corporation, Miami Lakes, FL). Small contrast boluses verified positioning of the introducer or catheter tip as it pulled back from the vessel lumen into the parenchyma (Saad and Madoff 2012); after flushing with dextrose 5%, 0.1–0.2 ml of 1:2 cyanoacrylate/Lipiodol mixture were injected under fluoroscopic guidance (Fig. 1). In groups 2 and 3, coils or gelfoam torpedoes were pushed with the stiff end of a 0.035″ hydrophilic guidewire (Terumo J; Terumo Corporation, Tokyo, Japan), until disappearance of blood reflux (Fig. 2). In all cases, following embolisation, manual compression was applied for 1–2 minutes. When no tract embolisation was performed, the introducer sheath was gradually pulled back and removed upon the disappearance of blood reflux; manual compression was then applied for 10 minutes.

Embolisation of transhepatic tract with cyanoacrylic glue after PPVC. Fluoroscopy image shows the deployment of cyanoacrylic glue in the hepatic parenchyma tract, through a 4F introducer sheath during its retraction (a). MIP reconstruction of contrast-enhanced CT performed after the procedure displays the location of glue cast in the hepatic parenchyma and confirms the adjacent segmental portal branches patency (b)

Embolisation of transhepatic tract with micro-coil after PPVC. Fluoroscopy image shows the deployment of a metallic micro-coil in the hepatic parenchyma tract, through a 4F catheter during its retraction (a). MIP reconstruction of contrast-enhanced CT performed after the procedure displays the location of micro-coil in the hepatic parenchyma and confirms the segmental portal branches patency (b)

Statistical analysis

Continuous data are presented as the medians and interquartile range (IQR), categorical data as numerical values and percentages. Descriptive and analytic statistics were calculated using IBM SPSS Statistics Version 26.0 (IBM Corp., Armonk, NY). Chi-squared test and Fisher’s exact test were applied to contingency tables with the Bonferroni corrected alpha level for post-hoc pairwise comparisons.