Endovascular management of portal vein obstruction in hepatobiliary cancer patients

The purpose of this article is to describe the procedural safety, technical success, and clinical success of endovascular management of portal and mesenteric venous obstruction in patients with hepatobiliary neoplasms.


| INTRODUCTION
Obstruction of the splenoportal or mesoportal venous system occurs in approximately 15%-25% of patients with hepatobiliary malignancies. 1,2 These patients are prone to develop obstruction of the portal and mesenteric veins both because of local factors such as tumor compression or stenosis after pancreato-biliary surgery and systemic factors such as cancer-related hypercoagulability. 3 Obstruction may be acute or chronic 3 ; acute obstruction presents with thrombus formation, abdominal pain, ascites, and abnormal liver function tests, and it is usually secondary to surgical complications after liver resection or pancreaticoduodenectomy with venous reconstruction. 2 [MRI]) are key to diagnosis, and high suspicion by imaging professionals is also important because the description of imaging findings may be focused on the neoplastic process and vascular findings may be missed or underreported. 2,5 The best treatment strategy has not been established; reported therapeutic options include anticoagulation, infusion of thrombolytics into the portal vein via a percutaneous or transjugular approach, transjugular intrahepatic portosystemic shunt (TIPS) creation, and percutaneous recanalization with stent placement. [6][7][8] Percutaneous recanalization followed by stent placement using a transhepatic or a trans-splenic approach has been described as safe and effective. 1,6,7,[9][10][11][12] The purpose of this article is to describe the procedural safety, technical success, and clinical success of endovascular management of portal and mesenteric venous obstruction with metallic stent placement in patients with hepatobiliary neoplasms.

| Procedural technique
The procedures were performed in a state-of-the-art interventional radiology suite by two board-certified interventional radiologists with more than 10 years of experience. All patients signed written informed consent for the procedure.
Conscious sedation with midazolam and fentanyl was used in 18 patients and general anesthesia in three. Broad-spectrum prophylactic antibiotics with coverage for Gram-negative bacteria were administered intravenously to all patients at least 30 min before the procedure.
Access into the portal venous system was obtained using a transhepatic approach in 20 patients and a trans-splenic approach in one. Access was ultrasound-guided, using a fine needle access system (Merit S-MAK, Merit Medical). Entry into the portal venous system was confirmed by injection of nonionic contrast through the needle.
Then, a 0.018" guidewire was advanced followed by tract dilation and placement of a 5 Fr dilator. A direct portogram was then performed to confirm obstruction of the portal venous system; a 0.035" Benston guidewire (Cook), was advanced followed by placement of a vascular access sheath (Pinnacle, Terumo).
The obstruction of the portal vein was crossed using a combination of a Bernstein catheter (AngioDyamics) and a stiff type glidewire (Terumo). Once the obstruction was crossed, a direct portogram using a measuring catheter (Cook Medical) was performed in preparation for stent placement.

| Stent selection and placement technique
Stent choice was based on operator's judgment and venographic findings. The stent length was selected based on the portogram with measuring catheter and the diameter was determined by measurements obtained from the CT scans. Bare self-expandable nitinol stents were used in 17 patients (Zilver, Cook and Protege EV-3), a balloon-expandable stent was used in one (Express, Boston Scientific), a balloon-expandable stent-graft in one (Atrium Medical), a selfexpandable stent-graft (Viabahn, WL Gore) was used in one patient, and a combination of self-expandable stent and a self-expandable stent-grafts (Viabahn, WL Gore) in one patient.

| Management after intervention and follow-up
Patients were followed from the date of stent insertion until the latest clinical follow-up or patient's death (2 weeks to 4 years). All patients were seen 1 week after intervention in the Interventional Radiology (IR) clinic for recognition of early complications. An abdominal ultrasound was done within a week after the procedure to assess stent patency.
All patients were followed in the surgical oncology clinic.
Contrast-enhanced CT scans were performed every 3-6 months to monitor disease progression. All follow-up scans were reviewed by the interventional radiologists. In case of recurrent symptoms, the indication for imaging studies was discussed by the medical oncologist in consultation with the hepatobiliary surgeon and the interventional radiologist. If a stent abnormality was identified, the indication for stent revision was discussed.

| Statistical analysis
Study results are presented in means and percentages. Statistical analysis was performed using SPSS version 26. Stent patency and patient survival are presented with Kaplan-Meier curves. There were no acute stent occlusions. Primary stent patency was 95.2%, 84%, and 68% at 1, 3, and 6 months, respectively ( Figure 1).
All stent occlusions were caused by tumor progression. Two patients had stent occlusion 2 months after insertion; one patient underwent successful recanalization with restenting but there was no symptom improvement. The other patient had extensive disease progression and recanalization was not attempted. One patient had a stent occlusion 5 months after insertion. Extension of primary disease was identified on CT and stent revision was not attempted. A patient had stent occlusion 10 months after insertion. Stent revision was attempted but technically unsuccessful. Occlusion 17 months after insertion occurred in one patient, and no revision was attempted.
One patient presented 20 months after stent insertion with recurrent ascites and abdominal pain. This patient had a successful revision with clinical improvement, however, 2 months after stent revision she developed variceal bleeding. Second revision that included TIPS creation was performed and bleeding was controlled but the patient died 2 months later from progressive disease. Table 2 13 There was one early death but the cause of death could not be determined.

| DISCUSSION
The results reported in this study support placement of stents to palliate portal vein obstruction in selected patients with hepatobiliary malignancies. This has proven to have benefit in both nonoperative and postoperative patients. The procedure was safe, with high technical success, acceptable clinical success, and low complication rate. The procedure is especially useful in patients who present with ascites that responded to stent intervention. This represents a significant improvement in quality of life, even if life expectancy is not improved as survival is essentially dictated by the course of the primary malignancy.
The weakness of this report is that it is a retrospective study and may be affected by patient selection bias, however, the results presented here are similar to previously published reports and supports the application of this intervention in suitable patients. Results presented here support a multidisciplinary approach for the management of these patients. Early identification of the problem with intervention may be key in improving patient outcomes.

| CONCLUSION
Endovascular recanalization with stent placement is safe. Clinical palliation was achieved in 80% of patients. Stent patency is accep-

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.