Percutaneous retroperitoneal splenorenal shunt: an experimental study in swine

Management of Sinistral Portal Hypertension after Pancreaticoduodenectomy

BACKGROUND

Sinistral, or left-sided, portal hypertension (SPH) is a rare cause of upper gastrointestinal (GI) hemorrhage resulting from obstruction of the splenic vein. Venous drainage from the spleen via collaterals can result in venous hemorrhage into both the retroperitoneal and intra-abdominal spaces due to increased venous blood pressure in peripancreatic and gastroduodenal vasculature. SPH can occur secondary to pancreatitis with thrombosis of the splenic vein. Another possible cause is the surgical ligation of the splenic vein as part of pancreaticoduodenectomy (PD). Although splenectomy has been traditionally considered as the treatment of choice to relieve venous hypertension, individual concepts for each patient have to be developed. Considering the venous collateral drainage pathways, a comprehensive approach involving surgical, endoscopic, and interventional radiology interventions may be necessary to address the underlying cause of variceal bleeding. Among these approaches, splenic artery embolization (SAE) has demonstrated efficacy in mitigating the adverse effects associated with elevated venous outflow pressure.

SUMMARY

This review summarizes key imaging findings in SPH patients after PD and highlights the potential of minimally invasive embolization for curative treatment of variceal hemorrhage.

KEY MESSAGES

(i) SPH is a potential consequence after major pancreas surgery. (ii) Collateral flow can lead to life-threatening abdominal bleeding. (iii) Depending on the origin and localization of the bleeding, a dedicated management is required, frequently involving interventional radiology techniques.

Fluoroscopy-Guided Gastrojejunostomy Creation with Lumen-Apposing Metal Stent in a Porcine Model

PURPOSE

To evaluate the technical feasibility of fluoroscopy-guided gastrojejunostomy creation in a porcine model.

METHODS

Eight domestic female pigs (median, 15.6 kg; range, 14.5-16.3 kg) were included in this study. The proximal jejunum was punctured from the stomach using a Rösch-Uchida Transjugular Liver Access Set through the mouth, and a lumen-apposing metal stent was placed across the puncture tract between the stomach and the proximal jejunum. All animals were euthanized 6 weeks after the procedure.

RESULTS

The fistulous tract creation and stent insertion with confirmed patency were successful in eight animals, rendering a technical success rate of 100%. Gross inspection showed a matured and patent fistulous tract between the stomach and the proximal jejunum in seven animals. In one animal, the colon between the stomach and the proximal jejunum was inadvertently punctured followed by migration of the stent from the stomach into the colon after the procedure to form a delayed jejunocolostomy. A stent migration and an inadvertent traversing the tail of pancreas by the stent were observed in another two animals without signs of bleeding, infection, or pancreatitis. All animals survived until the end of this study without change in their behavior or appetite. Histological analysis showed that all the fistulous tracts had matured with continuity of submucosal, muscular, and serosal layers, and without destruction of epithelial layers.

CONCLUSIONS

Fluoroscopy-guided gastrojejunostomy creation is technically feasible in a porcine model but requires refinement of the targeting technique to avoid transgression of nontarget organs.

Twenty-five years after the first TIPS in Spain

The incorporation, 25 years ago, of transjugular intrahepatic portosystemic shunting, better known by the acronym TIPS, represents an indisputable improvement in the treatment and management of patients with symptoms due to portal hypertension. This article discusses the origins of the technique and the technical innovations that have been progressively added through the years. The implantation of coated stents, which protect the stent from processes in the parenchymal track that can lead to stenosis, have helped ensure long-term patency, thus reducing the need for reintervention. Solid evidence from valuable publications has situated TIPS at the forefront of the treatment options in a wide variety of clinical situations associated with portal hypertension.

Percutaneous Retroperitoneal Splenorenal Shunt for Symptomatic Portal Vein Thrombosis After Liver Transplantation

Acute or recurrent bleeding from ectopic varices is a potentially life-threatening condition in rare patients with extrahepatic complete portal vein thrombosis (PVT) after liver transplantation (LT). In this setting, the role of interventional radiology is very limited and surgical shunts, in particular splenorenal shunts are usually used, despite the high associated mortality. We present the first reports of the clinical use of a new minimally invasive technique, percutaneous retroperitoneal splenorenal shunt (PRESS), in two LT recipients with life-threatening variceal hemorrhage secondary to PVT. Both patients had a successful PRESS using a transplenic approach with resolution of bleeding, avoiding the need for a potentially complicated laparotomy. The PRESS procedure is a useful addition to the interventional armamentarium that can be used in cases unsuitable for surgical shunt, and refractory to endoscopic management. In the future, this technique may be an alternative to surgical shunts as the standard procedure in patients with extra-hepatic PVT, just as the transjugular intrahepatic portosystemic shunt (TIPS) procedure has become for the management of portal hypertension in the absence of PVT. Longer-term follow-up will be needed to establish the long-term success of this procedure.

Percutaneous Portosystemic Shunts: TIPS and Beyond

Percutaneous interventions for portal hypertension have been available since the 1990s. Over time, improved technology-including covered stent grafts-and clinical understanding has expanded the available procedures for percutaneous portal decompression. While transjugular intrahepatic portosystemic shunt creation is the most commonly cited percutaneous intervention, direct intrahepatic portocaval shunt and percutaneous mesocaval shunt creation are important alternatives with specific advantages and applications. This article reviews contemporary, minimally invasive interventional approaches to percutaneous portosystemic shunt creation in terms of procedure rationale, patient selection, interventional technique, and technical outcomes.

Percutaneous endovascular creation of an inferior vena cava in a patient with caval agenesis, Budd-Chiari syndrome, and iliofemorocaval thrombosis

A 29-year-old woman with acute iliofemorocaval thrombosis was discovered to have suprarenal caval agenesis with azygous continuation, hepatic congestion, and fibrosis as a result of chronic Budd-Chiari syndrome. Three staged procedures were performed: pharmacomechanical thrombolysis of acute thromboses, transfemoral liver biopsy and hemodynamic assessment, and percutaneous endovascular creation of a "neocava" lined with endografts. Symptomatic improvement and patency were maintained at 12-week follow-up.

Evaluation of MR/Fluoroscopy–guided Portosystemic Shunt Creation in a Swine Model

PURPOSE

To evaluate three different percutaneous portosystemic shunts created with magnetic resonance (MR) imaging and fluoroscopy guidance in a swine model.

MATERIALS AND METHODS

In stage 1 of the experiment, an active MR intravascular needle system was created for needle tracking and extracaval punctures. Twenty inferior vena cava (IVC)/superior mesenteric vein (SMV)/portal vein (PV) punctures were performed in 10 swine (weight, 40-45 kg) in a 1.5-T short-bore interventional MR imager. With use of a real-time MR imaging sequence, the needle was guided through the IVC and into the SMV or PV (N = 20 punctures). After confirmation, a wire was advanced into the portal venous system under MR imaging guidance (N = 20). In stage 2, animals were transferred to the radiographic fluoroscopy suite for deployment of shunts. Three different shunts were evaluated in this study: (i) a commercial stent-graft, (ii) a prototype bridging stent, and (iii) a prototype nitinol vascular anastomotic device. Postprocedural necropsy was performed in all animals.

RESULTS

Successful MR-guided IVC/SMV punctures were performed in all 20 procedures (100%). All three shunts were deployed. Stent-grafts had the poorest mechanism for securing a shunt. The vascular anastomotic device and the bridging stent had more secure anchoring mechanisms but also had higher technical failure rates (50% and 40%, respectively). When deployed successfully, the vascular anastomotic device resulted in no bleeding at the sites of punctures at necropsy.

CONCLUSION

Percutaneous shunts and vascular anastomoses between the portal mesenteric venous system and IVC were successfully created with use of a combination of MR imaging and conventional fluoroscopy for guidance.

Percutaneous MR imaging-guided transvascular access of mesenteric venous system: study in swine model

PURPOSE

To determine if, with use of magnetic resonance (MR) imaging guidance alone, transcaval puncture of the superior mesenteric vein (SMV) and/or portal vein is feasible with a percutaneous femoral vein approach.

MATERIALS AND METHODS

The Institutional Animal Care and Use Committee approved the animal studies. Ten inferior vena cava (IVC)-SMV punctures were performed in six pigs. An active MR intravascular needle system was used for all transvascular punctures, and all procedures were performed with a 1.5-T MR unit. The needle was introduced via a 12-F femoral vein sheath and advanced into the IVC by using a real-time gradient-recalled-echo sequence (3.4/1.2 [repetition time msec/echo time msec], 45 degrees flip angle, and six to eight frames per second). Fast transverse spoiled gradient-recalled acquisition in the steady state (SPGR) (6.0/1.5, 60 degrees flip angle, one frame per second) was performed to confirm needle trajectory. The needle system was advanced under real-time MR imaging to puncture the SMV. The location of the needle tip was confirmed with a fast spin-echo sequence (1904/4.5, 36-cm field of view). A direct MR portogram was obtained after the administration of gadopentetate dimeglumine at a concentration of 25% with fast SPGR (6/1.3, 90 degrees flip angle, no section selection, three frames per second). Success was defined as entry into the mesenteric venous system without traversal of any retroperitoneal organs or adjacent vasculature.

RESULTS

Successful MR imaging-guided IVC-SMV punctures were performed in all 10 procedures (100%). The needle was fully visualized as it traversed the retroperitoneum and entered the SMV. MR portograms were successfully obtained following all punctures through the needle. Conventional transverse MR imaging helped confirm that the needle did not traverse any retroperitoneal organs or vessels.

CONCLUSION

With use of only MR imaging guidance and an active MR imaging intravascular needle system, the authors were able to successfully puncture the SMV from the IVC with direct visualization of the needle and all retroperitoneal structures.

Experimental Percutaneous Extrahepatic Portacaval Shunt Creation by Transjugular Approach in Swine

The purpose of the study was to evaluate the feasibility of the creation of a percutaneous extrahepatic portacaval shunt (PEPS) in swine by a transjugular approach and to find a suitable stent-graft to use in PEPS. In 12 swine, the extrahepatic portal vein (PV) was entered from the inferior vena cava (IVC) by a needle system introduced from the transjugular approach. A catheter introduced through the transhepatic approach served as a target. Five types of stent-graft consisting of homemade Z stents and a polytetrafluoethylene cover were explored for PEPS creation. Eight animals had follow-up venograms up to 6 weeks or until the shunt became severely stenotic. Gross and histologic examinations were performed after the final follow-up venography. The PV punctures and stent-graft placement were difficult, but the PEPS was established in all animals. In four animals, the stent-graft failed to adequately cover the tract, causing severe hemorrhage. Only two shunts remained patent up to 6 weeks. The other shunts exhibited severe stenosis or occlusion. At gross examination, all shunts traversed the liver parenchyma of the caudate lobe surrounding the IVC. The extravascular PEPS portion was 4 mm to 2 cm long. All shunts entered the PV close to the splenomesenteric junction and exhibited neointimal formation. Shunt stenoses were caused by neointimal hyperplasia and occlusions by a superimposed thrombus. PEPS can be created by the transjugular approach in swine, but only the PV shunt entrance is extrahepatic. None of the tested rigid stent-grafts were suitable for PEPS creation. A short flexible stent-graft with flanged ends is suggested for further exploration.