Visualization of flow dynamics in the portal circulation using 320-detector-row computed tomography: a feasibility study

Multidetector row computed tomography (CT) scanners perform dynamic scanning and have a wide scan range. Time-resolved three-dimensional CT (i.e., 4D CT) has recently enabled visualization of flow in neurovascular vessels. We hypothesized that 4D CT technology would be a useful and non-invasive method for visualizing the flow dynamics of the portal circulation. The aim of this study was to evaluate the technical feasibility of 4D CT for visualizing flow dynamics in the portal circulation using 320-detector-row CT. 4D CT images of 18 consecutive patients with portal circulation including gastrorenal shunt were retrospectively evaluated for their ability to generate flow dynamics of the portal circulation. Flow dynamics could be visualized by 4D CT in 68 of the 72 vessels in the portal vein, splenic vein, superior mesenteric vein, and gastrorenal shunt. Flow direction could not be identified in four vessels, all of them being superior mesenteric veins. Flow direction was recognized on 4D CT in the 68 vessels of the portal circulation. A preliminary validation study revealed that flow direction of all 19 vessels in the portal circulation had concordance between 4D CT and color Doppler ultrasound. 4D CT could visualize flow dynamics of the portal circulation.

Clip-assisted endoscopic cyanoacrylate injection for gastric varices with a gastrorenal shunt: a multicenter study

Background The aim of this study was to evaluate the safety and efficacy of clip-assisted endoscopic cyanoacrylate injection for gastric varices with a gastrorenal shunt. Methods Records were reviewed of patients with gastric varices and concomitant gastrorenal shunts who underwent clip-assisted endoscopic cyanoacrylate injection at three tertiary centers between April 2016 and October 2018. The assessed outcomes were technical success rate, eradication of gastric varices, cyanoacrylate embolization, and all-cause rebleeding. Results A total of 61 patients were analyzed. The procedure was successful in all patients (100 %). Gastric varices were eradicated in 30 of 33 patients (90.9 %) according to contrast-enhanced computed tomography re-examination within 1 month after the procedure. No symptoms or signs of cyanoacrylate embolization related to the procedure were observed. Four patients (6.6 %) were lost to follow-up. All-cause rebleeding occurred in 13/57 patients (22.8 %) during a median follow-up period of 225 days (interquartile range 114 – 507 days). Conclusions Clip-assisted endoscopic cyanoacrylate injection appeared to be a safe procedure that was convenient and efficacious in the treatment of gastric varices with concomitant gastrorenal shunt.

Measurement of Inferior Vena Cava to Shunt Distance in Deciding Access Route for Balloon-Occluded Retrograde Transvenous Obliteration Procedure: A Pilot Study

Purpose: Why and how to decide whether femoral or jugular approach should be used for shunt catheterization for a successful balloon-occluded retrograde transvenous obliteration (BRTO) procedure. Materials and Methods: Sixteen patients had undergone BRTO for variceal bleeding (11 cases) and encephalopathy (5 cases) with the femoral (13) and jugular approach (5). In two patients, both femoral and jugular approaches were used. There were four failed shunt catheterizations with the femoral or jugular approach two each. In all patients, the inferior vena cava (IVC) to shunt distance (ISD) was measured on the reformatted coronal computed tomography image. Results: The IVC to shunt distance (ISD) was between 2.0 and 3.5 cm in 13 patients and >3.5 cm in five. Two patients were having both proximal gastrorenal and distal splenorenal shunts. The ISD was >3.5 cm in two patients with failed initial femoral approach and < 3.5 cm in two other patients with failed initial jugular approach. In each of the four failures, the alternative approach resulted in obtaining a successful BRTO. Conclusion: The femoral approach is recommended for catheterization of the gastrorenal shunt for BRTO when the shunt joins the renal vein within 3.5 cm from the IVC. However, when the shunt is farther than 3.5 cm from the IVC, the jugular approach is suitable for a BRTO procedure.

Use of a Coda Balloon to Assist Left Renal Vein Sheath Delivery During Balloon-Occluded Retrograde Transvenous Obliteration

Fundamental to all balloon-occluded retrograde transvenous obliteration procedures is the catheterization of the gastric varix via its drainage through a gastrorenal shunt and its subsequent sclerosis. Although routinely performed with little difficulty in experienced hands, there exist clinical scenarios and anatomic factors that present technical challenges to the procedure. A common challenge is the delivery of the occlusion balloon to the neck of the gastrorenal shunt to allow occlusion. Two main factors affect this: the angulation of the veins relative to one another and the size of the balloon required to achieve occlusion. This chapter describes a technique to facilitate delivery of a sheath to the left renal vein from a femoral approach when the caudal angulation of the left renal vein makes catheterization unfavorable.

Evolution of Retrograde Transvenous Obliteration Techniques

Gastric variceal hemorrhage is a life-threatening complication of portal hypertension with a poorer prognosis compared with esophageal variceal hemorrhage. The presence of an infradiaphragmatic portosystemic shunt, often a gastrorenal shunt, allows for treatment with retrograde transvenous obliteration (RTO). RTO is an evolving treatment strategy, which includes balloon-assisted RTO, plug-assisted RTO, and coil-assisted RTO, for both gastric variceal hemorrhage and hepatic encephalopathy. RTO techniques are less invasive than transjugular intrahepatic portosystemic shunt creation, with the benefit of improved hepatic function, but at the expense of increased portal pressure. This article discusses the techniques of RTO, including patient eligibility, as well as technical and clinical outcomes, including adverse events.