Portal flow into the liver through veins at the site of biliary-enteric anastomosis

Unusual venous collateral pathways allow for reperfusion of the intrahepatic portal venous system in children with portal vein thrombosis after split liver transplantation: Clinical relevance and management implications

PVT is the most frequent vascular complication after LT in small children, and a higher incidence has been observed in those transplanted for biliary atresia or with a LLSG. Thrombosis of the PV causes extrahepatic portal hypertension and is associated with splenomegaly and the development of venous neo-collaterals, including gastro-oesophageal varices and splenorenal shunts. It has also been incidentally suggested in the literature that patients who have had a Roux-en-Y loop for a biliary reconstruction may present with a cavernomatous transformation of the distal portion of the loop. In this study, 13 children with CEPH caused by thrombosis of the PV after LT were analysed. The study evidenced the development of two types of hepatopetal venous networks: (a) a large cavernoma along the Roux loop and around the biliary anastomosis, and (b) a network of neo-collaterals in the gastro-duodeno-pancreatic area that connected to the intrahepatic portal branches directly through the liver capsule. These hepatopetal venous networks between the venous system of the surrounding organs or the omentum and the intrahepatic portal branches can be identified by radiologists. The relevance for the transplanting physician and the transplant surgeon is discussed.

Spectrum of hepatofugal collateral pathways in portal hypertension: an illustrated radiological review

The purpose of this article is to describe the various portosystemic collateral pathways pertinent to portal hypertension on multi-detector row computed tomography (MDCT) and their clinical relevance, with special emphasis on the uncommon ones. The knowledge and understanding of the various patterns of portosystemic collateral channels has important implications both for the clinician and the interventionist. MDCT with its advanced post processing capabilities can exquisitely demonstrate these vascular pathways to help in therapeutic decision making.

Teaching points

• Portosystemic collaterals are an important cause of bleeding and hepatic encephalopathy.

• Radiologists should be familiar with the imaging findings to effectively identify them.

• Pre-operative knowledge of portosystemic collaterals is essential to avoid inadvertent vascular injury.

CT findings of afferent loop varices after bilioenteric anastomosis in patients with malignant disease

OBJECTIVE

The purpose of this study was to determine the prevalence and CT findings of afferent jejunal loop varices after bilioenteric anastomosis in patients with malignancy.

MATERIALS AND METHODS

The study included 99 patients who underwent bilioenteric anastomosis for malignancy and follow-up CT examinations. Two abdominal radiologists reviewed CT images for the presence of afferent loop varices. They also assessed for the presence of extrahepatic portal occlusion or stenosis, other collateral vessels, ascites, splenomegaly, and recurrent tumor. Clinical data regarding age, sex, and histories of pancreaticoduodenectomy and surgery on the portal vein, radiation therapy, and postoperative gastrointestinal bleeding were collected. Univariate and multivariate analyses were performed to discern significant factors associated with afferent loop varices. Cumulative incidence was estimated with the Kaplan-Meier method.

RESULTS

Afferent loop varices were found in 22 of the 99 patients (22.2%), and the 48-month cumulative incidence of afferent loop varices was 28.0%. Three of the 22 patients (13.6%) eventually experienced gastrointestinal bleeding. Obstruction in the extrahepatic portal system was the only feature that exhibited a significant difference in multivariate analysis (relative risk, 71.4; 95% CI, 7.4-1000).

CONCLUSION

Afferent loop varices detected after bilioenteric anastomosis on CT images had a prevalence of 22.2% and can result in gastrointestinal bleeding. The presence of obstruction in the extrahepatic portal system was significantly associated with afferent loop varices.

Collateral pathways in portal hypertension

Presence of portosystemic collateral veins (PSCV) is common in portal hypertension due to cirrhosis. Physiologically, normal portosystemic anastomoses exist which exhibit hepatofugal flow. With the development of portal hypertension, transmission of backpressure leads to increased flow in these patent normal portosystemic anastomoses. In extrahepatic portal vein obstruction collateral circulation develops in a hepatopetal direction and portoportal pathways are frequently found. The objective of this review is to illustrate the various PSCV and portoportal collateral vein pathways pertinent to portal hypertension in liver cirrhosis and EHPVO.

Chronic portal vein thrombosis: transcapsular hepatic collateral vessels and communicating ectopic varices

PURPOSE

To assess patients with chronic portal vein thrombosis (PVT) with respect to transcapsular collateral veins, the communication between these veins and ectopic varices, and the cause of PVT.

MATERIALS AND METHODS

This study was approved by the institutional review committees, and written informed consent was obtained. From November 2003 to March 2008, 145 consecutive patients with chronic PVT due to a variety of causes were assessed for transcapsular collaterals and ectopic varices with ultrasonography (US). Analysis of contingency tables was performed with the Fisher exact test.

RESULTS

Transcapsular collaterals were detected in 15 (10.3%) of 145 patients with chronic PVT. They were restricted to patients with a history of hepatobilary surgery, severe pancreatitis, or abdominal surgery (n = 21) and were not detected in patients with liver cirrhosis, systemic coagulopathy, extrahepatic malignancy, idiopathic PVT, chronic pancreatitis, or infectious or inflammatory diseases (n = 124) (P < .001). Ectopic varices were infrequent in 70 patients with liver cirrhosis (n = 2, 3%) but were common in 14 patients with PVT after hepatobiliary surgery (n = 9, 64%) (P < .001, odds ratio = 21.4). Direct communication between transcapsular collaterals and ectopic varices was visible in all nine patients in this cohort. In eight of these patients, ectopic varices were found to be the bleeding source in gastrointestinal hemorrhage.

CONCLUSION

Transcapsular collaterals frequently occur in patients with chronic PVT due to hepatobilary surgery or necrotizing pancreatitis. They are associated with ectopic varices; therefore, awareness of transcapsular collaterals in this patient subgroup will help to localize ectopic varices as potential bleeding source.