Spontaneous portosystemic venous shunts in liver cirrhosis: Anatomy, pathophysiology, hemodynamic changes and imaging findings Poster No.: C-3193 Congress: ECR 2010 Type: Educational Exhibit Topic: Vascular Authors: A. M. De Gaetano, P. Rinaldi, M. Torge, L. Bonomo; Roma/IT Keywords: portal vein, portal hypertension, portosystemic shunt DOI: 10.1594/ecr2010/C-3193 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 21
Learning objectives The learning objectives of this exhibit are: 1) To describe anatomic changes related to the occurrence of spontaneous portosystemic venous shunts (SPSVS) that develop to decompress the portal vein. 2) To review pathophysiology of SPSVS. 3) To evaluate with Color Doppler US hemodynamic disturbances in the portal system. 4) To assess imaging findings at US and three dimensional CT and MR angiography. Background In the setting of elevated resistance to portal vein inflow, SPSVS develop by means of distention of preexisting small vessels and portal blood gains access to systemic circulation. These collateral pathways are widespread and varied in appearance, therefore a thorough understanding of vascular anatomy is essential for proper diagnosis. Hemodynamic disturbances are closely related to the location and type of SPSVS and reversed portal flow appears to be associated with specific collaterals. Three-dimensional (3D) reconstruction of portal-phase CT or MR angiograms clearly depicts vascular anatomy [1]. Color Doppler sonography is an important non invasive diagnostic tool in the evaluation of flow abnormalities in the portal system and in intrahepatic vessels [2]. Page 2 of 21
Imaging findings OR Procedure details Major hepatofugal collateral pathways that can develop in patients with portal hypertension are here described: CORONARY VENOUS COLLATERALS Are the most common varices with a frequency of 86% seen with angiography[3]. This collateral channels drain into the superior vena cava and are located in the fatty tissue between the medial wall of the gastric body and the posterior margin of the left hepatic lobe. Fig.: CORONARY VENOUS COLLATERAL VESSELS CT scan shows varices located in the fatty tissue between the medial wall of the gastric body and the posterior margin of the left liver lobe. Page 3 of 21
When enlarged, the coronary vein (left gastric) is easily identified as a vessel that arises near the portal confluence and courses cephalad to the lesser curvature side of the stomach. Fig.: CORONARY VEIN CT portal venography shows the coronary vein coursing from the splenic vein, near the portal confluence, to the lesser curvature side of the stomach. A coronary vein larger than 5-6 mm in diameter with reversed flow at Doppler evaluation is considered abnormal and is an indicator of portal hypertension [2]. Page 4 of 21
Fig.: CORONARY VEIN Color Doppler shows an enlarged coronary vein with high velocity (VM 0.33m/s) and reversed flow Coronary venous collateral vessels are usually accompanied by esophageal, or gastric varices. Among collateral pathways, esophageal varices are the most important clinically because they are a frequent source of gastrointestinal bleeding. They are formed by dilated submucosal veins situated in the wall of the lower esophagus draining into the azygos or hemiazygos system. Page 5 of 21
Fig.: ESOPHAGEAL VARICES CT shows dilated veins in the wall of the lower esophagus Gastric varices can also occur, affecting especially the gastric fundus. Page 6 of 21
Fig.: GASTRIC VARICES MR shows dilated veins in the wall of the gastric fundus Dilated short gastric veins that communicate with the splenic vein can be seen at the splenic hilum, along the gastric fundus and the left side of the greater curvature. The paraesophageal varices situated outside the wall of the esophagus can form pseudomasses in the posterior mediastinum. Page 7 of 21
Fig.: PARAESOPHAGEAL VARICES MR axial scan shows paraesophageal varices located outside the wall of the esophagus with a pseudo-mass appearance Because of intestinal gas, coronary venous collaterals can be difficult to evaluate with ultrasonography but are readily seen on CT or MR; though the detection rate is lower than that achieved with endoscopy, associated paraesophageal varices can be visualized at CT or MR imaging. Portal flow in the main portal trunk is usually epatopedal at Doppler evaluation. PARAUMBILICAL VENOUS COLLATERALS In 10%-32% of patients with portal hypertension, paraumbelical venous collaterals develop with increase in number and caliber of collapsed paraumbelical veins of the falciform ligament. Page 8 of 21
This vessels from the left portal vein accompany the ligament to the anterior abdominal wall and may anastomose with the superior and inferior epigastric veins. Drainage into the veins of the anterior abdominal wall creates abdominal wall varices and a "Medusa's head" appearance due to prominent collateral veins radiating from the umbilicus. Fig.: PARAUMBILICAL VENOUS COLLATERALS Axial MR portal venography shows the paraumbilical vein coursing from the left portal vein through the falciform ligament to the anterior abdominal wall. Drainage into the veins of the anterior abdominal wall creates varices and a "Medusa's head" appearance due to prominent collateral veins radiating from the umbilicus. Page 9 of 21
Fig.: PARAUMBILICAL VENOUS COLLATERALS (A - B) US longitudinal scan A) and sagittal MR portal venography B) show the paraumbilical vein coursing from the left portal vein through the falciform ligament to the anterior abdominal wall. Drainage into the veins of the anterior abdominal wall creates varices and a "Medusa's head" appearance due to prominent collateral veins radiating from the umbilicus. Though small paraumbilical vessels do not cause significant changes of hepatic hemodynamics. A large paraumbilical vein is associated with high velocity hepatopetal flow in the main portal vein but portal flow becomes hepatofugal in intrahepatic portal branches. Therefore despite hepatopetal flow in the portal vein, the hepatic parenchyma is not perfused by splanchnic venous blood because portal venous inflow is completely shunted to the paraumbilical vein. Page 10 of 21
Fig.: PARAUMBILICAL VENOUS COLLATERALS The image shows hemodynamic changes related to a large paraumbilical shunt. A large paraumbilical vein is associated with high velocity hepatopetal flow in the main portal vein but portal flow becomes hepatofugal in intrahepatic portal branches. Therefore despite hepatopetal flow in the portal vein, the hepatic parenchyma is not perfused by splanchnic venous blood because portal venous inflow is completely shunted to the paraumbilical vein. The paraumbilical vein can be clearly visualized at US, and at 3D portal-phase CT or MR angiograms as a tortuous, longitudinal vascular structure. Doppler evaluation is essential to assess hemodynamic changes in hepatic portal flow. Page 11 of 21
Fig.: PARAUMBILICAL VENOUS COLLATERALS (A - B - C - D) Color Doppler is essential in the evaluation of hemodynamic chages related to a large paraumbilical shunt. In this case flow in the right portal branch is hepatofugal (A - B), while in the left branch (C - D) high velocity hepatopedal flow (VM 0,45m/s) is recorded toward the paraumbilical vein SPLENORENAL AND GASTRORENAL VENOUS COLLATERALS Two common types of SPSVS are the splenorenal and the gastrorenal shunt, with blood reaching the inferior vena cava via the left renal vein. The left renal vein is frequently involved in portosystemic collateral pathways. Splenorenal or gastrorenal shunts are seen as large, tortuous veins in the region of the splenic and left renal hila and drain into an enlarged left renal vein. Page 12 of 21
Fig.: SPLENORENAL VENOUS COLLATERALS At MR portal venography splenorenal shunts are seen as large, tortuous veins in the region of the splenic and left renal hila draining into an enlarged left renal vein. Dilatation of the inferior vena cava at the level of the left renal vein is also frequently seen. Page 13 of 21
Fig.: SPLENORENAL VENOUS COLLATERALS (A - B) In cases of splenorenal shunts an enlarged left renal vein and a dilated inferior vena cava are frequently seen, as shown in these axial A) and coronal B) TC scans. Among patients with large spontaneous shunts, there is a high frequency of hepatofugal flow in the main portal trunk and of related hepatic encephalopathy; a lower frequency of esophageal varices is recorded. Page 14 of 21
Fig.: SPLENORENAL VENOUS COLLATERALS (A - B) In cases of large splenorenal shunts portal flow is diverted through the left renal vein to the inferior vena cava. The main portal tunk and intrahepatic branches are usually narrowed as shown in this MR venous portography A) and Color Doppler shows hepatofugal portal flow B). OTHER VENOUS COLLATERALS Mesenteric collateral vessels usually appear as dilated and tortuous branches of the superior or inferior mesenteric veins within the mesenteric fat, draining into the systemic venous system via the retroperitoneal or pelvic veins. Page 15 of 21
Fig.: MESENTERIC VENOUS COLLATERALS CT venous portography shows mesenteric collateral vessels as dilated and tortuous branches connecting the superior mesenteric vein to the systemic venous system via an enlarged right spermatic vein Gastrointestinal bleeding from lower intestinal varices is reported to occur in up to 5% of patients with portal hypertension. Retroperitoneal and paravertebral varices can be seen representing porto-caval anastomoses formed from veins in the walls of retroperitoneal viscera, such as ascending and descending colon to the tributaries of the inferior vena cava (Retzius veins). Page 16 of 21
Fig.: RETROPEROTONEAL COLLATERALS CT scan shows retroperitoneal collateral vessels in the right perirenal fat. Numerous small collaterals can also be seen throughout the greater omentum representing omental varices. Unfrequently intrahepatic porto-systemic shunts can develop, connecting portal branches to hepatic veins. Page 17 of 21
Fig.: INTRAHEPATIC VENOUS COLLATERALS CT scan A) and US B) show intrahepatic collateral vessels as dilated and tortuous branches connecting the left portal branch to the left hepatic vein Page 18 of 21
Fig.: INTRAHEPATIC VENOUS COLLATERALS Color Doppler shows continuous flow in the intrahepatic collateral vessels (VM 0,14m/s) C ) and high velocity turbulent flow in the left hepatic vein (VM 0,77 m/s) D). Conclusion Page 19 of 21
Detection of portal collaterals may prompt diagnosis of portal hypertension. Evaluation of the presence type and relevance of SPVS is essential to understand hemodynamic disturbances of portal flow. Demonstration of the type of SPSVS is clinically important for overall prognosis in patients with cirrhosis and in planning surgery and liver transplantation as inadvertent disruption of these vessels can cause significant bleeding. Personal Information email address: adegaetano@ rm.unicatt.it References 1) Heoung K K, Yong Y J, Jun H C et al Three-dimensional Multi-Detector Row CT Portal Venography in the Evaluation of Portosystemic Collateral Vessels in Liver Cirrhosis Radiographics 2002; 22:1053-1061 2) Robinson KA, Middleton WD, Al-Sukaiti R et al. Doppler sonography of portal hypertension Ultrasound Q. 2009; 25(1):3-13. 3) Hoevels J. Lunderquist A, Ihse I. Page 20 of 21
Portosystemic collaterals in cirrhosis of the liver: selective percutaneous transhepatic catheterization of the portal venous system and pprtal hypertension Acta Radiol 1979; 20:865-887. 4) Subramanyam BR, Balthazar EJ, Madamba MR, et al. Sonography of portosystemic venous collaterals in portal hypertension. Radiology 1983; 146:161-166. Page 21 of 21