Direction of Blood Flow in Gastric Varices
Gastric varices typically originate from the mid to distal splenic vein, with blood flow directed toward the left renal vein, inferior vena cava, and other intra-abdominal systemic veins. 1
Anatomical Pathways of Gastric Variceal Flow
Gastric varices develop through two main portosystemic collateral drainage systems:
Gastrophrenic Venous System (Most common for isolated gastric varices)
- Blood flows from gastric varices → left inferior phrenic vein → left renal vein or inferior vena cava
- This pathway creates gastrorenal shunts that are important for treatment planning
- Common in fundal varices (GOV2, IGV1)
Gastroesophageal (Azygous) Venous System
- Blood flows from gastric varices → esophageal varices → paraesophageal varices → azygos vein → superior vena cava
- Common in GOV1 (gastroesophageal varices extending along lesser curve)
Flow Direction Based on Underlying Pathology
In Cirrhotic Portal Hypertension
- Portal blood flow is diverted through collateral vessels due to increased resistance in the liver
- Flow is hepatofugal (away from the liver) through gastric varices toward systemic circulation
- Gastric varices accompany esophageal varices in approximately 20% of cirrhotic patients 1
In Splenic Vein Occlusion (Sinistral Portal Hypertension)
- Blood from the spleen is diverted through collateral vessels (primarily gastric varices)
- Flow direction is from the splenic hilum → gastric varices → systemic veins
- This creates isolated gastric varices rather than gastroesophageal varices 1, 2
Clinical Implications of Flow Direction
Understanding the direction of blood flow is critical for treatment planning:
For BRTO/PARTO procedures: These techniques access gastric varices via the outflow pathway (typically through the left renal vein), requiring a gastrorenal shunt 3
For TIPS placement: Less effective for isolated gastric varices with dominant tributaries from splenic vein, as these may be distant from the liver hilum 3
For Endoscopic Treatment: Flow direction affects the choice of injection site and technique during endoscopic variceal obturation 1
Diagnostic Considerations
Contrast-enhanced CT or MRI is essential for visualizing the direction of blood flow in gastric varices, as recommended by the American College of Radiology 1. These imaging studies help:
- Identify the inflow and outflow vessels
- Detect the presence of gastrorenal shunts
- Determine the feasibility of BRTO or other interventional procedures
- Distinguish between different types of gastric varices (GOV1, GOV2, IGV1, IGV2)
Pitfalls and Caveats
- In patients with splenic vein occlusion, BRTO may have grave consequences as gastric varices may be the sole outflow for the entire splenomesenteric circulation 1
- Occlusion of this outflow could result in splenic engorgement, infarction, and potentially mesenteric venous thrombosis 1
- Unlike esophageal varices, a portosystemic pressure gradient of ≥12 mmHg is not necessary for gastric variceal bleeding, likely due to the high frequency of spontaneous gastrorenal shunts 4
Understanding the direction of blood flow through gastric varices is fundamental for selecting appropriate treatment strategies and preventing complications in patients with portal hypertension.