The problem: gastric varices and the spontaneous shunt
In cirrhosis, high pressure in the portal vein forces blood into fragile bypass veins. When these swell in the stomach wall they become gastric varices, which can bleed heavily and are often harder to treat than the more familiar oesophageal varices. Many patients with large gastric varices have a natural drainage channel, a spontaneous portosystemic shunt, usually a gastrorenal (splenorenal) shunt connecting the varix to the kidney vein. That shunt is the problem’s escape route, and, cleverly, also the route by which it can be treated.
What BRTO, CARTO and PARTO do
These are all forms of retrograde transvenous obliteration: an interventional radiologist threads a catheter backwards up the shunt vein, approaching the varix from the kidney-vein side rather than through the liver, and then blocks the varix off from within so it clots and shrinks. The three names refer to how the shunt is temporarily occluded so the blocking agent stays in place:
- BRTO (Balloon-occluded Retrograde Transvenous Obliteration): a balloon is inflated in the shunt to hold the sclerosant (a clotting agent) in the varix while it works, then removed.
- CARTO (Coil-Assisted RTO): metal coils are used to plug the shunt instead of a balloon, then the varix is obliterated. Avoids leaving an inflated balloon in place for hours.
- PARTO (Plug-Assisted RTO): a vascular plug is deployed to occlude the shunt, usually with a gelatin sponge, in a single, quicker sitting.
BRTO/CARTO/PARTO versus TIPS
The traditional answer to bleeding varices is TIPS, which creates a new channel through the liver to lower the portal pressure. Retrograde obliteration does the opposite locally: it closes the varix and its shunt. TIPS lowers pressure everywhere but can worsen confusion (hepatic encephalopathy) because it diverts blood past the liver. RTO techniques avoid, and can even improve, encephalopathy by preserving liver blood flow, and are especially good for isolated gastric varices in a patient with a suitable shunt; but by closing an escape route they can raise pressure elsewhere, sometimes worsening oesophageal varices or ascites over time. Often the two are complementary.
Who is suitable
The ideal candidate has bleeding or high-risk gastric varices and a suitable gastrorenal/splenorenal shunt for the catheter to travel through. Not everyone has the right anatomy, which is why careful cross-sectional imaging (CT venography) comes first to map the shunt.
Dr Kalal’s role
BRTO, CARTO and PARTO are performed by interventional radiology. As the hepatologist, Dr Kalal identifies the patients who should be considered, controls the acute bleed and the underlying liver disease, and works with the interventional radiology team to decide between an RTO technique, TIPS, endoscopic treatment, or a combination.