Published online Mar 7, 2019. doi: 10.3748/wjg.v25.i9.1088
Peer-review started: November 16, 2018
First decision: January 6, 2019
Revised: January 24, 2019
Accepted: January 28, 2019
Article in press: January 28, 2019
Published online: March 7, 2019
Transjugular intrahepatic portosystemic shunt (TIPS) is currently used for the treatment of complications of portal hypertension. The incidence of hepatic encephalopathy (HE) remains a problem in TIPS placement. It has been reported that the right branch mainly receives superior mesenteric venous blood, while the left branch mainly receives blood from the splenic vein. We hypothesized that targeted puncture of the left portal vein would divert the non-nutritive blood from the splenic vein into the TIPS shunt; therefore, targeted puncture of the left branch of the intrahepatic portal vein during TIPS may reduce the risk of HE.
TIPS is currently used for the treatment of complications of portal hypertension. With advances in materials, many experimental and clinical studies have been conducted using covered stent grafts, especially stent grafts covered with polytetrafluoroethylene, to improve the long-term patency of TIPS. However, the incidence of HE remains a problem in TIPS placement and affects the quality of life and long-term outcomes of patients.
It has been reported that the reflux blood from the splenic and superior mesenteric veins is distributed hydrodynamically in the main portal vein, that is, alongside the trunk on both sides of the wall of the portal vein. However, it is not fully mixed and enters the left and right branches of the portal vein. The right branch mainly receives superior mesenteric venous blood, while the left branch mainly receives blood from the splenic vein. We hypothesized that targeted puncture of the left portal vein would divert the non-nutritive blood from the splenic vein into the TIPS shunt and reduce the incidence of HE. The purpose of this study was to compare the effect of the left and right branches of the portal vein as TIPS shunt on the incidence of HE in patients who required TIPS placement for portal-hypertension-related complications of ascites or variceal bleeding. In the future, randomized controlled trials are needed to verify our results, and our hypothesis needs to be validated by animal experiments and further study.
The main objective was to establish whether the left branch of the intrahepatic portal vein as TIPS shunt reduced the risk of HE. If we realized this objective for future clinical practice in TIPS, we should target puncturing the left branch of the intrahepatic portal vein during TIPS as far as possible, because we hypothesized that targeted puncture of the left portal vein would divert the non-nutritive blood from the splenic vein into the TIPS shunt and reduce the incidence of HE.
We hypothesized that targeted puncture of the left portal vein would divert the non-nutritive blood from the splenic vein into the TIPS shunt and reduce the incidence of HE. To achieve this objective, we conducted a single-center retrospective study that compared the influence of targeted puncture of the left and right branches of the portal vein on the incidence of HE in patients who required TIPS placement for portal-hypertension-related complications of ascites or variceal bleeding. The patients were divided into two groups: A (targeting of left branch of portal vein, n = 937) and B (targeting of right branch of portal vein, n = 307) (Figure 2). The outcomes of HE, recurrent variceal bleeding and/or ascites, and mortality were compared and analyzed between the groups. This study was not reported previously. Results were expressed as mean ± standard deviation and compared using the independent sample t test or one-way analysis of variance, and categorical variables were expressed as frequencies and compared using χ2 tests. The differences between the groups were compared using one-way analysis of variance followed by least significant difference t tests. Differences were considered significant at P < 0.05. The statistical analyses were performed with SPSS version 20.0.
This study showed that targeted puncture of the left branch of the intrahepatic portal vein during TIPS reduced the risk of HE, although it did not directly influence the prognosis of portal-hypertension-related complications of refractory ascites or variceal bleeding. It verified the hypothesis that the reflux blood from the splenic and superior mesenteric veins is distributed hydrodynamically in the main portal vein, that is, alongside the trunk on both sides of the wall of the portal vein. However, it is not fully mixed and enters the left and right branches of the portal vein. The right branch mainly receives superior mesenteric venous blood, while the left branch mainly receives blood from the splenic vein indirectly.
We found that the left branch of the intrahepatic portal vein during TIPS reduced the risk of HE. One of the toxic substances that causes HE is blood ammonia. HE is mainly caused by absorption of toxic substances from the intestinal portal vein system, through the shunt without the liver first pass effect into the systemic circulation, caused by dysfunction of the central nervous system. It has been reported that the reflux blood from the splenic and superior mesenteric veins is distributed hydrodynamically in the main portal vein, that is, alongside the trunk on both sides of the wall of the portal vein. However, it is not fully mixed and enters the left and right branches of the portal vein. The right branch mainly receives superior mesenteric venous blood, while the left branch mainly receives blood from the splenic vein. We hypothesized that targeted puncture of the left portal vein would divert the non-nutritive blood from the splenic vein into the TIPS shunt and reduce the incidence of HE. As far as possible, we should target puncturing the left branch of the intrahepatic portal vein during TIPS procedure for clinical practice in the future.
We can learn from this study that, to reduce the risk of HE, we should target puncturing the left branch of the intrahepatic portal vein during TIPS for clinical practice in the future. We believe that, as long as intrahepatic vein angiography shows that the anatomical structure meets the requirements, we should puncture the left portal vein, which significantly decreases the incidence of HE. In future research, randomized controlled trials are needed to verify our results, and it will take some time to switch to the targeted puncture of the left intrahepatic portal vein during TIPS procedure. Finally, our hypothesis needs to be validated by animal experiments to find direct evidence for hydrodynamics of blood.