The normal pressure of portal vein is 13~24 cmH2O, the average is 18 cmH2O, which is 0.5~9 cmH2O higher than that of hepatic vein. when the portal blood flow is obstructed and blood is stagnant due to various reasons, the pressure of portal vein increases, there are numerous arteriovenous traffic branches between portal vein and hepatic artery in the confluence area between liver lobules, the traffic branches open after the pressure of portal vein increases, which leads to the blood of hepatic artery into portal vein. When the portal vein pressure is higher than the normal limit, a series of symptoms and signs of increased portal vein pressure will appear, which are clinically manifested as splenomegaly, hypersplenism, esophagogastric fundic varices and may lead to vomiting blood, black stool, ascites and other symptoms, called portal hypertension.
Surgical treatment
Indications for surgery, timing of surgery, and selection of surgical methods
Surgical treatment of portal hypertension is mainly aimed at the complications of portal hypertension and cirrhosis, including prevention and control of bleeding from ruptured varices in the lower esophageal fundus, removal of a severely enlarged spleen to eliminate or relieve combined hypersplenism, and liver transplantation for severe liver failure.
The following basic consensus should be taken into account before treatment of cirrhotic portal hypertension.
1. Because of the coexistence of multiple symptomatic treatment modalities, and symptomatic and radical treatment modalities, the appropriate treatment modality should be selected after a detailed evaluation of the disease, especially surgical treatment modalities. The evaluation of the disease is particularly aimed at the combined assessment of liver function and liver reserve function, including functional and morphological assessment. For example, if the patient is under 65 years of age, has a clear diagnosis of severe hypersplenism, with or without upper gastrointestinal bleeding, has a Child A or B liver function, has an indocyanine green (ICG) 15-minute retention rate (ICGR15) between 10% and 30%, and has a CT showing a non-significant liver shrinkage, a combined splenectomy with portacaval flow dissection or flow dissection and shunt may be considered. Although the patient has Child B liver function, CT shows significant liver shrinkage, severe sclerosis, and ICGR15 > 30%, even splenectomy with a small blow to liver function is risky, and the 5-year survival rate will be lower, so liver transplantation should be considered. Usually, patients with Child C grade should not undergo flow dissection or shunt.
2.The mortality rate of patients with ruptured lower esophageal fundic varices bleeding is 30% to 50%; once bleeding occurs, the possibility of rebleeding within 2 years is 70% to 80%.
3.Emergency surgery should be avoided as much as possible. However, for patients who have a history of bleeding in the past, this bleeding is aggressive, the bleeding volume is large, or there is recurrent bleeding even after short-term active hemostatic treatment, and patients with liver function Child A or B grade, emergency surgery should be considered; if the bleeding cannot be controlled even after 48 hours of strict medical treatment, or the bleeding recurs after a brief stop, surgery should be actively performed to stop the bleeding. Surgery not only can stop bleeding and prevent rebleeding, but also is an effective measure to prevent hepatic coma. However, patients are mostly combined with shock, so the mortality rate of emergency surgery is high. Emergency surgery is preferred to peripancreatic vascular dissection, which is a small surgical blow and a simpler operation.
4, consensus on prevention of bleeding: research data show that only 40% of patients with cirrhosis have lower esophageal fundic varices, while about 50% to 60% of patients with esophagogastric varices will have bleeding. It has also been seen clinically that some patients bleed profusely after prophylactic surgery instead. Therefore, prophylactic surgery, mainly flow dissection, should only be considered in patients with severe lower esophageal fundic varices and/or severe splenomegaly with hypersplenism (white blood cells below 3000 and platelets below 50,000), as appropriate. In particular, patients with severe esophagogastric fundic varices with gastroscopic “red sign”, esophagogastroscopic findings of esophageal wall thickness >8 mm, reverse flow in esophageal or left gastric veins, esophageal variceal pressure >15 mmHg, hepatic venous pressure gradient >12 mmHg are indicators of high risk of bleeding and should be considered for prophylactic surgery.
5. Conventional surgery should be performed in such a way that it does not interfere with the possibility of liver transplantation in the future.
Surgical methods
1.Flow dissection surgery: There are many ways of flow dissection surgery, including peripancreatic vascular dissection, lower esophageal fundoplication, lower esophageal transection and fundoplication. Lower esophageal fundoplication has a large surgical scope, many complications and high mortality. The lower esophageal transection and fundoplication are incomplete and inexact in blocking the paradoxical blood flow between the portal and odd veins. Splenectomy with peripancreatic vascular dissection is the most effective procedure for flow dissection, which not only disconnects the venous side branches of the esophagogastric fundus, but also preserves the blood flow from the portal vein into the liver. To achieve complete dissection, it is important to understand the local anatomy of the peripancreatic vessels.
The peripancreatic vessels are divided into 4 groups.
(1) Coronary veins: including gastric branch, esophageal branch and high esophageal branch. The high esophageal branch starts from the bulge of the coronary vein and enters the esophageal muscle layer 3-4 cm or higher above the cardia. Sometimes there is “ectopic high esophageal branch”, which originates from the main trunk of coronary vein or left trunk of portal vein and enters the esophageal muscle layer more than 5 cm above the cardia.
(2) Posterior gastric vein: it starts from the posterior wall of the fundus, with the eponymous artery going down and injecting into the splenic vein.
(3) Short gastric vein: mostly 3 to 4 branches, accompanied by short gastric artery, distributed in the anterior and posterior wall of gastric fundus, injecting into splenic vein.
(4) Left subphrenic vein: it may enter the left side of the muscular layer of the lower esophagus in single or multiple branches. In portal hypertension, these four groups of peripancreatic veins are significantly dilated, even reaching a diameter of 0.6 cm to 1.0 cm or more. Complete dissection and ligation of these four groups of veins and their accompanying arteries is necessary to completely block the paradoxical blood flow between the portal veins.
Splenectomy is usually performed at the time of flow dissection. Splenectomy can relieve or alleviate hypersplenism. In splenomegaly, splenic blood volume can reach 20% to 40% of the blood volume of the portal venous system, and splenectomy reduces portal blood flow and lowers portal venous pressure. In portal hypertension the spleen is pathological and the incidence of post-splenectomy aggressive infection (OPSI) in adults is extremely low. Many studies have also shown that splenectomy has beneficial effects on liver function in cirrhosis.
The major surgical complications of splenectomy for portal channelling include: intra-abdominal bleeding, splenic vein and/or portal vein thrombosis, splenic fossa effusion or infection, pancreatic leak and hepatic insufficiency. If the case is properly selected, the 5-year survival rate after splenectomy with portacaval shunt can reach 90%.
2. Portal body shunt: Nowadays, it is basically not used. The main problem is that postoperative hepatic encephalopathy and shunt port thrombosis are likely to occur.
3, combined shunt and dissection surgery: Some studies have concluded that the combined surgery can further reduce the rebleeding rate without increasing the incidence of hepatic encephalopathy and liver failure. Moreover, combined surgery can be performed when complete hepatic hemodynamic information is not available, thus relaxing the indications for surgery. However, the anastomosis can also be thrombosed after bypass surgery.
4. Liver transplantation.