Preoperative Portal Vein Embolization - Procedure and Risks

Introduction

A portal vein supplies blood to the liver. The PVE procedure blocks the portal vein from supplying blood to the liver tumor, causing atrophy (tissue degeneration) in the affected part of the liver and hypertrophy (increase in the growth) in the healthy part. PVE is indicated in patients with hepatocellular carcinoma (liver cancer), where primary liver resection (removal) is required. It also increases safety during liver resection by avoiding a sudden increase in pressure in the portal venous system and avoids postoperative liver insufficiency.

What Is PVE?

Preoperative portal vein embolization (PVE) is a minor surgery done three to four weeks before the major surgery to enhance the treatment outcome and decrease complications associated with the subsequent surgery.

The surgery entails blocking a portal vein using embolic materials like:

• Gelatin sponge.

• Gelatin powder.

• Thrombin.

• Fibrin glue.

• Polyvinyl alcohol particles.

• Absolute ethanol.

Ideal embolic material leads to a rapid increase in healthy tissue growth without causing toxicity.

What Precautions Are Taken Before PVE?

1. Stop certain medications like blood thinners (medicines that prevent the formation of blood clots), nonsteroidal anti-inflammatory drugs (NSAIDs), and diuretics.

Examples of Blood Thinners:

• Celecoxib.

• Cilostazol.

• Heparin (shot under the skin).

• Aspirin.

Examples of NSAIDs:

NSAIDs are medicines that reduce pain and fever, such as:

• Ibuprofen

• Naproxen.

Examples of Diuretics:

1. Diuretics are drugs that increase urine production to remove excess salts and fluids from the body, such as:

• Chlorthalidone

• Methyclothiazide.

2. Removing devices from the skin, such as glucose monitor devices (a device that keeps track of body sugars during the day and night) and insulin pumps (insulin delivery devices that help patients to manage blood sugar).

3. Reducing the dosage of diabetic medicines

4. Stop eating after midnight the night before the procedure.

5. Drink a good amount of water, nearly 12 ounces, between midnight and 2 hours before the surgery.

Patient selection is an essential part of the procedure. Many factors are considered, including the extent of liver resection, remaining liver function, and complexity of the surgery. Indocyanine green clearance test (ICG) is carried out to measure blood flow, quantifying liver function. ICG is a dye that combines with body protein and is distributed in the blood. The liver clears this dye. This degree of clearance is measured by an optical sensor or blood test. This value also determines the selection of the patient for PVE.

How Is PVE (Portal Vein Embolization) Procedure Done?

This procedure takes about 2 to 3 hours and is performed under general anesthesia. First, a contrast dye is administered for proper imaging to assess the portal vein and then to block it. Next, a needle with a catheter (a thin tube) is passed through the skin into the liver, the blood vessel supplying the tumor is identified, and the embolic material is injected, blocking the blood vessel.

PVE is a technique-sensitive procedure that follows either the percutaneous transhepatic route or the transileocolic route approach.

The procedure is a less invasive approach performed under general anesthesia. The optimal approach is selected according to the tumor location and history of laparotomy (a surgical incision into the abdominal cavity). During a more extended hepatic resection, embolization of the segment four portal branches and the right portal vein branch gives a positive outcome.

How Is the Recovery Phase After PVE?

After the procedure, the catheter is removed, and the patient is put under observation. A maximum number of patients get discharged the day after. Usually, it takes seven to ten days to recover, but in some instances, it might extend up to four to six weeks to fully recover. After this, a CT (computed tomography) scan is performed to confirm the required recovery.

When Is PVE Indicated?

• Liver malignancies (cancer).

• To prevent postoperative liver insufficiency (inability of the liver to perform its functions).

• Liver tumors with multiple lesions or a single small tumor.

When Is PVE Contraindicated?

1. Extensive tumor thrombus (extension of tumor into a vessel).

2. Mild-to-moderate portal hypertension (pressure elevated in the portal venous system, which supplies the liver).

3. Advanced fibrosis (extensive accumulation of fibers, including collagen, which leads to liver failure).

4. When the embolic agent cannot be delivered safely.

5. Liver cirrhosis (a severe condition of liver disease in which healthy liver tissue is replaced). However, if indicated, PVE is carried out cautiously in such patients using specific approaches to carry out the procedure successfully.

6. The procedure is contraindicated in Child-Pugh Class B or C patients (criteria for patient selection instituted by Child and Turcotte in 1964 based on liver function). The classes are characterized by:

• Class A - Good liver function.
• Class B - Moderately impaired liver function.
• Class C - Advanced liver dysfunction.

What Are the Alternatives to PVE?

Recent studies have paved the way for advances and alternatives to PVE.ALPPS (Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy) procedure that combines resection of the liver and ligation of the portal vein.

It is carried out in two stages.

• First Stage - Liver parenchyma is removed, and portal ligation is added to the larger liver lobe to be removed. The patient can recover within one to two weeks.

• Second Stage - The demoralized area of the liver is removed.

What Are the Advantages of ALPPS?

The primary recognized benefits of the ALPPS operation include a rapid and practicable increase in liver capacity within a brief period of time, which results in a second-stage treatment in two to three weeks. The duration to second stage hepatectomy is shorter than with other methods like the traditional portal vein embolization (PVE), which theoretically has the benefit of slowing disease progression after the first stage. After the initial series, where it was discovered that such a high assault to the liver resulted in a modest number of individuals in whom regeneration did not proceed, the primary benefits of ALPPS were not as great.

It is interesting to note that it was also explicitly stated that individuals who had poor liver function, uncontrolled oncological illness, hepatic cholangiocarcinomas, or cholestasis should be excluded from the ALPPS screening process. The use of ALPPS should be predicated on three fundamental principles first, sufficient preoperative liver function for proper regeneration; second, accurate oncological study with neoadjuvant control as needed; and third, avoidance of any surgery increasing the risk of infection or decompensation or causing a bile leak.

What Are the Risks Associated With PVE?

• Bowel obstruction (blockage in the bowel).

• Surgical site infection.

• Hemorrhage (bleeding from a broken blood vessel).

• Subcapsular hematoma (accumulation of blood between certain parts of the liver).

• Peritonitis (inflammation of inner layers).

• Injury to vessels in the healthy areas of the liver.

• Abdominal pain.

• Fever.

• Nausea.

• Blood clots (limited chance of embolic material deposited in the wrong place and blocking the blood supply).

These risks can be controlled with proper medications.

Conclusion

Preoperative portal vein embolization is a procedure that is performed to enhance the clinical success rate in patients suffering from liver cancers. Only some patients are asked to follow the same protocol for the treatment. Following the instructions throughout the procedure and proper follow-up helps achieve the desired result, resulting in a tumor-free patient.