Portal Vein Ligation in Hepatic Malignancies: What Surgeons Need to Know

Portal vein ligation (PVL) is a critical surgical technique primarily used to induce hypertrophy of the liver's contralateral lobe in patients undergoing major hepatic resections. This procedure is essential in managing patients with hepatic malignancies, particularly when the future liver remnant (FLR) is insufficient to sustain postoperative liver function. Given its complexity and significance, portal vein ligation requires careful consideration of patient selection, meticulous preoperative planning, and a deep understanding of the surgical techniques involved. This article delves into the various aspects of PVL, providing a detailed exploration for surgeons.

Indications for Portal Vein Ligation

Portal vein ligation is indicated in several clinical scenarios where there is a need to enhance the size of the future liver remnant (FLR) before major hepatic resection. The primary indications include:

1. Hepatic Malignancies: In cases of hepatocellular carcinoma (HCC), cholangiocarcinoma, or metastatic liver disease, where the planned liver resection may leave an inadequate FLR, PVL is used to induce hypertrophy of the remaining liver segments.
2. Liver Metastases: Patients with colorectal cancer metastases to the liver, where an extensive liver resection is required, may benefit from PVL to ensure the residual liver can sustain postoperative function.
3. Insufficient FLR: When preoperative imaging indicates that the FLR is less than 25-30% of the total liver volume, PVL can be performed to promote hypertrophy and reduce the risk of postoperative liver failure.
4. Cirrhosis: Patients with cirrhosis undergoing liver resection may have compromised liver function. PVL can help by increasing the volume of the non-cirrhotic liver parenchyma before surgery.
5. Portal Hypertension: In select cases, PVL can also be used to manage portal hypertension by redirecting blood flow and reducing pressure in the portal system.

Preoperative Evaluation

A thorough preoperative evaluation is essential to determine the suitability of a patient for portal vein ligation. This process involves several steps:

1. Imaging Studies: Contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) of the liver is performed to assess the size, location, and extent of the tumor, as well as the volume of the FLR.
2. Liver Function Tests: Serum markers, including bilirubin, albumin, and prothrombin time, are evaluated to assess baseline liver function. Indocyanine green (ICG) clearance may also be used to determine hepatic functional reserve.
3. Volume Assessment: Volumetric analysis of the liver is conducted using imaging software to calculate the FLR. An FLR less than 25-30% of total liver volume is generally considered inadequate for safe resection without prior hypertrophy.
4. Assessment of Portal Vein Anatomy: Preoperative imaging should also include an evaluation of the portal vein anatomy to identify any anatomical variations that may impact the surgical approach.
5. Multidisciplinary Discussion: The decision to proceed with PVL should be made in a multidisciplinary setting, involving hepatobiliary surgeons, radiologists, oncologists, and anesthesiologists, to ensure a comprehensive assessment of the risks and benefits.

Contraindications

While PVL is a valuable technique, it is not suitable for all patients. Contraindications include:

1. Severe Liver Dysfunction: Patients with severe cirrhosis or decompensated liver disease may not tolerate the additional stress of portal vein ligation and subsequent liver resection.
2. Portal Vein Thrombosis: The presence of a portal vein thrombosis (PVT) may complicate the procedure and increase the risk of postoperative complications.
3. Advanced Tumor Invasion: If the tumor has invaded the portal vein or adjacent vascular structures, PVL may not be feasible or safe.
4. Insufficient Liver Reserve: Patients with an FLR that is already close to or less than the minimum required for survival post-resection may not benefit from PVL, as the risk of liver failure remains high.
5. Coagulopathy: Significant coagulopathy can increase the risk of bleeding complications during PVL and should be corrected before the procedure.

Surgical Techniques and Steps

Portal vein ligation can be performed using various techniques, depending on the patient's anatomy and the surgeon's preference. The main techniques include open surgery, laparoscopic ligation, and percutaneous approaches.

1. Open Portal Vein Ligation:
   • Incision and Exposure: A right subcostal or midline incision is made to access the liver. The liver is mobilized to expose the portal structures.
   • Identification of Portal Structures: The hepatoduodenal ligament is carefully dissected to expose the portal vein bifurcation. Care is taken to preserve the hepatic artery and bile duct.
   • Ligation: The right or left portal vein branch is identified and isolated. A non-absorbable suture is used to ligate the targeted portal vein branch, effectively redirecting blood flow to the contralateral liver lobe.
   • Closure: The abdominal cavity is inspected for hemostasis, and the incision is closed in layers.
2. Laparoscopic Portal Vein Ligation:
   • Trocar Placement: Laparoscopic ports are placed under direct visualization, typically including a camera port and several working ports.
   • Dissection: The hepatoduodenal ligament is dissected laparoscopically to expose the portal vein.
   • Ligation: The targeted portal vein branch is isolated and ligated using endoscopic clips or sutures.
   • Completion: The abdomen is desufflated, and the port sites are closed.
3. Percutaneous Portal Vein Embolization (PVE):
   • Access: Under ultrasound or fluoroscopic guidance, a percutaneous approach is used to access the portal vein.
   • Embolization: Embolic agents, such as coils, particles, or glue, are delivered through a catheter to occlude the targeted portal vein branch.
   • Follow-Up: Imaging is performed to confirm successful embolization, and the patient is monitored for hypertrophy of the FLR.

Postoperative Care

After PVL, careful postoperative management is crucial to ensure a successful outcome. Key aspects include:

1. Monitoring Liver Function: Liver function tests are closely monitored postoperatively to assess the liver's response to the ligation. Bilirubin levels, transaminases, and coagulation profiles are particularly important.
2. Imaging Follow-Up: Serial imaging, usually with CT or MRI, is performed to evaluate the degree of hypertrophy of the FLR. This typically occurs 4-6 weeks post-PVL.
3. Nutritional Support: Adequate nutrition, including supplementation of vitamins and trace elements, is essential to support liver regeneration and overall recovery.
4. Management of Complications: Any complications, such as bile leaks, infections, or thrombosis, should be promptly identified and managed. This may require interventions such as drainage, antibiotics, or anticoagulation.
5. Preparation for Second-Stage Surgery: If hypertrophy is adequate, the patient is prepared for the planned liver resection. Preoperative optimization, including addressing any nutritional deficiencies and ensuring optimal liver function, is essential.

Possible Complications

As with any surgical procedure, PVL is associated with potential complications. These include:

1. Liver Failure: Inadequate hypertrophy or pre-existing liver dysfunction can lead to liver failure, which may be life-threatening.
2. Portal Vein Thrombosis: Thrombosis of the portal vein can occur postoperatively, leading to portal hypertension and reduced liver perfusion.
3. Bile Leak: Inadvertent injury to the bile duct during ligation can result in a bile leak, requiring drainage or surgical repair.
4. Infection: Surgical site infections or intra-abdominal abscesses can occur, necessitating antibiotic therapy or drainage.
5. Bleeding: Intraoperative or postoperative bleeding can be a significant complication, particularly in patients with coagulopathy.

Different Techniques

PVL can be performed using different approaches, depending on the clinical scenario and surgeon preference:

1. Sequential Ligation: In some cases, sequential ligation of the portal vein branches is performed, allowing staged hypertrophy and resection.
2. Simultaneous Portal Vein Ligation and Hepatic Vein Embolization: This combined approach may be used to enhance hypertrophy by occluding both the portal vein and the hepatic veins.
3. Hybrid Techniques: Hybrid techniques that combine surgical ligation with percutaneous embolization are also employed in select cases to optimize outcomes.

Prognosis and Outcome

The prognosis following PVL is generally favorable if adequate hypertrophy of the FLR is achieved. The success of the procedure is measured by the volume increase of the FLR and the patient's ability to tolerate the subsequent liver resection.

• Hypertrophy Rate: The average rate of hypertrophy ranges from 40-80% over 4-6 weeks, depending on the technique used and patient factors.
• Survival Outcomes: For patients undergoing liver resection after successful PVL, long-term survival is significantly improved compared to those with inadequate FLR.
• Liver Function: Most patients experience a return to baseline liver function within weeks to months after PVL and subsequent resection.

Alternative Options

In cases where PVL is contraindicated or not feasible, alternative strategies may be considered:

1. Two-Stage Hepatectomy: For extensive liver tumors, a two-stage hepatectomy may be performed, where a limited resection is initially done, followed by a second resection after liver regeneration.
2. Portal Vein Embolization (PVE): PVE is a less invasive alternative to PVL, where the portal vein branch is occluded using embolic agents via a percutaneous approach.
3. Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy (ALPPS): ALPPS is an aggressive approach that combines portal vein ligation with in situ splitting of the liver parenchyma, allowing rapid hypertrophy of the FLR.
4. Liver Transplantation: In select cases, liver transplantation may be considered for patients with extensive liver disease or tumors that are not resectable.

Average Cost

The cost of portal vein ligation can vary widely depending on the healthcare setting, geographic location, and specific techniques used. Generally, the procedure can be expensive due to the need for specialized surgical teams, advanced imaging, and postoperative care.

• Surgical Costs: The cost of the surgical procedure itself can range from $10,000 to $50,000, depending on the complexity of the case and the need for additional interventions.
• Hospitalization: Postoperative hospitalization costs, including intensive care, can add significantly to the overall cost.
• Imaging and Follow-Up: The cost of imaging studies and follow-up care should also be factored into the total expense.

Recent Advances

Recent advances in the field of portal vein ligation have focused on improving the safety and efficacy of the procedure. These include:

1. Enhanced Imaging Techniques: Advances in imaging, such as 3D volumetric analysis and functional MRI, have improved the accuracy of FLR assessment and surgical planning.
2. Minimally Invasive Approaches: The development of laparoscopic and robotic-assisted techniques has reduced the morbidity associated with PVL, allowing for faster recovery and shorter hospital stays.
3. Combined Procedures: The use of combined procedures, such as ALPPS or simultaneous embolization of the hepatic and portal veins, has expanded the indications for PVL and improved hypertrophy rates.
4. Biological Agents: Research into biological agents that promote liver regeneration, such as growth factors or stem cell therapy, holds promise for enhancing the outcomes of PVL.