New Thrombectomy Technique for Total Portal Vein Thrombosis in Liver Transplantation

Summary

Portal vein thrombosis (PVT) is a frequent complication in patients with portal hypertension resulting from end-stage liver disease. In certain instances, PVT may be a contraindication for liver transplantation. We have developed a novel approach for managing PVT cases involving complete occlusion of the main trunk of the portal vein.

Abstract

Portal vein thrombosis is present in approximately 5-16% of patients with end-stage liver disease who undergo liver transplantation. In this report, we describe a new surgical approach that has been established in our center. Two patients with total thrombosis of the main trunk of the portal vein have been treated currently. Briefly, the portal vein was dissected as caudally as needed to reach an area without thrombus and occlude its cranial portion near the liver. Incision of the portal vein was then performed without cutting the thrombus and by everting the portal vein wall, carefully liberating it from the thrombus until it was removed entirely and remained attached to the native liver. With this new thrombectomy technique, we achieved excellent portal flow in both cases, since the thrombus was not fractured and was entirely removed, leading to optimal reperfusion of the liver graft. Both patients underwent control abdominal CT scans days after the liver transplant, in which no residual thrombi and excellent portal flow in the graft were observed. This novel thrombectomy technique seems safe and feasible, although further experience is necessary to evaluate its long-term outcomes.

Introduction

The portal vein is a crucial structure in the body, transporting approximately 75% of the blood to the liver from the gastrointestinal tract and spleen¹. In patients with advanced liver diseases, portal vein thrombosis may develop, consisting of the formation of clots within the vein, obstructing the blood flow². Portal vein thrombosis (PVT) is a complex complication that poses a significant challenge during liver transplantation³. To ensure optimal graft and patient survival, it is essential to maintain good portal inflow^1,3.

Portal Vein Thrombosis can be classified as acute or chronic and categorized based on the extent of vein involvement⁴. Among the numerous PVT categorizations, the Yerdel Classification is often used to guide surgical approaches in liver transplantation (Table 1)⁴. It consists of four categories: restricted to the main portal vein trunk and affecting less than 50% of its lumen; Grade 1 with more than 50% of occluded lumen, including complete obstruction of the main portal vein trunk; complete obstruction of the portal vein and proximal portion of the superior mesenteric vein; entire venous splanchnic system thrombosis with development of large or small collaterals^3,4.

Intraoperatively, Yerdel Grade I/II or early PVT can be managed with a simple thrombectomy (cutting of the vein and the thrombus together with eversion of the vein wall and removal of the thrombus with the aid of a needle holder), or even a thromboendovenectomy (resection of the affected part of the vein with the thrombus)^1,5. However, complications with these two techniques (traditional thrombectomy and thromboendovenectomy) include thrombus fragmentation, incomplete removal, or vein injury in anatomically challenging positions, such as the retro-pancreatic portion of the portal vein⁵.

Yerdel Grade III PVT may require other techniques such as a jump graft from the superior mesenteric vein or splenic vein². It is important to remember that varices often have thin walls, making them difficult to handle during anastomosis^2,6. For a jump graft from the superior mesenteric vein, first we must pass the venous graft obtained from the cadaver donor through the transverse mesocolon and place it anatomically straight in the direction of the portal vein to avoid compression or kinking⁶. After that, the superior mesenteric vein is isolated for better vascular control. After clamping the vein, an end-to-side anastomosis of the superior mesenteric vein and venous graft is performed⁵. The surgery is then completed with an end-to-end anastomosis of the venous graft and portal vein of the liver graft⁶.

Grade IV presents a significant challenge, depending on the presence of portosystemic shunts, enlarged left gastric vein, or pericholedochal varices^3,6. The best options include a reno-portal anastomosis if a large splenorenal shunt is present or a direct anastomosis between the graft and an enlarged collateral vein⁴. In cases where an adequate portal inflow cannot be obtained with these measures, a multivisceral transplant may be the best option⁶.

This new technique ensures less risk for thrombus fragmentation, incomplete removal, or vein injury⁵. Delicately performing this technique can guarantee an integral removal of the thrombus in selected cases, so we developed this new type of thrombectomy⁶.

Two cases of Grade II portal vein thrombosis are presented in which a new technique for thrombectomy was utilized.

Case 1: A 64-year-old man presented with a diagnosis of cirrhosis of the liver with hepatocellular carcinoma. As a complication of the liver disease, he presented with liver encephalopathy and ascites. The patient had a history of heavy drinking that led to cirrhosis. Laboratory examinations revealed a MELD-Na (Model of End-Stage Liver Disease-Sodium) Score of 17 and CHILD-PUGH Class C11. Triphasic dynamic contrast-enhanced abdominal computed tomography (CT) scan showed hematic thrombosis of the main trunk and of the right and left branches of the portal vein (Figure 1).

Case 2: A 37-year-old man presented with primary sclerosing cholangitis that led to cirrhosis. As a complication of the liver disease, he presented with acute-on-chronic liver failure, triggered by spontaneous bacterial peritonitis, leading to liver encephalopathy, ascites, and hepatorenal syndrome. Laboratory exams revealed a MELD-Na Score of 36 and CHILD-PUGH Class C11. Triphasic dynamic contrast-enhanced abdominal CT scan revealed chronic hematic thrombosis in the main trunk of the portal vein, extending to its intrahepatic branches, which were partially recanalized (Figure 2).

Protocol

The patients provided written informed consent for the operation and the use of medical data for scientific purposes. This research was performed in compliance with the Declaration of Helsinki and was approved by the local Institution's Human Research Ethics Committee and the Institutional Review Board. For the protocol presentation and explanation, we present two case reports of Grade II PVT that were managed with a novel thrombectomy technique.

1. Preoperative procedure

1. Prohibit the patient from eating and drinking 8 h before the surgery.
2. Use tracheal intubation under general anesthesia. Place a central venous catheter, a Swan-Ganz catheter, and an intra-arterial pressure catheter.
3. Sterilize the skin with a 2% Clorhexidine-based scrub. Place sterile towels on the inter-nipple connection, symphysis pubis, right midaxillary, and left midclavicular lines.

2. Surgery

1. Realize an inverted Makuuchi incision and liberate the liver from all the ligaments. Start the dissection of the hepatic hilum and ligation of the hepatic artery and common bile duct, isolate the portal vein in the hepatic pedicle, and individualize the right and left hepatic veins.
2. Continue isolating the portal vein, ligating all the collaterals caudally as possible until the left gastric vein or even the retro-pancreatic portion of the vein is reached.
3. Once the portal vein is isolated, apply a German clamp or ligate the right and left portal veins, stabilizing the thrombus within the vein to allow a more controlled and easier thrombectomy (Figure 3A).
   NOTE: The traditional technique involves cutting the vein alongside the thrombus.
4. Pass a vessel loop twice as a tourniquet as caudally as possible for better hemostatic control and to avoid excessive bleeding during the thrombectomy.
5. With vascular control of the vein established, perform incision in a circular fashion in the portal vein without rupturing the thrombus (Figure 3B). It is important to perform this step with gentle movements.
6. Once the thrombus is completely separated from the vein at the incision site, proceed with the thrombectomy by caudally everting the portal vein wall with anatomical forceps (Figure 3C).
7. In areas where the thrombus is firmly attached to the vein, make small incisions in the adhesions or use a small periosteal dissector to separate the thrombus from the vein wall.
8. After completely liberating the thrombus from the portal vein, carefully remove it, securing the vessel loop gently to prevent bleeding from the portal flow (Figure 3D).
   NOTE: Using this technique, the thrombus remains attached to the native liver (Figure 4).
9. Perform thrombectomy
   1. Apply a portal clamp above the vessel loop, which is subsequently removed. The portal flow is tested, and the transplantation procedure continues with total hepatectomy using the piggyback technique.
   2. Perform the implantation of the new liver with end-to-end anastomosis of the portal vein, hepatic artery, and common bile duct.
   3. Place a Jackson-Pratt drain in the hepatic hilum. Close the incisions with polypropylene suture 0 for aponeurosis, polyglactin suture 2-0 for deep cellular tissue, and nylon suture 3-0 for the skin.

3. Post-operative procedure

1. Remove the nasogastric tube the day after the operation. Start a liquid enteric diet and expand to a normal diet in 3 days.
2. On postoperative day 1, begin with Tacrolimus and a high dose of Prednisone. Also, perform Doppler Ultrasound of the transplanted liver to identify the portal and arterial flow. Remove the orotracheal tube, if permitted.
3. On postoperative day 3, remove all the catheters and change to peripheral access.
4. On postoperative day 4, discharge the patient from the ICU.
5. Perform a blood routine examination, tacrolimus dosage, and blood biochemistry examination daily, to assess postoperative control of the transplanted liver.
6. On postoperative day 10, discharge the patient from the hospital.

Results

This new thrombectomy technique allowed a complete removal of the thrombus in both cases, resulting in excellent portal flow. An end-to-end portal-portal anastomosis could be performed, achieving quick and homogeneous reperfusion of the graft (Figure 5 and Figure 6). The total operative time was 600 min in Case 1 and 365 min in Case 2, with a transfusion of 3 units of packed red blood cells in each case. As a protocol of our hospital, we perform...

Discussion

Portal vein thrombosis is a significant and important complication in patients requiring liver transplantation⁷. For cases with a thrombus that occludes the total lumen of the vein, it is often challenging to perform thrombectomy, especially in cases of chronic thrombosis with fibrotic changes in the vessel and thrombus partially or totally adhered to the vessel wall^6,8. Additionally, complications of traditional thrombectomy techniques in...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
SILK 2-0 PRECUTTED	SHALON MEDICAL, USA.	W3410013	Synthetic non-absorbable Suture
PROLENE 5-0	ETHICON, USA.	W8556	Synthetic non-absorbable Suture
VESSEL LOOP	ASPEN SURGICAL PRODUCTS, USA.		Sterile Silicone