There are in situ liver transplantation and ectopic liver transplantation according to the location of transplanted liver implantation. According to the source of transplanted liver, there are brain dead donor liver transplantation, heartless donor liver transplantation, living donor liver transplantation and Domino liver transplantation. According to the vein reconstruction method, there are classical liver transplantation and backpack liver transplantation. Partial liver transplantation includes reduced volume liver transplantation, split liver transplantation and living donor liver transplantation.
Liver transplantation is performed in two groups, namely the donor liver extraction group and the recipient surgery group. The donor liver excision group is responsible for the complete excision of the donor liver, the cooling and irrigation, the cryopreservation, and the necessary recuperation before implantation. The recipient surgery group removes the diseased liver and then implants the rested donor liver, anastomoses the blood vessels and reconstructs the bile ducts.
Donor liver acquisition surgery for cadaveric liver transplantation: Currently, rapid donor liver resection is mostly used in China, especially for cases where the donor is hemodynamically unstable or has gone into cardiac arrest. Immediately after the donor’s death, a large cross-shaped incision is made and the small intestine is turned to the left side, free near the bifurcation of the abdominal aorta, the distal end is ligated, the anterior wall is cut, and a balloon catheter is inserted above the opening of the abdominal artery. Immediately after filling the balloon, the abdominal aorta was perfused with 2500-3000 ml of UW fluid or renal preservation fluid. Ensure that the cadaveric liver is thermally ischemic for no more than 5 minutes. At the same time, the transverse colon is lifted, the small intestine is ruffled, and the superior mesenteric vein is dissected out at the root of the mesentery, with the distal end clamped shut and its proximal end inserted into the perfusion tube. Immediately start portal vein perfusion with 1-4°C UW fluid or renal preservation fluid. This is followed by clipping of the inferior hepatic vena cava at the same level, i.e., below both renal veins. If only liver organs are harvested, effective perfusion can be achieved by perfusing the portal vein. For combined organ harvesting, incision lifts the duodenum and pancreas to reveal both kidneys, and below the plane of the renal vessels, the abdominal aorta and the inferior hepatic vena cava are cut, and both kidneys and the liver are cut simultaneously. The liver is sealed in a sterile plastic bag filled with 1-4°C UW fluid, kept cold with ice chips, and quickly transported to the transplantation operating room.
For live liver transplantation, the right hemicolectomy is used as an example, and a right subcostal margin incision is mostly used to routinely take liver biopsies. Intraoperative ultrasound is used to understand the vascular anatomy, the course of the left, middle and right hepatic veins and the main branches of the portal vein. Intraoperative cholangiography is performed to understand the biliary anatomy through the placement of the cystic duct. Perform perihepatic freeing, freeing the 1st, 2nd and 3rd hepatic hilum, trying not to damage the hepatic artery and biliary blood flow, and pay attention to preserve the well-positioned gallbladder artery. The liver was cut with an ultrasonic emulsion suction knife without blocking the hepatic blood flow, and the liver section was treated with bipolar electrocoagulation of vessels below 1 mm in diameter and ligation of ducts above 1 mm. When the middle hepatic vein is not brought, the branches of the middle hepatic vein with thick sections (>5 mm in diameter) are temporarily clamped with large titanium clips and left for vascular bypass anastomosis when the donor liver is trimmed. If the thicker 4a segmental vein converges with the middle hepatic vein, the confluence of the middle hepatic vein and 4a segmental vein should be dissected, and the middle hepatic vein should be dissected immediately at the base, and part of the middle hepatic vein should be cut. The bile duct dissection line should be at least 2 mm above the opening of the right hepatic duct to prevent stenosis of the left hepatic duct after suturing. The corresponding hepatic vessels are sequentially blocked and cut, and the donor liver is removed and moved to the back table for perfusion and trimming. Perfusion and trimming of the donor liver: Perfusion is performed with 4°C UW fluid or HTK fluid at more than 3 times the volume of the liver. During the perfusion process, the vein to be reconstructed in the liver section and the right inferior hepatic vein to be reconstructed are opened, and the thrombus is carefully removed and fully perfused. If the donor liver contains the middle hepatic vein, the right and middle hepatic veins should be reconstructed or the right hepatic vein should be reconstructed after partial bypass of the middle hepatic vein, and if the donor liver does not contain the middle hepatic vein, the thick branch of the middle hepatic vein in section V and VIII should be reconstructed by allogeneic iliac vein, autologous portal vein, hepatic vein or attached umbilical vein.
Classical in situ liver transplantation
A curved epigastric incision with a midpoint extending upward to the sternocarpal process is commonly used. A special liver graft retractor is used to pull the bilateral helper arches upward to fully expose the subphrenic area. Patients requiring extracorporeal vein-venous transfer should have both the left axillary area and the left inguinal area ready. The resection of the diseased liver begins with extensive ligation of the huge collateral vessels to minimize blood loss to a large extent possible. The coronary ligament and the left deltoid ligament will be tied in sequence. The hilar region is dissected to expose the common bile duct, hepatic artery and portal vein respectively near the diseased liver side. (1) extracorporeal venous-venous diversion method (Bypass method): This method can reduce venous blood depression in the lower trunk, protect renal function and reduce blood loss. When intending to perform venous diversion, the posterior segment of the vena cava of the liver is removed together with the diseased liver, and the inferior vena cava needs to be blocked above and below the liver, and then the upper and lower vena cava of the donor liver are anastomosed separately to reconstruct the caval blood flow; (2) non-diversion method: the procedure is the same as the diversion method, except that extracorporeal venous-venous diversion is not performed, requiring a short hepatolithiasis-free period, and the recipient may experience hemodynamic instability. Vascular anastomosis procedures: inferior and inferior hepatic vena cava, inferior hepatic vena cava, portal vein; hepatic flow reconstitution followed by arterial and biliary tract reconstruction. There are two types of biliary tract reconstruction: common bile duct – common bile duct para-end anastomosis and Roux-en-Y biliary-intestinal anastomosis.
Dorsal pack in situ liver transplantation
When the recipient’s diseased liver is removed, the posterior inferior vena cava and the left, middle and right hepatic veins at the second hepatic portal are preserved, and the transplanted liver is implanted with end-to-end anastomosis between the inferior and superior vena cava and the recipient’s hepatic veins (usually the left and middle hepatic veins).
Initially, it was limited to whole liver transplantation, but with the development of transplantation techniques, it is now used in combination with other procedures such as volume reduction liver transplantation, living liver transplantation, split liver transplantation, and multi-organ combination transplantation. The advantage is that the vena cava remains undamaged intraoperatively and the blood flow is continuously unobstructed, reducing major disturbances to the hemodynamic forces. The method involves further dissection of the diseased liver from the vena cava after dissection of the liver tip, followed by sequential blockage of the left, middle, and right hepatic veins, with the stumps of the three hepatic veins being used to form a common opening to anastomose with the superior hepatic vena cava port of the donor liver to divert blood flow to the transplanted liver. The inferior hepatic vena cava port of the transplanted liver is ligated. This is followed by completion of arterial bile duct reconstruction.
Living Liver Transplantation
Living liver transplantation can be performed as an elective procedure, as early as possible before the recipient’s condition deteriorates. Close surgical coordination between donor and recipient can minimize the ischemic time of the donor liver. Histocompatibility of the living donor liver between blood relatives is better, and the use of immunosuppressive drugs can be reduced after surgery.
The recipient’s surgery begins with resection of the diseased liver with a bilateral subcostal incision and a combined median incision to the glabella, with the ducts at the recipient’s end and their blood flow preserved for as long as possible during hepatic portal freeing. The right hepatic vein is dissected close to the posterior inferior hepatic vein, and a triangular outlet with the right side of the right hepatic vein as the base is made with the tip to the left to prevent anastomotic stenosis, and if there is a thick right inferior hepatic vein in the donor liver, an oval incision is made in the appropriate part of the posterior inferior hepatic vein to anastomose with it. The right branch of the donor portal vein is anastomosed end to end with the trunk of the recipient portal vein, paying attention to the appropriate length of the trunk of the portal vein after the anastomosis. The hepatic vein and portal vein are then opened and the donor liver is restored to perfusion, ending the anaphylactic phase, and the hepatic artery anastomosis and biliary anastomosis are completed sequentially.
Volume Reduction Liver Transplantation
Reduced volume liver transplantation is an anatomical removal of a portion of the liver and transplantation of only part of the liver, with the untransplanted portion being discarded. Because there is only one recipient, longer vessels and bile ducts can be obtained, and the procedure is much less difficult and complex than split liver transplantation. Volume reduction liver transplantation was initially used mainly for pediatric recipients, and while it has increased the number of pediatric liver transplants, it has decreased the number of transplant opportunities for adults. With the current shortage of donors and the advancement of technology, volume reduction liver transplantation is rarely performed and split liver transplantation is mostly performed.
Split-Liver Transplantation
The original intent of split liver transplantation was to provide an appropriate volume of donor liver for children without compromising the number of adult recipients transplanted. The donor liver parenchyma, vascular and biliary structures are split appropriately and transplanted into two recipients. Initially used primarily for pediatric liver transplantation, splitting is now becoming routine and is being expanded to adult liver transplantation. The cadaveric liver donor cleavage can be done ex vivo, after cutting the donor liver, the isolated body is cleaved in the organ preservation fluid, the cold ischemia time will be prolonged; there is also in the case of hemodynamic stability, first in the donor body cleavage before cutting, the in situ cleavage method mainly increases the operation time of donor liver cutting, and may even affect the other organs cutting operation. Currently, the actual situation in China is mostly ex vivo splitting.
Adjuvant Liver Transplantation
The concept of assisted liver transplantation was first introduced by Welch in 1955, in which all or part of the transplanted liver is implanted into the recipient while preserving part or all of the recipient’s liver, so that patients with liver failure can receive temporary support pending the recovery of the original liver function, or so that the metabolic and detoxification functions missing in the original liver can be compensated. Currently, in situ liver transplantation is the treatment of choice for end-stage liver disease. However, there are still many intractable problems with in situ liver transplantation, including the lifelong administration of immunosuppressive drugs to the patient’s blood and the resulting complications such as serious infections and neoplastic malignancies that cannot be ignored; and the distant failure of the transplanted liver. Therefore, people have started to re-evaluate the role of adjuvant liver transplantation, especially for adjuvant liver transplantation to preserve the chance of regeneration of the original liver cells, making it possible for patients to obtain a regenerated liver and complete withdrawal of immunosuppressive drugs. Adjuvant liver transplantation is divided into adjuvant total liver transplantation and adjuvant partial liver transplantation depending on the transplanted liver. Adjuvant in situ liver transplantation and adjuvant allograft liver transplantation are classified according to the site of the transplanted liver. Adjuvant living liver transplantation and adjuvant cadaveric liver transplantation are classified according to the source of the donor liver. The main types of liver transplantation used in clinical practice are ectopic assisted partial liver transplantation, where the donor liver is usually placed in the right paracolic sulcus, and in situ partial assisted liver transplantation, where the donor liver is implanted in situ after partial resection of the original liver. Since both procedures use partial donor liver transplantation, the problem of intra-abdominal space and pressure is effectively solved.
Allogeneic liver transplantation
In 1955, Welch first performed an ectopic liver transplant, but found many obstacles that were difficult to overcome, including the difficulty of implanting the transplanted liver into a normal anatomical site because the diseased liver was not removed, the significant increase in abdominal volume after implantation, severe postoperative respiratory distress, and compression of the hepatic vessels; if the transplanted liver was implanted in the iliac fossa, the transplanted liver could not receive portal blood supply and was deprived of nutrients necessary for liver growth. This procedure is also not suitable for patients with hepatobiliary malignancies. Currently, only adjuvant liver transplantation may be performed with allogeneic liver transplantation; in situ liver transplantation is generally performed.
Domino Liver Transplantation
Domino liver transplantation is the simultaneous transplantation of the liver removed from the first liver transplant recipient as a donor liver to other patients, in a domino-like sequence. The liver to be used in a domino liver transplant must be functional, and there must be a long enough latency period for the development of metabolic deficiency disease in the domino recipient implanted with the resected liver. Currently, the most commonly used donor for Domino liver transplantation is a patient with familial amyloid polyneuropathy.