In a recently published study, Dr Scientific report, A group of researchers evaluated the effectiveness of magnetic anastomosis technology (MAT) in reducing the duration of vascular anastomosis and improving the outcome of pig orthotopic liver transplantation (OLT).
Study: Liver transplantation using magnetic anastomosis in pigs. Image credit: mi_viri/Shutterstock.com
Liver transplantation is an important treatment for end-stage liver disease, the duration of the anhepatic phase being a significant factor influencing the prognosis of recipients.
A prolonged anhepatic period, associated with prolonged warm ischemia time and blood flow disturbances, increases the risk of various complications, such as allograft dysfunction and renal insufficiency. Although effective, traditional hand-sewn vascular anastomosis techniques are time-consuming and contribute to the length of the anhepatic phase.
MAT represents a convenient, time-saving method for revascularization, potentially reducing these risks. Despite its promising applications in animal models, further research is needed to refine this technology to understand its long-term effects and biocompatibility, especially for clinical use in human liver transplantation.
About the study
The study used a novel magnetic device for MAT to transplant pig livers for which twenty healthy adult Bama pigs, randomly divided into donors and recipients, were used.
Donor livers were harvested, flushed cold with University of Wisconsin solution, and stored at 4°C in the same solution. During transplantation, magnetic rings were applied to both the donor and recipient liver stumps in the portal vein and inferior vena cava (suprahepatic and infrahepatic).
The anastomosis was achieved by bringing the magnetic rings of the respective vessels into proximity allowing rapid magnetic attachment and vascular connection. Hepatic artery and biliary anastomosis was done manually.
Preoperative management included antibiotics and analgesics but excluded immunosuppressants. Liver and kidney function were monitored pre-surgery and at various intervals after surgery. Imaging studies including abdominal vascular ultrasound and venography were performed to assess patency of vascular anastomoses.
Tissues were sampled for histopathological analysis after euthanasia. Data were presented as either counts (percentages) or median values with interquartile ranges (IQR).
Paired t-test or Wilcoxon signed rank test was employed to assess differences between means depending on the suitability of the data set. A p-value of less than 0.05 was considered to indicate statistical significance.
Results of the study
In the current study involving liver transplants using MAT in pigs, all surgeries performed on the recipients were successful. The mean duration of the operation was recorded as 225 minutes, the cold ischemia time of the donor liver was about 59 minutes.
The anhepatic phase, crucial in liver transplantation, was relatively short, with a duration of 13 minutes. At this stage, the suprahepatic and infrahepatic inferior vena cava were ligated, taking 4, 3, and 3 minutes, respectively. Additionally, recipients had an ischemia time of only 4 minutes. On the other hand, suturing techniques to connect arteries and bile ducts are more time-consuming manually.
After surgery, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels increased, which are indicators of liver injury. However, these levels begin to decrease within 24 hours.
Serum total bilirubin also showed a significant increase after surgery but decreased after 24 hours. Kidney function was stable during both surgical periods as assessed by blood urea nitrogen (BUN) and serum creatinine (CRE) levels.
The median survival time for recipients after transplantation was 115 days. Major causes of death include liver failure, systemic rejection, and infection. Other contributing factors are edema and bleeding from arterial anastomosis. Fortunately, during the recovery period after surgery, there were no complications such as blockage or leakage of blood vessels in the liver.
A detailed examination of vascular anastomoses performed with MAT revealed positive results. In one instance, a recipient who survived for 13 days postoperatively showed a well-healed vascular anastomosis.
The magnetic devices used for anastomosis were perfectly aligned, there was no sign of stenosis or angulation, and the anastomotic stoma surface was smooth. Histological analysis supports these findings, showing a regular arrangement of intima and endothelial cells and collagen fibers at the anastomotic site.
These results demonstrate the potential of MAT in liver transplantation to effectively reduce critical operation times while ensuring the integrity and function of vascular anastomoses.
In summary, in the study, MAT was successfully used for rapid donor liver implantation in pig liver transplantation without any postoperative complications related to the technique. Traditional hand-sewn vascular anastomosis procedures in liver transplantation are complex and time-consuming, often leading to prolonged anhepatic phases.
The newly designed MAT, employing a Ti-NdFeB composite magnetic ring suitable for permanent implantation, demonstrated excellent biocompatibility and significantly reduced the anhepatic duration to 13 minutes.
This innovation not only facilitates vascular anastomosis but also minimizes renal and intestinal damage associated with prolonged anhepatic phases.
The study also addressed potential concerns regarding anastomotic angulation or distortion due to magnetic forces. This confirmed the safety and efficacy of magnetic rings, underscoring the potential to improve liver transplant outcomes by reducing ischemia-reperfusion injury.