The liver

A vital centre for many physiological functions is the liver. These include the metabolism of macronutrients, blood volume control, immune system support, endocrine regulation of growth signalling pathways, homeostasis of lipids and cholesterol, and the metabolism of xenobiotics, which includes many modern medications. 

Among the liver's most important tasks are the processing, partitioning, and metabolism of macronutrients, which supply the energy required to power the above-mentioned operations. In addition to oxidizing fats, the liver can package extra fat for secretion into and storage in other tissues, like adipose tissue. Lastly, the liver plays a significant role in the metabolism of proteins and amino acids.¹

Liver transplantation 

For liver failure, liver transplantation (LT) is the recommended course of treatment. There is a scarcity of organs as a result of the rise in transplantation activity and the expansion of LT indications over time. An increase in the donor pool and a strict recipient selection process with prioritising mechanisms were required to address this condition.²

History of liver transplantation 

Welch was the first to officially describe liver transplantation as a treatment in science in 1955. He suggested an ectopic liver transplant in the abdominal cavity at that time. Francis Moore first wrote about the first orthotopic liver transplant in a dog in 1958.

Starz et al. performed the world's first liver transplant on March 1st, 1963.

The primary causes of early and late deaths in liver transplantation were, respectively, infection-related complications and chronic rejection.

After analysing the outcomes of 531 cases, the National Institutes of Health authorised liver transplantation as a legitimate treatment for end-stage liver diseases in 1983.

Eventually, in 1990, Starzl et al. reported the first use of the novel tacrolimus as an immunosuppressive agent in liver transplant recipients who experienced rejection despite receiving standard immunosuppressive therapy. 

Over 10,000 liver transplants have been carried out worldwide to date, more than 40 years after the first liver transplant. Within the first year following a liver transplant, the survival rate is between 80% and 90%. Results began to gradually improve, and issues with surgery, rejection management, and untreated sepsis control were all resolved.³

Perspectives:

A major obstacle in the field of liver transplantation is the dearth of donors in comparison to the increasing need for transplant candidates.As a result, we draw attention to the pertinent issues of recipient and donor selection, allocation, and organ preservation, all of which are necessary to improve liver transplant outcomes.

The scarcity of allografts can be significantly altered by the use of xenotransplantation, which primarily involves the use of genetically modified pigs, as well as bioengineering, which involves the creation of synthetic liver in a lab.

However, new strategies must concentrate on providing the greatest possible use of hepatic allografts in Brazil until we reach this next level. It might be possible to use allografts that would otherwise be discarded by employing mechanical or pharmacological techniques.³

Complications in post-liver transplant patients

Principal graft failure:

With a frequency of 5.2-20%, early allograft dysfunction (EAD) is a potentially fatal consequence.  Primary non-function (PNF), is the most severe variation of this issue. Intraoperative flow modulation is a means of prevention.

While plasma exchange might help patients heal more quickly, a retransplant is still necessary.The goal of treatment is to lower portal hypertension, usually by sacrificing the spleen. However, the mortality rate remains high (up to 50%) and they are frequently ineffective. When managed properly, using potentially small grafts is associated with slightly worse short-term outcomes but long-term results comparable to "normal size" grafts, so it is definitely worth considering. 

Refusing to accept the graft

Rejection is categorised as hyperacute (occurring within hours of LT), acute (occurring within two to six weeks), or chronic based on the onset time.

The extremely low rate of hyperacute rejection results from the presence of particular preformed recipient antibodies, which in turn cause low graft survival rates. An important risk factor is ABO incompatibility. A retransplant is urgently needed.

The T-lymphocyte response leads to acute rejection. 15–25% of LT recipients are affected by this type of graft rejection, which is the most common. 

The gold standard for diagnosis is a biopsy with typical findings, which should be used to confirm rejection, recurrence, or therapy insensitivity.  The loss of bile ducts, or "ductopenia," and the macrophage blockage of the arterioles are signs of chronic rejection. The diagnosis needs to be confirmed by a liver biopsy. This complication can be the result of an antibody-mediated response, chronic rejection due to recurrent acute rejections, CMV infection, or graft ischemia associated with artery stenosis.

Infections after transplantation:

 To avoid a potential recurrence under an IS regimen, all recipients should be screened for acute or chronic bacterial, fungal, or viral infections prior to transplantation. 

Prophylaxis, vaccination, and preemptive therapy are all part of prevention. Immunisations against hepatitis A and B viruses, tetanus, pneumococcus, VZV, and H. influenza are among those that are advised.

 A higher susceptibility to infection was caused by surgical stress and the use of IS, and the vast majority of LT patients will experience an infection of some kind. Even with appropriate preventive measures, surgical sites, the abdomen, the bloodstream, the urinary or respiratory tract, and the surgical site may all experience bacterial and fungal infections (mostly nosocomial) within the first month. The two most prevalent types of bacteria are Pseudomonas and Escherichia coli.

Community-acquired infections, such as respiratory, urinary tract, or biliary infections, are the most prevalent after six months from LT.

Regular hand washing, wearing gloves when gardening or farming, quitting smoking, avoiding contact with sick people, avoiding potentially contaminated water (public fountains can harbour giardiasis or cryptosporidiosis), avoiding raw food, and living with healthy pets are all practical ways to lower the risk of infection.

Additional medical postoperative problems

Following surgical procedures, pulmonary complications are often encountered. Long-term surgery, significant intraoperative blood loss, the need for blood transfusions and large fluid infusions, sepsis, pulmonary aspiration, and alterations in liver reperfusion hemodynamics are among the specific risk factors following liver transplantation.

Severe ischemia/reperfusion injury to the liver results in post-reperfusion syndrome (PRS), which is an overabundance of inflammatory response activation. 

Following LT, neurologic problems are fairly common and could contribute to postoperative mortality. While these issues typically arise in the first month for patients, neurological complications can happen up to a year following the LT. The multifactorial complications consist of focal motor deficits, encephalopathy, and seizures.⁴

After-transplantation 

 Since survival rates have increased, attention has turned to long-term survivors' quality of life (QOL) following LT and the treatment of immunosuppressive disorders and primary liver disease recurrence, which are major causes of morbidity and mortality. These days, routine health examinations are included in standard follow-up protocols along with the necessary screening for a range of benign and malignant conditions.

Increasing life quality

Based on available data, quality of life (QOL) significantly improves following lung transplantation (LT) in comparison to pre-transplantation health. Physical functioning, cognitive abilities, social functioning, and emotional well-being are domains that show improved quality of life after LT. Nevertheless, there is conflicting data when comparing the QOL post-LT to the overall population. According to certain research, LT patients' quality of life is either higher than or comparable to that of the general public. On the other hand, a systematic review has shown that although QOL increases following LT, LT patients' QOL is lower than that of healthy controls. Furthermore, it has been noted that the recipient's age, race, and sex all affect how well they respond to LT.

 In a similar vein, the QOL following LT seems to be strongly correlated with the type of underlying illness. ALD, de novo diseases, hepatitis C, and prolonged immunosuppressive exposure are all linked to a lower quality of life. In light of the current circumstances, future research should focus on gender-specific quality of life (QOL), particular patient populations (those with hepatitis C, ALD, and de novo diseases), and particular areas of psychological and general health in order to lessen or completely eradicate the difference in QOL between transplant recipients and the general public.⁵

Summary

Liver transplantation is a crucial treatment for liver failure, with a history dating back to the pioneering work of Starzl et al. in 1963. Despite advancements, donor scarcity remains a challenge, prompting exploration into xenotransplantation and bioengineering solutions. Post-transplant complications include graft failure, rejection, infections, and medical issues like pulmonary and neurological complications. Despite improved survival rates, attention is now shifting towards enhancing long-term quality of life for recipients through comprehensive follow-up protocols. Quality of life post-transplant varies based on factors like underlying illness and recipient demographics, urging further research for targeted improvements.