Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1739_Библиотеки_им_академика_М_И_Перельмана.pdf
24
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
an immune response in the recipient, despite being anatomically similar
to allografts.
Xenograft
Xenografts, on the other hand, encompass the transplantation of organs
or tissues from one species to another. A notable example of xenograft
is the successful and widely performed procedure involving porcine
heart valve transplants. In another intriguing application, researchers
have ventured into experimental xenotransplantation by introducing
piscine (sh) islet tissue into non-human primates. This ground-breaking
endeavour aims to explore the feasibility of utilizing such transplants for
human recipients in the future. It is important, however, to acknowledge
the inherent challenges associated with xenotransplantation, including
the risks of non-compatibility, rejection, and the potential transmission
of diseases harboured within the transplanted tissue.
Split Transplants
In certain cases, a deceased-donor organ, typically a liver, may be divided
and allocated to two recipients, often an adult and a child. Although this
approach is not typically the preferred option, it can be a viable solution in
certain circumstances where suitable organ matches for both recipients are
limited. Split transplants provide an opportunity to maximize the utility of
a single organ, offering life-saving benets to multiple individuals in need.
These various transplantation techniques represent significant
advancements in the medical eld, providing hope and opportunities
for patients in need of life-saving procedures. The success and further
development of isografts, xenografts, and split transplants require continuous
research, careful consideration of risks, and ethical considerations to enhance
the overall effectiveness and safety of organ and tissue transplantation
procedures. By continually rening these methods, medical professionals
aim to improve patient outcomes and address the ongoing challenges
associated with organ shortage and transplant-related complications.
Transplantable Organs and Tissues
1. Kidneys: Kidney transplantation is the most common type of organ
transplantation and is used to treat end-stage kidney disease.
Organ Transplantation
25
Dr Gopi Ayyaswamy
2. Liver: Liver transplantation is done for patients with end-stage liver
disease, liver cancer, or acute liver failure.
3. Heart: Heart transplantation is performed for patients with severe heart
failure or certain congenital heart defects.
4. Lungs: Lung transplantation is performed for patients with advanced
lung diseases such as chronic obstructive pulmonary disease (COPD) or
cystic brosis.
5. Pancreas: Pancreas transplantation is done for patients with type 1
diabetes and severe complications related to the disease.
6. Intestines: Intestinal transplantation is performed in cases of intestinal
failure, often combined with liver transplantation for some patients.
7. Uterus transplant: It aims to help women with infertility by transplanting
a healthy uterus from a living or deceased donor. After recovery, the
recipient may undergo IVF using her own or donor eggs. Though some
successful births have occurred, it is experimental and requires further
research.
8. Stomach transplant: Reserved for severe stomach damage, it involves
procuring the stomach from a deceased donor during multi-organ
retrieval. Lifelong immunosuppressive medication is necessary to
prevent rejection.
9. Testis transplant: Experimental due to complexity and risks, it involves
transplanting a healthy testicle into a recipient with testicular failure.
As of September 2021, it is in early research stages with limited
practical applications.
Tissues
1. Corneas: Corneal transplantation is a common procedure to restore
vision in patients with corneal damage or disease.
2. Heart valves: Heart valve transplantation is performed to replace
damaged or malfunctioning heart valves.
3. Islets of langerhans (pancreas islet cells) (deceased-donor and living-
donor).
4. Skin: Skin grafts are used for patients with severe burns or chronic
wounds that require replacement of damaged skin.
26
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
5. Bone: Bone transplantation helps in the treatment of bone fractures,
non-healing bone defects, and bone-related conditions.
6. Tendons: Tendon transplantation is used to repair damaged or ruptured
tendons in various parts of the body.
7. Cartilage: Cartilage transplantation is used to treat joint damage or
defects, often in the knee or shoulder.
8. Blood vessels: Transplantation of blood vessels is done for patients with
vascular diseases or during certain reconstructive surgeries.
These organs and tissues can be donated by living donors (e.g. kidney,
partial liver, and partial lung) or deceased donors (from individuals who
have consented to organ donation prior to their death). Organ and tissue
transplantation have signicantly improved the quality of life and survival
rates for many patients worldwide. The future of transplantable organs and
tissues holds great promise with advancements in regenerative medicine,
tissue engineering, and organ preservation techniques. These innovations
could address the shortage of organs, improve transplant success rates, and
potentially allow for the growth of custom-made organs from a patient’s
own cells.
Types of Donor
• Living donor
• Deceased donor
• Paired exchange
• Good samaritan
Donors can be categorized into various types based on their
circumstances. They can be either living donors or individuals who have
unfortunately passed away, either due to brain death or circulatory death.
The majority of deceased donors fall into the category of brain-dead
individuals. Brain death occurs when there is a complete cessation of
brain function, usually caused by severe traumatic or pathological brain
injury, or a disruption in blood circulation to the brain (such as in cases
of drowning or suffocation). In these situations, medical interventions
are employed to sustain breathing, which in turn keeps the heart beating.
Organ Transplantation
27
Dr Gopi Ayyaswamy
Once brain death is determined, the person becomes a potential candidate
for organ donation. However, it is important to note that the criteria for
diagnosing brain death can vary. Unfortunately, brain death accounts
for less than 3% of all deaths in the United States, leading to a signicant
shortage of available organs for transplantation.
In certain cases, organ donation can also occur after cardiac death. This
occurs primarily when an individual has suffered a severe brain injury
and is not expected to survive without articial ventilation and mechanical
support. Irrespective of the decision to donate, the next-of-kin of the
person can choose to withdraw articial support. If it is anticipated that the
person will pass away shortly after support is withdrawn, arrangements
can be made to withdraw the support in an operating room. This allows
for prompt recovery of organs following circulatory death.
Tissues can be retrieved from donors who have died either due to brain
death or circulatory death. Generally, tissues can be harvested up to
24 hours after the cessation of heart activity, with the exception of corneas,
which can be preserved for a longer duration. Unlike organs, most tissues
can be preserved and stored for up to ve years, which enables them to
be stored in tissue banks. Moreover, a single tissue donor can provide
over 60 grafts, making tissue transplants signicantly more common
than organ transplants. In fact, the American Association of Tissue Banks
estimates that over one million tissue transplants are performed annually
in the United States, beneting numerous recipients in need.
Living Donor
Living donors play a crucial role in the realm of transplantation, as they
selessly contribute renewable tissues, cells, or uids while still alive. This
remarkable act of generosity can encompass various types of donations,
including blood, skin, and even organs or specic portions of organs that
possess the ability to regenerate or compensate for the functions of the
remaining organ. Prominent examples of living donations include kidney
donation, where a healthy individual can donate one of their kidneys, as
well as partial liver donation, lung lobe donation, and small bowel donation.
Looking ahead, the field of regenerative medicine holds immense
promise for the future of organ transplantation. It offers the potential
28
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
to cultivate laboratory-grown organs by utilizing a person’s own cells,
obtained through the innovative technology of stem cells. Another avenue
involves the utilization of healthy cells extracted from failing organs,
which can aid in developing viable organ substitutes. The advancements
in regenerative medicine offer hope for overcoming the limitations
posed by organ shortages and signicantly improving the outcomes of
transplantation procedures.
Deceased Donor
Deceased donors, referred to as cadaveric donors, are individuals who
have been determined to be brain-dead. Their organs are sustained and
kept viable through the use of ventilators or other mechanical means until
they can be surgically retrieved for transplantation. Traditionally, brain-
stem dead donors have constituted the majority of deceased donors over
the past two decades. However, to expand the potential pool of donors due
to the growing demand for transplants, there is an increasing utilization
of donation-after-circulatory-death (DCD) donors, previously known as
non-heart-beating donors.
Prior to the recognition of brain death in the 1980s, all organs procured
from deceased donors came from individuals who had experienced
circulatory death. It is important to note that organs obtained through
circulatory death have shown to have inferior outcomes compared to those
from brain-dead donors. However, given the scarcity of suitable organs
and the number of people awaiting transplants, any potentially suitable
organ must be carefully considered in order to save lives.
Living Related Donors
Living related donors are individuals who choose to donate organs or
tissues to family members or close friends with whom they share an
emotional bond. The decision to become a living related donor is often
driven by a deep sense of connection and a desire to help a loved one in
need. These donors are motivated by the emotional investment they have
in the recipient, and they are willing to undergo the surgical procedure
despite the inherent risks involved.
For living related donors, the prospect of surgery and its associated risks
is outweighed by the psychological benets of not losing a family member
Organ Transplantation
29
Dr Gopi Ayyaswamy
or witnessing their loved one suffer the detrimental effects of being on a
waiting list for an organ transplant. The opportunity to directly contribute
to the well-being and quality of life of someone dear to them serves as a
powerful motivator, leading them to make the seless decision to donate
a part of their own body to their loved one in need.
Paired Exchange
A “paired-exchange” is a technique of matching willing living donors to
compatible recipients using serotyping. For example, a spouse may be
willing to donate a kidney to their partner but cannot since there is not a
biological match. The willing spouse’s kidney is donated to a matching
recipient who also has an incompatible but willing spouse. The second
donor must match the first recipient to complete the pair exchange.
Typically the surgeries are scheduled simultaneously in case one of the
donors decides to back out and the couples are kept anonymous from each
other until after the transplant.
Paired exchange programs were popularized in the New England
Journal of Medicine article “Ethics of a paired-kidney-exchange program”
in 1997 by L.F. Ross. It was also proposed by Felix T. Rapport in 1986 as
part of his initial proposals for live-donor transplants: “The case for a
living emotionally related international kidney donor exchange registry”
in Transplant Proceedings. A paired exchange is the simplest case of a
much larger exchange registry program where willing donors are matched
with any number of compatible recipients. Transplant exchange programs
have been suggested as early as 1970: “A cooperative kidney typing and
exchange program.”
Good Samaritan
The concept of the “Good Samaritan,” also known as “altruistic” donation,
delves into the profound act of giving an organ or tissue to an individual
whom the donor has no prior connection with. This form of donation
transcends mere benevolence; it is a manifestation of an intrinsic desire
to alleviate the suffering of others, propelled solely by compassion and a
profound sense of selessness. It epitomizes the inherent human tendency
to reach out and positively impact the lives of strangers, irrespective of
personal gain or recognition.
30
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
The decision to engage in Good Samaritan donation often stems from
a deep-seated aspiration to contribute to the collective welfare and enact
meaningful change on a broader scale. Those who undertake such altruistic
acts are fueled by an innate empathy and a belief in the transformative
potential of human kindness. As eloquently expressed by an anonymous
Good Samaritan donor, the motivation behind their decision resonates with
a fundamental belief in the ability of acts of kindness to catalyze profound,
life-altering transformations. Through the seless act of donating a part
of themselves, they aspire to sow seeds of hope and facilitate healing in
individuals who nd themselves in dire need.
When it comes to the selection of a recipient, Good Samaritan donors
approach the decision with a variety of perspectives. Some may choose
to defer to the established transplant waiting list, placing trust in the
medical system to identify the most urgent case in need of assistance.
Conversely, others may opt for a more personalized approach, taking
into consideration specic criteria that hold personal signicance. These
criteria could encompass a range of factors, including the recipient’s age,
familial situation, or potential for long-term impact. Such considerations
are made with the overarching goal of maximizing the effectiveness and
signicance of the contribution, ensuring that it serves as a beacon of hope
and resilience.
At its essence, the act of donating as a Good Samaritan is rooted in a
deeply entrenched belief in the interconnectedness of all humanity and the
profound resonance of even the smallest acts of generosity. As articulated
by a compassionate contributor, despite lacking a personal connection with
the recipient, they were keenly attuned to the transformative potential
inherent in their deed. Despite the apparent modesty of their sacrice, they
acknowledged its capacity to infuse hope, happiness, and a revitalized
sense of purpose into the life of someone grappling with significant
challenges. Ultimately, it is the cascading effect of kindness and empathy
that permeates society, serving as a poignant testament to the enduring
strength of human solidarity and empathy. And in the grand scheme of
things, that is what truly counts.
Dr Gopi Ayyaswamy
The scarcity of organs for transplantation presents a signicant disparity
between developed and developing countries, where organ availability
ranges from 45–50% in developed nations to 85% in developing nations
(Chakravorty et al., 2021). While major religions in Asia generally do
not object to cadaveric transplants, there are prevalent misconceptions
and mistrust surrounding the ethical aspects of organ procurement and
concerns about potential misuse. These factors signicantly limit the
consent for organ donation from potential donor families.
From an ethical perspective, a survey conducted in China revealed that
more than 80% of respondents believed that organ transplantation could
extend life. However, there were concerns about the fair and appropriate
utilization of donated organs, with 74% expressing apprehension that the
wealthy and celebrities might receive preferential treatment. Furthermore,
61% agreed that organ donation laws and regulations were not well-
developed, resulting in unnecessary difculties (Chakravorty et al., 2021).
In a study conducted in western India by Balwani et al. it was found
that a majority of participants (59%) were aware of organ donation but
harboured concerns about the potential dangers of organ misuse, abuse,
or misappropriation. Among those who were aware, approximately 47%
expressed willingness to consider organ donation, while only 16% stated
that they would denitely donate regardless of circumstances (Balwani
et al. date).
The emergence of organ trafcking and patient-tourism from afuent
countries prompted the World Health Organization to urge member states
Ethical, Religious,
Sociocultural Factors
5
32
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
to take measures to protect vulnerable groups from transplant tourism and
the illicit sale of tissues and organs. The Istanbul Declaration was aimed
at promoting transparency and implementing stricter controls over organ
sales (World Health Organization, 2004).
While no major religion explicitly prohibits organ donation or
transplantation from living or deceased donors, there are isolated cases
within specic religious groups where such prohibitions may exist.
For example, some orthodox Jews may have religious objections to
“opting in” for donation, and certain religious communities, such as
Native Americans, Roma Gypsies, Confucians, Shintoists, and specic
orthodox Rabbis, may discourage transplantation from deceased donors.
In certain south Asian Muslim communities, opposition to donation
from both living and deceased donors may be rooted in the belief that
the human body is a trust from God and should not be desecrated after
death, although these communities may support xenotransplantation
(Chakravorty I, 2020).
Cultural challenges arise due to inadequate cultural competence and
sensitivity among healthcare professionals when engaging with potential
donor families. The lack of understanding regarding the cultural and
religious perspectives of Muslim families, for instance, can hinder
effective discussions about brain death and organ donation in critical
care settings.
In addition to religious obstacles, misinformation also poses signicant
challenges. In an orthodox Muslim country, a notable percentage of
respondents (69%) considered organ donation and transplantation
acceptable from a religious standpoint. However, concerns were raised
about the belief that one kidney would not be sufcient for survival (50%),
potential harm to the remaining kidney (26%), and fear of the operation
itself (15%).
Despite these challenges, faith-based non-profit organizations like
Matnat Chaim (“Gift of Life” in Hebrew) have emerged as inuential forces
in facilitating living unrelated donor kidney transplantation, primarily
focusing on promoting altruistic donations.
Addressing the ethical, religious, social, and cultural determinants
surrounding organ donation necessitates comprehensive efforts to increase
Ethical, Religious, Sociocultural Factors
33
Dr Gopi Ayyaswamy
awareness, dispel misinformation, and enhance cultural competence
among healthcare professionals, and foster open dialogue that respects
diverse perspectives and beliefs. By understanding and addressing these
factors, we can strive to bridge the gap in organ availability and meet the
growing demand for life-saving transplants on a global scale.
Policy of Organ Donation and Transplant
More than fty years ago, the American Bar Association approved the
Uniform Anatomical Gift Act (UAGA) in the United States, providing
a legal framework for a nationwide organ donation system based on
the principles of altruism, autonomy, and public trust. In 2006, an
amendment to the UAGA aimed to increase the availability of organs for
transplantation. However, this amendment shifted the authority over end-
of-life decisions from patients or their surrogates to organ procurement
organizations, which may be inconsistent with common law and the ethical
and legal standards governing medicine.
The concept of “presumed consent” is a legislative approach in which
citizens are assumed to consent to organ donation unless they explicitly
opt out by registering their decision. Implementing presumed consent
legislation to address the organ shortage has raised ethical concerns. In
2015, the Welsh Assembly passed legislation to enable the introduction
of presumed consent. However, there is limited evidence to suggest that
presumed consent alone will effectively increase organ donation rates.
It is unlikely that presumed consent can fully explain the variations
in organ donation rates between different countries, nor can it serve as
a cure-all solution for the signicant shortage of organs. Infrastructure
improvements have played a crucial role in increasing deceased donation
rates in the UK by 63% since 2007. If consent rates from families could be
improved to match the levels seen in Spain (85%), the UK’s organ donation
rate could become one of the best in the world (Chakravorty I, 2020).
However, in developing countries, the lack of adequate infrastructure
and resources presents a significant barrier to organ retrieval and
matching, even if consent is available. Enormous government investments
in retrieval hardware and logistics would be necessary to overcome these
challenges.