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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_999_Библиотеки_им_академика_М_И_Перельмана
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M. Zhang et al.
Table 14.3
to Liver Transplantation
Contraindications
Absolute
Flow-limiting coronary artery disease
Severe valvular disease
Reduced left ventricular ejection fraction
Severe right heart dysfunction
Mean pulmonary artery pressure>40mmHg
Extra-hepatic malignancy
Uncontrolled psychiatric illness
Absence of social support
Inability to pay for post-transplant medications
Relative
Advanced age with signicant co-morbid
conditions
Advanced frailty
Severe obesity
Non-treatable infections or SIRS, sepsis, ARDS
Absence of surgical options for portal inow
Untreated drug/alcohol addiction
SIRS Systemic inammatory response syndrome,
ARDS Acute respiratory distress syndrome
status and comorbid conditions. Without doubt, older recipients have a more difcult time recovering from liver transplantation. Accordingly, they should have fewer
comorbidities and a better functional status than otherwise similar younger candidates (Table14.3).
Frailty
Although age and frailty do not strictly correlate, it is often true that frailty
increases with increasing age. Preoperative assessment of frailty is important in
any potential candidate for liver transplantation [15, 16]. Grip strength or number
of transitions between sitting and standing in a xed time period are combined
with nutritional assessment and sometimes quantication of muscle mass.
Although there is not, as yet, a universally agreed upon frailty index for liver
transplantation, most transplant providers utilize a personal gestalt in judging
physical readiness for transplant. Unless the candidate has been recently hospitalized and has had a precipitous decline, persistent non-ambulatory status is highly
concerning.
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Obesity
Akin to age, there is no recommended maximum body mass index for transplant
candidates [17, 18]. Despite this, all transplant surgeons will acknowledge that
operative difculty increases with increasing recipient BMI, notably in the presence
of ascites and a high degree of intra-abdominal (visceral) adiposity.
Hepatocellular Carcinoma (HCC)
The Milan criteria [19] proposed that favorable transplant outcomes could be
achieved for single tumors <5cm in size and for up to 2–3 tumors, provided each is
less than 3cm in size. More recently UCSF [20] (a single tumor ≤6.5cm or ≤3
tumor each less than ≤4.5cm in size with a cumulative diameter of ≤8cm.) and
Toronto criteria [21, 22] (no limit on tumor size or number, provided there is no
extra-hepatic extension and tissue biopsy is free of vascular invasion or poorly differentiated cell morphology) have been adopted.
Infection
Infection is sometimes, but not always, a contraindication to liver transplantation
[23–25]. Common recipient infections include spontaneous bacterial peritonitis,
pneumonia, bacteremias, C.Difcile infection, and active lower extremity cellulitis. Localized infections that are actively being treated are usually not a barrier to
successful transplantation. Infections not amenable to rapid clearance (e.g. endocarditis) and systemic infections causing systemic inammatory response syndrome (SIRS), sepsis or acute respiratory distress syndrome (ARDS) are
contraindications to liver transplant.
Recipient Anatomy
Anatomic considerations rarely preclude liver transplantation. Nevertheless technical success requires robust portal and arterial inow to the liver, unobstructed
venous outow, and ability to reconstruct the biliary tract. Hepatic venous outow
into the inferior vena cava is rarely an issue except in certain patients with
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Budd- Chiari syndrome, or tumor margins close to the vena cava. Problems with
the recipient hepatic artery do not preclude liver transplantation because arterial
conduits built with donor iliac vessels can be anastomosed to the supraceliac or
infrarenal aorta; however, severe atherosclerosis of the recipient celiac tree and
abdominal aorta is problematic. Portal vein thrombosis or absence (cavernous
transformation of the portal vein) pose unique technical challenges but do not
preclude liver transplantation unless all other sources of alternative portal inow
are unsuitable. Biliary reconstruction can be difcult but is always achievable
using a duct-to-duct anastomosis, Roux-en-Y hepaticojejunostomy, or even
choledochoduodenostomy.
M. Zhang et al.
Active Substance Abuse
Active substance abuse is not uncommon in liver transplant candidates [26,
27]. Center polices on marijuana use are variable and national guidelines do
not exist [28]. Active use of “hard” drugs (cocaine, heroine, amphetamine,
ecstasy) is generally considered a contraindication to transplant. Alcohol use
is controversial. Many centers have protocols for selection and transplantation
of patients with acute alcoholic hepatitis, often with excellent results [29, 30].
In cases of established alcoholism where patients have previously been advised
by a physician to stop drinking, a period of complete sobriety and participation in substance abuse counseling are generally required. The necessity of
counseling and the length of sobriety required are complex issues because
alcohol-related recidivism has been notoriously difficult to predict in liver
transplant recipients [31, 32].
Acute/Fulminant Liver Failure
Transplant professionals must carefully weigh the magnitude of critical illness
against the ability to rapidly and completely correct the proximal causes of illness
[33, 34]. Most transplant centers will consider intubated candidates so long as the
fraction of inspired oxygen (FiO2) and degree of ventilatory support are not
excessively high. Likewise most centers will proceed with candidates on low
doses of one or two vasopressors but not candidates on near-maximal support.
Renal failure can be managed both intraoperatively and postoperatively and need
not be a contraindication. Neurologic evaluation is essential, and CT-imaging is
generally used to monitor for cerebral edema. High-dose continuous renal
replacement therapy (CRRT) [35, 36] and/or adjunctive therapies such as the
molecular absorbent recirculation system (MARS) [37, 38] should be used to
clear ammonia and other toxins from the circulation. Hypernatremia is an ominous sign [39].
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Living Versus Deceased Donor Liver Transplant
All transplant candidates should be considered for both living and deceased liver
transplantation. Currently, liver allocation in the United States is guided by “sickestrst” prioritization wherein the MELD score [40, 41] is used to quantify the degree
of illness and rank-order candidates. The median MELD score at transplant in the
United States is approximately 29 [42], with a range from 6–40 (the higher the
score, the worse the prognosis), and the median waiting time from listing to transplant is 13.5months [43]. MELD-based allocation strongly favors acutely ill candidates. There are many candidates with signicant symptoms and a poor quality of
life who face long waiting times to transplant because of low-medium MELD scores
that do not rise rapidly [44]. For these candidates, living donor liver transplantation
(LDLT) can offer the fastest route to transplantation and cure.
Living Versus Deceased Donor
Most studies suggest that long-term graft and patient survival are slightly superior
for living donor recipients [45, 46]. These ndings must be tempered by knowledge
that living donor recipients are carefully selected. Nonetheless, because living
donors are exceedingly healthy and the transplanted liver mass is typically pristine,
superior graft survival is expected. This advantage of living donor liver transplantation is counterbalanced by increased rates of biliary complications and hepatic arterial thrombosis (HAT) [47]. The re-intervention rate following living donation,
including percutaneous, endoscopic, and operative procedures, is generally much
higher than that seen following transplantation with a deceased donor allograft. The
increased re-intervention rate is easily explained by the technical challenges of the
smaller sized vessels present on the donor hemi-liver.
Due to the increased technical complexity of living donor liver transplant, not
every candidate is appropriate for this operation. Candidates with prior upper
abdominal surgery, extensive portal vein thrombosis, or need for caval replacement
require careful preoperative consideration if living donation is to be used.
Additionally, selected recipients should have a baseline level of stamina and tness
that will allow them to endure the re-interventions that are common following
LDLT.Recipient selection for LDLT depends heavily on center expertise and the
program maturity of the LDLT center.
Brain Dead (BD) Versus Cardiac Death (DCD) Donors
BD donors are generally considered favorable because these organs are never subjected to a period of asystole during which tissues are warm, non-oxygenated, and
prone to microvascular clot formation. Recognized complications of DCD liver
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transplantation include ischemic cholangiopathy (IC) and early allograft dysfunction (EAD) [48–50]. Historically, DCD liver transplantation was associated with
both decreased patient and graft survival; however, recent reports suggest that
equivalent outcomes can be achieved by experienced centers with rigorous DCD
protocols [51]. Just as in LDLT, recipient selection is critical to success in DCD
liver transplantation. Short cold ischemic times are required to mitigate the risk of
IC and therefore, an expeditious hepatectomy is required. For this reason, candidates with complex prior surgical histories or extensive portal vein thrombosis are
sometimes avoided in DCD transplantation. Interestingly, recent advances in normothermic oxygenated perfusion pumps [52, 53] and normothermic regional perfusion [54, 55] offer opportunity to offer DCD liver transplantation to a far wider pool
of potential recipients.
Overall, donor and recipient pairing is an exercise in risk management. Critically
ill recipients and frail recipients have the least capacity to withstand complications
and benet from high-quality donor allografts with low risk for primary nonfunction (PNF), EAD, or IC.As recipient acuity drops donor selection can be liberalized. The risk of waitlist mortality should always be compared against the risk of
perioperative mortality when non-ideal donor allografts are used [56].
M. Zhang et al.
Timing andTeam Coordination
Logistics and timing are crucial to success in liver transplantation. Numerous studies
highlight the importance of minimizing allograft cold ischemic time (CIT) [57, 58].
CITs of 12h are considered maximally acceptable and are only appropriate for the
healthiest donor organs. With meticulous planning and coordinated teamwork, CITs
of 4–8h are routinely achievable. Most donor operations occur at some distance
from the transplant center, and the donor and recipient teams must remain in close
communication. To prioritize recipient safety, the recipient operation is typically not
started until the donor allograft has been visualized, cross-clamped, ushed, and
carefully examined on the back-table at the donor hospital. Some centers begin the
recipient hepatectomy while the donor organ is in transit to the transplant center, and
others wait until the organ has arrived. In either case it is imperative to have prompt
transport of the recipient to the operating room and efcient preparation for surgery.
The Donor Operation
Although operative details of the donor hepatectomy are beyond the scope of this
chapter, several critical aspects of the donor operation deserve emphasis. First,
visual and tactile assessment of the donor liver are critically important components
of donor selection. Experienced donor surgeons can detect early brosis, steatosis,
and other anatomic concerns (e.g. calcied vessels in the porta hepatis) that might
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necessitate non-transplantation of the liver. When donor quality is uncertain, liver
biopsies can be obtained. Identication and preservation of accessory or variant
hepatic arterial anatomy is important. Thorough ushing of the donor liver with
preservation solution is imperative, and rapid external cooling of the liver with ice
is recommended. Once the donor liver has been ushed, safe but rapid explant is
necessary followed by a careful inspection for iatrogenic surgical damage on the
donor-hospital back-table, and rapid transportation to the transplant center. In DCD
procurements these critical steps happen on a very accelerated timescale and require
an experienced surgeon.
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Operative Set-Up andRecipient Preparation
Larger operating suites are preferred for liver transplantation to accommodate the
equipment and personnel required. Electrocautery and argon plasma coagulation
are generally considered essential. A variety of other surgical energy devices are
variably utilized including bipolar, ultrasonic, and radiofrequency vessel sealing
devices. Intraoperative blood salvage devices are frequently utilized. Anesthetic
equipment must include a uid warmer and rapid infusion device. Historically, liver
transplantation was performed using veno-veno bypass; however, this invasive
approach is now used less commonly [59].
Recipients are positioned supine with arms extended. Following intubation nasoor orogastric decompression is recommended and a Foley urinary catheter is placed.
Arterial and central venous access are obtained. Use of a multi-lumen access catheter is preferred as the introducer portion allows for pulmonary artery catheter insertion and the infusion ports allow for rapid large-volume resuscitation. Additional
large-bore intravenous access is highly recommended. Most liver transplant anesthesiologists employ either pulmonary artery catheter monitoring or continuous
transesophageal echocardiographic monitoring, for minute-to-minute feedback on
volume status and resuscitation needs. Preoperative antibiotics should include
broad-spectrum Gram-positive and Gram-negative coverage. Antifungals are recommended in large-volume transfusions cases and are sometimes used in special
circumstances (e.g. normothermic machine perfusion of the donor liver).
Preoperative doses of steroid and calcineurin inhibitor are generally given. True
inductive immunosuppression with lymphocyte depleting agents or other agents are
not necessary. Coordination with the hospital blood bank is critical.
Intraoperative Anesthetic Care
Hemodynamics are typically labile during liver transplantation with large uctuations in intravascular volume and signicant acid-base shifts. Anesthetic care must
be responsive and dynamic. Constant assessment of left ventricular lling and left
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ventricular function are keys to a safe operative course. Acute kidney injury and
even renal failure requiring dialysis are common complications following liver
transplantation, and these are best avoided with constant attention to volume status
and effective communication between the surgical and anesthesia teams.
Intraoperative CRRT is sometimes required to manage volume status in renal failure
patients or acidosis in acute liver failure patients. Neuroprotection is equally important and requires monitoring of serum sodium and osmolarity, particularly in noncompensated recipients with acute liver failure. Active preparation for the
hypotension, hyperkalemia, acidosis, and blood loss that can accompany allograft
reperfusion are needed. Right heart dysfunction and intracardiac thrombosis are
also risks.
M. Zhang et al.
Recipient Hepatectomy
A bilateral subcostal incision, with or without upward midline extension to the
xiphoid, is commonly used for liver transplantation. A variety of other incisions
including midline incisions, “hockey stick” incisions (right subcostal with midline
extension), and “inverted T” incisions (bilateral subcostal with caudad midline
extension) can be used in recipients with an accommodating body habitus. The falciform ligament is commonly recanalized and is usually divided with ties or a vascular stapler. The liver is fully mobilized taking down the right and left triangular
ligaments. The anterior surface of the right and left-middle hepatic veins is exposed,
and the right adrenal gland is released to allow visualization of the vena cava beneath
the right hepatic lobe. The pars accida is opened. Excellent retraction is critical for
success in liver transplantation and can be achieved with a variety of xed retraction
systems.
Once the liver is fully mobilized, the porta hepatis is dissected. Goals are to
identify and carefully divide the hepatic artery and bile duct and to fully skeletonize
the portal vein. It is important to preserve sufcient length on the hepatic artery and
bile duct to allow for tension-free anastomoses to the donor equivalents. In deceased
donor transplantation, dissection at the level of the mid-porta is usually sufcient.
In LDLT, dissection takes place as close to the hilar plate as possible to preserve
maximal length on all structures. In deceased donor transplantation, the proper
hepatic artery may be used for anastomosis if it is of sufcient caliber, or dissection
can proceed proximal to the gastroduodenal artery or even to the take-off of the
splenic artery from the celiac trunk (Fig.14.1). In LDLT, the gallbladder is retracted
and the right hepatic artery is dissected all the way onto the cystic plate in an effort
to attain maximal length and a caliber that will size-match well with the donor
artery. The portal vein should be divided at its bifurcation in deceased donor transplantation and the right and left branches are usually taken individually in LDLT.The
choice of when to divide the portal vein is situation-specic. Early division allows
for greater mobility of the liver and can facilitate caval dissection, but prolonged
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Fig. 14.1 Ideal dissection of the recipient hepatic artery during hepatectomy. With this exposure
the proper hepatic artery can be clamped and the arterial anastomosis created where the right and
left hepatic arteries bifurcate. Alternatively, the common hepatic artery can be clamped proximal
to the gastroduodenal artery/GDA, the GDA can be divided, and the arterial anastomosis can be
created using the common hepatic artery at the level of the GDA take-off
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portal clamping times in patients without collateralization can lead to bowel edema
and loss of domain.
The recipient hepatectomy is then typically completed in one of two ways. If
caval interposition is planned, clamps are placed circumferentially about the suprahepatic vena cava and distal vena cava between the right adrenal vein and right renal
vein. The liver is then cut out sharply preserving cuffs of tissue on the proximal and
distal cavae to allow for subsequent anastomoses to the donor vena cava. If “piggyback” technique is employed, the short hepatic veins are ligated with clips and
ties. The liver is “peeled off” of the cava until the right hepatic vein and left-middle
hepatic veins can be divided and the liver fully explanted.
There are several keys to a successful recipient hepatectomy. Speed and efciency are important to minimize cold ischemic time and reduce blood loss. Blood
loss is sometimes vigorous, and two-way communication with the anesthesia team
is important. Interval clamping the portal vein prior to its division can reduce blood
loss from the liver itself, reduce liver volume to allow for better visibility, and portal
venous congestion can be relieved by removing the portal vein clamp prior to nal
division of the portal vein. Prior to implantation, it is absolutely essential to verify
that the portal vein and hepatic artery will provide the necessary vascular inow and
that the vena cava is clamped in a manner that will allow creation of unobstructed
venous outow. All potential inow and outow issues should be addressed before
the donor liver is brought to the eld for implantation.
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M. Zhang et al.
Unique Vascular Considerations
Portal Vein Complications
Preoperatively the recipient surgeon should review CT or MR imaging and identify
major porto-systemic collaterals. If portal ow is sluggish, ligation of collaterals can
restore normal hepatopetal ow. Left renal vein ligation is a convenient strategy for
closing splenorenal shunts [60, 61]. If portal vein thrombosis is encountered, eversion
thromboendovenectomy [62] is the preferred approach. If the clot cannot be removed,
donor iliac vein is generally attached to the superior mesenteric vein (SMV), and this
“SMV jump graft” is tunneled to the porta in retrocolic fashion. If the SMV is unsuitable or inaccessible, alternative inow options include large upper abdominal varices
and the left renal vein [63, 64]. In emergent situations, portacaval transposition [65]
or arterialization of the portal vein [66] can be considered. In LDTL, portal inow
can sometimes be too robust for the smaller living donor graft. Attenuation of portal
ow is best achieved through splenic artery ligation or splenectomy [67].
Hepatic Artery Handling
If the recipient hepatic artery dissects or is otherwise unusable, donor iliac artery is
used to create an aortic conduit. Preoperatively, it is useful to review recipient imaging and know the atherosclerotic burden in various sections of the aorta in case an
aortic conduit is needed. If the conduit is created during the anhepatic phase, the
supraceliac aorta is usually accessible. If the recipient hepatic artery dissects or
thromboses during or after implantation, it is sometimes difcult to expose the
supraceliac aorta, and in these cases, an infrarenal aortic conduit can be created. The
ligament of Treitz is taken down to expose the infrarenal aorta and the conduit is
tunneled to the porta in retrogastric retrocolic fashion. If the entire aorta is atherosclerotic, donor iliac arteries can be joined end-to-end, and a long conduit can be
brought to the porta from the common or external iliac artery. Regardless of
technique, robust arterial and portal inow are essential to the success and longevity
of any transplant (Table14.4).
Table 14.4 Surgical options
for portal vein problems
Ligation of porto-systemic collaterals to augment
hepatopetal ow
Eversion thromboendovenectomy
Superior mesenteric vein jump grafting
Varicoportal anastomosis
Renoportal bypass
Portacaval transposition
Arterialization of the portal vein
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Implantation
Implantation begins with the caval anastomosis. If caval interposition is used endto- end, anastomoses are created between the donor and recipient suprahepatic and
lower cavae (Fig.14.2). In piggyback technique, several variants are possible. One
option is to preserve length on the hepatic veins during hepatectomy. The hepatic
veins can then be clamped at their junction with the cava. The donor suprahepatic
cava is then sewn to either the left-middle hepatic vein orice (while the right is
oversewn) or to a large common orice created by joining the left-middle and right
Fig. 14.2 Techniques for venous
anastomosis during implantation.
(a) Caval interposition technique,
(b) piggyback technique using the
recipient native hepatic vein
orices, (c) piggyback technique
using a side-to-side anastomosis of
the donor and recipient vena cava
a
b
c
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