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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1841_Библиотеки_им_академика_М_И_Перельмана.pdf
RESECTION PRINCIPLES
123
Intrahepatic approach
Over the past 15 years, reports have included experience with the intrahepatic
approach popularized by Bernard Launois in Rennes. It remains a technique
that is difficult to illustrate and explain but does offers an alternative, more
rapid method of gaining not only control of the right side of the liver but its
segmental supply to segments V, VI, VII, and VIII (Launois and Jamieson,
1992a , b ). The hilar plate is mobilized and this will usually bring down the con-
fluence of the left and right sheaths. The important principle to understand is
that the portal vein, hepatic artery, and bile ducts are encased by an extrusion
of the Glissonian sheath (a continuation of the liver capsule which forms a
tough fibrous outer layer holding the contents in tight apposition) ( Fig. 3.21 ).
A small 1–2 cm incision can be made anterior to and against this sheath just
as it enters the liver. A similar incision is made 1–2cm posterior to the sheath
(the so-called posterior approach of Launois). With these two incisions (ante-
rior and posterior to the sheath) it is possible to use two digits (finger and
thumb) to separate the sheath from the liver parenchyma. With gentle dissec-
tion the two fingertips can be made to meet intrahepatically.
By staying as close as possible to the sheath, significant bleeding will be
avoided and a large curved clamp can be passed around the right hepatic inflow
sheath.
Once this has been achieved, the liver parenchyma can be brushed off the
sheath appearing to render it extrahepatic ( Fig. 3.22 – 3.24 ). Cross clamping
with a vascular clamp will confirm that the right main pedicle has been isolated
Fig. 3.21 The Glissonian sheath envelops the hepatic artery, bile duct, and portal
vein as they enter the liver parenchyma.
LIVER
124
and occluded due to the change in colour on the liver surface between the
normally vascularized left lobe and the contrasting darker-looking right lobe.
If additional sheaths to the right segments have been mobilized separately
these can also be surrounded by a sling and clamped ( Fig. 3.24 ).
In this way, all four right-sided segments can be occluded and an ‘a la carte’
resection is then possible (see ‘Resection options’). It is vital to stress again the
importance of considering the possibility of an anomalous portal vein and an
equally sized sheath to the left side must be identified. This is relatively easy to
mobilize once the right side has been defined.
Fig. 3.22 Following anterior and posterior incisions into the liver substance, finger
dissection can be used to free the sheaths from the liver.
Fig. 3.23 The right sheath is slung during mobilization.
METHODS OF PARENCHYMAL TRANSECTION
125
Identification of segmental pedicles
The intrahepatic approach provides a means of locating the pedicles to the
segments. If the extrahepatic approach is preferred, then intraoperative ultra-
sound is needed to aid in accurate identification.
Methods of parenchymal transection
An array of techniques and technologies has been developed to aid the paren-
chymal dissection. The dual aims are precision and safety in dealing with ves-
sels and bile ducts, and efficacy in tumour clearance. Close resection margins
occur usually in centrally-placed tumours near either the confluence of the
hepatic veins and the vena cava or the inflow sheaths. Providing these two aims
can be achieved with minimal blood loss then the choice of a crushing clamp,
CUSA® (Cavitron Ultrasonic Surgical Aspirator®), harmonic scalpel, or radi-
ofrequency ablation is a matter of personal preference (Hanna et al ., 1996 ;
Clavien et al ., 2004 ). We find a combination of a fine crushing clamp and/or
CUSA dissection combined with clips, surgical ligation, and diathermy achieves
these aims. Hepatic veins and the Glissonian sheath are now routinely stapled
with an endoscopic vascular stapler; the design of the head of this device makes
it ideal to ensure that these structures are secured quickly and safely (Fong and
Blumgart 1997 ; El Moghazy et al ., 2009 ).
Fig. 3.24 Segmental supply to the right liver has been identified and slung in
preparation for individual clamping.
LIVER
126
Resection options
Segmental resections
Segment I (the caudate lobe)
Anterior to Segment I is a film of lesser omentum separating it from Segments
II and III. The aorta lies posteriorly. It has a left free border, is fused to Segment
VIII and has an anterior aspect that melds with Segment IV. There are direct
venous connections between the caudate lobe and the cava and similarly direct
and multiple connections to the right and left portal structures. To resect the
caudate lobe, the veins between the lobe and the vena cava need to be identi-
fied, ligated, and divided. This is done by retracting the left side of the caudate
lobe and carefully dividing the venous connections. This continues up towards
the middle and left hepatic veins. The connections to the left and right portal
pedicles must next be divided. The dissection will usually cut across the con-
nection between Segment VIII and Segment I once the tumour margin is
defined. In practice, it is unusual to perform an isolated Segment I resection. It
is more often included as part of a left hepatectomy or Segments IV and I for
hilar cholangiocarcinoma. The challenge with a caudate lobe resection is to
avoid causing damage as the dissection proceeds towards the middle and left
hepatic veins. In large patients with less compliant liver substance, a loss of
control in this region can be very difficult to manage and potentially fatal. If
control is difficult then it is occasionally necessary to mobilize and sling the
IVC which allows the use of side-biting vascular clamps which obviate the
need to completely occlude the venous return during the resection.
Segment II
Segment II resections should occur to the left of the left hepatic vein. The left
triangular ligament is divided and the liver swung upwards to allow an incision
to the left of the umbilical fissure. The sheath to the segment can be readily
found and a curved clamp placed around it. Once mobilized, it can be clamped
and the delineated segment marked on its anterior and posterior surfaces.
Preservation of the left hepatic vein is desirable in order to preserve drainage
of Segment III.
Segment III ( Fig. 3.25 )
The sheath to Segment III runs in the root of the ligamentum teres. Once the
left triangular ligament has been divided, the dissection is directed into
the liver substance, to the left of the ligamentum teres as it attaches to the left
side of the liver. Usually there is more than one sectoral sheath and two, three,
or even more may need to be identified and ligated. With each ligation, increas-
ing devascularization of the segment occurs.
RESECTION OPTIONS
127
Once the lesion has been defined, a parenchymal dissection is possible. Again,
in theory, the left hepatic vein can be preserved. Intraoperative ultrasound can
help determine not only its location but how feasible resection will be in any
given situation.
Segment II and III resection
The left hepatic vein should be isolated and the left triangular ligament divided.
Careful dissection down the left side of the insertion of ligamentum teres ena-
bles all the sheaths supplying Segments II and III to be divided ( Fig. 3.25 ). The
dissection continues just to the left of the discoloured segment and the left
hepatic vein is ligated or divided with a stapler. The Pringle manoeuvre is
rarely needed but can be used if bleeding from the residual liver is a problem.
Segment IV
This segment is bounded by the main fissure of the liver on the right and the
umbilical fissure on the left, with the middle hepatic vein separating it from
Segments V and VIII. Segment IV resections involve dividing the usually mul-
tiple sheaths feeding the segment to the right of the ligamentum teres. Once
divided, the right margin of the segment can be clearly seen as the line of
demarcation between perfused and ischaemic liver ( Fig. 3.26 ).
Inferiorly, the segment needs to be freed from the left portal structures. This
is readily achieved by lifting the segment upwards and with the base mobilized
and the left margin divided, cutting the liver parenchyma just to the left of the
right line of demarcation, so avoiding the middle hepatic vein ( Fig. 3.27 ).
Fig. 3.25 Mobilization of the sheath to segments II and III.
LIVER
128
Fig. 3.26 Segment IV demarcation as the sheaths to the right of the ligamentum teres are ligated.
RESECTION OPTIONS
129
If only the anterior part of the segment (segment IVA) is to be removed then
resection is performed. If a more posterior segment IVB resection is required,
then the dissection must be continued towards the IVC and hepatic vein con-
fluence. In practice this is difficult to perform and one takes as much of the
segment as required rather than attempting a strict anatomical clearance which
posteriorly can be technically difficult and dangerous.
Segment V
Segments on the right side of the liver are very variable in size and shape. The
feasibility of an effective segmental resection can only be reliably determined at
the time of surgery. Access to the right Glissonian sheath is obtained and the
branched Segments V, VI, and VIII can usually be readily mobilized. Segment
VII sheath arises posteriorly and behind the sheath and can be difficult to
adequately encircle. The Segment V sheath is clamped and the medial side of
discolouration represents the main fissure with the middle hepatic vein run-
ning along this plane. The proposed resection lines are marked by diathermy
on the surface of the liver. The medial capsular incision should be made so that
the dissection proceeds along the right side of the main fissure to the right of
the liver to avoid the middle hepatic vein. As the liver is opened additional
Fig. 3.27 Inferior attachment of segment IV mobilized from the left main sheath.
A stapler is in position to occlude the right main sheath as part of an extended right
hepatectomy.
LIVER
130
sheaths may be located feeding Segment V. The lateral boundary of the segment
should now be incised with care to avoid damage to Segment VI branches. If
bleeding is troublesome, the right hepatic sheath can be clamped. The medial
and lateral lines of resection are then joined by a transverse line marking the
anterior border of Segment VIII.
Segment VI
A similar procedure applies to Segment VI resections, with an even greater
likelihood of multiple sheaths supplying the segment. Segment VI venous
drainage is primarily to terminal branches of the right hepatic vein and with
some additional drainage to the middle hepatic vein.
Segment VII
In order for this segment to be resected in isolation, or with Segment VI, care-
ful mobilization of the liver from the small caval veins needs to be completed.
As stated earlier, locating the sheath to Segment VII can be difficult and a
combination of ultrasound to detect the right hepatic vein intrahepatically and
further dissection may be required to locate the sheaths.
Segment VIII
Segment VIII resections in isolation are often the most difficult to perform.
The right lateral margin is made up of the right hepatic vein and the medial
margin the middle hepatic vein ( Figs. 3.1 and 3.2 ), and because of this, bleed-
ing can be a significant problem and difficult to control. The sheath to Segment
VIII is clamped and the lateral and medial boundaries are displayed. We tend
to lift up the anterior margin as we incise the parenchyma in order to elevate
the segment prior to making the posterior incision in front of the IVC. The
right hepatic vein may have an early bifurcation and this large tributary will
need to be taken intrahepatically. Intraoperative ultrasound will often help
warn of this possibility and reassures the operator that the main trunk of the
right hepatic vein has not been damaged.
Traditional resections
Right hepatectomy (Segments V–VIII) ( Figs. 3.28 and 3.29 )
Complete mobilization of the right lobe from the cava and its peritoneal
attachments is performed. The main right portal sheath (posterior approach)
is clamped or the hilar structures (extrahepatic) divided and the main fissure
defined by the line of discolouration. The dissection is continued anteriorly
until the portal sheaths are reached. At this stage the clamp should be placed as
laterally as possible and either an endoscopic vascular stapler or ligation and
transfixion used to divide the inflow structures. It is important to have the
RESECTION OPTIONS
131
staple line as far laterally as possible to avoid damage to bile ducts that may be
passing along the right lateral aspect prior to giving off the main right hepatic
duct and becoming the left hepatic duct. Once the portal structures have been
divided, the right hepatic vein can also be divided, reducing the blood loss
from the remainder of the dissection significantly and providing for greater
control.
Fig. 3.29 A stapler has
been positioned to
occlude the right hepatic
vein once the inflow has
been divided.
Fig. 3.28 Mobilization of the right liver from its caval attachments with the right
hepatic vein slung. Note a large inferior right hepatic vein, which has been ligated.
LIVER
132
Left hepatectomy ( Fig. 3.30 )
For a left hepatectomy (Segments II, III, and IV) the posterior approach can
again be used to isolate the left hepatic sheath and this can be encircled with a
vascular tape. The procedure is usually somewhat easier than on the right side
as the sheath is more extrahepatic at the confluence. The sheath should be
clamped and the main fissure of the liver identified. Mobilization of the left
triangular ligament is essential.
The dissection is down through the main fissure to the left side if possible, to
preserve the middle hepatic vein which enables it to continue to drain the right
liver remnant.
The caudate lobe can be included in the resection or spared depending on
the clinical situation.
Extended left hepatectomy ( Fig. 3.31 )
This includes segments II, III, IV, V, VIII, and I. Not a common procedure, it
represents the most difficult of the major resections, in part because the dissec-
tion is performed deep within the posterior aspect of the liver. The left-sided
attachments to the liver are divided and the caudate lobe freed from the cava
left-to-right. With the posterior approach to the right and left inflow achieved
the left hepatic sheath can be divided. The right side of the sheath can have
Segments VIII and VI ligated ( Fig. 3.31 ). The left and middle hepatic veins
(generally with a common origin) should be divided with the right hepatic
vein having been isolated and slung.
Fig. 3.30 For a left hepa-
tectomy, the left main
sheath needs to be ligated
and the left hepatic vein
can be divided with
preservation of the middle
hepatic vein to the left of
the main fissure.