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_3683_Библиотеки_им_академика_М_И_Перельмана
.pdf
P.233
A right thoracotomy through the fourth intercostal space provides satisfactory exposure.
Technique
The right lung is retracted inferiorly and posteriorly, and the local anatomy is evaluated. The right pulmonary
artery is identified. The parietal pleura overlying it is incised, and the artery is mobilized medially toward the
pericardium and distally to the hilum of the lung and proximally toward the mediastinum. Often the use of a blunt
peanut dissector allows for mobilization without disruption of the pericardial edge. It is often helpful to ligate and
divide the azygous vein, and also resect the lymphatic tissue that lies posterior and lateral to the superior vena
cava, as this tissue will be in most direct path from the innominate artery to the right pulmonary artery.
FIG. 18.4 Right-modified Blalock-Taussig shunt: Operative view of the hilum of the right lung and right
subclavian artery with loose snares around the right pulmonary artery and its lobar branches.
Identification of the Right Pulmonary Artery
Sometimes the exact identity of the vessels within the hilum of the lung may not be clear. If there is any doubt as
to the exact location of the pulmonary artery, it can be traced from within the pericardium through a short
longitudinal incision on the pericardium, just anterior and parallel to the left phrenic nerve.
The right pulmonary artery, with its lobar branches having been clearly identified, is prepared for clamping or
snaring with fine vascular elastic bands. The parietal pleura over the innominate or subclavian artery is incised,
and the artery is mobilized and dissected free of its parietal sheath (Fig. 18.4).
A 3.5- or 4-mm Gore-Tex tube graft is used for neonates, and a 5-mm graft is rarely used for older patients.
Because the size of the lumen of the innominate or subclavian artery is the limiting factor to the flow of blood,
grafts larger than the subclavian artery do not necessarily increase the flow to the lungs and therefore are not
responsible for pulmonary flooding, if it occurs.
The distal end of the graft is trimmed obliquely. An appropriate segment of the subclavian artery is excluded
within a delicate vascular clamp. A longitudinal incision is then made in the artery. A fine adventitial traction
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.234
suture on the anterior edge of the arteriotomy will keep the lumen of the artery open.
The anastomosis is started near the toe with a 7-0 Prolene suture and completed as a continuous anastomosis
(Fig. 18.5).
With the other end of the graft temporarily occluded with fine, atraumatic forceps, the vascular clamp on the
subclavian artery is loosened to detect a gross anastomotic leak that may require additional suture
reinforcement. A cross-clamp is then reapplied to the graft. The length of the Gore-Tex tube graft is meticulously
evaluated; it is divided
transversely at the appropriate site so that when its divided end is in close apposition to the right pulmonary
artery, it is under no tension and is not kinked.
FIG. 18.5 (A and B) Left-modified Blalock-Taussig shunt: Stepwise technique for anastomosing a Gore-Tex tube
graft to the left subclavian artery.
The main right pulmonary artery is snared or clamped as proximally as possible. The silastic tapes around the
pulmonary artery branches are placed on traction. Alternatively, a fine vascular C-clamp may be applied to the
right pulmonary artery. A longitudinal incision is made on the cranial aspect of the right pulmonary artery. The
arterial opening should be approximately two-thirds of the diameter of the graft lumen (Fig. 18.6A) and the
anastomosis completed with a running 7-0 Prolene (Fig. 18.6B).
Use of Heparin
Light systemic heparinization with 50 units per kilogram of body weight is initiated before clamping the
subclavian/innominate artery. Although this may prolong bleeding at the anastomotic site, it lessens the risk of
early graft thrombosis.
Too Short a Tube Graft
P.235
Tension on the anastomosis owing to too short a tube graft not only causes suture line bleeding but also pulls
upward on the pulmonary artery, narrowing the lumen for distal flow and may result in early closure of the shunt.
Too long a tube can lead to twisting or kinking due to redundancy.
FIG. 18.6 Right-modified Blalock-Taussig shunt. A: Anastomosing the Gore-Tex tube graft to the right pulmonary
artery. B: Graft interposition between the right subclavian and right pulmonary arteries.
Suture Line Bleeding
Bleeding from the suture line is not uncommon. Packing the anastomotic site lightly with Surgicel or Gelfoam and
thrombin for approximately 5 minutes will achieve hemostasis in most cases. Additional sutures should be
avoided, if possible, because they may jeopardize the lumen of the shunt.
Transverse versus Longitudinal Incision on the Pulmonary Artery
A transverse incision on the superior aspect of the pulmonary artery has been advocated by some surgeons.
However, the risk of distortion and subsequent stenosis of the pulmonary artery appears to be greater with this
incision as opposed to the longitudinal opening.
Right Aortic Arch
When a right arch is present, it can make the approach for a modified Blalock-Taussig shunt from a thoracotomy
difficult. In such situations, consideration should be given to creating a central shunt (using a side-biting clamp
on the greater curvature of the ascending aorta). More often, a central approach is used via median sternotomy.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Aberrant Right Subclavian Artery
An aberrant retroesophageal right subclavian artery is a relative contraindication toward performing the operation
via right thoracotomy. If this approach is deemed necessary, the subclavian area of origin is more distally located
than with a left aortic arch.
Right Recurrent Laryngeal Nerve
The right recurrent laryngeal nerve surrounds the right subclavian artery and can be quite close to the area
chosen for the proximal shunt placement. Extreme care must be used not to damage the nerve with placement of
the partial occluding clamp, given the space constraints of a small thoracotomy and the deep angulation of the
clamp.
At the end of the procedure, a small chest tube is inserted and the thoracotomy is closed in the usual manner.
CENTRAL SHUNT
This procedure entails interposing a tube graft between the main pulmonary artery and ascending aorta. It
provides an alternative technique when other shunts have failed or in cases where the branch pulmonary
arteries are very small. The approach is through a median sternotomy.
Technique
The ascending aorta and main pulmonary artery are dissected free of each other. A small side-biting clamp is
placed on the main pulmonary artery. A vertical pulmonary arteriotomy is made (Fig. 18.7). A 3.0, 3.5- or 4-mm
Gore-Tex tube graft (with or without ringed reinforcement) is cut transversely and anastomosed to the pulmonary
artery with continuous 7-0 Prolene suture. The Gore-Tex graft is now clamped with a fine straight vascular clamp
close to the pulmonary anastomosis and the pulmonary artery clamp is removed. A side-biting clamp is now
applied to the left lateral aspect of the ascending aorta and a small opening is made with a knife blade. This is
enlarged to the appropriate size with an aortic punch. The other end of the Gore-Tex tube graft is cut obliquely
and anastomosed to the aorta with 7-0 Prolene suture (Fig. 18.8). Air is removed by unclamping the tube graft
before tying down the suture on the aortic side of the anastomosis. The aortic clamp is removed as the last step.
A good thrill should be felt.
Kinking of the Graft
A Gore-Tex tube graft that is too long or angled inappropriately at its junction with the aorta is likely to kink and
lead to early shunt failure. In some cases, it may be simpler to not trim the tube graft following the pulmonary
artery anastomosis. The Gore-Tex tube graft is gently pulled against the side of the aorta, and both the aorta
and tube are marked where they meet comfortably. A 3.5- to 4-mm hole is created at the marked site on the graft
and, with a partial occlusion clamp on the ascending aorta, an aortic punch is used to create a matching
opening. A side-to side anastomosis is performed with 7-0 Prolene suture. The distal end of the graft is then
transected 4 to 5 mm distal to the aortic anastomosis, and the end is oversewn with a 7-0 Prolene suture (Fig.
18.9). Alternatively, a ringed reinforced graft can be used, and in addition some oblique angulation can be placed
on the proximal (aortic) end of the graft to afford a more “vertical” lie.
P.236
FIG. 18.7 Central shunt: Isolation and incision of the pulmonary artery.
PROSTHETIC ASCENDING AORTA-RIGHT PULMONARY ARTERY SHUNT
Occasionally, the aortic arch anatomy may make interposition from the innominate to the right pulmonary artery
problematic. In these cases, a graft may be placed from the ascending aorta to the right pulmonary artery.
Limiting Factor to the Pulmonary Blood Flow
In modified Blalock-Taussig shunt interposition with a Gore-Tex tube graft, the size of the subclavian or
innominate artery is the limiting factor to the flow of blood to the lungs. In an ascending aorta-right pulmonary
shunt, however, the diameter and length of the Gore-Tex tube graft are important factors regulating the
pulmonary blood flow. Therefore, except on very rare occasions, a 3.0-, or 3.5-tube graft should be used to
prevent pulmonary overcirculation.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.237
FIG. 18.8 Stepwise technique for creating a central shunt.
FIG. 18.9 Central shunt with a side-to-side aortic anastomosis and oversewing the end of the Gore-Tex tube
graft.
Incision
A median sternotomy approach is used.
Technique
After removing the thymus, the pericardium is opened and traction sutures are placed. If the ductus arteriosus is
patent, it is dissected free circumferentially for later closure after completion of the shunt. The right pulmonary
artery is mobilized by gently retracting the aorta leftward and the superior vena cava rightward. The upper lobe
branch of the right pulmonary artery is identified so that the shunt can be placed proximal to it. After systemic
heparinization (50 units/kg), a C-clamp is placed on the proximal right pulmonary artery positioning the anterior
portion of the artery in the center of the clamp. The appropriately sized Gore-Tex tube graft is cut transversely. A
longitudinal arteriotomy is made in the pulmonary artery, approximately two-thirds of the diameter of the graft. A
traction suture is placed on the inferior edge of the arteriotomy. A double-armed, 7-0 Prolene suture is used for a
continuous running anastomosis. The graft is marked as is the ascending aorta. The graft may
be cut obliquely to meet the opening on the ascending aorta without distortion. However, it is often advisable to
create an opening on the aortic side of the graft matching the aortic opening and to perform a side-to-side
anastomosis. This procedure is described as shown in Fig. 18.10.
After marking the graft, a fine vascular clamp is placed on the graft close to the pulmonary artery anastomosis. A
small incision is made at the mark on the graft and enlarged to a size equal to the diameter of the graft with a 2.8-
mm aortic punch. A side-biting clamp is now placed on the ascending aorta so that the marked area is centered
in the clamp. A small incision is made and enlarged with the aortic punch. The end-to-side anastomosis is
performed using a double-armed, 7-0 Prolene suture. If the ductus arteriosus is patent, it is now occluded with a
heavy tie or metal clip. The pericardium is loosely approximated with a Gore-Tex pericardial membrane, a small
chest tube is placed in the anterior mediastinum, and standard sternotomy closure is performed.
Aortic Partial Occlusion
The side-biting clamp must be placed carefully on the ascending aorta, especially in neonates and infants with
small aortas to avoid hypotension or myocardial ischemia secondary to compromised coronary flow. Before
incising the aorta, the position of the clamp should be tested to ensure that no hemodynamic changes are going
to occur. Multiple reapplications of the clamp from different angles may be required before a satisfactory
placement is found.
Coronary Ischemia
It can be challenging to apply the partial occluding clamp while on cardiopulmonary bypass without causing
coronary insufficiency. Should this occur, the procedure should be performed under cardioplegic arrest. Marking
the future site of the central shunt on the ascending aorta is helpful so as to maintain orientation when the aorta
is open and decompressed.
Thrombosis or Distortion of the Graft above the Aortic Anastomosis
The length of graft beyond the side-to-side anastomosis is crucial with this technique. If too much graft extends
above the aortic anastomosis, there will be an area of relatively stagnant flow that may predispose to graft
thrombosis. If too little graft remains, the suture line may distort or compromise flow into the graft from the aorta. If
the graft has been cut too short, the end can be closed with a circular piece of Gore-Tex graft cut from extra graft
material (Fig. 18.10). This prevents distortion and minimizes dead space.
Coronary Ischemia
It can be challenging to apply the partial occluding clamp while on cardiopulmonary bypass without causing
coronary insufficiency. Should this occur, the procedure should be performed under cardioplegic arrest. Marking
the future site of the central shunt on the ascending aorta is helpful so as to maintain orientation when the aorta
is open and decompressed.
FIG. 18.10 Completed ascending aorta to the right pulmonary artery shunt: Note a circular patch closing the tube
graft above the side-to-side aortic anastomosis.
Melbourne Shunt
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.238
For patients with severe pulmonary atresia and confluent pulmonary arteries, it can be efficacious to transect the
main (diminutive) pulmonary artery and anastomose this directly to the posterior aspect of the ascending aorta,
thereby creating the equivalent of a central shunt without the use of prosthetic graft. Some suggest that this
configuration maximizes pulmonary artery growth in part because of the growth potential (and lack of restriction)
of the main pulmonary artery when compared with Gore-Tex (Fig 18.11).
CLOSURE OF SYSTEMIC PULMONARY SHUNTS
All these shunts should be dissected free and exposed for complete occlusion just after initiation of
cardiopulmonary bypass, when contemplating complete correction of the anomaly or further palliative
procedures.
Right-Sided Modified Blalock-Taussig Shunts
The aorta and superior vena cava are retracted away from each other, and the posterior pericardium is incised
above the superior margin of the right pulmonary artery. The
Gore-Tex tube graft is identified and occluded with one or two medium or medium-large metal clips just after the
initiation of cardiopulmonary bypass (Fig. 18.12).
FIG 18.11 Melbourne shunt with anastomosis of the diminutive main pulmonary artery to the posterior aspect of
the ascending aorta.
Dissection around the Right Pulmonary Artery
There are many adhesions and collateral vessels in this area. A minimal dissection to isolate the shunt should
suffice. It is usually not necessary to pass a silk tie around the shunt.
P.239
Right Pulmonary Artery Stenosis
If significant stenosis is present at the insertion site of the shunt into the right pulmonary artery, the tube graft
should be divided after the initiation of cardiopulmonary bypass. The transected end should be secured with at
least two adequately sized metal clips or oversewn with a 6-0 or 5-0 Prolene suture. The residual Gore-Tex
material should then be removed from the right pulmonary artery and this area is enlarged with an oval-shaped
patch of autologous pericardium or pulmonary homograft.
Division of the Gore-Tex Shunt
Theoretically, as a child grows, an intact Gore-Tex tube graft may cause upward traction on the right pulmonary
artery, which may lead to distortion and possible late development of pulmonary artery stenosis. If an adequate
length of Gore-Tex tube graft can be dissected free without incurring excessive bleeding, the tube may be
secured with two metal clips on each side and divided to prevent this potential late complication.
FIG. 18.12 Exposure of the right-modified Blalock-Taussig shunt.
Accessing the Gore-Tex Shunt
It is easiest to ligate the shunt if the surgeon can accurately develop a plane around the shunt. Using a scalpel
and a sharp, fine dissector (e.g., Jacobson clamp), this plane is most easily found and developed so as to afford
surrounding the shunt with a right-angled clamp without effort.
Left-Sided Modified Blalock-Taussig Shunts
Isolation of the left-sided shunt is somewhat more cumbersome and can be accomplished in many ways. Some
surgeons prefer opening the left pleura. The Gore-Tex tube graft is then identified as it enters the left pulmonary
artery (Fig. 18.13). It is minimally dissected free and doubly clipped, just before initiation of cardiopulmonary
bypass. Alternatively, the left pulmonary artery is dissected free from within the pericardium, and the Gore-Tex
tube graft is clipped just above its junction with the pulmonary artery.
Clip Injury
Clips must be at least large enough to occlude the entire width of the graft. Smaller clips may pierce the graft and
cause bleeding, in addition to closing the shunt incompletely.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Central Shunt
With the initiation of cardiopulmonary bypass, the Gore-Tex tube graft is occluded with a metal clip.
Prosthetic Ascending Aorta-Right Pulmonary Artery Shunt
The tube graft is carefully dissected free from the lateral aspect of the ascending aorta and occluded with a
metal clip as cardiopulmonary bypass is commenced. Usually, the shunt tubing is divided while on bypass and
the aortic and pulmonary ends are oversewn with a running 6-0 or 5-0 Prolene suture.
Aortic Injury
The Gore-Tex shunt is often very adherent to the side of the aorta. The correct plane for dissection must be
identified, staying right on the Gore-Tex graft itself to avoid entry into the aorta. If the shunt cannot be safely
dissected from the aorta, it should be occluded as much as possible with a vascular clamp or forceps when
cardiopulmonary bypass is commenced and the dissection completed with the patient on bypass.
Waterston and Potts Shunts
Waterston and Potts shunts are no longer performed, but familiarity with the techniques of their closure is
essential for the surgeon who operates on patients who have undergone these shunting procedures in the past.
FIG. 18.13 Exposure of left-modified Blalock-Taussig shunt.
Technique: Waterston Shunt
The easiest way to close a Waterston shunt is on cardiopulmonary bypass with the aorta cross-clamped. After
administering cardioplegic solution, a small transverse aortotomy is made, and the shunt may be closed from
within the aorta with a few interrupted sutures. The preferred method is to detach the right pulmonary artery from
the aorta and oversew the defect in the ascending aorta with a running 5-0 Prolene suture. The defect in the
pulmonary artery can be closed transversely by direct suture or preferably patched with a piece of autologous
pericardium or pulmonary homograft.
Pulmonary Artery Distortion
If the shunt has created some stenosis or kinking of the right pulmonary artery, this should be reconstructed with
Соседние файлы в папке Библиотека им академика М.И. Перельмана