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.134
FIG. 8.15 Valve-sparing root replacement: A: Excising coronary arteries as buttons. B: Interrupted proximal
sutures.
Aortic Valve-Sparing Root Replacement
Patients with aortic root disease, such as those with Marfan syndrome, have progressive dilation of the aortic
sinuses and aortic annulus, which can lead to aortic valve insufficiency despite normal aortic valve leaflets. In
these patients, it is possible to replace the diseased aortic root and preserve the aortic valve by reimplanting it
inside a Dacron tube graft.
The aorta is transected just beyond the aneurysmal dilation. Both coronary arteries are mobilized as individual
buttons, as described previously. The root is dissected circumferentially down to a level just below the nadir of
the aortic annulus. All three sinuses of Valsalva are excised, leaving approximately 5 mm of arterial wall attached
to the aortic annulus (Fig. 8.15A). A series of 12 to 14 interrupted horizontal mattress sutures of 2-0 Ticron are
passed
from inside to outside the left ventricular outflow tract just below the aortic valve. Where the aortic valve is
attached to ventricular muscle, the sutures follow the contour of the commissure between the left and right
coronary sinuses (Fig. 8.15B). On the side of the left ventricular outflow tract where the aortic valve is attached
to fibrous tissue, the sutures are placed in a single horizontal plane.
Traditionally, a Dacron tube graft with a diameter matching the calculated external diameter of the
ventriculoaortic junction is chosen according to the formula:
Diameter = (Average leaflet height × 1.33) + (2 × Aortic wall thickness).
However, to simulate the natural mechanics of the sinuses of Valsalva, a graft 4 to 6 mm larger is selected
instead. Theoretically, the creation of these pseudosinuses minimizes systolic contact between the valve cusps
and the Dacron graft and reduces diastolic closing leaflet stresses, both of which may enhance valve durability.
Three equidistant marks are made at one end of the tube graft. The previously placed horizontal mattress
sutures are then passed through the Dacron graft, taking care to match the commissures to the markings on the
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
graft. Because there are more sutures in the fibrous portion of the left ventricular outflow tract in patients with
annuloaortic ectasia, they are placed correspondingly closer in the Dacron graft, thereby correcting the dilation.
The tube is lowered over the scalloped aortic valve and the sutures are tied on the outside with a narrow strip of
felt sandwiched into the suture line. The graft is cut 2 to 3 cm above the commissures, which are suspended to
the graft with mattress 4-0 Prolene sutures reinforced with pledgets. The graft is filled with saline solution to
confirm the correct orientation of the commissures and the competence of the valve. The valve is reimplanted
inside the graft using the 4-0 or 5-0 Prolene sutures in a running manner (Fig. 8.16). The use of a larger graft
facilitates the suturing of the valve without bunching of aortic tissue. The coronary buttons are then reattached to
their respective neosinuses on the graft using 5-0 Prolene sutures. The root reconstruction is completed by
placing a figure of eight 5-0 Prolene suture to plicate 2 to 3 mm of graft material in each sinus, 1 cm above and
between the commissures. In cases where the ascending aorta is also dilated, these plicating sutures are not
used. Instead, a second, smaller tube graft corresponding to the external diameter of the ventriculoaortic junction
according to the preceding formula is anastomosed to the top of the aortic root graft, thereby effectively reducing
the neosinotubular junction. This second graft is then used to replace the ascending aorta (Fig. 8.17).
TECHNIQUE FOR REPLACEMENT OF AN AORTIC ARCH ANEURYSM
The aortic arch may have to be replaced if there is an enlarging aneurysm affecting the arch or there is extension
of the disease process from the ascending or descending aorta into the arch. The technique involves the use of
deep hypothermic arrest and selective antegrade cerebral protection through right axillary artery perfusion.
FIG. 8.16 Valve-sparing root replacement: Distal suture line.
P.135
FIG. 8.17 Completed valve-sparing root replacement using a second smaller tube graft.
Ice packs are placed around the patient's head, and core cooling is continued to a temperature of 18°C. During
core cooling, the aortic arch and brachiocephalic vessels are dissected and mobilized. A trifurcation graft is
constructed
by sewing two 8-mm branch Hemashield Dacron grafts to a 12-mm graft or two 10-mm side-branch grafts to a
14-mm graft in an end-to-side manner. After circulatory arrest is achieved, the arch vessels are clamped and
divided 0.5 cm beyond their origins. Selective antegrade cerebral perfusion is begun and the flow adjusted to
maintain a perfusion pressure of 50 to 60 mm Hg. The limbs of the trifurcation graft are trimmed to appropriate
lengths and sutured sequentially to the arch vessels with 5-0 Prolene beginning with the left subclavian artery,
then the left carotid artery, and finally the innominate artery (Fig. 8.18). The clamps on the left subclavian and left
carotid arteries are released. With an intact Circle of Willis, there is usually back bleeding to allow flushing of air
and debris through these side branches into the main graft. The innominate artery is then unclamped for final
deairing. The main graft is clamped proximal to the side branches to allow antegrade perfusion to the head and
upper extremities.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
FIG. 8.18 Arch replacement: Completed trifurcation graft to left subclavian, left carotid, and innominate arteries.
Attention is now directed to the arch reconstruction. An aortotomy is made across the arch, the redundant arch
tissue with debris and blood clots is removed, and ascending and descending aortic segments are completely
divided. A Hemashield tube graft of appropriate size is introduced into the lumen of the descending aorta (Fig.
8.19). It is sewn to the normal aortic wall with a continuous suture of 3-0 Prolene. Sometimes, it is buttressed
with a Teflon felt strip on the outside of the descending aorta (Fig. 8.20). The suture line may be further secured
with BioGlue. The tube graft is then pulled out of the descending aorta (Fig. 8.21). An arterial cannula is inserted
into the arch graft, which is then clamped. Perfusion to the lower body is gradually instituted while the arch graft
is aspirated to evacuate air. The arch graft is then sutured to the transected end of the ascending aorta using 4-
0 Prolene. At this time, an opening in the arch graft is made and the beveled end of the trifurcation graft is sewn
to the arch graft with 5-0 Prolene suture (Fig. 8.22) without interrupting perfusion. During this anastomosis, the
heart is perfused with warm blood through the retrograde cardioplegia cannula. After deairing maneuvers, all
clamps are released.
P.136
FIG. 8.19 Arch replacement: Insertion of a tube graft into the descending aorta and performance of distal suture
line.
FIG. 8.20 Arch replacement: Sewing a graft to the aortic wall.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
FIG. 8.21 Arch replacement. A: Tube graft is withdrawn from the distal aorta. B: Close-up of an inverted distal
suture line.
Elephant-Trunk Technique
When the descending aorta is also diseased and requires subsequent excision and replacement, an elephant-
trunk technique is used. This entails inverting approximately 3 cm of Hemashield tube graft on itself.
Tube Graft Inversion
The short segment is on the outside of the larger segment of the tube graft.
The double-layer tube graft is introduced into the lumen of the descending aorta as before (Fig. 8.23). The
double-layer tube graft edge is then sewn to the descending aorta, buttressed with a Teflon felt strip on the
outside with a continuous suture of 3-0 Prolene. Again, the use of BioGlue may reinforce the anastomosis.
FIG. 8.22 Completed arch replacement with elephant-trunk extension into descending aorta.
FIG. 8.23 Elephant-trunk technique: A double-layer graft is sewn to the aortic wall.
The needle bite includes the two layers of tube graft, aortic wall, and a Teflon felt strip.
At the completion of the anastomosis, the longer segment of the graft is pulled out of the lumen of the tube graft,
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.137
leaving a “trunk” of approximately 3 cm behind within the lumen of the descending aorta.
FIG. 8.24 Performing elephant-trunk anastomosis more proximally on aortic arch or distal ascending aorta.
The trunk is anastomosed to another tube graft when excision of the descending thoracic aorta is
undertaken weeks to months subsequently.
If a neck for the elephant-trunk anastomosis is not present distal to the left subclavian artery, the site of the
distal suture line can be as far proximally as the ascending aorta depending on the narrowest part of the aortic
arch (Fig. 8.24). In these cases, the arch vessel stumps are oversewn with 4-0 Prolene sutures.
MANAGEMENT OF TYPE B AORTICDISSECTION
Initial management of patients with type B dissection affecting the descending aorta is to control the high blood
pressure with medical therapy. In contradistinction to type A aortic dissection, which requires urgent surgical
intervention, patients with type B dissection have a relatively good prognosis with medical therapy. However,
elective surgical intervention remains the best form of management and provides superior long-term results in
patients who are young and free of other concomitant diseases. Therefore, replacement or stenting of the
descending thoracic aorta is the treatment of choice in young, otherwise healthy patients with chronic type B
dissection and in older patients with expanding descending aortic aneurysms. Nevertheless, patients who
continue to have pain despite maximal medical management, have evidence of contained rupture, or have
ischemia of a limb or major organ owing to involvement of an arterial branch by the dissection process should
undergo urgent surgical intervention.
Interventional radiologists have been important participants in the care of patients with aortic dissections.
They are often able to reestablish flow to compromised or occluded aortic branches by fenestrating the intimal
flap or stenting the true or false lumen. This may allow a patient with a type B dissection to be stabilized and
have surgery on an elective basis. More recently, segments of contained rupture in the acutely dissected
descending aorta have been stent grafted (see subsequent text). Some patients with type A dissections continue
to demonstrate clinically significant obstruction to flow in one or more aortic branches after ascending aortic
replacement. These patients may also be successfully treated by the interventional radiologist.
Technique for Replacement of the Descending Thoracic Aorta
A postero-lateral thoracotomy through the fifth intercostal space provides adequate exposure of the descending
P.138
thoracic aorta. At times, a second lower incision may facilitate the distal anastomosis. Adhesions must be taken
down with utmost care to prevent injury to the lung or the diseased aorta. A plane of dissection is identified, and
vascular loops or umbilical tapes are passed around the transverse arch between the left carotid and the left
subclavian arteries, the left subclavian artery, and the descending aorta distally. The left groin area is always
prepared and should be within the operative field in all cases.
We routinely use partial left-sided heart bypass for nearly all surgeries on the descending thoracic aorta. The
femoral artery is cannulated for arterial return, and either the femoral vein, pulmonary artery, or pulmonary vein is
selected for venous drainage (see Replacement of the Ascending Aorta section). The use of partial bypass
allows control of the patient's blood pressure. It also provides perfusion of the lower body and may protect the
spinal cord.
Initially, the transverse arch and the left subclavian artery are clamped. The distal aorta is clamped a short
distance below the proximal clamp, although the distal extent of aortic dissection may have progressed well
below the
diaphragm. A short aortotomy is made; it is then extended to provide adequate exposure (Fig. 8.25A). When the
aorta is opened and decompressed, it is often possible and preferable to reapply a single clamp below the origin
of the subclavian artery above the site of dissection to ensure perfusion through the left subclavian artery
because this may decrease the incidence of paraplegia. The ostia of the intercostal arteries are oversewn with 3-
0 Prolene sutures.
FIG. 8.25 Stepwise technique for the replacement of the descending aorta. A: An aortotomy. B: The proximal
suture line.
An appropriately sized Hemashield tube graft is sewn into the proximal aortic lumen with continuous sutures of 3-
0 Prolene (Fig. 8.25B). The suture line is always buttressed and reinforced with strips of Teflon felt, which may
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.139
be outside and around the aorta or within its lumen or both. A clamp is then applied to the tube graft, and the
proximal clamp placed on the aorta is removed. The suture line is checked for bleeding, and additional sutures
are placed if deemed necessary. Use of BioGlue on the outside of the anastomosis will provide additional
reinforcement of the suture line. The tube graft is cut to the precise length and sewn to the distal aortic wall with
continuous 3-0 Prolene suture incorporating a strip of Teflon felt in the suturing to reinforce the anastomotic line
(Fig. 8.26A). The remaining aortic wall is then reapproximated over the graft (Fig. 8.26B). Alternatively, the aorta
may be transected at the proposed site of anastomosis. A generous cuff of aortic wall is dissected free and
reinforced with a strip of Teflon felt. The tube graft is then interposed, and both proximal and distal anastomoses
are completed with continuous suture of 3-0 Prolene.
Reimplantation of the intercostal arteries
The lower thoracic intercostal arteries may on occasion be quite large in patients with chronic dissection or
aneurysm. Although oversewing them has been the accepted technique, consideration should be given to their
reimplantation to reduce the incidence of paralysis.
Technique
A small, elliptic segment of the tube graft overlying the intercostal arteries is removed. The island of intercostal
arteries is then sewn to the tube graft with deep bites of continuous suture of 3-0 Prolene (Fig. 8.27). Use of Bio-
Glue may additionally secure the suture line.
In patients who have previously undergone ascending aorta and arch replacements with the so-called elephant-
trunk technique, the proximal anastomosis is simplified. After the initiation of cardiopulmonary bypass, the blood
pressure is temporarily lowered to 60 mm Hg. The distal aorta is opened, the graft extension is identified, and the
clamp is placed on this graft (Fig. 8.28). The proximal descending graft is then anastomosed to the trunk
extension with running 3-0 or 4-0 Prolene sutures. The distal anastomosis is completed as described previously.
The surgery can also be performed without the use of left-sided cardiopulmonary bypass. Often the aorta is
clamped only proximally. Blood from the distal aorta is removed through a cell saver sucker for reinfusion. The
distal anastomosis is carried out by this open technique unimpeded by the distal clamp.
Соседние файлы в папке Библиотека им академика М.И. Перельмана