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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3683_Библиотеки_им_академика_М_И_Перельмана
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P.69
It is often prudent to perform the right coronary attachment after completion of the distal aortic
anastomosis. The aortic clamp can be removed for a moment to distend the aortic root and the precise
location of the right coronary anastomosis can be noted. The aorta is clamped again, and the right coronary
artery anastomosis is completed.
The pulmonary autograft is now trimmed to meet the transected ascending aorta and the distal anastomosis
is performed with 4-0 or 5-0 continuous Prolene suture (Fig. 5.39). The aortic cross-clamp can be removed
at this point, and the reconstruction of the right ventricular outflow tract completed while the patient is being
rewarmed.
FIG. 5.35 Pulmonary root is enucleated without injury to the first septal coronary artery.
FIG. 5.36 Interrupted sutures are placed in the annulus and pulmonary autograft (see text).
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FIG. 5.37 Sutures are tied over a strip of pericardium.
An appropriately sized, cryopreserved pulmonary homograft is selected and oriented with one sinus
posteriorly and two sinuses anteriorly in an anatomic manner. It is trimmed appropriately, and the distal
anastomosis is carried out with 4-0 or 5-0 Prolene suture.
Kinking of the Pulmonary Homograft
Leaving the pulmonary homograft too long may result in kinking of the distal suture line when the heart is
filled with blood.
Gradient across Distal Suture Line
There is a tendency for a gradient to develop across the distal anastomosis. This may be secondary to an
immune reaction with subsequent fibrosis. It may also be due to the purse-string effect of a continuous
suture line. To prevent this complication, sutures should be spaced close together. Additionally, the
pulmonary homograft should be oversized to minimize the gradient even if some narrowing of the
anastomosis occurs.
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FIG. 5.38 Anastomosing the left coronary button to the pulmonary autograft.
FIG. 5.39 Attachment of the pulmonary autograft to the aorta.
Using 4-0 Prolene, the proximal anastomosis is started on the posterior aspect of the incision on the right
ventricular outflow tract. After completing the suture line medially, the lateral aspect of the posterior suture
line is accomplished, taking shallow bites of the endocardium to avoid the septal branches of the left
anterior descending coronary artery (Fig. 5.40B). The remainder of the suture line anteriorly is completed
(Fig. 5.41). The heart is filled, deairing performed, and the patient is weaned from cardiopulmonary bypass.
Septal Artery Injury
Full-thickness bites on the right ventricle posteriorly risks injury to high septal coronary branches.
The surgeon may elect to complete the right ventricle to pulmonary artery connection with a pulmonary
homograft before implanting the pulmonary autograft in the aortic root.
Dilation of Autograft
In infants and young children, implantation of the pulmonary autograft as a complete root has been
demonstrated to allow somatic growth to occur. The concern is that dilation may also take place, resulting in
aortic valve insufficiency. Excising the entire left and right aortic sinuses and using this native aortic tissue
to replace the corresponding sinuses of the autograft, and reinforcing the noncoronary portion of the
autograft with the retained native aortic wall
may help prevent dilation (Fig. 5.42). Another technique to prevent dilation of the pulmonary autograft is to
wrap it with Hemashield (Fig. 5.43). In older children and adults, geometric matching of the aortic and
pulmonary artery roots is necessary to avoid aortic insufficiency if the root replacement technique is used.
This may involve plication of the aortic annulus with pledgeted horizontal mattress sutures at the
commissures and/or the use of an interposition tube graft to fix the diameter of the sinotubular junction.
Alternatively, many institutions prefer to implant the pulmonary autograft in older children and adults using a
modified subcoronary technique, as was originally performed by Ross. The technique is similar to that
described for the implantation of a stentless bioprosthesis.
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FIG. 5.40 A: Approximating the cryopreserved pulmonary artery homograft to the right ventricular outflow
tract. B: Full-thickness sutures may occlude the septal artery.
Technique: Aortic Valve Replacement Using Stentless Bioprosthesis or Aortic Homograft
It is clear that the normal geometry of the aortic root can be better maintained if the whole root is replaced with
an aortic allograft or stentless aortic bioprosthesis. This technique is described in detail in the section on
pulmonary autograft replacement of the aortic root (Ross procedure). Nevertheless, a modified subcoronary
technique for the replacement of the aortic valve with an aortic homograft has been practiced since its
introduction with excellent results. Below, one will find out technique for subcoronary
implanation of stentless aortic root bioprosthesis; however, similar principles apply when using an aortic
homograft. We have employed a similar technique when implanting the stentless aortic root bioprosthesis.
FIG. 5.41 Completed pulmonary autograft replacement of the aortic root.
FIG. 5.42 Large coronary buttons completely replace native aortic sinuses. Preserved noncoronary aortic sinus
is incorporated in anastomosis of autograft to ascending aorta, thereby reinforcing noncoronary sinus of
autograft.
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FIG. 5.43 Wrapping of pulmonary autograft with a Hemashield graft.
Three traction sutures are placed on the anterior surface of the aorta (Fig. 5.44). A small transverse aortotomy is
made and then extended both upward and downward under direct vision to provide good exposure of the aortic
root. The aortic valve is excised. Three 4-0 Ticron simple sutures are placed in the nadir of each annulus.
Traction on these sutures opens the aortic annulus and left ventricular outflow tract maximally, allowing accurate
sizing (Fig. 5.45).
Too Low Aortotomy
If the aortotomy is too proximal, it will be impossible to resuspend the commissures of the prosthetic valve or
homograft high enough (see later). A small transverse aortotomy is made initially at least 1 cm above the right
coronary ostium. The aortic root should be visualized through this opening. If the incision is too close to the valve
commissures, it should be closed and a new incision made more distally on the aorta.
Undersizing the Valve
The valve sizer should fit snugly in the aortic annulus. It is advisable to oversize the valve 1 to 3 mm. The larger
surface area of the cusps allows greater apposition of the leaflet tissue, thereby reducing the possibility of
valvular insufficiency.
Discrepancy between the Sinotubular and Aortic Annulus Diameter
If the diameter of the sinotubular junction is more than 2 mm greater than that of the annulus, the modified
subcoronary technique should not be used. Some patients with poststenotic dilation of the aorta will demonstrate
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this finding. Performing a subcoronary implant of a stentless prosthesis or homograft valve in these patients will
result in valvular insufficiency when the aortic root is pressurized and the commissures of the implanted valve are
pulled outward. Some surgeons have advocated reducing the size of the sinotubular junction in such patients.
However, it is probably safer to perform the implant as a root replacement (see previously) or select a stented
prosthesis.
Type of Aortotomy
In patients with good-sized aortic roots, the aortotomy should be made transversely several millimeters above the
native commissures. This allows precise sizing and resuspension of the prosthetic commissures. In patients with
small aortic roots, an oblique aortotomy extended downward into the noncoronary sinus allows better
visualization and easier placement of sutures. However, the oblique
incision does distort the anatomy of the aortic root so that resuspending the commissures is more challenging.
FIG. 5.44 Arteriotomy and exposure for aortic valve replacement with a stentless bioprosthesis.
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FIG. 5.45 Sizing the left ventricular outflow tract.
Simple interrupted sutures of 4-0 Ticron are now placed 2 to 3 mm apart at the level of the annulus and below
the level of the commissures to create a circle of stitches in a single plane. This entails taking bites of the
subaortic curtain, the membranous, and muscular segment of the left ventricular outflow tract. The three sutures
that were originally placed in the nadir of the aortic annulus are now passed through the Dacron skirt of the
appropriately sized stentless bioprosthesis just below the lowest aspect of the leaflet cusps (Fig. 5.46).
Leaflet Injury
It is important to place the needle well away from the margin of the bioprothetic leaflet attachment. Needle
perforation of the leaflet tissue of the bioprosthesis results in irreparable injury (Fig. 5.47).
The remaining sutures are placed in the skirt of the device in a similar manner. The prosthesis is lowered into
position, and the sutures are tied snugly and cut short.
Many surgeons using homografts prefer to invert the device into the left ventricle and attach the homograft
to the annulus with a continuous suture. This technique takes less time and can be accomplished with very good
results. However, the porcine aortic root bioprosthesis is not as pliable as a homograft and may be damaged
during the process of its inversion into left ventricular outflow tract followed by being pulled up into the aorta. The
use of multiple interrupted simple sutures allows a precise proximal suture line without distortion or purse
stringing.
With the prosthesis seated within the aortic root, the right and left coronary sinus portions of the stentless
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bioprosthesis are scalloped to fit beneath the patient's own coronary ostia, leaving a 4- to 5-mm rim of prosthetic
tissue behind (Fig. 5.48). All excess tissue is cut away, leaving the noncoronary sinus portion below the
sinotubular junction intact (Fig. 5.49). The three commissures are now pulled upward 2 to 3 mm above the native
commissures and attached to the aorta at equidistant points with 4-0 Prolene sutures, which may be buttressed
with pledgets. These sutures are not tied down at this stage. They are placed there to allow proper orientation of
the device (Fig. 5.50). Alternatively, these sutures are omitted and the surgeon frequently checks the positioning
of the bioprosthetic commissures while performing the distal suture line (Fig. 5.51).
FIG. 5.46 Simple interrupted suture placement in the annulus, subaortic curtain, and muscular segment of the left
ventricular outflow tract and bioprosthesis.
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FIG. 5.47 Incorrect needle position causing leaflet injury.
The importance of resuspending the commissures of the bioprosthesis as high as feasible cannot be
overemphasized. This maneuver stretches the device upward and allows a larger segment of the leaflets to
coapt during diastole, preventing any central aortic leak.
FIG. 5.48 Removal of the coronary sinuses of the prosthesis.
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