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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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FIG. 5.22 Tying sutures down parallel with the direction of the sewing ring (A), not across the prosthetic leaflets
(B).
Aortotomy Closure
The aortotomy closure is usually accomplished with continuous 4-0 Prolene or 5-0 Prolene sutures in a double-
layer manner starting at each end of the incision. The sutures are then tied to each other anteriorly (Fig. 5.25).
Bleeding from the Ends of Aortotomy
Troublesome bleeding from the ends of the aortotomy can be prevented to some extent by suturing back and
taking a bite of undivided aortic wall before continuing forward along the incision or using a pledget at each end
(Fig. 5.25, inset).
Coronary Air Embolism
Air embolism to the coronary arteries, particularly the right coronary artery, probably does occur during the
evacuation of air from the left ventricle. Every precaution should be taken to prevent or reduce coronary air
embolism. The pump flow is reduced, and the right coronary artery is temporarily occluded with digital pressure.
The surgeon then partially unclamps the aorta and allows blood mixed with air trapped in the aortic root to flow
freely from the vent opening on the aortotomy. High suction is applied to a slotted vent needle in the aortic root to
continuously remove any air bubbles that may be ejected as the heart is filled and ventilation is begun (see
Chapter 4). Only when all air has been evacuated can the vent needle be removed and the vent suture tied
down.
Friable Aortic Wall
A friable aortic wall may necessitate the placement of additional reinforcing pledgeted sutures. Occasionally,
when the aortic wall has been denuded of its adventitia or if the aorta is thin walled or friable, the aortotomy
suture line can be reinforced with strips of autologous pericardium (Fig. 5.26).
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FIG. 5.23 A: Aberrant location of coronary artery ostia at the commissures. B: Rotation of the bioprosthesis to
prevent coronary artery flow interference by the struts.
Controlling Bleeding from the Aortotomy Ends
To control bleeding from either end of the aortotomy, it is prudent to cross-clamp the aorta temporarily or to
reduce the perfusion flow considerably; this will provide good exposure of the bleeding sites and facilitate
satisfactory placement of pledgeted sutures to obtain absolute control of bleeding.
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FIG. 5.24 Myectomy to open left ventricular outflow tract.
Closure of Oblique Aortotomy
Before seating the prosthesis, the closing aortotomy suture is started at the inferior extent of the opening, well
into the noncoronary sinus, and tied. The suture line is continued for five or six bites and is left loose and tagged.
The prosthesis is then seated and the valve sutures securely tied. The aortotomy closure suture is tightened with
a nerve hook and continued to completion.
Augmentation of the Aortotomy
Sometimes the struts of the tissue prosthesis protrude into the aortotomy and could result in tension along the
suture line. Patch enlargement of the aortotomy with a Hemashield Dacron patch allows ample room for the
prosthetic struts and ensures a safe closure (Fig. 5.27) .
Aortic Wall Injury
Rarely the strut of a bioprosthesis may perforate the aortic root during closure of the aortotomy secondary to
tenting
of the anterior aorta over the strut (Fig. 5.28). This may necessitate resection of the damaged ascending aorta
and replacement with an interposition tube graft. It is important to ensure that the aortic suture does not catch the
strut of the bioprosthesis during closure. This error may not only lead to prosthetic regurgitation, but will also
weaken the suture line.
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FIG. 5.25 Aortotomy closure with a special precaution to prevent bleeding from the ends of the incision.
Technique
The aorta is cross-clamped as high as possible, retrograde cold blood cardioplegic solution is administered, and
cardioplegic arrest of the heart is established. A right superior pulmonary vein vent is placed (see Chapter 4),
and the heart is decompressed. The torn and diseased aorta is resected. If the quality of the aortic wall is good,
the defect can be closed with a patch of glutaraldehyde-treated pericardium or Hemashield Dacron. Conversely,
if the aortic wall is very thin, dilated, and friable, then the aorta is dissected free from pulmonary artery and
transected just above the commissures. The aortic wall is reinforced with a strip of felt and anastomosed to an
appropriately sized tube graft (see Chapter 8). The distal end of the tube graft is then sewn to the distal aorta in
a similar manner.
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FIG. 5.26 Reinforcement of the aortotomy with strips of pericardium.
HOMOGRAFT, AUTOGRAFT, AND PORCINE STENTLESS AORTIC ROOT IN
AORTIC VALVE REPLACEMENT
The mechanical and bioprosthetic valves used in clinical practice have proved to be effective valve substitutes.
Nevertheless, the inconvenience and risk of lifelong anticoagulation therapy for mechanical valves and limited
longevity of bioprostheses are of concern. Donald Ross of London and Sir Brian Barrat-Boyes of Auckland, New
Zealand, introduced the aortic homograft for aortic valve replacement nearly five decades ago. Ross extended
the concept and used a pulmonary autograft in the aortic position. Both the aortic homograft and pulmonary
autograft are good replacement options for children and young adults. Stentless porcine aortic valves have
become available. The stentless porcine valves have been shown to have hemodynamics similar to those of
aortic homografts, and have the advantage that all sizes can be available in the operating room. The long-term
durability of these valves is still not known.
Technique: Pulmonary Autograft Replacement of the Aortic Root: the Ross
Procedure
Through a median sternotomy approach, the aorta is cannulated as distally as possible. A single atriocaval
cannula is usually sufficient, but bicaval cannulation is equally satisfactory. A left ventricular vent through
the right superior pulmonary vein will decompress the heart and keep
the field relatively dry. After initiation of cardiopulmonary bypass, systemic cooling is started. The aorta is
clamped, and antegrade blood cardioplegic solution is administered. This is complemented by continuous
retrograde cold blood followed by cold blood cardioplegic solution (see Myocardial Preservation earlier).
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FIG. 5.27 Patch enlargement of the aortotomy.
Of course it is of paramount importance that the pulmonary valve be normal. All patients who are considered
to be candidates for aortic valve replacement with a pulmonary autograft undergo extensive evaluation
preoperatively. Nevertheless, it is necessary for the surgeon to visualize and ascertain the normality of the
pulmonary valve at the outset before committing to this procedure.
FIG. 5.28 Perforation of the aortic wall by a bioprosthetic strut.
A transverse incision is made on the anterior aspect of the pulmonary artery near the confluence of the right
and left pulmonary arteries. The pulmonary valve is visualized. It must be a normal-appearing trileaflet
valve, free of any disease.
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Abnormal Pulmonary Valve
If there is any evidence of pulmonary valve disease, such as previous endocarditis, bicuspid leaflets, or the
presence of perforations in the leaflet, the valve is left intact and the pulmonary artery opening is closed
with 4-0 Prolene suture. The aortic valve should then be replaced with another alternative such as a
homograft or any other appropriate prosthetic valve.
After satisfactory inspection of the pulmonary valve, a low transverse aortotomy is made. Cold blood
cardioplegia is administered directly into the coronary ostia, in particular the right coronary artery, for better
protection of the right ventricle.
Congenital Anomaly of the Coronary Arteries
Abnormal origin of the coronary arteries from the aortic root may complicate the procedure and requires
some technical modifications.
FIG. 5.29 Aorta has been transected. Coronary ostia are removed as large buttons of the aortic wall.
The aortic valve is removed and the annulus debrided of calcium as described previously. The aorta is
transected, and the left and the right coronary artery ostia are both removed with a large button of aortic
wall. The buttons are dissected free along the course of the coronary arteries to ensure their full mobility
(Fig. 5.29).
Aberrant Branches of Coronary Arteries
Special care must be exercised not to injure any aberrant coronary arteries.
The pulmonary artery is now completely transected at the confluence of its branches (Fig. 5.30). The
dissection is continued with a low-current electrocautery, freeing the pulmonary artery and its root from the
root of the aorta down to right ventricular muscle (Fig. 5.31). All small bleeding vessels are
electrocoagulated.
Injury to the Left Main Coronary Artery
The course of the left main coronary artery is intimately related to the pulmonary artery and its root.
Dissection in this area must be carried out with utmost care.
Retrograde perfusion of blood through the coronary sinus identifies small bleeding vessels that
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otherwise would have gone unnoticed. Hemostasis at this stage of the surgery is important, as bleeding
from this area is difficult to control once the procedure is completed and the aortic clamp removed.
When the pulmonary artery is well mobilized, a right-angled clamp is introduced into the right ventricle
through the pulmonary valve. An incision is made on the right ventricular outflow tract down onto the right-
angled clamp 6 to 8 mm below the pulmonary valve annulus (Fig. 5.32A).
FIG. 5.30 Pulmonary artery is transected at the confluence of right and left pulmonary arteries.
FIG. 5.31 Pulmonary artery is dissected free of the aortic root with a low-current electrocautery.
Injury to the Pulmonary Valve
It is of utmost importance to prevent any injury to the pulmonary valve that is to be used in the aortic
position (Fig. 5.32B).
This incision is then extended transversely across the right ventricular outflow tract (Fig. 5.33). The
endocardium on the posterior aspect of the right ventricular outflow tract is incised with a knife 6 to 8 mm
below the pulmonary valve annulus (Fig. 5.34). The pulmonary artery is now enucleated using Metzenbaum
scissors with the blade angled in such a way as to not injure the first septal branch of the left anterior
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descending coronary artery (Fig. 5.35).
FIG. 5.32 Tip of the right angle should be 6 to 8 mm below the pulmonary annulus. A: The optimal site for
detachment of the pulmonary root from the right ventricle. B: Pulmonary valve can be injured if the
ventriculotomy is too high.
FIG. 5.33 The tip of the right-angled clamp and right ventricular incision along the dashed line.
Injury to the First Septal Coronary Artery
The first septal branch of the left anterior descending coronary artery has a variable course and may at
times be very large. The enucleating technique allows detachment of the pulmonary artery root without
injury to this branch, which can lead to massive septal infarction. Some surgeons require patients who are
candidates for the Ross procedure to undergo coronary angiography preoperatively for the specific
delineation of coronary artery anatomy. If the first septal artery takeoff is very high and its size is significant,
the Ross procedure may be contraindicated. If the septal artery is severed, both ends should be oversewn
to prevent fistulous runoff into the right ventricle.
The pulmonary autograft is freed from the right ventricular outflow tract and is trimmed of excess fatty
tissue. It is then placed in a pool of blood alongside the right atrium.
Buttonhole in the Pulmonary Artery
To prevent buttonhole injury to the pulmonary artery wall, a finger is carefully placed inside it across the
pulmonary valve while removing epicardial fatty tissue.
Simple interrupted 4-0 Ticron sutures are now placed very closely together at the level of the annulus and
below the level of the commissures to create a circle of stitches in a single plane (Fig. 5.36). This entails
taking bites of the subaortic curtain, the membranous, and muscular segments of the left ventricular outflow
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tract. The aortic annular sutures are now passed through the pulmonary autograft just below its annulus.
Alternatively, the pulmonary autograft can be anastomosed to the aortic root with a continuous suture of 4-0
Prolene. The suture line should begin at the commissure between the left and right coronary sinuses,
passing the needle inside out on the aortic annulus and outside in on the pulmonary autograft. The
posterior suture line is completed, and then the second needle is used to complete the anterior
anastomosis. A nerve hook may be used to ensure that the suture line is tight before tying the two ends
together.
Orientation of the Pulmonary Autograft
The correct orientation of the pulmonary autograft is of great importance. It should be placed in such a
manner so that its sinuses overlie the sinuses of the native aorta to facilitate left main coronary artery
implantation.
Injury to the Pulmonary Autograft Leaflet
When placing sutures in the pulmonary autograft, care must be taken not to pass the needle through the
pulmonary valve leaflet.
The pulmonary autograft is lowered into position, and the sutures are tied over a strip of autologous
pericardium (Fig. 5.37). With the continuous suture technique, a strip of pericardium may be incorporated
into the anastomosis.
An incision is then made in the area of the proposed implantation of the left main coronary artery button. A
4.0-mm punch is used to enlarge the opening. The left main coronary button is attached to the pulmonary
autograft with 5-0 or 6-0 continuous Prolene suture (Fig. 5.38). The right coronary button is attached to the
pulmonary autograft in the same manner.
FIG. 5.34 The endocardium on the posterior right ventricular outflow tract is incised 6 to 8 mm below the
pulmonary annulus.
Kinking of the Left Main Coronary Artery
There should be no kinking of the left main coronary artery. An appropriately sized probe must be passed
into the left main coronary artery to ensure its unobstructed course.
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