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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. 22.12 Attaching mitral and tricuspid valve components to the pericardial patch. Running suture is
completed inferiorly and interrupted reinforcing mattress sutures are placed from the left side through the
mitral component, patch, and then tricuspid component and tied on the right side. A: Left-sided view. B:
Right-sided view.
One-Patch Technique with Direct Ventricular Defect Closure
Recently, some surgeons have advocated direct suture closure of the ventricular septal defect in patients with
complete atrioventricular septal defects. This technique involves the placement of interrupted pledgeted 5-0
polyester
sutures on the right ventricular aspect of the septal crest, avoiding the conduction tissue. These sutures are
brought up through the superior and inferior bridging leaflets and then through the pericardial patch used to
close the atrial defect. When deficient left-sided leaflet tissue is present, the sutures are placed more toward the
right side to create a larger mitral valve. The cleft between the left superior and inferior leaflets is closed with
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interrupted 6-0 or 7-0 Prolene sutures. The septal sutures are tied securely, thereby closing the ventricular
septal defect. The mitral valve is tested with saline, and if needed, annuloplasty sutures are placed as described
in the preceding text. The pericardial patch is sewn into place with a continuous 6-0 Prolene suture, taking
shallow bites between the annulus inferiorly and the coronary sinus to avoid the atrioventricular node.
FIG. 22.13 The remainder of the pericardial patch is used to close the atrial septal defect.
Patient Indications
This simplified technique should be applied judiciously. If the ventricular septal defect is too deep, the
tension required to pull the leaflets down to the septum may cause the sutures to pull through the muscle or
may distort the valve and lead to unacceptable mitral insufficiency. At least theoretically, this direct closure
of the ventriculoseptal defect could cause left ventricular outflow tract obstruction. A modification of this
technique, closing the superior and/or inferior most extents of the ventricular septal defect directly and
patching the other side or midportion of the defect may be useful.
Completion of the Operation
The right atriotomy is closed with a running 6-0 or 5-0 Prolene suture. If the operation has been performed on
cardiopulmonary bypass, rewarming is begun during closure of the atrial septal defect component. After closing
the right atrium, the heart is filled, the aortic cross-clamp is removed, and deairing procedures are performed. If
the operation has been accomplished under circulatory arrest, the heart is filled with saline after closing the right
atriotomy. Cardiopulmonary bypass is recommenced, the aortic cross-clamp is removed while deairing through
the ascending aorta, and rewarming is carried out in the usual manner.
UNBALANCED ATRIOVENTRICULAR SEPTAL DEFECT
Patients with unbalanced atrioventricular septal defects to the right often have underdeveloped left-sided
structures. Most of these patients are not candidates for biventricular repair and should undergo a Norwood-type
initial procedure followed by staging to a completion Fontan operation (see Chapters 30 and 31). Patients with
unbalanced atrioventricular septal defects to the left may tolerate a biventricular approach by leaving a restrictive
atrial septal defect. Alternatively, they may be candidates for a one and one-half ventricle repair combining a
septation procedure with a bidirectional cavopulmonary anastomosis (see Chapter 31).
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23
Right Ventricular Outflow Tract Obstruction
The right ventricular outflow tract includes the right ventricular outlet chamber (or the infundibulum); the
pulmonary valve; the main, right, and left pulmonary arteries; and the peripheral pulmonary arterial branches.
Obstruction can occur at a specific site or involve many segments of the right ventricular outflow tract.
Obstruction of the right ventricular outflow tract is commonly associated with other cardiac anomalies.
DOUBLE-CHAMBERED RIGHT VENTRICLE
This consists of a hypertrophied muscle band creating obstruction between the inlet and infundibular portion of
the right ventricle. An enlarged acute marginal branch of the right coronary artery often overlies the area of
obstruction where an area of “dimpling” of the right ventricular free wall is also often present. Most often, a
double-chambered right ventricle is associated with a perimembranous type of ventricular septal defect.
Technique for Repair
Cardiopulmonary bypass with bicaval cannulation is used. After aortic cross-clamping and cardioplegia delivery,
a right atriotomy is performed. After identifying the papillary muscles of the tricuspid valve, the remainder of the
obstructing muscle is resected until the fibrous “os infundibulum” is visible. Once this is resected, the pulmonary
valve should be evident. The accompanying ventricular septal defect should now be apparent. This ventricular
septal defect may be closed through the right atriotomy (see Chapter 21).
Misidentifying the Ventricular Septal Defect
The circular opening visualized if a right ventriculotomy approach is used may, on first examination, appear to be
the ventricular septal defect. Care must be taken to identify the location of the tricuspid valve to avoid this
mistake.
Creating a Right Ventriculotomy
In resecting the dense muscle bundles of double chamber right ventricle, it is important not to debride muscle
through (and out) the right ventricular free wall. As a general rule, if a right angle clamp can be placed behind the
muscle bundle and the bundle divided over the clamp, the surgeon will not “button hole” the right ventricle.
TETRALOGY OF FALLOT
An anatomic anomaly consisting of a ventricular septal defect, right ventricular outflow tract obstruction with
resultant right ventricular hypertrophy, and dextroposition of the aorta was described by Fallot in 1888. These
children usually present with mild to moderate cyanosis and may have intermittent hypoxic spells.
The anatomy must be accurately defined to plan the management of these patients. Echocardiography can
demonstrate the presence of additional ventricular septal defects, can usually delineate the initial course of the
right and left coronary arteries, and can size the main and proximal right and left pulmonary arteries. Cardiac
catheterization is reserved for those patients in whom the echocardiographic diagnosis is incomplete, when
aortopulmonary collateral vessels are suspected, or for patients with previous palliative procedures.
Staged Approach
Several centers have reported satisfactory results with complete repair of tetralogy of Fallot in neonates.
However, as the long-term results of repair of tetralogy of Fallot become available, the significant problem of right
ventricular failure and its causes are being elucidated. It is now believed that pulmonary regurgitation plays a
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major role in the development of right ventricular dysfunction. For this reason, some surgeons advocate a staged
approach in patients who require surgery before 4 to 6 months of age. Patients who become symptomatic early
in life or are ductal dependent tend to have small pulmonic valves and usually require a transannular patch. By
performing an initial shunt procedure (see Chapter 18) and delaying definitive repair, the hope is that the native
valve and/or annulus can be preserved.
In addition, 3% to 5% of patients with tetralogy of Fallot have an anomalous left anterior descending coronary
artery arising from the right coronary artery. The course of the left anterior descending coronary artery across
the right ventricular outflow tract may preclude an appropriate transannular incision. If these patients need
surgery in the first few months of life, a shunt procedure is preferred. Some of these patients may be able to
undergo a transatrial repair. However, many will require a right ventricular to pulmonary artery conduit as part of
their repair, and this is best delayed as long as is possible and practical clinically.
Technique for Complete Repair
A median sternotomy provides excellent exposure. A generous patch of autologous pericardium is harvested,
attached with metal clips to a piece of plastic, placed in 0.6% glutaraldehyde solution, and then rinsed in saline.
Such treatment fixes the pericardium and thereby lessens the chances of aneurysmal dilation of the patch. If the
patient has undergone a previous systemic to pulmonary shunt, it is dissected circumferentially to allow for
closure with a metal clip at the initiation of cardiopulmonary bypass (see Chapter 18). In the absence of a shunt,
minimal manipulation should be performed before cannulation to prevent hypoxic spells.
Besides confirming the anatomy with transesophageal echocardiography, an external examination of the heart is
conducted. The surgeon looks for an anomalous coronary artery crossing the right ventricular outflow area,
evaluates the size of the main and branch pulmonary arteries, and notes the distance between the aortic valve
and the left anterior descending artery, which indicates the width of the right ventricular outflow tract. These
observations help determine the surgical approach. A hypoplastic right ventricular outflow tract may favor the
need for a right ventriculotomy or the probability of a transannular patch.
Standard bicaval and aortic cannulation is used to initiate cardiopulmonary bypass. A vent is placed through the
right superior pulmonary vein into the left ventricle. Systemic cooling to 28°C to 34°C is achieved, the aorta is
clamped, and cold blood cardioplegic solution is infused into the aortic root (see Chapter 3). In patients with
discrete infundibular muscular obstruction and an adequate pulmonary annulus, the repair can be done through
a transatrial approach.
Transatrial Technique
After achieving cardioplegic arrest, the tapes around the vena cavae are snugged down, and an oblique right
atriotomy is made. The septal leaflet of the tricuspid valve is retracted to allow exposure of the ventricular septal
defect and the right ventricular outflow tract. A right angle clamp is then used to identify hypertrophied muscle
bands. With the clamp in place, each muscle band is divided with a no. 15 knife blade, cutting the band until the
clamp is reached. The cut edge of the band can then be grasped with a forceps and resected with sharp
scissors. When adequate resection of hypertrophied muscle has been completed, it should be possible to
visualize the pulmonic valve (Fig. 23.1). A valvotomy can be performed by everting the leaflets and incising the
commissures, if necessary. The annulus is sized with a Hegar dilator to ensure an adequate valve opening for
the patient's size (see Appendix section).
Buttonholing of Anterior Right Ventricle
Care must be exercised when resecting muscle from the right ventricular outflow tract not to perforate the
anterior wall. Checking outside the heart intermittently may be helpful. If a hole is created, it must be closed,
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usually with a pericardial patch (see subsequent text).
Resection near Ventricular Septal Defect
It is important to limit the resection of muscle along the anterior margin of the ventricular septal defect as this may
compromise suturing of the patch to this edge.
The ventricular septal defect is closed with a patch of GORTEX cut slightly larger than the defect. This can be
secured in place with a continuous suture or multiple interrupted horizontal mattress 5-0 braided sutures with felt
pledgets (see Chapter 21).
Transventricular Technique
Some surgeons prefer a right ventriculotomy approach for patients with tetralogy of Fallot. The advantages
include the ability to resect all obstructing muscle bundles under direct vision and to enlarge an underdeveloped
infundibulum with a patch. The potential disadvantages include scarring of the right ventricle, which may give
rise to ventricular dysfunction and dysrrhythmias. Even when a transventricular approach is used, every attempt
is made to preserve the pulmonic valve leaflets and to avoid a transannular patch.
A vertical right ventriculotomy is made, and the edges are retracted with pledgeted sutures. The hypertrophied
infundibular muscle bundles are incised and selectively excised as needed to open up the outflow tract (Fig.
23.2). The large malalignment type of ventricular septal defect can now be seen and is closed with a GORTEX
patch using a continuous suture of 5-0 Prolene. With this technique, traction on the patch by the assistant
facilitates placement of the next stitch. Suturing begins at the 1 o'clock position and continues clockwise around
the tricuspid annulus, taking shallow bites of thickened endocardium up to the aortic annulus where the suture is
tagged at the 8 o'clock position (Fig. 23.3).
Limiting Right Ventriculotomy
To better preserve long-term right ventricular function, the length of the ventriculotomy should be limited to that
needed to open the hypoplastic portion of the infundibulum.
FIG. 23.1 A: Exposure of ventricular septal defect and right ventricular outflow tract through tricuspid valve. B:
Infundibular resection is complete and pulmonic valve can be seen.
FIG. 23.2 Transection of muscle band. Dotted line shows resection lines to excise hypertrophied muscle.
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FIG. 23.3 Continuous suture technique for the closure of ventricular septal defect through right ventriculotomy.
Difficulty in Exposing Ventricular Septal Defect
If the right ventriculotomy must be extended to provide adequate exposure for closure of the ventricular septal
defect, it is preferable to open the right atrium and close the ventricular septal defect through the tricuspid valve.
Detachment of the anterior leaflet of the tricuspid valve may be useful to expose the outlet portion of the defect
(see Chapter 21).
Extensive Resection of Muscle Bands
When a right ventriculotomy is performed, muscle resection can be more limited because the patch itself will
open up the outflow tract. Aggressive muscle resection leads to more endocardial scarring that may contribute to
right ventricular dysfunction.
Injury to the Aortic Valve
The aortic valve leaflets are immediately below the superior margin of the defect and can be punctured during
suturing if deep needle bites are taken in this area (Fig. 23.4). Suturing in this area should therefore incorporate
the crista marginalis, which holds sutures well.
The pulmonary valve and annulus are evaluated with Hegar dilators. Pulmonary valvotomy, if necessary, is
carried out by bringing the pulmonary valve leaflets downward into the ventriculotomy.
Transpulmonary Approach to Pulmonic Valve and Annulus
Whether a transatrial or transventricular approach is used, evaluation of the pulmonic valve may be difficult
working from below. In these cases, a separate vertical incision is made on the main pulmonary artery. Many
surgeons prefer to use a transpulmonary approach to the pulmonic valve in all patients. After inspecting the valve
and completing a valvotomy, if required, a Hegar dilator of the appropriate size is passed into the right ventricle
(see Appendix section). If the annulus cannot be opened adequately with passage of sequentially larger dilators,
the incision on the pulmonary artery is extended across the annulus only as far as necessary. This incision
should be made through the anterior commissure of the pulmonic valve to reduce the amount of pulmonary
insufficiency.
FIG. 23.4 Proximity of an aortic valve leaflet to the rim of septal defect.
FIG. 23.5 Pulmonary arteriotomy extended across annulus onto infundibulum parallel to anomalous coronary
artery.
Anomalous Coronary Artery
The transatrial-transpulmonary approach can be used in some patients with an anomalous coronary artery
crossing the right ventricular outflow tract. In these cases, if transannular extension of the pulmonary arteriotomy
is required, the incision must be made parallel to the anomalous vessel and an appropriately shaped patch used
to maximize the opening of the right ventricular outflow tract (Fig. 23.5).
The orifices of the right and left pulmonary arteries are then evaluated. If stenosis of the takeoff of the left
pulmonary artery is noted, the pulmonary arteriotomy can be carried out onto the left pulmonary artery as far as
necessary to adequately relieve the stenosis. If narrowing of the right pulmonary artery is present, this may be
best handled by extending the pulmonary arteriotomy onto the anterior surface of the right pulmonary artery
behind the aorta. In this case, a separate rectangular patch is used to enlarge the opening of the right, or right
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and left pulmonary arteries (Fig. 23.6).
If the annulus is of adequate size, the pulmonary arteriotomy may be sutured primarily with a running 6-0 Prolene
stitch, or closed with an appropriately sized patch of autologous pericardium to enlarge the main or left
pulmonary arteries, as indicated. When used to enlarge the left pulmonary artery, the patch should be tailored
with a squared-off end to provide optimal enlargement. The right ventriculotomy is then closed with an elongated
oval patch
of autologous pericardium or Gore-Tex, using a running 5-0 Prolene suture.
FIG. 23.6 Two-patch technique to enlarge the proximal right and left pulmonary arteries.
If the infundibulum and annulus are hypoplastic, a transannular patch is required. Many surgeons use a patch
with a monocusp valve made from pericardium, Gore-Tex, or excised from a large pulmonary homograft (Fig.
23.7A). The patch may extend only onto the proximal main pulmonary artery if the right and left pulmonary
arteries are of adequate size (Fig. 23.7B). Often the distal main artery and the origin of the left pulmonary artery
are small and the transannular incision is extended out onto the left pulmonary artery (Fig. 23.8A). The patch
should be tailored in such a way that the new pulmonary artery dimension is equal to or slightly larger than the Z-
zero value for the pulmonary valve based on the patient's body surface area (see Appendix section). When a
monocusp is used, the patch is tailored so that the position of the valve leaflet is at the level of the patient's
annulus (Fig. 23.7A and C). The patch is sewn into place starting at the distal pulmonary arterial opening, using
running 6-0 or 5-0 Prolene suture. If a standard pericardial patch is used, it may be useful to place the correct
size of a Hegar dilator into the new main pulmonary artery as the patch reaches the level of the pulmonary valve
annulus. The patch can then be trimmed to fit snugly over the Hegar dilator at this level as it is being sewn into
place (Fig. 23.8B).
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