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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. 19.7 A: Secundum atrial septal defect. B: Direct suture closure of a secundum atrial septal defect. C: Using
the fossa ovalis flap to close the defect. Very small fenestrations of the flap can be primarily sutured.
FIG. 19.8 Patch closure of a secundum atrial septal defect.
Unless the size of the defect is small and the rim of the opening is quite strong, a patch of glutaraldehyde-treated
autologous pericardium or Gore-Tex is used to close a secundum defect to eliminate any tension along suture
lines. An appropriately sized patch is prepared and sewn into position with continuous sutures of 5-0 or 6-0
Prolene (Fig. 19.8).
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Extension of the Defect into the Inferior Vena Cava
Occasionally, the defect may extend into the orifice of the inferior vena cava, making its exposure difficult. The
inferior vena caval cannula should be retracted to allow closure of this margin under direct vision, with a
continuous suture of 5-0 Prolene incorporating the patch.
Creating a Right-to-Left Shunt
The inferior free margin of the defect must be identified and distinguished from the eustachian valve. Inadvertent
approximation of the edge of the eustachian valve to the patch will create a tunnel, diverting the drainage from
the inferior vena cava into the left atrium.
Depth of Sutures
As with direct closure, the suture must incorporate the thickened endocardium on both sides of the septum and
not the fossa ovalis tissue, which is often very thin and friable.
Air in Left Heart
The best way to prevent air embolism is to avoid introducing air into the left side of the heart. Whether the
surgery is performed under cardioplegic arrest or with the heart fibrillating, care should be taken to not place the
sucker through the atrial septal defect. By having the anesthesiologist inflate the lungs before securing the
suture line or the patch closure, the left side of the heart is flooded with blood, displacing air from within the
pulmonary veins and left atrium.
Right Pulmonary Vein Drainage into the Right Atrium
The posterior margin of the defect may be so deficient as to allow the drainage of the right pulmonary veins
directly into the right atrium. The patch must then be sewn to the atrial wall, anterior to the pulmonary vein
orifices, to allow diversion of their drainage behind the patch into the left atrium (Fig. 19.9).
After the septal defect has been addressed, the right atriotomy is closed and the caval snares are released. The
heart is filled and ventilations are performed. If the aorta was clamped, the cross-clamp is removed, deairing
accomplished, and cardiopulmonary bypass discontinued.
Minimally Invasive Approaches
When limited incisions are used, the aorta is generally not clamped. Two pacing wires are attached to the right
ventricle and connected to a fibrillator after cardiopulmonary bypass is initiated. The caval tapes are tightened,
and with the ventricle fibrillating, the right atrium is opened. A concerted effort is made not to place a sucker
through the atrial septal defect, thereby preventing air from entering the left atrium. The lungs are inflated before
tying the suture line of the patch. A large needle on a syringe is used to aspirate the ascending aorta when
fibrillation is discontinued, and this needle hole is allowed to bleed for 1 or 2 minutes after the heart is full and
ejecting.
Inadvertent Discontinuation of Fibrillation
The failure to continue ventricular fibrillation when the heart is open may result in ejection of air into the
ascending aorta with disastrous consequences. The pacing wires must be sewn securely to the right ventricle.
The cable connections must be protected from contact with metal, which can cause a short circuit, resulting in
the loss of fibrillating current.
Defibrillation
Some patients will spontaneously regain sinus rhythm when the fibrillator is turned off. Many patients will require
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defibrillation. With limited incisions, small paddles must be used and frequently higher settings are required for
successful defibrillation. Alternatively, external defibrillator patches secured on the patient's back and anterior
chest wall before sterile draping may be used.
TRANSCATHETER CLOSURE OF ATRIAL SEPTAL DEFECTS
A considerable number of patients with atrial septal defects are currently undergoing placement of devices in the
catheterization laboratory to close their defects. These procedures are effective in patients with secundum-type
defects that are not too large and have good rims on all sides. Rarely, the surgeon may be called upon to
operate for a complication in these procedures such as malposition or embolization of the device, or incomplete
closure of the shunt.
COMMON ATRIUM
On rare occasions, the atrial septum may be absent, giving rise to a single common atrial chamber. Other
lesions, such as anomalous systemic venous drainage with or without a left superior vena cava and endocardial
cushion defects, may also coexist. Each anomaly should be managed individually with subsequent septation of
the common atrium.
A patient with complete absence of the atrial septum, absence of the right superior vena cava, persistent left
superior vena cava, and a cleft mitral valve (Fig. 19.10) underwent complete correction, taking into consideration
the following guidelines.
Aortic cannulation is carried out in the usual manner. Tapes are passed around the left superior vena cava and
inferior vena cava. Both inferior vena cava and left superior vena cava are cannulated directly. The aorta is
cross-clamped, and cold-blood cardioplegia is administered into the aortic root. The snares around both vena
cava are snugged down, and a traditional atriotomy (above and parallel to the sulcus terminalis) is then made.
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FIG. 19.9 Patch closure of an ostium secundum defect with malpositioned right pulmonary veins opening into the
right atrium. The patch is sutured anterior to the orifices of the veins to reroute drainage into the left atrium.
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FIG. 19.10 Operative view of a single atrium with the absence of the right superior vena cava, persistent left
superior vena cava, and cleft mitral valve.
Difficult Exposure of the Left Superior Vena Cava
If direct cannulation of the left superior vena cava is difficult, bypass may be initiated with only the inferior vena
caval cannula. After the aorta is cross-clamped and cardioplegia is given, the inferior cava is snared, the
atriotomy is made, and the left superior vena cava is cannulated from within the right atrium. If not placed
previously, a snare can now be placed around the left superior vena cava and snugged down. In this manner,
complete cardiopulmonary bypass is achieved.
The cleft mitral valve is repaired with multiple interrupted sutures (see Chapter 22). A large patch of pericardium
or Gore-Tex is then sewn to the posterior wall (Fig. 19.11).
The septation should start in the region of the annulus between the atrioventricular valves. Suturing should
include the annulus and a small amount of tricuspid valve tissue (Fig. 19.11C). The mitral valve leaflet should be
spared to avoid producing mitral insufficiency. The suturing is continued in a clockwise direction around the
orifice of the coronary sinus (that may be absent) so that it drains into the pulmonary venous atrium. The same
suture is continued further along the posterior atrial wall around the orifices of the right pulmonary veins. The
other end of the suture is continued in a counterclockwise direction below and behind the orifice of the left
superior vena cava until the patch takes on the configuration of a septum (Fig. 19.12). The patch should be
generous in size; if excess patch is present, it can be trimmed before suturing is completed. Otherwise, it may
need to be augmented by sewing another patch to it.
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FIG. 19.11 A: Technique for repair of the defect shown in Fig. 19.8. B: Schematic illustration of repair. C:
Suturing patch to tricuspid valve tissue.
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FIG. 19.12 Completed repair of the defect shown in Fig. 19.10.
Reseptation of Atria after Takedown of Mustard or Senning
A modification of the technique given in the preceding text may be used in those patients who are undergoing
conversion from atrial switch anatomy to an arterial switch procedure (see Chapter 25). Following removal of the
baffle, a common atrium is created, which must be septated.
RIGHT-SIDED PARTIAL ANOMALOUS PULMONARY VENOUS RETURN
The most common type of partial anomalous pulmonary venous return is seen in association with a sinus
venosus atrial septal defect (see previously). Rarely, the right superior pulmonary vein enters the superior vena
cava directly without an associated atrial septal defect. Repair of this anomaly requires creation of an adequately
sized atrial septal defect and tunnel closure of the anomalous pulmonary vein to the left atrium (Fig. 19.4).
Scimitar syndrome consists of a large anomalous pulmonary vein draining the entire right lung or the right middle
and lower lobes, passing inferiorly to enter the inferior vena cava just above or below the diaphragm. An
intraatrial baffle technique can be used to tunnel the flow from the anomalous pulmonary vein orifice within the
inferior vena cava up to an existing or surgically created atrial septal defect. Alternatively, the anomalous vein
may be ligated at its entrance into the inferior vena cava, transected, and anastomosed directly to the left atrium.
Baffle obstruction
Intratrial baffle obstruction is not uncommon because of the acute angle that the pulmonary venous return must
make within the inferior vena cava (Fig. 19.13). This obstruction can be mitigated in selected cases by
performing a side-to-side type connection (Fig. 19.14). More recently, some have advocated repair via
reimplantation through a right lateral thoracotomy off bypass.
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FIG. 19.13 Repair of Scimitar syndrome using a single patch. Note the acute angle that the pulmonary venous
return must make as it enters near the IVC and is redirected through the more cranial atrial septal defect (which
may require enlargement to afford unobstructed flow).
FIG. 19.14 Side-to-side repair of Scimitar syndrome. To reduce the acute angulation of pulmonary venous return
with the single patch (Fig. 19.C), a side-to-side anastomosis along the posterior aspect of the right atrium makes
for a larger connection, and one that is considerably closer to the atrial defect through which flow must be
directed. Note the course of the phrenic nerve and how the anastomosis sits posterior. The patch connecting the
new opening of the pulmonary venous drainage through the atrial septal defect is similar to that used in Fig.
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19.C.
LEFT-SIDED PARTIAL ANOMALOUS PULMONARY VENOUS RETURN
Anomalous drainage from the left upper lobe or entire left lung to a vertical vein as an isolated lesion is rare.
Surgical repair can be done through a left thoracotomy without cardiopulmonary bypass if the diagnosis is
certain. Most often, this abnormality is approached through a median sternotomy. However, recently, some have
advocated for repair off bypass via left lateral thoracotomy.
Technique
Standard aortic cannulation is used, and if there is no atrial septal defect, a single venous cannula can be placed
in the right atrium. On cardiopulmonary bypass, the left vertical vein is exposed from the hilum to the innominate
vein, and any systemic branches are ligated and divided. Opening the pericardium posterior to the phrenic nerve
may facilitate exposure. The relationship of the left atrial appendage to the vertical vein is assessed before
clamping the aorta and arresting the heart. A right-angle clamp is placed on the vertical vein at its junction with
the innominate vein. The vertical vein is transected and traction sutures placed to maintain its orientation. The
innominate end is oversewn with running 5-0 or 6-0 Prolene suture. A generous opening is made posteriorly on
the left atrial appendage, and the vertical vein is now opened anteriorly. The vertical vein is anastomosed to the
atrial appendage with running 6-0 or 7-0 Prolene, taking care to not twist or distort the vein (Fig. 19.15).
Alternatively, the left atrial appendage can be amputated and the open end of the vertical vein anastomosed to
the resultant opening. The heart is allowed to fill and the absence of kinking of the anastomosis ensured before
standard deairing and cross-clamp removal.
FIG. 19.15 Anastomosing vertical vein to left atrial appendage.
Anastomotic Gradient
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Intraoperative transesophageal echocardiography should confirm unobstructed flow from the left pulmonary veins
into the left atrium. If a significant gradient is noted, anastomotic revision should be undertaken.
Maintaining Correct Orientation of Vertical Vein
Placing a bulldog-type clamp across the base of the vertical vein at the confluence of the pulmonary veins helps
to prevent twisting of the vertical vein.
Pericardiotomy
It is important to remember that the pulmonary veins are largely posteriorly oriented, and in bringing the vein
through the pericardium, it should enter posterior to the phrenic nerve so as to avoid angulation and kinking.
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