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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. 14.2 Medial reflection of the vagus nerve on the pleural flap.
FIG. 14.3 Dissecting the lappet of pericardium to ensure complete exposure of the ductus.
Alternatively, the ductus is divided between clamps and oversewn with fine, nonabsorbable sutures (Fig. 14.6).
This technique is particularly useful when the ductus is exceptionally short and large. Another option is to
occlude the ductus with one or two metal clips. This latter technique is especially applicable to premature infants
and is the most commonly practiced.
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FIG. 14.4 Using a Waterston dissector to expose and separate the transverse arch from the cranial aspect of the
ductus, and freeing the recurrent nerve from the inferior aspect.
Injury to the Recurrent Laryngeal Nerve during Ligation of the Ductus Arteriosus
The surgeon must always pay special attention to the recurrent laryngeal nerve. It can easily be divided during
ductus mobilization. It can also be caught in the ligature, metal clip, or ductal clamp.
FIG 14.5 Ligation of the ductus. Inset: Securing the occlusion with purse-string sutures.
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FIG. 14.6 Dividing the ductus arteriosus between clamps and oversewing it with fine, nonabsorbable sutures.
A Ductus Arteriosus Tear
The ductus arteriosus is liable to be injured and torn any time during dissection, ligation, or division, resulting in
massive hemorrhage. Digital pressure over the ductus usually controls the bleeding and provides adequate
exposure in a dry field. The aorta can then be temporarily clamped above and below the ductus while the torn
ductus is oversewn with nonabsorbable sutures. The pulmonary artery end of the ductus can be similarly
oversewn. Occasionally, this end of the ductus, if completely severed, may retract medially and its
exposure may become impossible. Under these circumstances, while continuing digital control of the bleeding,
the surgeon must gain access to the pericardium by incising it longitudinally, anterior to the left phrenic nerve.
Control of bleeding from the ductal end is then achieved by temporarily occluding the left pulmonary artery from
within the pericardium. The ductal opening is then oversewn under direct vision in a relatively dry field (Fig.
14.7).
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FIG. 14.7 Control of bleeding from and management of the torn ductus arteriosus.
Clamping for Division of Ductus
Whenever the surgeon elects to divide the ductus arteriosus, it is essential that the clamps are applied on the
aorta and the pulmonary artery, and not on the ductus itself, which is friable and liable to be disrupted. Similarly,
the ductus must never be directly gripped and/or pulled.
Inadvertent Ligation of the Aortic Arch
The ductus arteriosus and aortic arch must both be identified. Occasionally, the ductus is very much larger than
the arch, which may be underdeveloped and hypoplastic. This can be seen in infants and neonates. Inadvertent
ligation of the arch instead of the ductus is a catastrophe that can be prevented by sequentially occluding the
ductus and arch while monitoring the blood pressure in the left arm (Fig. 14.8).
Inadvertent Ligation of the Left Pulmonary Artery
A clip placed too far toward the mediastinum runs the risk of impinging upon the left pulmonary artery; in the most
exaggerated form of this error, the left pulmonary artery itself can be ligated (Fig. 14.9).
Occluding the Ductus Arteriosus
In certain circumstances, the ductus arteriosus can be occluded temporarily with an atraumatic tissue forceps
before its ligation or division. The occurrence of hypotension, bradycardia, or changes in oxygen saturation
suggests that the patient has a ductal-dependent congenital anomaly and needs further diagnostic studies.
FIG. 14.8 Temporary occlusion of the ductus arteriosus to prevent the inadvertent ligation of the aortic arch.
FIG. 14.9 Placement of a clip too proximal can cause narrowing (or complete occlusion) of the left pulmonary
artery.
Closure of the Ductus Arteriosus in Premature Infants
The ductus arteriosus is visualized through a short, left lateral thoracotomy in the fourth intercostal interspace.
The parietal pleura over the descending thoracic aorta is incised. Minimal dissection with scissors or a fine-
tipped clamp is needed above and below the ductus. Occlusion of the ductus with a metal clip is the preferred
method in premature infants. A medium or medium-large metal clip is selected depending on the size of the
ductus. The clip applier is positioned over the ductus arteriosus, directing the tips of the clip slightly inferiorly and
away from the wall of the descending aorta and orienting the clip parallel with the aorta (Fig. 14.10). The ductus
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is then occluded with the metal clip. There is no need to pass an instrument around the ductus.
Erosion or Cutting by the Clip
If the ends of the clip are adjacent to the descending aorta or distal aortic arch, the clip may cut into these
structures, resulting in immediate or delayed bleeding.
Scissoring of Metal Clip
Some clip appliers may cause the two sides of the metal clip to miss each other and cut through the ductus
rather than occlude it. The surgeon should test the clip applier with a clip away from the operative field to verify
proper closure of the clip before using the applier on the ductus itself (Fig. 14.11).
Tearing of Ductus with Tip of Instrument
The scissors or clamp used to create an adequate opening above and below the ductus for clip placement
should have a rounded, smooth tip. The surgeon must inspect the instrument to verify that there is not a burr at
or near the tip that could tear the delicate ductal tissue.
Completing the Operation
Rib blocks have been most effective in reducing postoperative thoracotomy pain. A long-acting local anesthetic
agent is injected near the neurovascular bundle at least two interspaces above and two below the level of the
incision. The chest tube is brought through the skin and muscle opening and introduced through the fifth or sixth
intercostal space. Heavy braided sutures are passed around the ribs above and below to reapproximate the
opening. The muscle layers, subcutaneous tissues, and skin are closed around the chest tube, which is
connected to an underwater seal suction system. When the skin closure reaches the chest tube, several
vigorous sustained ventilations are administered by the anesthesiologist. The chest tube is then withdrawn with
the lungs inflated. A chest x-ray obtained in the operating room confirms reexpansion of the left lung and
absence of pneumothorax.
Bleeding Caused by Intercostal Injections
In patients with coagulopathies or who are anticoagulated, rib blocks should be avoided to prevent extrapleural
hematomas or intrapleural bleeding. Many premature infants
have thrombocytopenia and should not receive intercostal injections.
FIG. 14.10 It is important to place the clip completely across the ductus, parallel with the aorta, so as to not angle
cranially (and the tips entrap the transverse aortic arch), or angle inferiorly or incompletely clip the ductus (as
shown). The ideal placement of the clip allows distance from the recurrent nerve and also a “ductal bump” of
tissue on the descending aorta (thus not causing a coarctation).
FIG. 14.11 Surgeon must test the clip applier to verify symmetric closure of the metal clip components (A), to
avoid using an applier that scissors the clip (B).
Placement of Pericostal Sutures
The suture should hug the top of the rib to avoid injury to the intercostal artery or vein.
Injury to the Lung
If injury to the lung is noted, the chest tube should be left in place on suction for 12 to 24 hours.
Thoracoscopic Closure of the Ductus Arteriosus
Some surgeons use thoracoscopic techniques for closure of the ductus arteriosus. The risk of recurrent
laryngeal nerve injury is slightly higher with this approach; however, some surgeons feel that avoiding a
thoracotomy incision may prevent future chest wall deformities.
Transcatheter Closure of the Ductus Arteriosus
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Transcatheter closure of a small patent ductus arteriosus with a coil or occluder device can be accomplished
satisfactorily and avoids surgery in selected patients.
Calcification of the Ductus Arteriosus
The ductus may be calcified and/or aneurysmal, and simple ligation or division may not be feasible. Under these
circumstances, it may be easier and safer to close the ductal opening through the left pulmonary artery under
direct vision with the patient on cardiopulmonary bypass (see later).
Friable Tissues
If the tissues are friable, the patch can be sewn into place with interrupted pledgeted sutures.
ANTERIOR APPROACH TO CLOSURE OF THE PATENT DUCTUS ARTERIOSUS
A median sternotomy incision is used for infants and children with a patent ductus arteriosus undergoing repair of
other congenital heart defects. This approach is also useful in adults with calcified and noncalcified as well as
aneurysmal ducts.
Technique in Infants and Children
Before the initiation of cardiopulmonary bypass, the ascending aorta is retracted slightly to the right and the main
pulmonary artery is retracted gently downward. The ductus is then dissected free of the left pulmonary artery and
the aortic arch using scissors or a fine-tipped clamp. The ductus is encircled with a 2-0 braided suture and
ligated or occluded with a metal clip at the onset of cardiopulmonary bypass (Fig. 14.12).
Flooding of the Pulmonary Circulation
With the initiation of cardiopulmonary bypass, flooding of the pulmonary circulation and low systemic blood
pressure are likely to occur unless the ductus is occluded. All children undergoing cardiopulmonary bypass are
evaluated for the presence of a patent ductus either by echocardiogram, direct inspection, or both.
FIG. 14.12 Exposure and occlusion of the ductus arteriosus from the anterior approach.
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Tearing of Ductal Tissue
The ductal tissue is friable, and care must be taken to prevent the suture or clip from cutting through the
ductus. This results in bleeding that may be difficult to control, especially on the aortic side.
Stenosis of the Left Pulmonary Artery
The tie or clip should be placed far enough away from the origin of the left pulmonary artery to prevent narrowing
of this vessel. This can result from external compression by the ligature or clip or from extrusion of ductal tissue
into the lumen of the left pulmonary artery.
Technique in Adults
Closure of a patent ductus arteriosus in an adult can be safely accomplished through a median sternotomy on
cardiopulmonary bypass. The patient is cooled systemically for 5 to 10 minutes to allow a brief period of very low
perfusion. During low flow, the main pulmonary artery is opened longitudinally. The opening of the ductus is
identified, and an appropriately sized Foley catheter is passed into the aorta (Fig. 14.13). After inflating the
balloon
with saline, the flow through the ductus is controlled by placing traction on the Foley catheter (the connector end
of the catheter must be occluded to prevent the backflow of blood). Cardiopulmonary bypass flow can be
increased while a patch of autologous pericardium treated with glutaraldehyde, Gore-Tex or hemashield is sewn
away from the edges of the ductal orifice using 5-0 monofilament suture (Fig. 14.14). Just before placing the last
one or two stitches, the pump flow is turned very low while the Foley balloon is deflated, the catheter is removed,
and the final stitches placed. Full flow is resumed, and the pulmonary arteriotomy is closed. The patient is
weaned off cardiopulmonary bypass when systemic rewarming is completed.
FIG. 14.13 Opening the main pulmonary artery and placing a Foley catheter in the ductus arteriosus.
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FIG. 14.14 Completing a patch closure of the pulmonary side of the ductus arteriosus with an inflated Foley
balloon.
Flooding of the Pulmonary Circulation
During cooling, the ductal flow must be occluded to prevent runoff of the aortic cannula flow into the pulmonary
arterial bed. This is accomplished with forceful digital pressure on the distal main pulmonary artery.
Air Embolism through the Ductus Arteriosus
When the pulmonary artery is opened, some flow must be maintained through the aortic cannula to prevent air
embolism. In addition, the patient may be placed in Trendelenburg position to prevent this complication.
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