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15
Coarctation of the Aorta
More than 50% of infants with a coarctation of the aorta become symptomatic during the first month of life.
Associated cardiac anomalies accompany this lesion in more than 75% of patients. In neonates, infusion of
prostaglandin E1 prevents or reverses constriction of the ductal tissue. An open ductus improves lower body
perfusion by allowing right-to-left shunting into the descending aorta. By relaxing the aortic end of the ductus,
prostaglandin E1 often results in a larger lumen at the coarctation site. Surgery can then be safely delayed until
the left ventricular function, which is often poor, improves and any signs of low cardiac output syndrome, such as
renal insufficiency, resolve. Older children may present with upper-body hypertension and/or signs and
symptoms of decreased lower-extremity perfusion.
INCISION
In patients with an isolated aortic coarctation, the involved area can be adequately exposed through a fourth
intercostal left posterolateral thoracotomy. For any patient undergoing coarctation repair through a thoracotomy,
it is paramount in the morning of the operation to rule out fever and also to allow the patient to cool passively
during the anesthetic preparation; mild hypothermia may mitigate the risk of spinal cord injury during the
operation. Infants with associated lesions may be better served with a complete repair on cardiopulmonary
bypass through a median sternotomy using a period of deep hypothermia to resect or augment the coarcted
segment. Even in infants with no other cardiac anomalies, the aortic arch may be hypoplastic. These patients
should undergo patch augmentation of the entire arch and proximal descending aorta under deep hypothermia
(see Chapter 29).
SURGICAL ANATOMY
A coarctation of the aorta affects the junction of the aortic arch, descending aorta, and ductus arteriosus in more
than 98% of patients. It can, however, occur anywhere along the course of the aorta.
The left vagus nerve enters the thoracic cavity from the root of the neck between the left subclavian and left
common carotid arteries, crosses the aortic arch, and continues downward anteromedial to the descending
aorta, traversing the ligamentum arteriosum. The recurrent laryngeal nerve has its origin in the vagus nerve,
curves around the ligamentum arteriosum, and continues back upward into the neck (Fig. 15.1). There may be
poststenotic dilation just distal to the coarctation. In older patients, the poststenotic dilation may be more
pronounced and there may be extensive enlargement of collateral vessels about the shoulder and back muscles.
This may include the intercostal arteries, whose walls may be paper thin and friable.
EXPOSURE OF THE COARCTATION
The left lung is retracted inferiorly and anteriorly, often with placement of a so-called “Kirklin tent” to help in
exposure. The parietal pleura is divided longitudinally over the left subclavian artery and descending thoracic
aorta across the coarctation segment. The pleural edges are then suspended (Fig. 15.1). The left subclavian
artery, aortic arch distal to the left carotid artery, and the descending aorta are mobilized from the root of the
neck to a distance well below the coarctation. Vessel loops may be passed around the aorta and the subclavian
artery to facilitate exposure (Fig. 15.2).
Protection of the Vagus and Recurrent Laryngeal Nerves
The left vagus nerve and its recurrent laryngeal branch may be injured during mobilization.
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Enlarged Intercostal Arteries
The intercostal arteries are usually enlarged. They have extremely thin walls and can cause troublesome
bleeding if traumatized.
Bleeding from Aortic Branches
Bronchial arteries may occasionally arise from the posterior surface of the aorta and the left subclavian artery.
They can be inadvertently torn during mobilization and dissection.
FIG. 15.1 Surgical anatomy of a coarctation of the aorta.
COARCTECTOMY
Whenever possible, a coarctectomy is the procedure of choice. It entails removal of stenosed or hypoplastic
segments of the aorta and of abnormal ductal tissue in neonates. Appropriate clamps are selected, usually a
straight vascular clamp for the descending aorta and a curved clamp to be placed across the left subclavian
artery and distal arch. The descending aorta is clamped first and then the proximal clamp is applied. The ductus
arteriosus or ligamentum arteriosum is ligated or clipped on the pulmonary artery side and divided to give the
aorta additional mobility. The coarcted segment is excised, with attention paid toward making the proximal
aortotomy on a bevel to increase the anastomotic surface, and the two clamps are now carefully maneuvered to
bring the aortic ends together. The anastomosis is accomplished with a running Prolene suture (Fig. 15.3). The
distal clamp and then the proximal clamp are removed, and the anastomosis is inspected for hemostasis as well
as the absence of constriction or torsion.
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FIG. 15.2 Exposure of a coarctation.
Use of Approximator
A combination of straight and spoon-shaped atraumatic clamps with an approximator is useful. This allows the
clamps to remain immobile while the aortic ends are being sutured together without tension. The operative field
is not obscured by the assistant’s hands, which is especially important in neonates. Alternatively, the assistant
surgeon has the critical responsibility of holding the two ends of the aorta together so that a satisfactory
anastomosis can be completed.
Placement of Clamps
The clamps should be positioned far enough away from the excision lines to provide adequate aortic cuffs for
suturing. The aortic wall is elastic and will retract after each end is transected. At least 5 mm in neonates or 1 cm
in older children is required to secure a satisfactory anastomosis.
Residual Coarctation
Inadequate resection of a coarctation may leave the patient with residual disease (Fig. 15.4).
Preserving the Maximal Diameter of the Lumen
The aortic anastomosis should incorporate the widest lumen of the aorta to prevent any local constriction. The
proximal opening can be enlarged, if necessary, to conform with the poststenotic dilation of the lower aortic
segment (Fig. 15.5).
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FIG. 15.3 Technique for a coarctectomy.
Intercostal Arteries
The first set of intercostal arteries is often located close to the distal extent of the coartation. They can usually be
preserved and temporarily occluded with small bulldog clamps during the resection and anastomosis. The distal
aortic clamp is placed below the first intercostal vessels (Fig. 15.5). However, if their division is required for full
mobilization to perform and extended end-to-end anastomosis, this should be pursued.
FIG. 15.4 Inadequate resection in a coarctectomy.
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Interrupted Sutures in Neonates
Although continuous suturing provides better hemostasis and functions quite satisfactorily in most cases,
interrupted suturing in the neonate is used by some surgeons to reduce the possibility of recurrent stenosis.
Alternatively, the posterior layer is completed with a continuous technique, and the anterior layer is approximated
with interrupted sutures. Some surgeons use absorbable suture, such as polydioxanone (PDS), which at least
theoretically should ensure better growth at the site of the anastomosis.
Hemostasis
There may be bleeding along the suture line requiring additional sutures. Often, adventitial U-stitches are
effective. It may be advisable to temporarily reapply the proximal clamp so that the sutures can be placed and
tied without tension on the anastomosis.
FIG. 15.5 Enlarging the proximal aortic segment to ensure the maximal lumen diameter.
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Spinal Cord Ischemia
Paraplegia is a devastating complication of surgical repair of coarctation of the aorta. Factors associated with
spinal cord injury are longer cross-clamp time, higher body temperature, and lower distal aortic pressure during
the procedure.
Intraoperative Mild Hypothermia
The core body temperature should be maintained at or below 35°C by keeping the room cold, using a cooling
blanket, and/or chest irrigation with cold saline solution to minimize the risk of spinal cord ischemia during the
cross-clamp period.
No or Small Collaterals
Patients with underdeveloped collaterals tend to have low distal perfusion pressures with aortic clamping. This is
also seen in patients with aberrant origin of the right subclavian artery from the descending aorta.
Distal Circulatory Support
To avoid spinal cord injury, distal circulatory support should be used if a cross-clamp time over 30 minutes is
anticipated, or if test clamping of the aorta results in a distal pressure of less than 50 mm Hg. Partial
cardiopulmonary bypass is the preferred technique.
Technique with Partial Bypass
These patients should be monitored with right radial and femoral arterial lines. After full heparinization, the
descending aorta below the anticipated clamp site is cannulated with an aortic cannula through a purse-string
suture. The lung is retracted posteriorly and a longitudinal incision is made on the pericardium anterior to the
phrenic nerve. A purse-string suture is placed on the left atrial appendage and a venous cannula is introduced
into the left atrium during a Valsalva maneuver. Ventilation is continued and the venous flow is controlled by the
perfusionist to maintain a normal pressure in the right radial artery and to keep the femoral pressure above 45
mm Hg. Following repair of the coarctation, the patient is weaned from bypass and the venous cannula is
removed from the left atrium during a Valsalva maneuver. The heparin is reversed with protamine and the
descending aortic cannula is removed.
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FIG. 15.6 A-C: Technique for a subclavian flap angioplasty: Preparing the subclavian flap.
Air Embolism
To prevent entry of air into the left atrium during placement and removal of the venous cannula, the
anesthesiologist must perform a sustained inflation of the lungs until the purse-string suture is secured.
SUBCLAVIAN FLAP ANGIOPLASTY
This procedure may be useful in a neonate with a long-segment coarctaion. The left subclavian artery is well
mobilized up to the origin of its branches in the root of the neck; all the branches are ligated (Fig. 15.6). The
proximal clamp is placed across the aortic arch just distal to the left carotid artery, and the descending aorta is
clamped with a straight clamp (Fig. 15.7A). Alternatively, a single curved clamp can be used (Fig. 15.7C). The
left subclavian artery is
incised longitudinally downward along the aorta, well beyond the coarctation segment. Whenever a prominent
coarctation ridge is present, it should be excised (Fig. 15.6C). The subclavian artery is then divided at the level
of its branches, folded down, and sewn into the aortic incision as a patch using two continuous 7-0 Prolene
sutures (Fig. 15.7B).
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FIG. 15.7 A and B: Technique for a subclavian flap angioplasty using two clamps. Note that the upper clamp is
placed just distal to the left common carotid artery. C: Single-clamp technique.
Subclavian Steal Syndrome
The vertebral artery must be identified and ligated separately to eliminate the possibility of the development of
subclavian steal syndrome.
Resection of the Coarctation Ridge
The coarctation ridge within the lumen of the aorta must be excised, but not so deeply as to weaken the posterior
aortic wall. Any perforation must be sutured with fine Prolene and tied on the outside (Fig. 15.8).
FIG. 15.8 Repairing a perforation in the posterior aortic wall.
Short Subclavian Artery
Too short a subclavian artery will not reach beyond the coarcted segment and will leave residual stenosis (Fig.
15.9). A diamond-shaped prosthetic patch angioplasty (see subsequent text) must then be performed.
Distal Stenosis
The toe of the anastomosis should be at least 8 to 10 mm distal to the site of coarctation. Otherwise, healing with
its resulting fibrosis gives rise to recoarctation.
Positioning the Subclavian Artery Patch
Ideally, the subclavian artery patch must balloon out evenly over the coarctation. A kink at the heel of the
anastomosis results from overstretching of the subclavian flap (Fig. 15.10).
FIG. 15.9 Persistence of residual stenosis when the subclavian artery is too short to reach beyond the
coarcted segment.
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FIG. 15.10 A kink at the heel of the anastomosis resulting from overstretching of the subclavian flap.
Incision on the Subclavian Artery and the Aorta
The line of incision on the subclavian artery and the aorta should be straight along the lateral aspect of the both
vessels. Any deviation interferes with a satisfactory anastomosis.
LONG-SEGMENT COARCTATION
If the coarctation segment is too long, a coarctectomy with an end-to-end anastomosis or subclavian flap
angioplasty may not be feasible. One option in older children and adults is to resect the coarctation segment and
replace this portion of the aorta with an adult-sized tube graft (Fig. 15.11, see Chapter 8).
An alternative to graft interposition is to roof the defect with a patch. This procedure is equally useful in cases of
recoarctation of the aorta. The aorta is clamped above and below the coarctation segment as described
previously. The aorta is then incised longitudinally across the lesion. The prominent coarctation ridge is excised,
taking the usual precautions. A wide, diamond-shaped Gore-Tex, Hemashield, or pulmonary homograft patch is
sewn to the aortic edges with a running 4-0 or 5-0 Prolene suture (Fig. 15.12).
FIG. 15.11 Tube graft replacement for a long coarctation segment.
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