PBF (such as pulmonary atresia) or inadequate systemic blood flow (as in severe coarctation of the

aorta). The discovery that extrinsic delivery of prostaglandins can maintain ductal patency has played a

critical role in improving the survival of these patients.125

The physiologic manifestation of PDA is shunting of blood across the ductus. The shunt volume is

determined by the size of the ductus and by the ratio of pulmonary to systemic vascular resistance. At

birth, the PVR drops dramatically and continues to decline over the first several weeks of life. As a

result, shunting across a PDA is from left to right. Excessive PBF can lead to CHF. In extreme cases,

hypotension and systemic malperfusion may result. Patients with a large PDA who survive infancy tend

to develop pulmonary vascular obstructive disease. Eisenmenger physiology results when the PVR

exceeds the systemic vascular resistance, producing a reversal of shunting across the ductus to right to

left. This leads to cyanosis and, eventually, right ventricular failure. Small PDAs may persist to

adulthood without producing any symptoms or physiologic derangement. Endocarditis and endarteritis

have been reported as long-term complications of PDA.126

In patients with PDA, symptoms are proportional to the shunt volume and the presence of associated

defects. Left-to-right shunting produces volume overload of the left heart. Infants with CHF demonstrate

symptoms of tachypnea, tachycardia, and poor feeding. Older children may present with recurrent

respiratory infections, fatigue, and failure to thrive. Physical findings include a widened pulse pressure

and a continuous “machinery” murmur heard best along the left upper sternal border. Chest radiography

shows increased pulmonary vascular markings and left heart enlargement. Left ventricular hypertrophy

and left atrial enlargement may be evident on the ECG. Echocardiography is the diagnostic method of

choice. Diagnostic cardiac catheterization is performed only in older patients with suspected pulmonary

hypertension to evaluate for pulmonary vascular obstructive disease. More frequently, catheterization is

utilized for transcatheter occlusion of the ductus in selected cases.

PDA closure is performed for all symptomatic patients. Closure is also recommended for

asymptomatic patients due to the risk of heart failure, pulmonary hypertension, and endocarditis.

Closure of the ductus may be accomplished by one of three approaches: pharmacologic, surgical, and

endovascular. Indomethacin and ibuprofen, which are cyclooxygenase inhibitors, stimulate PDA closure

in premature infants.127,128 Both are rarely effective in full-term infants. Due to improved side effect

profile of gastrointestinal bleeding and renal dysfunction, ibuprofen is the current drug of choice.128 The

dosing regimen is 10 mg/kg intravenously, followed by 5 mg/kg intravenously at 24-hour intervals for

a total of three doses. This is effective in about 70% to 80% of premature babies.128,129 Due to their side

effects, indomethacin and ibuprofen are contraindicated in patients with sepsis, renal insufficiency,

intracranial hemorrhage, or bleeding disorders. Failure of ibuprofen after two complete courses results

in referral for surgical closure.

The surgical approach to PDA is through a left posterolateral thoracotomy via the third or fourth

intercostal space. The pleura is incised over the proximal descending thoracic aorta. This allows medial

retraction of the vagus nerve. The recurrent laryngeal nerve curves behind the ductus and should be

protected throughout the procedure. Dissection is then performed to demonstrate the pertinent

anatomy. In many cases, the ductus is the largest vascular structure present, and it must not be confused

with the aorta. Ductal tissue is extremely friable, so direct manipulation is minimized. In premature

infants, the ductus is controlled with a single surgical clip; this procedure is commonly performed in the

neonatal intensive care unit, thereby avoiding problems associated with patient transfer.130,131 In older

patients, occlusion of the ductus is achieved with simple silk ligature, or, preferably, by division

between ligatures to minimize recurrence.

Thoracoscopic techniques have been developed to perform PDA ligation.132 This approach has the

potential benefits of decreased pain and quicker recovery. Disadvantages include a substantial learning

curve and increased operating time.

A number of endovascular devices have been developed for the purpose of transcatheter occlusion of

the PDA.133–135 This approach is very successful in older infants, children, and adults with small and

moderate-sized PDAs and has become the treatment of choice at many centers. Surgical therapy is

reserved for PDAs having a large diameter or very short length.

Rarely, an adult will present with a significant PDA. These patients must be carefully evaluated for

the presence of pulmonary vascular obstructive disease prior to ductal closure. If the patient is not a

candidate for device closure, surgical closure can be problematic. Calcification of the ductal wall is

common in adults, making ligation hazardous. In some cases, cardiopulmonary bypass may be required

with closure of the ductus from within the PA.136,137

Closure of the ductus by surgical or transcatheter techniques is achieved with a mortality that

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approaches zero.130 Potential complications include pneumothorax, phrenic nerve injury, recurrent

laryngeal nerve injury, and chylothorax (from injury to the thoracic duct). Long-term survival should be

normal following PDA ligation in most patients. Survival in premature infants depends primarily on the

extent of prematurity with its attendant complications.

VASCULAR RINGS

Vascular rings comprise a spectrum of vascular anomalies of the aortic arch, pulmonary artery, and

brachiocephalic vessels. The clinically significant manifestation of these lesions is a varying degree of

tracheoesophageal compression. These vascular anomalies can be divided into complete vascular rings

and partial vascular rings. Incomplete vascular rings include aberrant right subclavian artery,

innominate artery compression, and pulmonary artery sling. The incidence of clinically significant

vascular rings is 1% to 2% of all congenital heart defects.7

Vascular rings and pulmonary slings have been described in conjunction with other cardiac defects,

including TOF, ASD, branch pulmonary artery stenosis, coarctation, AVSD, VSD, interrupted aortic arch,

and aortopulmonary window. Significant associated cardiac anomalies occur in 11% to 20% of patients

with a vascular ring.138,139 A right aortic arch is generally associated with a greater incidence of

coexisting anomalies.

By the end of the fourth week of embryonic development, the six aortic or branchial arches have

formed between the dorsal aortae and ventral roots. Subsequent involution and migration of the arches

results in the anatomically normal or abnormal development of the aorta and its branches. The majority

of the first, second, and fifth arches regress. The third arch forms the common carotid artery and

proximal internal carotid artery. The right fourth arch forms the proximal right subclavian artery. The

left fourth arch contributes to the portion of the aortic arch from the left carotid to left subclavian

arteries. The proximal portion of the right sixth arch becomes the proximal portion of the right

pulmonary artery, while the distal segment involutes. Similarly, the proximal left sixth arch contributes

to the proximal left pulmonary artery, and the distal sixth arch becomes the ductus arteriosus.

Children with a complete vascular ring generally present within the first weeks to months of life.

Typically, children with a double aortic arch present earlier in life than those with a right arch and

retroesophageal left ligamentum. In the younger age group, respiratory symptoms predominate, as

liquids are generally well tolerated. Respiratory symptoms may include stridor, nonproductive cough,

apnea, or frequent respiratory infections. The cough is classically described as a “seal bark” or “brassy.”

These symptoms may mimic asthma, respiratory infection, or reflux, and children with vascular rings

are often initially misdiagnosed. With the transition to solid food, dysphagia becomes more apparent.

The presentation of a patient with an incomplete vascular ring is variable. Children with innominate

artery compression usually present within the first 1 to 2 years of life with respiratory symptoms.

Aberrant right subclavian artery is the most common arch abnormality, occurring in approximately

0.5% to 1% of the population, and it rarely causes symptoms. Classically, when symptoms do occur,

they present in the seventh and eighth decades, as the aberrant vessel becomes ectatic and calcified,

causing dysphagia lusoria due to impingement of the artery on the posterior esophagus.

Children with pulmonary artery slings generally present with respiratory symptoms within the first

few weeks to months of life. As with complete rings, respiratory symptoms may include stridor,

nonproductive cough, apnea, or frequent respiratory infections and may mimic other conditions, leading

to misdiagnosis. Pulmonary artery slings are associated with complete tracheal rings in 30% to 40% of

patients, leading to focal or diffuse tracheal stenosis.

The methods for diagnosing a vascular ring are variable, due to the variability in presentation and the

spectrum of diagnostic tests available. A child with a presumptive diagnosis of asthma or tracheomalacia

may be referred to a pulmonologist and a diagnosis of vascular ring made or suspected initially by chest

radiograph and bronchoscopy. In some situations, the diagnosis is made by echocardiography during

evaluation for concurrent cardiac defects. Regardless, the diagnosis generally begins with a chest

radiograph. Complementary studies may include barium esophagogram, CT, MRI, and bronchoscopy.

CT, MRI, and bronchoscopy are important modalities to define the tracheal anatomy in a patient with a

pulmonary artery sling. Echocardiography may be diagnostic, and may be used to rule out other cardiac

anomalies. Tracheograms and cardiac catheterizations, which have been used extensively in the past, are

rarely currently indicated.

A double aortic arch occurs when the distal portion of the right dorsal aorta fails to regress. The two

arches form a complete ring, encircling the trachea and esophagus. The right arch is dominant in the

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majority of the cases, followed by left dominant, with codominant arches being the least common. The

left and right carotid and subclavian arteries generally arise from their respective arches. The

ligamentum arteriosum and descending aorta usually remain on the left.

The approach to repair of a double aortic arch is via a left posterolateral thoracotomy. The pleura is

incised, after identifying the vagus and phrenic nerves. The ligamentum or ductus arteriosum is divided

while preserving the recurrent laryngeal nerve. The nondominant arch is then divided between two

vascular clamps at the point where brachiocephalic flow is optimally preserved. If there is concern

regarding the location for division, the arches can be temporarily occluded at various points while

monitoring pulse and blood pressure in each limb. If there is an atretic segment, the division is done at

the point of the atresia. Dissection around the esophagus and trachea in the regions of the

ligamentum/ductus and nondominant arch allows for retraction of the vascular structures and lysis of

any residual obstructing adhesions.

The surgical approach for a right aortic arch with retroesophageal left ligamentum arteriosum is the

same as for a double arch. The ligamentum is divided and any adhesions around the esophagus and

trachea are lysed. Rarely, the Kommerell diverticulum has been reported to cause compression even

after division of the ligamentum. As such, it may be prudent to resect or suspend the diverticulum

posteriorly.

In innominate artery compression syndrome, the aortic arch and ligamentum are in their normal

leftward position. However, the innominate artery arises partially or totally to the left of midline. As

the artery courses from left to right anterior to the trachea, it causes tracheal compression. The

symptoms of innominate artery compression may be mild to severe. With mild symptoms and minimal

tracheal compression on bronchoscopy, children can be observed expectantly as the symptoms may

resolve with growth. Indications for surgery include apnea, severe respiratory distress, significant

stridor, and recurrent respiratory tract infection. Several approaches for the correction of innominate

artery compression syndrome have been described. These include simple division, division with

reimplantation into the right side of the ascending aorta, and suspension to the overlying sternum.

An aberrant right subclavian artery occurs when there is regression of the right fourth arch between

the right common carotid and right subclavian arteries. The right subclavian then arises from the

leftward descending aorta, laying posterior to the esophagus as it crosses from left to right. Although

the artery can compress the esophagus posteriorly, it is rarely the cause of symptoms in children.

Surgical treatment involves simple division via a left posterolateral thoracotomy. Rarely, reimplantation

or grafting from the right carotid or aortic arch may be necessary.

Normally, the right and left sixth aortic arches contribute to the proximal portions of their respective

pulmonary arteries. If the proximal left sixth arch involutes and the bud from the left lung migrates

rightward to meet the right pulmonary artery, a pulmonary artery sling is formed. Pulmonary artery

slings are associated with complete tracheal rings and tracheal stenosis in 30% to 40% of patients.

Initial attempts at the repair of a pulmonary artery sling involved reimplantation after division of the

left pulmonary artery (LPA) and translocation of the trachea without cardiopulmonary bypass. These

early reports had a high incidence of LPA thrombosis. This has led some authors to advocate division of

the trachea and translocation of the LPA. This approach would seem sensible if the trachea were being

divided in the course of tracheal reconstruction. However, currently most authors advocate the

reimplantation of the LPA, which has resulted in excellent results. The procedure is done via a median

sternotomy on cardiopulmonary bypass to ensure optimal visualization of the repair. Aortic crossclamping is not necessary. The LPA is divided off of the right pulmonary artery, translocated anterior to

the trachea, and reimplanted into the main pulmonary artery.

Any necessary reconstruction of the trachea is done concurrently with bronchoscopic assistance. Many

techniques for tracheal reconstruction have been described, the most common of which are resection

with primary reanastomosis and sliding tracheoplasty for short-segment stenosis, and rib cartilage or

pericardial patch for long areas of narrowing.140

Over 95% of vascular rings without concurrent cardiac defects can be performed through a left

thoracotomy. A right thoracotomy is indicated for the rare cases where there is a right ligamentum

arteriosum. In addition, a double aortic arch with an atretic segment proximal to the right carotid artery

is more easily divided through a right thoracotomy. The approach to these anomalies is the same as for

a left-sided ring division, with the caveat that the right recurrent laryngeal nerve will loop around the

right ligamentum.

Repair of vascular rings has been described using video-assisted thoracoscopic surgery (VATS) both

with and without robotic assistance. Candidates for thoracoscopic division are limited to those patients

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requiring only the division of nonpatent vascular structures. In general, VATS is used for patients

greater than 15 kg due to current size limitations of the instruments.141

Mortality for the repair of a vascular ring is 0% to 4%, with improved survival occurring in more

recent series.138,139,142 The majority of deaths are related to other cardiac defects or respiratory

infection and failure. Backer et al. reported a series of 16 patients repaired utilizing LPA division and

reimplantation for pulmonary artery sling, all of whom also required tracheal reconstruction. There

were no operative mortalities and one late death due to respiratory complications.140 The major source

of morbidity, as well as mortality, in this and other series is related to the tracheal reconstruction.

CORONARY ARTERY ANOMALIES

Coronary artery anomalies occur in 0.3% to 1.3% of the population.143,144 They can be classified as

minor, secondary, or major based on their clinical significance.145 Minor defects have no functional

significance and are usually detected as incidental findings at cardiac catheterization. Secondary defects

have no intrinsic significance, but alter surgical management when they are present. An example of a

secondary defect is an anomalous origin of the left anterior descending artery from the right coronary

artery that crosses the hypoplastic infundibulum in a patient with TOF. The presence of this vessel may

prevent the safe performance of a transannular incision and thereby mandate the use of a conduit.

Major defects are the most important form of coronary anomaly, because they exert an intrinsically

adverse effect on the myocardium. Major anomalies can be subdivided based on anatomy: coronary

arteriovenous fistula, anomalous pulmonary origin of a coronary artery, anomalous aortic origin of a

coronary artery, myocardial bridging, or coronary artery aneurysm.

8 Coronary arteriovenous fistula is the most common major coronary anomaly. An abnormal

connection exists between a coronary artery (usually the right) and another vascular structure (usually

one of the right heart chambers). Most fistulas are isolated and solitary. The fistula leads to left-to-right

shunting, which can produce CHF. Other symptoms include angina, endocarditis, myocardial infarction,

arrhythmia, and sudden death. The diagnosis is suggested by echocardiography and confirmed by

catheterization. All symptomatic fistulas should be occluded, either surgically or by transcatheter

techniques. In some cases, coronary bypass grafting may be necessary when distal flow is compromised

by fistula occlusion. Treatment of asymptomatic fistulas is controversial, but occlusion should probably

be undertaken when significant left-to-right shunting is present.

The second most common major coronary anomaly is origin of a coronary artery from the PA. The

most common manifestation is the anomalous left coronary artery arising from the pulmonary artery

(ALCAPA). The right coronary (or both coronaries) may also arise anomalously from the PA, but only in

very rare cases. ALCAPA is usually well tolerated during fetal development, but after birth, the

pulmonary systolic pressure usually drops (following ductal closure and decline in PVR) and the

anomalous coronary is perfused with desaturated blood at low pressure. Collateral vessels develop

between the normal right coronary artery and the abnormal left coronary, but the benefit is negated

due to the development of coronary steal, whereby the collateral blood shunts left to right by

retrograde flow in the anomalous coronary into the low-pressure PA. Most patients will present

between 6 weeks and 3 months of life. Typical symptoms include irritability, difficulty in feeding, and

other signs of CHF. Untreated, ALCAPA is nearly always fatal. Rarely, patients will survive to adulthood

and present with symptoms of angina or sudden death. On examination, patients with ALCAPA

frequently have a holosystolic murmur of ischemic mitral regurgitation. The pulmonary component of

the second heart sound may be pronounced due to pulmonary hypertension. Chest radiography is

significant for cardiomegaly and pulmonary edema. Electrocardiographic evidence of ischemia and

infarction is usually present. Echocardiography is usually diagnostic and is useful for assessing the

severity of left ventricular dysfunction and ischemic mitral regurgitation, which are commonly present.

Catheterization is occasionally necessary to clarify the anatomy, but this technique is used less

frequently due to the risk of inducing life-threatening arrhythmias.

Surgical repair is indicated for all patients with ALCAPA. Historically, the initial surgical approach

involved ligation of the proximal left coronary artery. This served to eliminate coronary steal and allow

perfusion of the left coronary system by collaterals from the right. Despite the ease of simple ligation,

most centers have abandoned this approach in favor of establishment of a two-coronary system, which

offers better long-term freedom from ischemia. In older patients, this may be achieved by proximal

ligation of the left coronary artery in conjunction with coronary artery bypass, ideally with a left

internal mammary graft. Coronary bypass is technically difficult in neonates, and a number of

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