Currently, one-stage repair of TOF is preferred by most centers. Initial palliation with a shunt is still

indicated for some patients who are at high risk for early complete repair, such as those with multiple

congenital anomalies, severe concurrent illness, intracranial hemorrhage, or an anomalous coronary

artery crossing a hypoplastic infundibulum. In the absence of these risk factors, complete repair in the

symptomatic neonate can be performed with lower mortality and reoperation rate compared to staged

palliation.41,42

Complete repair of TOF is performed using a median sternotomy and cardiopulmonary bypass with

bicaval venous cannulation. By a transatrial approach, the right ventricular outflow tract can be

examined through the tricuspid valve. Muscle bundles obstructing the right ventricular outflow tract are

divided or rarely resected. The VSD is closed with a patch. Pulmonary valvotomy is performed, when

indicated, via a vertical incision in the main PA. When the pulmonary valve annulus or infundibulum is

severely hypoplastic, a transannular outflow tract patch may be necessary to relieve the obstruction.

When an anomalous coronary artery crosses the infundibulum, a transannular incision may be

contraindicated. In these cases, and in patients with pulmonary atresia, placement of a conduit

(cryopreserved homograft, valved xenograft, or bioprosthetic heterograft) between the right ventricle

(via a separate ventriculotomy) and main PA will be necessary. Patients who have a transannular patch

develop pulmonary insufficiency as a consequence. This is surprisingly well tolerated in most infants

and children, as long as the tricuspid valve is competent. As these patients grow older, some will

develop right ventricular failure due to chronic pulmonary insufficiency, and pulmonary valve

implantation may be necessary, often in the second or third decade of life.43,44

The early mortality following repair of TOF is between 1% and 5%.40,45 The results are worse for

patients with TOF and pulmonary atresia. Long-term complications include recurrent obstruction of the

right ventricular outflow tract and development of right ventricular dysfunction due to chronic

pulmonary insufficiency. Actuarial survival at 20 years is 86% with excellent functional status.46

DOUBLE-OUTLET RIGHT VENTRICLE

Double-outlet ventricle includes a variety of malformations in which, by 50% or more, both great

arteries arise from one ventricle. Although double-outlet LVs occur, a far more common anomaly is the

DORV. A VSD is usually present in DORV, in addition to other defects, including discordant

ventriculoarterial connections, valvar or subvalvar stenosis of the PA and aortic outflow, and single

ventricle.

The physiologic consequences of DORV vary depending on the associated defects. The three most

critical factors determining the net effects on the circulation are the size of the VSD, the presence or

absence of PS, and the presence and degree of left-sided obstruction. As a result, DORV may clinically

resemble an isolated VSD, TOF, or transposition of the great arteries (TGA).

The size and location of the VSD are important considerations in planning operative management. The

VSD may be primarily directed toward the aorta, toward the PA, equally toward both arteries (doubly

committed), or remote from both great vessels (noncommitted). The location of the VSD affects the

direction of flow of oxygenated blood and thus affects the degree of cyanosis. VSDs in DORV seldom

close spontaneously. This is fortunate, as closure would result in severe hemodynamic decompensation

or death.

If the VSD is large, nonrestrictive, and committed to the aorta, it can be closed with a tunnel-like

patch that directs left ventricular flow into the aorta. A restrictive VSD must be enlarged to avoid

creating subaortic stenosis. For patients with DORV and PS, repair requires right ventricular outflow

tract reconstruction with a patch or a valved allograft conduit, in addition to patch closure of the VSD.

DORV with transposition-type physiology (malposed great vessels with the VSD committed to the

PA), also known as a Taussig–Bing anomaly, may be treated by a variety of methods, depending on the

specific anatomic details. The preferred approach would be to perform an arterial switch operation, thus

making the VSD committed to the aorta, and baffling the left ventricular outflow from the VSD to this

neoaorta. Another preferred approach, which depends on a favorable orientation of the two great

vessels and VSD, would be an intraventricular tunnel from the VSD to the aorta. A third approach

utilizes the Damus–Kaye–Stanzel operation (DKS). During the DKS, the proximal PA is anastomosed end

to side into the aorta. The VSD is baffled to both semilunar valves, which both connect to the aorta. An

extracardiac conduit is then placed to reconstruct right ventricle-to-PA continuity. This approach may

also be useful when the VSD is doubly committed or noncommitted, so that making a direct connection

to either single great vessel is problematic.

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The current results for correction of DORV with subaortic VSD are excellent, with a 15-year survival,

including hospital mortality, of 96%.47,48 Mortality for the more complex repairs tends to be slightly

higher. Hospital mortality for an arterial switch operation with VSD closure for DORV ranges from 3.7%

to 14.3%.49,50

TRANSPOSITION OF THE GREAT ARTERIES

6 TGA is a congenital cardiac anomaly in which the aorta arises from the right ventricle and the PA

originates from the LV (ventriculoarterial discordance; Fig. 81-4). Looping refers to the right or left

looping of the primitive heart tube during fetal development, which determines whether the atria and

ventricles are concordant (right atrium attaches to right ventricle and left atrium attaches to LV) or

discordant. Levo-TGA (l-TGA) is associated with AV discordance (right atrium attaches to LV and left

atrium attaches to right ventricle), and is also termed congenitally corrected TGA. l-TGA is a rare variant

of TGA and is beyond the scope of this chapter, which will focus on dextro-TGA (d-TGA). The defect can

be subdivided into d-TGA with intact ventricular septum (IVS) (55% to 60%) and d-TGA with VSD (40%

to 45%), one third of which are hemodynamically insignificant. Pulmonic stenosis (PS), causing

significant left ventricular outflow tract obstruction, occurs rarely with an IVS and in approximately

10% of d-TGA/VSD.51

d-TGA is a relatively common cardiac anomaly and is the most common form of congenital heart

disease presenting as cyanosis in the first week of life. The malformation accounts for approximately

10% of all congenital cardiovascular malformations in infants.52 The degree of cyanosis depends on the

amount of mixing between the pulmonary and systemic circulations. In d-TGA, oxygenated pulmonary

venous blood is returned to the lungs and desaturated systemic blood is returned to the body. Because

the two circulations exist in parallel, some mixing between them must occur to allow oxygenated blood

to reach the systemic circulation and the desaturated blood to reach the lungs. Mixing may occur at a

number of levels, most commonly at the atrial level through an ASD or a PFO. Generally, two levels of

mixing are necessary to maintain adequate systemic oxygen delivery with a VSD or PDA serving as an

additional site for cardiac mixing. In d-TGA, there can be no fixed shunt in one direction without an

equal amount of blood passing in the other direction; otherwise, one circulation would eventually

empty into the other. Therefore, the amount of desaturated blood reaching the lungs (effective PBF)

must equal the amount of saturated blood reaching the aorta (effective systemic blood flow). Clinical

characteristics are dependent on the degree of mixing and the amount of PBF. These factors relate to the

specific anatomic subtype of d-TGA. Neonates with d-TGA with IVS (or small VSD) have mixing limited

to the atrial level and PDA. The ASD may be restrictive and the PDA generally will close over the first

days to week of life. As the degree of mixing decreases, the patient becomes increasingly cyanotic and

will eventually suffer cardiovascular collapse. Fortunately, the majority of these neonates will manifest

cyanosis early in life, which is recognized by a nurse or physician within the first hour in 56% and in the

first day in 92%.53 In d-TGA with a large VSD, there is additional opportunity for mixing and increased

PBF. The neonate with d-TGA/VSD may only manifest mild cyanosis, which may be initially overlooked.

However, generally within 2 to 6 weeks signs and symptoms of CHF will emerge. Tachypnea and

tachycardia become prominent, whereas cyanosis may remain mild. Auscultatory findings are consistent

with CHF with increased PBF, including a pansystolic murmur, third heart sound, middiastolic rumble,

gallop, and narrowly split second heart sound with increased pulmonary component. Neonates with dTGA and significant PS present with severe cyanosis at birth. Lesser degrees of PS will result in varying

levels of cyanosis. The ECG is normal at birth, demonstrating the typical pattern of right ventricular

dominance. Although the classic chest radiographic appearance of an egg-shaped heart with a narrow

superior mediastinum may be seen, this finding is often obscured by an enlarged thymic shadow. The

abnormal ventriculoarterial connection is clearly seen on echocardiography, which demonstrates that

the posterior great vessel arising from the LV is a PA that bifurcates soon after its origin. The anterior

great vessel is the aorta and arises from the right ventricle. Associated lesions, including VSD, left

ventricular outflow tract obstruction, and coarctation, may also be diagnosed. Although used less

frequently, cardiac catheterization may be helpful to confirm the basic anatomy, discern associated

lesions, define the coronary anatomy, and improve cardiac mixing by means of balloon atrial

septostomy.

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Figure 81-4. Anatomy of the most common type of transposition of the great arteries. The location of the ascending aorta is

usually anterior to and to the right of the pulmonary artery.

The infant with d-TGA and severe cyanosis requires prompt diagnosis and treatment to improve

mixing and increase the arterial oxygen saturation. The first intervention to improve mixing in a

cyanotic newborn suspected of having d-TGA is to ensure ductal patency by beginning an infusion of

prostaglandin E1

(PGE1

). In the presence of a restrictive ASD, a balloon atrial septostomy, a technique

developed by William Rashkind54 in 1966, is performed. The procedure involves inserting a balloontipped catheter across the foramen ovale into the left atrium. Inflation and forcible withdrawal of the

catheter tears the septum primum and enlarges the ASD. Mixing generally increases immediately, with a

substantial increase in arterial oxygen saturation.

Without intervention, d-TGA is universally fatal. Untreated, 30% of neonates will die in the first week

of life, 50% by the first month, 70% within 6 months, and 90% by 1 year.55 The definitive surgical

treatment of patients with d-TGA has changed dramatically in the past decade with the advent of the

arterial switch operation. Before this procedure, repair of d-TGA was generally delayed until patients

were at least 6 months of age. Historically, palliative procedures were often necessary to improve the

systemic saturation or protect the pulmonary vascular bed before definitive repair. If balloon atrial

septostomy failed to enlarge the ASD adequately, a Blalock–Hanlon septectomy was performed. Rarely

used today, this operation is a method of surgically enlarging the ASD without cardiopulmonary bypass.

In patients with large VSDs, significant CHF and pulmonary hypertension are present early in life.

Historically, the main PA was banded to reduce distal PA pressure and prevent the development of

pulmonary vascular occlusive disease. Changes of pulmonary vascular disease may develop in about

25% of patients with hemodynamically large VSDs by 3 months of age; therefore, early reduction of PA

pressure was essential. In those cases of transposition with severe left ventricular outflow tract

obstruction, total pulmonary flow is reduced and systemic-to-PA shunting was undertaken until

definitive repair could be accomplished.

Historically, definitive repair was achieved by redirecting venous inflow at the atrial level. First

successfully performed by Senning56 in 1959, the operation was further modified by Mustard57 in 1964

(Fig. 81-5). In both techniques, the atrial septum is repositioned such that superior and inferior vena

caval blood is rerouted to the mitral valve and then to the LV and PA. Pulmonary venous blood is

redirected to the tricuspid valve and right ventricle. The right ventricle then ejects the oxygenated

blood to the systemic circulation. The Mustard operation uses a large patch of pericardium or prosthetic

material to create the intra-atrial baffle. In the Senning procedure, the patient’s atrial tissue is used, and

little or no foreign material is necessary. Although physiologic repair at the atrial level is associated

with a low operative mortality rate (<5%), even in infants, a number of late problems have occurred.

Obstruction to vena caval inflow, particularly at the junction of the superior vena cava and the right

atrium, still occurs in about 5% of patients and may be more common when the procedure is performed

in an infant. Additionally, pulmonary venous obstruction may develop and is often difficult to repair.

Perhaps because of the complex atrial suture lines, atrial dysrhythmias are common and occur in more

than half of patients observed on a long-term basis. In addition, pacemakers may be necessary for

troubling bradyarrhythmias in as many as 10% of these patients.

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Figure 81-5. The Mustard operation for transposition of the great arteries. In this procedure, the atrial septum is excised and

replaced with a pericardial baffle, so that pulmonary venous blood is redirected over the baffle to the tricuspid valve. Superior and

inferior vena caval blood then drains to the mitral valve.

The most serious long-term complication of repair by either the Senning or Mustard technique has

been right ventricular dysfunction. Right ventricular failure with an enlarged, poorly contractile

chamber and secondary tricuspid regurgitation has been found in a significant number of these patients

in long-term follow-up studies. The true incidence of significant right ventricular failure in these cases

remains difficult to define and is clearly influenced by an earlier era of operation with different methods

of myocardial protection and surgical technique. The fact that many of these infants underwent

definitive repair after many months of significant cyanosis may also have influenced right ventricular

function.

The long-term complications of atrial repair prompted a reexamination of direct arterial repair for

transposing the great arteries. The “arterial switch” operation, first successfully performed by Jatene in

1975, has become the optimal surgical procedure for infants with this condition.58 Current techniques

have reduced the operative mortality to levels comparable with those of atrial repair. Additionally,

because the operation is performed early in life, this approach has virtually eliminated the interim

morbidity and mortality associated with postponement of surgery until at least 6 months of age. The

operative technique involves transection of both great vessels and direct reanastomosis to reestablish

ventriculoarterial concordance (Fig. 81-6). Additionally, the coronary arteries are removed from the

anterior aorta and relocated to the posterior great vessel (neoaorta). The extensive experience gained

with this procedure has confirmed that any variant of coronary artery anatomy can be successfully

repaired. Certain coronary anatomy variants were previously felt to be associated with higher risk;

however, this concern has been neutralized in recent series.59,60 Many patients with d-TGA have an IVS,

and left ventricular pressure falls early in life as PVR decreases. In this situation, it is essential that the

arterial repair be performed within the first 1 to 2 weeks of life, while the LV is still able to meet

systemic workloads. In patients presenting later, the LV can be retrained with a preliminary PA banding

and an aorticopulmonary shunt, if necessary, followed by the definitive arterial repair. Although

patients with large VSDs do not require early repair because they maintain systemic left ventricular

pressures, experience has indicated that, even in this subgroup, the operation is best performed within

the first month of life, before secondary complications such as pulmonary hypertension, CHF, or

infection develop.

Patients with fixed left ventricular outflow tract obstruction are not candidates for the arterial repair

because correction would result in systemic ventricular outflow tract obstruction. Most of these patients

also have large VSDs. Palliation early in life with systemic-to-PA shunting is an option, with definitive

repair postponed until somatic growth results in cyanosis as the shunt is outgrown. At that time, the

Rastelli procedure is performed, in which left ventricular blood is redirected through the VSD and to the

anterior aorta by placement of an intraventricular patch (Fig. 81-7). The PA is ligated, and right

ventricle–to–distal PA continuity is reestablished with a valved conduit. An increasing number of

experienced centers currently recommend early complete repair in the neonatal period using a Rastelli

procedure. Early repair eliminates the interim morbidity and mortality associated with a systemic-to-PA

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