-Dr Dheeraj Sharma

(M.Ch resident)

Complete transposition of great

arteries

Part 1

1. development of heart

2. historical aspects

3. anatomy and morphology

4. associated cardiac conditions

5. natural history

6. presentation

7. diagnostic features

Part 2

1. surgical treatment

2. complications

3. results

4. special situations

Development of heart

1. Formation of heart tube

2. Division of heart tube

3. Elongation and rotation of heart

tube

4. Septation of heart

5. Partition of truncus and twisting

and rotation of great arteries

Theories for TGA Straight truncoconal septum hypothesis incriminating the abnormal

septation of aorta and pulmonary trunk.

Abnormal fibrous skeleton hypothesis where PA-MV continuity occurs instead of AO-MV continuity.

Abnormal embryonic hemodynamic hypothesis caused by obstructive and altered flow characteristics.

Inverted truncal swelling theory citing inverted development below the semilunar valves.

Embrological spectrum of

disease

DEFINITION

Complete transposition of the great arteries

(TGA) is a congenital cardiac anomaly in which

the aorta arises entirely or largely from the right

ventricle (RV) and in which the pulmonary trunk

arises entirely or largely from the left ventricle

(LV), known as ventriculoarterial discordant

connection.

HISTORICAL NOTE The first morphologic description of TGA is attributed to Baillie in

1797.

The term transposition of the aorta and pulmonary artery was

coined by Farre.

Transposition {trans, across; ponere, to place) meaning that

aorta and pulmonary trunk were displaced across the ventricular

septum.

van praagh gave the term malposition to describe those

abnormal positions of the aorta in which both great arteries fail to

be displaced across the ventricular septum.

Surgery of TGA commenced in 1950 when Blalock and Hanlon

at Johns Hopkins Hospital described a closed method of atrial

septectomy.

In 1953, Lillehei and Varco described a "partial physiologic

correction" (or atrial switch) consisting of anastomosis of right

pulmonary veins to right atrium and inferiorvena cava (IVC) to

left atrium, a technique that became known as the "Baffes

Palliation of TGA was revolutionized when Rashkind and Miller in

Philadelphia introduced balloon atrial septostomy (BAS) in 1966.

A modification of this procedure was introduced in 1975 by Park

and colleagues with their substitution of a blade rather than a

balloon at the end of the catheter.

Senning in 1959, who refashioned the walls of the right atrium

and the atrial septum to accomplish atrial-level transposition of

venous return.

The Mustard procedure, in which the atrial septum is excised

and a pericardial baffle used to redirect systemic and pulmonary

venous flow was successfully introduced at the Toronto Sick

Children's Hospital in 1963 and reported in 1964.

In 1972, Lindesmith and colleagues introduced the use of a

palliative Mustard procedure, in which the VSD was left

unclosed, for patients with high pulmonary vascular resistance.

In 1969,Rastelli and colleagues combined intraventricular tunnel

repair (LV to aorta) of the double outlet RV operation with a

rerouting valved extracardiac conduit (RV to pulmonary artery)

and closure of the origin of the pulmonary trunk from the LV to

produce an anatomic repair of TGA, VSD, and LVOTO.

Idriss and colleagues attempted such a procedure in two patients

with an intact ventricular septum in 1961 using cardiopulmonary

bypass (CPB), transferring the great arteries and a ring of aorta

carrying the coronary arteries.

Jatene and colleagues in Brazil achieved a major breakthrough

in 1975 with the first successful use of an arterial switch

procedure {Jatene procedure), applying it in infants with TGA

and VSD.

MORPHOLOGY

1. Right Ventricle The RV is normally positioned, hypertrophied, and large in TGA.

In about 90% of cases, there is a subaortic conus (infundibulum),

and the aorta is rightward and anterior and ascends parallel to

the posterior and leftward pulmonary trunk.

There is less wedging of the pulmonary trunk between mitral and

tricuspid valves in TGA than of the aorta in normal hearts. As a

result, a larger area of contiguity exists between mitral and

tricuspid valves than normally.

These atrioventricular (AV) valves may be at virtually the same

level.

In about 10% of hearts with TGA and intact ventricular septum,

the subaortic conus in the right ventricle is absent or very

hypoplastic. Then the aorta is either directly anterior, or anterior

and to the left, of the pulmonary trunk origin, or rarely posterior.

2.Left Ventricle The LV infrequently contains an infundibulum (conus); typically

pulmonary-mitral fibrous continuity exists, comparable to aortic-

mitral continuity in the normal heart.

In the normal heart the LV wall is thicker than the RV wall in

utero. After birth, LV wall thickness increases progressively,

whereas the RV wall becomes relatively thinner.

In TGA the RV wall is considerably thicker than normal at birth

and increases in thickness with age. When the ventricular

septum is intact and no important pulmonary stenosis is present,

the LV wall is of normal thickness at birth. Wall thickness remains

static, however, leading to less than normal thickness within a

few weeks of birth and a relatively thin wall by age 2 to 4 months.

When a VSD is present, LV wall thickness increases slightly less

than in the normal heart but remains well within the normal range

during the first year of life.With LVOTO (pulmonary stenosis) the

evolution is similar.

In infants with TGA the LV cavity is the usual ellipsoid in shape at

birth but soon becomes banana shaped. Alteration in LV function

accompanies this geometric change.

RV function is usually normal in TGA in the perinatal period.

Thereafter, when the ventricular septum is intact, RV end-

diastolic volume is increased and RV ejectionfraction decreased.

Depressed RV ejection fraction is unlikely to be caused by

increased afterload or decreased preload and probably results

from depressed RV function from relative myocardial hypoxia or

the geometry of the chamber.

3. Atria The atria are normally formed in TGA. Right atrial size is usually

larger than normal, particularly when the ventricular septum is

intact.

4. Conduction System The AV node and bundle of His lie in a normal position, although

the AV node is abnormally shaped and may be partly engulfed in

the right trigone.

The left bundle branch originates more distally from the bundle of

His than usual.

5. Great Arteries The aorta is most often directly anteriorly or slightly to theright .

In the Taussig-Bing heart, great arteries may be side by side,

with the aorta to the right.

Rarely the aorta is directly posterior.

Leiden convention, in which sinus 1 is on the right of an

imagined observer standing in the nonfacing noncoronary aortic

sinus of Valsalva looking toward the pulmonary trunk.

Proceeding counterclockwise, the next sinus is sinus 2.

6. Coronary Arteries Coronary arteries in TGA usually arise from the aortic sinuses

that face the pulmonary trunk, regardless of the interrelationships

of the great arteries.

Most often the left anterior descending (LAD) and circumflex (Cx)

coronary arteries arise as a single trunk {left main coronary

artery [LCA]) from aortic sinus 1 and distribute in a normal

manner.The right coronary artery (RCA) arises from sinus 2 and

follows this artery's usual course.

All three main coronary arteries may arise from a single sinus

(single coronary artery), most frequently, and of utmost concern

to the surgeon, from sinus 2.

Usually the arteries all arise from a single ostium in the center of

the sinus .

Alternatively, they may arise from a double-barreled ostium

consisting of two ostia immediately adjacent to each other and

constituting essentially a single ostium.

At times, the LCA or LAD passes forward between aorta and pulmonary trunk in an intramural course to emerge anteriorly.

In this situation, instead of all three main coronary arteries arising from an essentially single, more or less centrally positioned, ostium, LCA or LAD alone nearly always arises from an entirely separate ostium far to the left of the RCA ostium, adjacent to or just above the valvar commissure between sinus 2 and sinus 1.

A conus artery frequently arises separately and from its own ostiumin sinus 1. It may supply at least a considerable part of the anterior wall of the infundibulum of the RV.

The course of the sinus node artery may be important in the atrialswitch (Mustard or Senning) operation. This artery usually arises from the RCA close to its origin and passes superiorly and rightward, usually partly embedded in the most superior portion of the limbus of the atrial septum, where it can be damaged if this portion of the atrial septum is widely excised

Coexisting Cardiac Anomalies

1. Ventricular Septal Defect Conoventricular defects of the several different varieties are

most common.

In some hearts with conoventricular VSDs, the outlet (conal,

infundibular) septum is malaligned and fails to insert within the Y

of the septal band. The septum may be displaced leftward,

resulting in a variable degree of LVOTO or rightward, tending to

result in RV (subaortic) obstruction.

When the conal septum is displaced to the right, the pulmonary

trunk may be biventricular in origin and over a juxtapulmonary

VSD and may be associated with subaortic stenosis or aortic

arch obstruction (arch hypoplasia, coarctation, or interruption).

Occasionally the VSD is juxta-aortic and associated with a

malaligned but nondisplaced conal septum.

Theconal septum may be absent or almost gone, and the VSD

is then juxta-arterial (doubly committed).

2. Left Ventricular Outflow Tract

Obstruction Development of LVOTO, which produces subpulmonary

obstruction, is part of the natural history of many patients with

TGA.

The obstruction may be dynamic or anatomic.

LVOTO occurs in an important way at birth or within a few days

in only 0.7% of patients with TGA and intact ventricular septum.

Obstruction is present in about 20% of patients born with TGA

and VSD.

LVOTO may become apparent or develop after birth in other

patients, thus reaching an overall prevalence of 30% to 35%.

Dynamic type of LVOTO, developing in patients with TGA and

intact ventricular septum, is the result of leftward bulging of the

muscular ventricular septum secondary to higher RV than LV

pressure.

The septum impinges against the anterior mitral leaflet in

combination with abnormal systolic anterior leaflet motion (SAM).

Thus, the mechanism is similar to that present in hypertrophic

obstructive cardiomyopathy, but there is no asymmetric septal

hypertrophy.

When dynamic obstruction is severe, ridge of endocardial

thickening is produced on the septum at its point of contact with

the mitral leaflet.

In patients with TGA and VSD, stenosis is usually subvalvar and

valvar. Subvalvar stenosis is in the form of a localized fibrous

ring, long tunnel-type flbromuscular narrowing, or muscular

obstruction related to protrusion of the infundibular septum into

the medial or anterior aspect of the LV outflow tract.

3. Patent Ductus Arteriosus Patent ductus arteriosus (PDA) is more common in hearts with

TGA than in hearts with ventriculoarterial concordant connection.

Persistence of a large PDA for more than a few months is

associated with an increased prevalence of peripheral vascular

disease.

4. Tricuspid Valve Anomalies The tricuspid to mitral anulus circumference ratio, normally

greater than 1, is less than 1 in 46% of patients. This reduced

ratio is most marked in hearts with associated coarctation.

Functionally important tricuspid valve anomalies are present in

only about 4% of surgical patients.

The tricuspid leaflets can be redundant and dysplastic in TGA.

Accessory tricuspid tissue may prolapse through the VSD and

produce LVOTO.

The tricuspid anulus may be dilated, the valve may be

hypoplastic in association with underdevelopment of the RV

sinus.

Anular overriding or tensor straddling or both can occur.

5. Mitral Valve Anomalies Important structural anomalies of the mitral valve are present in

20% to 30% of hearts with TGA, mostly in combination with a

VSD.

Mitral valve anomalies can be categorized into four groups, as

those affecting the

• Leaflets

• Commissures

• Chordae tendineae

• Papillary muscles

The most important from a surgical standpoint are those of mitral

valve overriding or straddling, in which the mitral valve leaflet is

frequently also cleft.

6. Aortic Obstruction Coexisting aortic obstruction can be discrete (coarctation, or less

often interrupted aortic arch) or caused by distal arch hypoplasia.

it occurs in 7% to 10% of patients with TGA and VSD.

This coexistence is more frequent when the VSD is

juxtapulmonary and the pulmonary trunk is partly over the RV in

association with rightward and anterior displacement of the

infundibular septum and with some subaortic narrowing.

When there is associated coarctation, underdevelopment of the

RV sinus is more common.

7. Right Aortic Arch Right aortic arch occurs in about 5% of patients with TGA.

It is more common when there is an associated VSD than when

the ventricular septum is intact and when there is associated

leftward juxtaposition of the atrial appendages.

8. Leftward Juxtaposition of Atrial

Appendages Leftward juxtaposition of the atrial appendages occurs in about

2.5% of patients with TGA.

Bilateral conus and dextrocardia seem more common in TGA

associated with leftward juxtaposition than in TGA generally.

9. Right Ventricular Hypoplasia RV hypoplasia was found to some degree in 17% of the

necropsy series of TGA reported by Riemenschneider and

colleagues.

CLINICAL FEATURES AND

DIAGNOSTIC CRITERIA When the great arteries are transposed in hearts with AV

concordant connection, systemic and pulmonary circulations are

in parallel.

Symptoms and clinical presentation in patients with TGA depend

in large part on degree of mixing between the two parallel

circulatory circuits.

When there is a high degree of mixing and large pulmonary

blood flow Qp, arterial oxygen saturation (SaO2) may be near

normal, and unless there is pulmonary venous hypertension,

symptoms are minimal.

When mixing is minimal, SaO2 is low and symptoms of hypoxia

are severe.

Adequate mixing can occur only when there are communications

of reasonable size at atrial, ventricular, or great artery levels.

Factors that reduce Qp, such as LVOTO and increased Rp,

reduce mixing and increase cyanosis.

1.Essentially Intact Ventricular

Septum

(Poor Mixing) TGA with essentially intact ventricular septum includes infants

without a VSD or with a VSD 3 mm or less in diameter.

A patent foramen ovale or naturally occurring atrial septal defect

(ASD) is usually present.

Cyanosis is apparent in half these infants within the first hour of

life and in 90% within the first day and is rapidly progressive.

The baby becomes critically ill with tachypnea and tachycardia

and dies from hypoxia and acidosis without appearance of frank

heart failure.

This rapid downhill course is usually obviated with a naturally

occurring ASD of adequate size because cyanosis is less

severe.

In surviving infants, appearance of moderate or severe dynamic

LVOTO is associated with increasing cyanosis and hypoxic spells, even after an adequate atrial septostomy.

Generally, patients are of average birth weight and in good

general condition although with severe cyanosis.

Clubbing of fingers and toes is absent and generally does not

appear unless the infant survives to about age 6 months.

There is mild increase in heart and respiratory rates.

The heart is not hyperactive, and the liver is barely palpable.

A faint mid- systolic ejection-type murmur is present along the

midleft sternal edge in less than half these infants. This murmur

is more prominent with organic or dynamic LVOTO, first

appearing at age 1 or 2 months with the dynamic form and then

gradually increasing in intensity.

The second heart sound is unremarkable (often apparently single or narrowly split).

Chest radiography (Fig. 38-19) has three characteristic features:

• An oval- or egg-shaped cardiac silhouette with a narrow

superior mediastinum

• Mild cardiac enlargement

• Moderate pulmonary plethora

In the first week of life, however, the chest radiograph may be

normal, or occasionally cardiac enlargement may be more

marked.

The narrow mediastinum is caused in part by the great artery

positions and by shrinkage of the thymus, usually associated

with stress, and the plethora is caused by the increase in Qp.

Plethora is less marked when there is important LVOTO.

The electrocardiogram (ECG) is often normal at birth.

By the end of the first week, persistence of an upright T wave in right precordial leads indicates abnormal RV hypertrophy, and right-axis deviation predominates.

When important LVOTO is present or Rp elevated, ECG evidence indicates biventricular hypertrophy.

2.Large Ventricular Septal Defect, Large Patent

Ductus Arteriosus, or Both (Good Mixing) Presentation in this TGA group generally occurs in the latter half

of the first month, with mild cyanosis and signs of heart failure resulting from pulmonary venous hypertension and myocardial failure.

Tachycardia, tachypnea, important liver enlargement, and moist lung bases are present. The heart is more active and usually larger than in the poor-mixing group.

A large VSD is associated with a moderate-intensity pansystolicmurmur along the lower left sternal edge that may not be present initially.

There is usually an apical middiastolic murmur or gallop rhythm and narrow splitting of the second heart sound with accentuation of the pulmonary component.

With a large PDA, a continuous murmur, bounding pulses, and an apical middiastolic murmur are present in less than half the patients, even when the ventricular septum is intact.

Chest radiography may show more cardiomegaly, more plethora,

and a wider superior mediastinum than in the poor-mixing group.

ECG shows biventricular hypertrophy and, when there is a

persistent large VSD, a Q wave in V6. Isolated LV hypertrophy is

rare and suggests RV hypoplasia with tricuspid valve overriding.

Development of pulmonary vascular disease is associated with

reduction in Qp and less plethora, particularly in the peripheral

lung fields, as well as reduced heart size, but these features

generally appear after the neonatal period.

When coarctation of the aorta coexists with VSD and PDA,

femoral pulses are usually normal because the coarctation is

preductal and ductus arteriosus large. Rarely, differential cyanosis can occur, with cyanosis confined to the upper torso.

3.Large Ventricular Septal Defect and Left

Ventricular Outflow Tract Obstruction (Poor

Mixing without High Pulmonary Blood Flow)

Large VSD with LVOTO is the least common of the three TGA

groups.

LVOTO is associated with a decreased Qp and poor mixing, but

pulmonary venous hypertension and associated symptoms and

signs do not develop because of lack of increase in Qp.

Heart failure is therefore not present.

cyanosis is severe from birth.

The heart is not overactive, and there is a pulmonary ejection

murmur and often a single heart sound without an apical gallop

or middiastolic murmur.

Chest radiography shows a near normal-sized heart with normal

or ischemic lung fields.

ECG shows biventricular hypertrophy.

Echocardiography Definitive diagnosis of TGA can be made using two dimensional,

or M mode echocardiography.

Two-dimensional echocardiography is also particularly valuable

in detecting tricuspid valve abnormalities, including overriding

and straddling and the varieties of subpulmonary stenosis,

including dynamic obstruction.

Echocardiographic features of dynamic LVOTO include leftward

deviation of the ventricular septum, abnormal fluttering and

premature closure of the pulmonary valve, SAM of the mitral

leaflet and prolonged diastolic apposition of the anterior mitral

valve leaflet to the septum.

Echocardiography can also define with reasonable accuracy

morphology of the coronary arteries, including number, origin,

major branching pattern, and other features such as intramural course.

Cardiac Catheterization and Cineangiography A full study includes calculation of systemic and pulmonary blood

flows and pressures, including those across the LV outflow tract.

Using appropriate views, cineangiography demonstrates the

cardiac connections and great artery positions position and

number of VSDs site of any LVOTO the size and function of AV

valves, size and function of both ventricles, and presence of other cardiac anomalies.

Indications of cardiac catheterization Those hemodynamically unstable and rquire BAS.

Where more physiologic and anatomic data is required

concerning coronary artery, the VSD, degree of LVOTO.

Presence of other complex cardiac anomalies like CoA,

interrupted aortic arch.

To quantify pulmonary vascular resistance in patients of TGA

with VSD .

NATURAL HISTORY

1. Prevalence TGA is a common form of congenital heart disease, occurring in

1:2100 to 1:4500 births and accounting for 7% to 8% of all

congenital heart disease.

Male to female ratio is 2:1. Male predominance increases to

3.3:1 when the ventricular septum is essentially intact and

disappears in complex forms.

2. Survival When patients with all varieties of TGA are considered, 55%

survive 1 month, 15% survive 6 months, and only 10% survive 1

year.

Mean life expectancy is 0.65 year, rising to 4 years for those who

survive to 12 months and to 6 years for the few who survive for

18 months . Thereafter, life expectancy declines rapidly.

Survival without treatment is different among subsets.

It is particularly poor in untreated patients with TGA and

essentially intact ventricular septum: 80% at 1 week but only

17% at 2 months and 4% at 1 year. Survival in this group is

better when there is a true ASD.

In patients with TGA and important VSD, early survival is higher:

91% at 1 month, 43% at 5 months, and 32% at 1 year. It is lower

when the patient has a very large Qp.

The combination of large VSD and aortic obstruction

(coarctation, interrupted arch) is particularly lethal; all patients

die within a few months of birth with severe heart failure.

In patients with TGA, VSD, and LVOTO, early survival is still

better, reaching 70% at 1 year and 29% at 5 years, because in

many LVOTO is only moderate initially.

Leibman and colleagues found that PDA increased risk of early

death in all subsets of patients. This is particularly the case when

the ductus is large.

3.Modes of Death Poor survival in patients with TGA and essentially intact

ventricular septum is related primarily to anoxia. Intercurrent

pulmonary infections may develop and are particularly lethal

because they reduce Qep and lead rapidly to increasing

hypoxia, acidemia, and death.

Death in this group may also result from cerebrovascular

events, usually caused by the polycythemia and increased blood

viscosity secondary to severe cyanosis, particularly in

association with dehydration.

Patients with TGA and important VSD usually die with heart

failure.

Hypoxia is the primary cause of morbidity and mortality in patients with TGA, VSD, and LVOTO.

4. Patent Ductus Arteriosus PDA is present at age 1 week in about half the patients with

TGA, but thereafter the prevalence falls rapidly.

When patent, the ductus is small (less than 3 mm in diameter) in

about two thirds of patients and seems to have little influence on

natural history.

When it is large, LV output is increased and hypoxia lessens, but

heart failure becomes more severe.

Under these circumstances, acute and often early closure of the

ductus results in sudden increase in hypoxia and clinical

deterioration This is related not only to decreased mixing at

ductus level but also at atrial level because of the fall in left atrialpressure that results from decreased pulmonary venous return.

5. Atrial Septal Defects In patients with TGA, the patent foramen ovale tends to close at

the usual rate. This is the major cause of the time-related

increase in hypoxia and death in patients with TGA and

essentially intact ventricular septum without an important PDA.

A true ASD, on the other hand, remains unchanged in size and

palliates the patient longer.

6. Ventricular Septal Defects Large VSDs close or narrow in probably a smaller proportion

(about 20%) of patients with TGA than in patients with isolated

VSD.

the closing VSD is initially small and often muscular, and

spontaneous closure has been documented to occur as late as

the last part of the first decade of life.

7. Left Ventricular Outflow Tract

Obstruction Dynamic LVOTO is not present at birth but can appear within

several weeks. It gradually progresses in severity.

When dynamic LVOTO becomes important, hypoxia returns and

life expectancy is shortened. LVOTO develops infrequently in

patients with TGA and important VSD.

8. Pulmonary Vascular Disease When TGA occurs as an isolated lesion (simple TGA),

pulmonary vascular disease rarely develops in the first few

months of life. After about 6 to 24 months, however, its

prevalence increases to 10% to 30%. Its development reduces

Qp and increases hypoxia.

In patients with TGA and moderate or large VSD, pulmonary

vascular disease develops more rapidly than in patients with

simple TGA, as it does in those with persistently large PDA.

Among those dying at about age 6 months, 25% have

developed severe pulmonary vascular disease (grade 3 or

greater), and 50% of infants dying by age 12 months have developed it.

9. Increased Blood Flow to Right

Lung At birth, in TGA, as in normal patients, slightly more blood flows

to the right lung than to the left.

however, flow to the right lung in TGA increases as age

increases.

In addition to age, magnitude of increase is affected by the angle

between takeoff of the right pulmonary artery and pulmonary

trunk; the wider this angle (and thus the more the pulmonary

trunk faces directly into the right pulmonary artery), the greater

the blood flow to the right lung.

Once right lung flow increases, the right vascular bed grows

more and there is a relative increase in Rp and reduced

compliance in the left lung, which further reduces left lung flow.

Medical management

Important in patients with TGA with IVS.

Focuses on hemodynamic stabilization and

correction of physiological abbarations caused by

cyanosis and poor perfusion.

Correction of acid base balance, maintainance of

normothermia, prevention of hypoglycemia.

PGE1 infusion to maintain patencty of ductus to

provide mixing of saturated and desaturated

blood.

BAS

To be continued………………

Aims of surgery

1.to make the parallel circulations into series. So

that oxygenated blood goes to aorta and

deoxygenated blood goes to pulmonary trunk.

Correction of other cardiac anomalies like VSD,

PDA, TR, AORTIC OBSTRUCTION, LVOTO.

To provide a near normal functional status to

patients.

Surgical treatment

1. Arterial switch operation:

Simple Transposition of the Great Arteries with

Usual Great Artery and Coronary Patterns

Simple Transposition of the Great Arteries and

Origin of Circumflex Coronary Artery from Sinus 2

Simple Transposition of the Great Arteries and

Origin of All Coronary Arteries from Sinus 2

• 2. Atrial switch operation:

senning technique

Mustard technique

surgical treatment

3. Intraventricular repair:

Rastelli operation

REV procedure

Nikaidoh procedure

• 4. Palliative procedures:

pulmonary artery banding

Systemic to pulmonary artery shunt

INDICATIONS FOR

OPERATION1. Simple Transposition of the Great Arteries in

Neonates:

Presence of the malformation is an indication for operation.

If cyanosis and symptoms are severe, BAS is performed as soon as possible. A less attractive alternative is immediate arterial switch.

When indicated, arterial switch operation should be performed within the first week of life, and at least within the first 30 days of life. Increased Rp at this stage is not a contraindication to repair.LVOTO, which is typically dynamic in this setting, is also not a contraindication.

Risk of operation is probably lowest when it is performed in the first week of lifeand there is the additional advantage of minimizing exposure time of the brain to the hypoxia of uncorrected TGA.

2. Simple Transposition of the Great Arteries Presenting after Age 30 Days:

Primary arterial switch operation may carry a higher risk for infants with simple TGA who are beyond age 1 month, because by then the LV has usually become morphologically adapted to supporting the low-pressure pulmonary circulation.

Pulmonary trunk banding with concomitant systemicpulmonary artery shunting procedure, followed within 1 or 2 weeks by arterial switch operation

Atrial switch operation.

3. Transposition of the Great Arteries with

Ventricular Septal Defect:

TGA with VSD is an indication for arterial switch

operation and repair of the VSD. It is indicated at

the time the patient is first seen, with the

procedure performed within the first few weeks of

life.

4. Transposition of the Great Arteries with

Ventricular Septal Defect and Left Ventricular

Outflow Tract Obstruction:

Diagnosis of TGA with VSD and LVOTO is an

indication for operation, but type and timing of the

definitive procedure remain controversial.

The Lecompte procedure is probably the

indicated operation in patients with this anomaly

who appear for surgical repair between age 6

months and 4 to 5 years.

When cyanosis and symptoms are important

before age 6 months, either a systemic-

pulmonary artery shunt, followed by a Lecompte

operation within 6 to 18 months, or a primary

Lecompte operation is indicated.

In children age 3 to 5 years, either the Lecompte

or Rastelli operation provides good results.

SURGICAL OPTIONS AVAILABLE TO THE INFANT WITH TRANSPOSITION OF THE GREAT ARTERIES

Anatomy Surgical options Comments

TGA/IVS Physiologic repair

Senning or Mustard

Usually elective, neonatal-1 yr

Anatomic repair (primary)

Arterial switch (Jatene)

Neonatal period, usually within 2 wk of age

TGA/IVS with prolonged low LV pressure Physiologic repair

Senning or Mustard

Usually elective, 1 mo to “1 yr

Anatomic repair (delayed)

Two-stage arterial switch

Long preparation period (Yacoub)

Rapid two-stage switch (Jonas)

TGA/VSD Physiologic repair

Senning or mustard with VSD closure

Poor long-term results

Anatomic repair

Arterial switch with VSD closure

Usually neonatal repair; PAB occasionally

(multiple VSDs)

Interventricular baffle repair Not all VSDs suitable

Damus-“Kaye-“Stansel: VSD closure

(LVto’PA); proximal PA to Ao anastomosis;

RV to distal PA conduit

Used when coronary translocation impossible

aortic valve closure

TGA/VSD/PS VSD closure (LV to Ao), RV to PA

conduit (Rastelli)

Palliative systemic-to-pulmonary shunt

frequently performed

Conduit replacement frequently necessary

VSD closure (LV to Ao), anterior

translocation of PA with direct connection

to RV: REV procedure (Lecompte)

Long-term pulmonary regurgitation

TGA/PVOD Physiologic repair, palliative

Anatomic repair, palliative

Symptomatic improvement

TECHNIQUE OF OPERATION

Currently, the arterial switch operation is advised

for most patients with TGA except those with

important fixed LVOTO.

Patients with poor mixing, typically those with

intact ventricular septum and a small ASD, come

to the operating room receiving an infusion of

prostaglandin Ej and usually having had BAS.

Arterial Switch Operation1.Simple Transposition of the Great Arteries with Usual

Great Artery and Coronary Patterns

Three general types of support systems are in use for arterial switch operation, as follows:

• Continuous cardiopulmonary bypass (CPB), usually at 18°to 25°C and with a reduced flow rate after reaching the target temperature. Inferior and superior venae cavae are cannulated directly for venous return.

• Near-continuous CPB at 18° to 20°C and with reduced flow rates (0.5 to 10 L • min"1 • m~2), but with a single venous cannula inserted through the right atrial appendage. Total,circulatory arrest is established only for closure of the ASD, After this closure the venous cannula is reinserted, CPB reinstituted, and full flow restored for rewarming of the patient.

• Operation primarily is performed during total circulatory arrest after the patient has been cooled to 18°C by CPB, with rewarming also accomplished by CPB.

Repair of TGA with LCx originating

from sinus 2

Repair of TGA with single sinus oigin

of great arteries.

Repair of TGA with side by side great

arteries.

Complications of arterial switch

operation

Coronary insufficiency is most common cause of

early death.

RVOTO both supravalvar and subvalvar is most

common long term complication leading to

reoperation.

Post operative arrythmias: the are few if present

and too late after operation.

Neoaortic insufficiency and neoaortic anastomotic

stenosis: neoaortic insufficiency when present

seldom progresses and is seen with PAB group

where banding for larger duration causes

proximal pulmonary artery and annular dilatation.

2. Atrial switch operations A. senning operation:

Operation may be performed during hypothermic circulatory arrest at about 18°C or, preferably, using CPB and direct caval cannulation. When CPB is used, the patient is cooled to at least 25°C; blood flow is then stabilized at 1.6 L • min"1 • m~2 or lower, and if necessary a period of 10 to 15 minutes of low flow or circulatory arrest may be employed.

Before CPB is established, specific measurements are made that are critical in subsequent incisions. First, circumferences of superior (SVC) and inferior (IVC) venae cavae are determined (by compressing them momentarily with a clamp, measuring length of clamp occupied by compressed cava, and multiplying by 2)

Complications of atrial switch SVC and IVC tunnel obstruction.

Baffle leak

Atrial and ventricular arrythmias

Tricupid valve regurgitation

Right ventricular failure

Advantage of arterial switch over

atrial switch operation Arterial switch operations were not associated with

1. Atrial arrythmias

2. Baffle stenosis

3. Tricuspid insufficiency

4. Right ventricular failure

5. Sudden death

Advantages of atrial switch over

arterial switch

In patients with TGA + IVS who present after 1

month of birth , the atrial switch has better

prognosis as compared to single stage ASO.

Where the coronary artery anatomy is such that it

cannot be transferred like artery arising from non

facing cusp, in cases of intramural course , in

cases of dense adhesions due to previous

surgery. Atrial switch is a better option.

3. Intraventricular repair

Rastelli repair

REV repair

Nikaidoh procedure

In hearts with TGA and large VSD, occasionally a

completely intraventricular repair can be done by

the intraventricular tunnel technique.

1. Rastelli Operation

Usual preparations for operation are made when

performing the Rastelli procedure for TGA, VSD,

and LVOTO.

A valved conduit is preferred, and options include

pulmonary or aortic valved allografts and

composite grafts using either woven polyester or

PTFE conduits with bioprosthetic valves.

3. Nikaidoh procedure

Repair of Post-Mustard Technique

Complications 1. Caval Obstruction:

When obstruction involves only the pathway from theSVC, this

portion of the baffle may be enlarged. The baffle is incised

vertically at its midpoint with a knife and the incision carried

upward to open widely the pathway from the SVC.

When this is totally occluded, the SVC-right atrial junction, which

is always still patent beneath the baffle, is defined by inserting

the tip of a curved forcep through a stab wound in the SVC

(avoiding the sinus node area) and cutting down onto the tip of

the instrument as it tents the baffle toward the right atrial cavity

(pulmonary venous compartment). The baffle is opened at the

point at which it joins the right atrial wall in front of the SVC

junction, and fibrous thickening is excised to recontour the baffle and floor of the new tunnel.

Alternatively, the baffle can be removed entirely. When the entire

baffle is grossly thickened and distorted, especially if it contains

folded polyester and the pathway from the IVC is obstructed, the entire baffle must be excised.

2. Pulmonary Venous

Obstruction a transverse incision is made through the right atrial wall and

into the anterior pulmonary venous compartment. Incision is carried posteriorly through the waist between anterior and posterior pulmonary venous compartments and directly between right superior and right inferior pulmonary veins. Excess fibrous tissue surrounding the open stenosis is excised without breaching the baffle.

One technique for repair involves closing the transverse atriotomy with continuous No. 4-0 polypropylene suture to create a vertical atrial suture line.

Instead, a V-atrial flap may be created from the lateral right atrialwall anterior to the stenotic site, with the apex of the V advanced posteriorly as a V-Y atrioplasty.

Alternatively, a properly sized and shaped preclotted double-velour woven polyester gusset, cut from a tube to create a convex contour, is sutured into the atriotomy. This approach has the potential disadvantage that the stenosis may recur as the patch thickens.

SPECIAL FEATURES OF POSTOPERATIVE CARE

1. Arterial switch operation:

Because restlessness or agitation increases

metabolic demands and cardiac output, neonates

and infants are usually kept intubated and

sedated for 24 to 48 hours after operation.

If cardiac output is less than optimal, particularly

when two-dimensional echocardiographic study

indicates poor LV function, catecholamine support

is used rather than further increasing LV filling

pressure.

2. Atrial switch operation:

Positive end-expiratory pressure (PEEP) is not

used because it tends to obstruct the SVC.

Infants are nursed in a slightly head-up position.

Atrial pressures are kept as low as is compatible

with an adequate cardiac output; a low dose (2.5

to 5.0 mg • kg"1 • min"1) of dopamine during the

early postoperative hours is helpful.

RESULTS:

1. Simple Transposition of the Great Arteries and

Transposition of the Great Arteries with

Ventricular Septal Defect Using Arterial Switch

Operation.

2.Simple Transposition of the Great Arteries with

Atrial Switch Operation.

3.Transposition of the Great Arteries, Ventricular

Septal Defect, and Left Ventricular Outflow Tract

Obstruction.

1. Simple Transposition of the Great Arteries and Transposition of the Great Arteries with Ventricular Septal Defect Using Arterial Switch Operation

1. Early (Hospital) Death: early or hospital mortality in both

simple TGA and TGA with VSD is about 2% to 7%.

2. Time-Related Survival: Death rate (hazard function) is

extremely low by 6 to 12 months after arterial switch repair, and

survival declines minimally after that time . Thus, overall 5-year

survival, including hospital mortality, has been 82%.

3. Modes of Death : Mode of death is usually acute or

subacute cardiac failure secondary to ventricular dysfunction

resulting from imperfect transfer of coronary arteries to the

neoaorta. The only other important mode of death occurs with

RV dysfunction secondary to severe pulmonary vascular

disease, This mode has occurred in less than 1 % of patients.

4. Patient-Related Incremental Risk Factors for Death:

Coronary arterial pattern: Risk of death is increased when the

LCA or either of its branches arises from sinus 2 and risk is

further increased when the LCA or LAD passes anteriorly

between the two great arteries, a situation typically accompanied

by an intramural course of the artery in the aortic wall.

Multiple ventricular septal defects. Multiplicity of VSDs

increased risk of arterial switch repair in the first decade

following the procedure's introduction.

Older age at repair. During the initial decade of the neonatal

arterial switch experience, the younger the neonate at arterial

switch repair, the safer the operation.

Coexisting cardiac and noncardiac congenital

anomalies.These anomalies may increase risk of arterial switch repair.

5. Operative Support and Procedural Incremental Risk Factors

for Death:

The support technique (CPB versus hypothermic circulatory

arrest) has not been a risk factor for death

Longer global myocardial ischemic times have increased

probability of death.

Transection of the aorta or the pulmonary trunk at a site different

from that described earlier in this chapter under "Technique of

Operation" has been shown to be a risk factor for death.

6. Growth of Arteries:

All currently available information indicates that aortic,

pulmonary, and coronary arterial anastomoses grow at a rate

comparable to growth of the child.

7. Functional Status: positron emission tomography indicated significantly lower

coronary flow reserve in arterial switch patients compared with control subjects.

studies document exercise-induced perfusion defects and reduced coronary flow reserve at late follow-up, abnormal autonomic innervation especially in children undergoing arterial switch at older age, and small-caliber left coronary systems.

8. Ventricular Function:

• LV function is usually normal after an arterial switch operation.

preoperative dynamic LVOTO, even with a gradient of up to 120 mmHg, disappears after the arterial switch procedure.

systemic ventricular (LV) ejection fraction (EF) was within the range of normal in 98% of patients with simple TGA undergoing the arterial switch repair, but in 79% of those who underwent an atrial switch repair.

9. Rhythm Disturbances:

• free of supraventricular rhythm disturbances.

Only 3% of patients with simple TGA had arrhythmias after

arterial switch repair in one study, compared with 57% after atrial

switch repair.

10. Coronary Artery Obstruction:

Coronary artery obstruction has been documented in a

disturbingly high number of asymptomatic TGA patients

evaluated prospectively by angiography at 5- to 10-year follow-

up.

In general, coronary patterns involving a major coronary vessel

passing behind the pulmonary trunk and operations using

unusual techniques of coronary reimplantation demonstrate an

increased risk of coronary obstruction.

In studies, coronary occlusion or stenosis was found in 3.0% to 7.8% of patients at follow-up.

11. Neurodevelopmental Status:

overall physical and psychosocial health status was similar to

that of the general population.

Earlier evaluation, at age 2.5 years, suggested increased

problems with expressive language and problem behavior if

hypothermic circulatory arrest was used for the repair.

increased problems with attention, learning, speech, and

developmental delay are reported by parents.

12. Right Ventricular Outflow Tract Obstruction:

Right ventricular outflow obstruction (RVOTO) was observed as

a postoperative complication of arterial switch operation.

RVOTO has occurred in sufficient severity to require

reintervention in about 10% of patients and in one

multiinstitutional experience had a peak incidence about 6

months after arterial switch operation.

Usually, obstruction is in the pulmonary trunk. Less frequently,

RVOTO is at the bifurcation of the pulmonary trunk, and some

have thought stenosis at this area is the result of the Lecompte

maneuver.

Occasionally the obstruction is at the RV-pulmonary trunk junction or in the RV infundibulum.

13. Neoaortic Valve Regurgitation:

The neoaortic valve (which was the pulmonary valve at birth) is competent in about 60% of patients.

mild regurgitation has been found in about 35% of patients.

Moderate or severe regurgitation has been demonstrated in 5% or fewer patients. Prevalence of important regurgitation is greater in patients with prior pulmonary trunk banding and appears to be least in patients with TGA and VSD.

Risk factors include: older age at time of switch, prior pulmonary trunk banding, presence of VSD, discrepancy between sizes of aorta and pulmonary trunk, LVOTO, taussig- bing heart, trap door mechanism of implantation of coronary arteries.

14. Neopulmonary Valve Regurgitation.

15. Reoperation:

The arterial switch operation has been essentially free of reinterventions except for those directed against RVOTO.

Serraf and colleagues reported that reoperation for supravalvarpulmonary stenosis was necessary in 2.1%, whereas all other indications showed a prevalence of less than 1%.

2. Simple Transposition of the Great Arterieswith Atrial Switch Operation

1. Early (Hospital) Death:

Hospital mortality after the atrial switch operation ranges from

0% to 15%.

2. Time-Related Survival:

Survival after the atrial switch operation is strikingly lower in

patients with TGA and VSD than those with simple TGA. This

decreased survival is related to higher prevalence of deaths both

early after operation and in the months after hospital dismissal.

15-year survival after the Mustard procedure of 86% for simple

TGA and 64% for complex TGA.

Time-related survival of patients who have undergone the

Mustard operation appears in study to be superior to that after

the Senning operation.

3. Modes of Death:

low cardiac output being the most common early

postoperatively. This results from the relatively small size of the

atria, which makes the atria perform more as a conduit than a

reservoir and results in a lower ventricular filling pressure than

normal.

Forty percent of late deaths in a 20-year follow-up study were

attributable to systemic RV failure.

most common causes of late death were heart failure and sudden death.

4. Patient-Related Incremental Risk Factors for Death:

Younger age at repair

"Older age" at repair (i.e., older than 3 years) has been shown to

be a risk factor for late death, as have RV dysfunction and

presence of active dysrhythmias.

Smaller birth weight

5. Ventricular Septal Defect or Pulmonary Stenosis:

In Senning's long-term follow-up study, late systemic RV failure

was three times more common in patients with VSD or

pulmonary stenosis compared with patients with simple TGA,

and systemic RV failure was found to be the most common cause of late death.

6. Electrophysiologic Disturbances:

Acute changes include compression of the sinus node artery by sutures or less often, intimal thickening or thrombus formation and suture compression, necrosis, or infarction of the sinus node itself with interstitial hemorrhage and edema of nodal tissue and adjacent myocardium.

Chronic changes include marked fibrosis in the node and

paranodal tissue

Surgical maneuvers responsible for this damage include

incorrect techniques for SVC cannulation (too close to the node

so that purse-string suture damages it, use of crushing clamps in

this region), damage to the sinus node artery by overzealous

excision of the limbus and reendothelialization of the bare area so created, and placing suture lines too close to the sinus node.

these abnormalities are associated with dysrhythmias and are present in many individuals with late sudden death.

Junctional rhythm becomes progressively more prevalent as the years pass.

there is a gradual decrease in prevalence of sinus rhythm after Mustard-type repair as follow-up continues. Besides the apparent slight increase in risk of sudden death when a benign junctionalrhythm is present, this rhythm appears to have no other importance.

In patients with slow junctional rhythm there is a relatively normal rate response to exercise, often with reversion to sinus rhythm.

Occasionally rapid (accelerated) junctional rhythm can occur. This rhythm, and occasionally supraventricular tachycardias or atrial flutter as well, can lead to a malignant arrhythmia that reduces cardiac output and requires active measures for control

Sudden death occurs in about 5% of hospital survivors over 10

to 20 years. Sudden death is rare in patients who remain in sinus

rhythm postoperatively and when pacemaker recovery times are

normal.

Risk of sudden death in patients in junctional rhythm is 7%.

At late follow-up (23.4 years post-Mustard procedure),

prevalence of atrial fibrillation or flutter is approximately 20%,

and seems to be a marker of reduced RV function.

Episodes of supraventricular tachycardia occur in 3% to 5% of hospital survivors of the Mustard type atrial switch procedure.

7. Growth and Functional Status:

Most patients appear to be asymptomatic after an atrial switch

procedure, although at 9 to 12 years of follow-up , only 60% of

patients were in NYHA class I, and most of the rest in class II.

graded exercise testing has shown that up to 80% have reduced

exercise capacity associated with lower maximal oxygen

consumption values compared with normal.

These abnormalities are more prominent in patients operated on

at an older age and are often accompanied by abnormal cardiac

rhythms.

Functional capacity may be better in patients receiving the

Senning rather than the Mustard type of atrial switch procedure;

atrial function to be superior with the Senning operation.

Height and weight increase considerably after atrial switch repair.

normal height and weight may be achieved within 2 years of operation.

8. Coronary Arteries:

Abnormalities in caliber of proximal coronary arteries have been noted in patients after the atrial switch procedure. Diameter of the RCA is larger and that of LCA smaller in symptomatic patients.

9. Venous Pathway Obstruction

10. Right Ventricular Function :

RV systolic function, usually studied by measuring EF at rest or during exercise or another form of stress, is usually reduced after atrial switch operation in patients with simple TGA.

When RV systolic function decreases after an atrial switch procedure, it is usually associated with increased RV end-diastolic volume.

cause being the limited ventricular filling caused by rigid atrial baffles, or decreased RV compliance caused by hypertrophy. Myocardial fiber arrangement in the RV may differ from that in the LV, which may render it less able to function systemically.

Frank RV dysfunction is more common in patients with associated large VSD that also require repair

11. Left Ventricular Function:

LV function at rest is often normal late after atrial switch

operations

12. Tricuspid Valve Regurgitation :

Important (moderate or severe) tricuspid regurgitation occurs

infrequently after the atrial switch procedure for simple TGA.

13. Left Ventricular Outflow Tract Obstruction :

When an atrial switch procedure is performed for patients with

simple TGA and dynamic LVOTO , obstruction rarely progresses

thereafter. In fact, LVOTO usually regresses to some degrees.

14. Residual Atrial Shunting:

Leaks are most common in the trabeculated upper portion of the

atrium.

Trivial leaking at the baffle suture line occurs in about a fourth of

patients.

15. Pulmonary Vascular Disease:

When an atrial switch operation is performed in the first 3 months

for patients with TGA and essentially intact ventricular septum,

new and progressive pulmonary vascular disease is uncommon.

When repair is done after age 3 months, some patients (5% to

10%) with normal Rp preoperatively develop pulmonary vascular

disease postoperatively . The disease often progresses and

causes death.

3. Transposition of the Great Arteries, Ventricular Septal Defect, and Left Ventricular Outflow Tract Obstruction

1. Early (Hospital) Death:

mortality after both types of repairs has been

reduced to less than 5%.

Early mortality after both Rastelli and Lecompte

operations was high, 20% to 30%.

2. Time-Related Survival:

Predicted 10-year survival for patients operated

on in the latter part of that period was even

higher, about 95%.

15- and 20-year survival dropped to 68% and

52%, respectively for rastelli procedure.

3. Incremental Risk Factors for Death:

Advanced disability has been , probably in part

because it is usually associated with severe

cyanosis, polycythemia, advanced ventricular

hypertrophy, and heart failure.

Young age at operation has not been found to be

a risk factor with the Lecompte operation.

Straddling tricuspid valve has been identified as a

risk factor for early death.

Earlier date of operation has been a risk factor for

death after repair

4. Functional Status:

98% of patients undergoing these operations

were in New York Heart Association (NYHA) class

I or II.

5. Complete Heart Block:

Complete heart block may occur with slightly

greater frequency than after repair of simple

primary VSD.

6. Reoperation :

Reoperation is in general ultimately inevitable

when an extracardiac conduit is used.

Reoperation for obstruction in the subaortic

region within the surgically created tunnel

between LV and aorta may occur in as many as

35% to 40% of patients undergoing the Rastelli

operation or one of its variants.

Risk include small VSD size and early age at

operation. Other factors such as surgical

technique and ventricular geometric changes may

also be important.

SPECIAL SITUATIONS AND

CONTROVERSIES

1. Transposition of the Great Arteries with

Posterior Aorta:

Considered a contraindication to the arterial

switch operation until a successful case was

reported by Tarn, Murphy, and Norwood.

the conoventricular VSD was repaired through

the aorta after transecting the great arteries, and

transplantation of the coronary ostia was

accomplishe the same as in the routine approach.

Switch of the great arteries was accomplished

without the Lecompte maneuver.

2. Straddling Atrioventricular Valves:

straddling AV valves, either tricuspid or mitral, do

not represent a contraindication to two-ventricle

repair in TGA. When appropriate, arterial switch

operation can be combined with AV valve repair in

most patients, with good outcome.

OTHER TECHNIQUES:1. BEX TECHNIQUE:

The subaortic conus is divided so that the whole

aortic root, together with a muscular subvalvular rim

and the coronary arteries, is switched to lie over the

LV.

To provide maximal length to the neopulmonary

trunk, the pulmonary trunk is transected through the

pulmonary trunk-ventricular junction, sacrificing the

pulmonary valve leaflets. The distal pulmonary trunk

is then anastomosed to the right ventricular outflow

tract, often with the aid of a patch in the anterior

portion of the suture line.

This procedure in a modified form has been used by

Nikaidoh.

2. The Damus-Kaye-Stansel type of arterial

switch procedure:

This has also been used in patients with TGA

and large VSD. The pulmonary trunk is

transected near its bifurcation and the proximal

end anastomosed end-toside to ascending aorta.

A valved extracardiac conduit is placed between

RV and distal pulmonary trunk and the VSD

closed.

RV (pulmonary) systolic pressure falls to about 30

mmHg, and aortic pressure, which is above 100

mmHg, keeps the aortic valve closed.

Aubert operation. A. Illustration shows the procedure.

An aortopulmonary window is created (a) and the coronary artery

is diverted into the pulmonary artery (PA) through the window (b).

Then, the great arteries are switched (c and d). B. Aortogram shows

the single coronary artery connected to the aorta through a tunnel

(asterisk). C. Pulmonary arteriogram shows deformity and narrowing

(arrows) of the posterior part of the neopulmonary artery

Superior Vena Caval

Obstruction SVC pathway obstruction appears late

postoperatively in 5% to 10% of survivors of the

Mustard type of atrial switch procedure.

SVC obstruction is maximal at the site of excision of

the superior remnant (limbus) of the atrial septum

beneath the upper baffle compartment, and thus lies

within the right atrium rather than at the SVC-right

atrial junction.

This location was first described by Mazzei and

Mulder in 1971.

The venous pathway may be totally occluded for over

1 cm or more in this area, or there may be only a

localized zone of narrowing.

Prevalence of late SVC obstruction after a Senningoperation is probably lower than after a Mustard operation.

The patient may be asymptomatic.

The least conspicuous clinical feature, but one that suggests diagnosis, is ruddiness of the cheeks.

Puffiness of the eyelids, face, and neck can mask fixed distention of the jugular veins. Tortuous subcutaneous venous collaterals can occur.

A bilateral or right-sided pleural effusion may be present, sometimes chylous.

There may be bilateral cervical and axillarylymphadenopathy and paramediastinal densities caused by tortuous collaterals

Less common features are increasing head

circumference and hydrocephalus associated

with widening of the cranial sutures in children

less than age 18 months which is a response to

increased intracranial venous pressure.

Children older than age 3 years may develop

pseudotumor cerebri.

There may also be protein-losing enteropathy

presumably caused by interference with the

normal return of intestinal lymph to the venous

system secondary to a high venous pressure (this

is more common with IVC obstruction).

Time of onset:

SVC obstruction is usually apparentwithin 12

months of operation.

Prevalence is 9% at 4 years, with no further

events up to 17 years postoperatively.

Diagnosis.

Diagnosis can be made noninvasively using two-

dimensional echocardiography. cardiac

catheterization and

cineangiography are advisable before

reoperation.

When SVC obstruction is mild, the striking feature

is the damped waveform in the SVC tracing.

Obstruction severe enough to become apparent

clinically is associated with an SVC mean

pressure above about 15 mmHg and an SVC-

systemic venous atrium gradient of at least 10

mmHg.

Angiography shows either complete obstruction

or severe stenosis.

Angiogram showing unobstructed

venous return

SVC obstruction

Treatment

When symptoms are present, reoperation is

indicated . Reoperation is also indicated in any

child who shows progressive increase in head

size beyond the normal range.

Balloon expandable stents have been successful

in relieving some obstructions.

Alternatively, if Rp is acceptably low, a

bidirectional superior cavopulmonary

anastomosis can be performed.

Inferior Vena Caval

Obstruction

Postoperative IVC obstruction, as with SVC

obstruction, occurs within the heart at about the

midpoint of the lower portion of the systemic

venous compartment adjacent to the coronary

sinus ostium.

Patients with important IVC obstruction usually

are symptomatic, with liver enlargement, ascites,

and leg edema. A protein-losing enteropathy may

occur more frequently than with SVC obstruction

and particularly when combined with some

degree of SVC obstruction.

there may be low cardiac output and premature

late death.

Diagnostic techniques used in obstructed IVC are

similar to those for SVC obstruction.

Reoperation with insertion of a new baffle is

always indicated for IVC obstruction ,Balloon

expandable stents have been used for IVC as for

SVC obstruction.

Pulmonary Venous

Obstruction

Pulmonary venous obstruction is a less common

but more lethal type of venous pathway

obstruction.

It is more common when a polyester baffle is

used in Mustard repair.

Pulmonary venous obstruction usually occurs at

the waist of the pulmonary venous atrium, which

lies just anterior to entry of the right pulmonary

veins between the crista terminalis on the lateral

right atrial wall and the center of the baffle in the

Mustard operation.

In severe stenosis there is a circular fibrotic ostium at this point, which is less than 10 mm in diameter, which divides the pulmonary venous atrium into two almost equal compartments of adequate size. The right pulmonary vein ostia are usually not stenotic.

Pulmonary venous obstruction produces pulmonary venous hypertension and symptoms of progressive dyspnea with cough, fatigue, and at times cyanosis.

Pulmonary venous congestion may progress to interstitial pulmonary edema.

These signs are unilateral when only the left pulmonary veins are stenotic.

A continuous murmur with diastolic accentuation may be heard along the lower left sternal edge

Time of onset is similar to that of caval

obstruction and is usually within 6 to 12 months of

operation.

Diagnosis is confirmed by cardiac catheterization,

when ideally the catheter is passed retrogradely

across the stenosis to the posterior pulmonary

venous compartment to obtain a withdrawal

gradient.

If this is impossible, a comparison is made

between pulmonary artery wedge pressure and

RV diastolic pressure. Gradient greater than 10

mmHg is important.

Treatment. Urgent reoperation is indicated.

RV failure after atrial switch operation

RV failure can occur in about 10% cases after

atrial switch in long term and its incidence

increases further more when VSD is present.

Surgical options available:

1. Staged conversion to ASO

2. Tricuspid valve replacement(very dismal results)

3. Cardiac transplantation.

Staged conversion to ASO

First done and reported by Roger mee.

It begins with PAB to achieve PA pressure equal

to 75% of aortic or RV pressure.

It frequently requires a extention graft from

proximal neopulmonary artery to distal pulmonary

artery due to inadequate pulmonary artery length

due to scarring by PAB.

If the left ventricle does not respond to PAB the

answer is cardiac transplant.

To be continued with

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