- L-TGA, also known as corrected transposition of the great arteries, is a rare congenital heart defect where the ventricles are transposed and the atrioventricular valves are discordant. - The embryological cause is abnormal leftward looping of the heart during development, resulting in the morphologic right ventricle being on the left side and pumping blood to the lungs, while the morphologic left ventricle is on the right side and pumps blood to the body. - Associated abnormalities are common, including ventricular septal defects, pulmonary stenosis, tricuspid valve anomalies, and conduction system abnormalities. Long term, the right ventricle is poorly suited to function as the systemic

1. ANATOMY,EMBRYOLOGY
& MANAGEMENT OF L-TGA

2. • Overview
• Introduction
• Embryology
• Anatomy
• Specialised conduction system
• Coronary aryety system
• Associated abnormalities
• Management
• Follow up care

3. • Other names- Isolated ventricular
inversion/double discordance/physiologically
corrected transposition/L-TGA
• Systemic veins to morph RA, connected by a
MV to an LV, connected to a PA which is
transposed
• Pulmonary veins to morph LA, connected by a
TV to an RV, connected to an Ao which is
transposed
• --> AV & VA discordance
• NET result- systemic venous blood gets to
lungs and pulmonary venous blood gets to
body, so it appears good.
• However, even in the patient with no
associated abnormalities, it is increasingly
apparent that natural history and
hemodynamics will be far from normal
Introduction

4. • Prevalence, Etiology, and Morphogenesis
• Corrected transposition is an uncommon lesion.
• Data from several sources suggest a prevalence of 0.03 per 1,000 live births
accounting for approximately 0.05% of congenital heart malformations .
• Population-based studies continue to document the environmental factors in
the etiology of this condition.
• Still, the familial occurrence and recent molecular biology investigations
suggest the importance of genetic influence .
• It would seem wise therefore to continue to counsel a multifactorial
etiology with a recurrence risk in first-degree relatives of approximately
2%.

5. • ETIOPATHOGENESIS —
• A case-control study from the Baltimore Washington Infant Study
evaluated personal and occupational exposure data from 3495 live births
between 1981 and 1989 including 36 infants with L-TGA .
• Over three-quarters of the cases of L-TGA occurred in two small
contiguous regions of Maryland and Washington, DC.
• These two areas were characterized by release of toxic chemicals into the
air and by hazardous waste sites.
• In addition, parental exposures to hair dye, smoking, and laboratory
chemicals were more likely in infants with L-TGA than in the overall
cohort.
• Two case series reported a risk of 2 to 5 percent of L-TGA in siblings of
affected patients lending support to a genetic pathogenetic component

6. • Embryology:
• If development proceeds in normal fashion, the primary heart tube bends to
the right during early development.
• This leaves the atrioventricular canal connected primarily to the part of the
loop from which will develop the morphologically left ventricle.
• Expansion of the canal to the right then permits the right atrium to connect
directly with the developing morphologically right ventricle, which itself is
positioned rightward relative to the morphologically left ventricle.

7. Embryology
• 22 days gestation …
the primitive straight cardiac tube is formed
• Composed of 5 chambers with patterning regulated by homeobox genes
- Truncus = aorta and pulmonary artery
- Bulbis = outflow tracts and ventricle

8. • 23 days gestation … the straight cardiac tube
elongates and bends forming the cardiac loop.
– Cephalic portion bends ventrally, caudally, and right-ward.
– Caudal portion moves dorsally, cranially, and left-ward.
– The rotational motion folding over of the bulboventricular
portion bringing the future ventricles side-by-side.
Embryology

9. • Embryology
• In certain circumstances, instead of bending to the right during
development, the heart tube turns leftward.
• Such leftward looping places the outlet component of the primary
tube, from which will develop the morphologically right ventricle, to the
left of the morphologically left ventricle.
• In this setting,so as to permit the atrioventricular canal to open directly to
both ventricles, it must expand leftward rather than rightward, at the same
time placing the developing morphologically left atrium in communication
with the morphologically right ventricle, and leaving the morphologically
right atrium connecting to the morphologically left ventricle.
• This process, therefore, produces discordant atrioventricular connections.

10. loop rule for ventricular localization as proposed by De la Cruz et al. as an
explanation for corrected transposition of the great arteries.
d-Ventricular looping would result in normal ventricular situs, with the
morphologic right ventricle to the right and anterior and the morphologic left
ventricle to the left and posterior.
l-Ventricular looping would result in inverted ventricular situs

11. • The aortic root, arising from the RV, is anterior and leftward of the
pulmonary artery root (―L‖ transposed).
• The inverted atrioventricular (AV) connections, combined with the
reversed ventriculoarterial connections, ―correct‖ the flow pattern such that
deoxygenated systemic venous blood flows to the lungs, and oxygenated
pulmonary venous blood is pumped to the systemic circulation.
• Further twisting can result in a more superior-to-inferior relationship of the
right ventricle to the left ventricle .

12. • Morphology:
• 95% situs solitus
• 25% dextrocardia/mesocardia
• Ventricular Topology:
• Left hand ventricular looping (by
Dr. Anderson's palm - only Lt
hand can fit in RV with thumb in
inlet, fingers in outlet and palm on
IVS surface) ==>morph RV on
left, morph LV on right
• LV & RV might be in a more sup-
inf relationship because of further
twisting during looping.

13. • Atrial & Ventricular septa
• IVS tends to be more sagittal/horizontal--> malalignment of atrial septum
and ventricular septum (seen often with AV discordance).
• should meet at crux of heart, but the atrial septum continues
ant/rightward, it will deviate from the ventric septum--> gap from
malalignment of atrial septum==>implications in
– VSD, and
– variable outflow sizes and
– conduction system placement.

14. • R sided AV valve (Penny et al)
– Mitral valve- 2 pap muscles,
– no insertion onto IVS
– 10% of MV's have significant abnormalities
• L sided AV valve
– Tricuspid valve-
– often abnormal,
– Its anterior positioning brings the septal leaflet into the gap created by
the septal malalignment at the membranous septum.
– This leaflet may thus form the posterior wall of the left ventricular
outflow tract

15. • LVOT obstruction
• Most frequently, AV discordance is associated with transposition of the
great arteries (TGA) and a leftward anterior position of the aortic valve
relative to the pulmonary valve, though this is not absolute .
• The left ventricular outflow tract is deeply wedged between the left and
right atrioventricular valves and is therefore more readily subject to
obstruction.
• The pulmonary valve is most often in fibrous continuity with the mitral
valve.

16. • RVOTO
• The leftward anterior aorta is supported by a muscular infundibulum and is
not in fibrous continuity with either atrioventricular valve.
• Obstructive lesions of the right ventricular outflow tract and aorta are
underemphasized.
• Several reports suggest the higher frequency of this problem in association
with severe left AV valve regurgitation.
• Systemic outflow obstructions may take the form of functional and/or true
aortic valve atresia as well as obstructive anomalies of the aortic arch.

17. • PATHOPHYSOILOGY
• In patients with anatomically uncorrected L-TGA (ie, persistent
atrioventricular and ventriculoarterial discordance), the morphologic right
ventricle (RV) is not well suited to perform the workload of the systemic
ventricle over a normal lifespan.
• As a result, systemic ventricular failure (ie, systemic heart failure) is a
common late complication in L-TGA patients including those without
associated cardiac lesions.
• Right ventricular dysfunction is thought to be due to an unfavorable
tripartite geometric configuration that does not adapt to pressure or volume
overload .

18. 1. Ventricle shape
Cylindric vs. crescent-shaped cavity
2. Contraction pattern
Concentric vs. bellow-like contraction
3. Pumping action
Pressure pump vs. low pressure-volume pump
4. Coronary artery supply
Two system vs. one system
5. Embryology
Primitive ventricle vs. bulbus cordis
6. Papillary muscles
Two papillary vs. small & numerous (septophylic)
Characteristics of Both Ventricles LV Vs RV
The long-term systemic workload results in progressive tricuspid regurgitation
that increases volume overload and contributes to ventricular dysfunction and
failure. Increase the vulnerability of this ventricle to ischemia, particularly
when hypertrophy is present

19. • Coronary Artery Anatomy
• Changing approaches to the surgical
management of ccTGA have
refocused attention on the coronary
artery anatomy.
• In general, the coronary arteries
originate from the posterior-facing
sinuses of AV
• In patients with atrial situs solitus
and ccTGA, the coronary arteries
show a mirror-image distribution.
• The right-sided coronary artery has
the epicardial distribution of a
morphologic left coronary artery
with the main right-sided coronary
artery bifurcating into circumflex
and anterior descending
branches, whereas the left-sided
coronary artery runs in the left AV
groove and gives rise to
infundibular and marginal branches.

21. • Several studies have demonstrated a variable pattern of coronary artery
anomalies.
• A 14-specimen study by McKay et al. observed the persistent origin of the
sinus node artery off the circumflex artery and speculated on its course
along the medial side of the right atrial wall.
• They commented on the potential surgical risk of damaging the artery
during an atrial baffle procedure or atriotomy repair.
• In that same paper, a correlation between commissural malalignment and
eccentric coronary ostia was observed.

22. • Ismat et al. analyzed 20 specimens and found 7 specimens with eccentric
ostia.
• Uemara et al. The largest specimen study (46 specimens)
• They reported a 76% incidence of a relatively normal pattern with the right
and left coronaries off the left- and right-facing sinuses, respectively.
• Anomalies were found in 11 specimens.
– Single coronary was the most common in four with two off the right-
and two off the left-facing sinuses.
– A main coronary branch coursing anterior to the pulmonary trunk was
found in 96% of the specimens, and a large coronary branch crossing
the right ventricular outflow tract was found in 61% of the specimens .
– The latter finding is of most importance when considering the Rastelli
procedure

23. • Chiu et al. described a segmental approach to the coronary anatomy.
• From their study on 62 patients, they concluded that,
• First , the proximal coronary pattern at the aortic sinus depends on the
aortopulmonary rotation, and
• Second,the peripheral coronary pattern depends on the atrial situs and
apical position or the so-called apicocaval ipsilaterality, as well as the
ventricular looping.
• A good understanding of the type and degree of variability of the coronary
anatomy in patients with congenitally corrected transposition is crucial in
the emerging era of double-switch surgical approaches to these patients.

24. • Specialized Conduction Tissues
• abnormal and potentially unstable.
• Anderson, Becker, Losekoot, et al.
have elucidated conduction tissue.
• SA node lies in its normal position in
relation to the atrial situs.
• AV conduction tissue, on the other
hand, is abnormal.
• The classic description is that of two
AV nodes,
– a normal posterior AV node
located at the apex of the triangle
of Koch but with no AV
bundle, and
– an abnormal right anterior AV
node giving rise to the
penetrating AV bundle.

25. • The latter is located
anterosuperiorly in the area lateral
to the pulmonary/mitral valve
continuity, underneath the
opening of the right atrial
appendage.
• Its AV bundle has a superficial
course along the anterior aspect of
the subpulmonary outflow tract
and superior left ventricular wall,
into the upper interventricular
septum from which it descends
and branches.
• If a VSD is present, the anterior
AV bundle courses along its
anterosuperior margin.

26. • The conduction tissue abnormality is not universal to all patients with
ccTGA.
• The reason that certain patients had a normal AV node and AV bundle had
remained elusive until Hosseinpour et al. elegantly elucidated this long-
standing mystery.
• It is thought that the development of an AV bundle from the normal AV
node to the summit of the interventricular septum is anatomically hindered
by the atrial and ventricular septal malalignment

27. • The degree of malalignment is related to the size of the left ventricular
outflow tract and the pulmonary trunk.
• Hosseinpour et al. showed that - normal conduction system frequently are
characterized by the lesser degree of atrial and ventricular septal
malalignment.
• Therefore, a correlation is made between the size of the LV outflow
tract, the degree of septal malalignment, and the presence of normal AV
conduction tissue.

28. • It is thought that the normal conduction tissue is in addition to rather than
instead of the abnormal anterior conduction system.
• In patients with both conduction systems straddling the anterosuperior and
inferoposterior margins of a VSD, there can exist a slinglike bundle located
over the anterior margin of the VSD and connecting both AV bundles, as
described by Monckeberg.

29. • Associated anomalies (95% of patients)
• signs or symptoms are due to the pathophysiology of the associated cardiac
defects.
– VSD
– Pulmonary stenosis
– Tricuspid valve anomalies
– Congenital complete heart block
– Coarctation of the aorta and interruption of the aortic arch are rare

30. • 1.Ventricular Septal Defect
• Approximatel y 80%.
• Perimembranous and
• A consequence of the atrial and
ventricular septal malalignment .
• In a subpulmonary location and
in approximation to the septal
leaflet of the left-sided tricuspid
valve.
• The defects often are large with
anterior extension and therefore
suitable for intraventricular
tunneling.
• Other defects such as the
subarterial or muscular defect do
occur but are unusual.

31. • 2.Pulmonary Outflow
Obstruction(LVOTO)
• 30% to 50% of patients with
ccTGA and atrial situs solitus.
• Usually is associated with a large
VSD.
• Cyanosis is often a presenting
finding in neonates due to major
outflow tract obstruction and large
VSD because of a significant Rt -Lt
ventricular cardiac shunt
• commonly subvalvular and -due to
an
– aneurysm of the interventricular
septum,
– fibrous tissue tags, or a
– discrete ring of subvalvular
tissue
– intimately related to the non
branching atrioventricular
bundle.
• Less frequently, valvar pulmonary

32. • The left ventricular outflow tract obstruction
– may be muscular, reflecting wedging of the subpulmonary outflow tract
between the infundibular septum and the ventricular free wall, with
contributions from the right-sided ventriculoinfundibular fold.
– Fibrous tissue derived from the membranous septum may participate in
left ventricular outflow tract obstruction.
– Tissue tags derived from the tricuspid or mitral valve or
– stenosis of the pulmonary valve itself may obstruct flow into the
pulmonary trunk.
• Such tissue tags are likely the most common obstructive lesion.

33. • Lesions of the Morphologic Tricuspid Valve
• Abnormalities of TV (systemic atrioventricular) are intrinsic to ccTGA. -
90% .
• A clinically apparent functional disturbance less often manifested.
• Since this valve is associated with the systemic ventricle, tricuspid valve
abnormalities have an important impact in the development of ventricular
dysfunction and heart failure in older uncorrected patients.
• Pathology is dysplasia of the valve, with or without displacement of the
septal or posterior leaflets of the tricuspid valve.
• Regurgitation is frequent and generally progressive

34. • Anderson et al. have described the features associated with the Ebstein
anomaly of the left-sided tricuspid valve and these valves in general are a
poor substrate for repair.
• An Ebstein-like malformation of the tricuspid valve, which is usually
accompanied with right ventricular dysfunction and failure, has been
reported in 20 to 53 percent of patients with L-TGA .
• Symptoms related to tricuspid valve abnormalities are dependent on the
severity of the defect.
• Both the morphologic tricuspid valve and on occasion the mitral valve can
straddle the ventricular septum. This anomaly is of course very important to
recognize preoperatively

35. • Mitral valve abnormalities, although less frequent than tricuspid
abnormalities, still occur in 55 percent of cases in autopsy series .
• These lesions include
– abnormal number of cusps,
– straddling chordal attachments of the subvalvar apparatus creating
pulmonary outflow tract obstruction, and
– mitral valve dysplasia.
• This abnormality may not present with significant clinical findings

36. • Clinical features
• Isolated L-TGA — Less than 20 percent of L-TGA patients have L-TGA as
an isolated disorder and generally present later in life with signs and
symptoms related to either arrhythmias or heart failure.
• Complete heart block is the most common arrhythmia in patients with L-
TGA with signs and symptoms of bradycardia, fatigue, and poor exercise
tolerance.
• Progressive fibrosis of conduction system with advancing age, which
increases the risk of complete heart block (progressive incidence of 2
percent per year ) and re-entrant tachyarrhythmias including Wolff-
Parkinson-White (WPW) syndrome.

37. • Symptoms of heart failure (eg, dyspnea, fatigue, fluid retention, and
decreased exercise tolerance) typically occur in adult patients with
progressive dysfunction of the morphologic right ventricle and increasing
systemic tricuspid regurgitation .
• In one case series of 182 adult patients, two-thirds of patients with
associated lesions and one-quarter of patients without additional cardiac
defects had developed heart failure .

38. • Unoperated Natural History
• Early natural history is significantly affected by the severity of associated
lesions and surgical management.
• Although there have been repeated case reports of long-term survival with
ccTGA, this is likely unusual .
• Beauchesne et al. followed 44 unoperated patients for 144 months and
found that most (59%) had grade 3 or greater systemic atrioventricular
valve regurgitation and that many of these demonstrated significant
systemic RV dysfunction and were symptomatic.

39. • Presbitero et al. have followed 18 patients, again pointing to systemic
atrioventricular valve regurgitation and ventricular dysfunction as major
concerns.
• Graham et al. In a large multi-institutional study, found that, patients
without associated lesions had a lower occurrence rate of heart failure and
systemic ventricular dysfunction than those with associated lesions at a
given age, these problems tended to increase in frequency with advancing
age in both groups.

41. • Electrocardiography —
• In L-TGA, the interventricular septum is depolarized in the opposite
direction of normal.
• Q waves in the right precordial leads and an absence of Q waves in the left-
sided precordial leads
• These electrocardiographic findings may be misinterpreted as an inferior
myocardial infarction
• In addition, patients may also have varying degrees of AV heart block due
to abnormalities of the conduction system.
• As noted above, the risk of CHB rises over time with a 2 percent per year
increase in incidence

43. • Chest radiograph —
• Twenty-five percent of patients with L-TGA will have mesocardia
(ie, location of the apex of the heart in the midline of the thorax) or
dextrocardia (ie, the heart is on the right side of the chest and the apex
points to the right)
• In those patients with levocardia (normal location), the leftward positioned
aorta usually results in a prominence in the upper left border of the
mediastinum

44. • PA chest radiograph
shows cardiomegaly with
increased pulmonary
vascular markings
secondary to aVSD.
• The right pulmonary
artery appears to have a
high take-off because of
an absent aortic shadow
and is also quite
prominent indicating
ventricular inversion, L-
TGA.

45. congenitally corrected transposition of the great arteries, a nonrestrictive
ventricular septal defect, and increased pulmonary blood flow.
A septal notch (unmarked arrow, lower right) appears just above the left
hemidiaphragm.
The ascending aorta (AAo) is convex at the left base,
the dilated posterior pulmonary trunk causes rightward displacement of the
superior vena cava (SVC).

46. • ECHOCARDIOGRAPHY
• Detailed sequential segmental analysis
is the pivotal investigation. This will
show that the systemic veins drain to the
morphologically right atrium, which is
joined to the morphologically left
ventricle.
• The connection of the morphologically
left ventricle is then to the pulmonary
trunk. The pulmonary veins will be
identified joining the morphologically
left atrium, which is connected to the
morphologically right ventricle and
thence to the aorta .
• The morphologic nature of the left
ventricle is identified on the basis of its
smooth walls, and the presence of
paired papillary muscles supporting the
morphologically mitral valve

47. • The morphologically right
ventricle will be recognised on the
basis of its coarse apical
trabeculations, the presence of the
moderator band, and attachments
of the septal leaflet of the
morphologically tricuspid valve
directly to the septum.
• Associated lesions, such as
ventricular septal defects,different
types of obstruction within the
outflow tract of the
morphologically left ventricle
such as tissue tags or fibrous
shelve, and pulmonary valvar
stenosis or atresia will clearly be
seen.

49. • The morphology of the
morphologically tricuspid valve
must be studied with care.
• This can be markedly
dysplastic, with displacement of the
septal and inferior leaflets into the
morphologically right ventricular
cavity in those with associated
Ebstein’s malformation .
• When there is marked dysplasia of
the valvar leaflets, it is usual to see
moderate-to-severe tricuspid valvar
regurgitation on colour flow
mapping.
• Straddling and overriding of either
the right or left-sided
atrioventricular valves should be
identified if present, taking care to
exclude hypoplasia of either
ventricle sufficient to militate
against biventricular surgical

50. • Sequential segmental analysis will also serve to identify rarer combinations
found in some patients with discordant atrioventricular connections, such as
those with double outlet right or left ventricles, or concordant ventriculo-
arterial connections.
• The latter combination is of particular significance, since although the
patients present with the features of transposition, the segmental
combinations mean that an atrial redirection procedure is the corrective
procedure of choice, placing the morphologically left ventricle as the pump
to the systemic circulation

51. • Catheterization
• In the recent past, diagnostic right and left-sided heart cath-eterization was
performed prior to intracardiac repair, focusing on imaging the PA and
coronary anatomy .
• Diagnostic catheterization remains important in the preoperative assess-
ment of patients in whom
– Pulmonary vascular resistance may be elevated (long-standing VSD
shunt, severe left-sided AV valve regurgitation) along with the
response to pulmonary vasodilators,
– In patients with suspected aortopulmonary collaterals or unexplained
cyanosis, and
– Less commonly in those with abnormal coronary artery anatomy that is
not well-defined with noninvasive imaging.
– As a part of the assessment of left ventricular hemodynamics in patients
undergoing left ventricular retraining prior to anatomic repair .

52. • Since ccTGA of the great vessels may occur with cardiac
malposition, noting the catheter course in the abdomen to identify the
course of the IVC or aorta aids in the diagnosis of the underlying situs and
malposition.
• Observations about the course of the catheter may be important in
recognizing the abnormal position of the great arteries in relation to the
ventricles as well.
• Using anteroposterior and lateral fluoroscopy, their course can be
determined.
• In patients with situs solitus and levocardia, the PA lies medially and
posteriorly, with the venous catheter following a course close to the spine.
• The aorta lies anteriorly and along the left cardiac border.

53. • Because of the anterior position of the AV node and the intrinsically fragile
conduction system, patients with ccTGA are at higher risk of developing
heart block during catheter manipulation, especially, but not
invariably, when attempt-ing access into the PA.
• Floating balloon catheter is preffered.
• Thus, it is always important to have available a system for emergent
transvenous pacing during the procedure itself.

54. • ANGIOCARDIOGRAPHY
• Assuming the usual position of the
ventricular septum, a frontal and
lateral left ventriculogram, perhaps
with 20 to 25 degrees of right anterior
oblique (RAO), should profile the
ventricular septum, the left ventricular
outflow tract, and the mitral inflow
• A similar projection can be used for
the injection in the morphologic RV.
• Obviously, if there are defects in
other portions of the ventricular
septum, the axial projections will
have to be modified and expanded.
• The character of the subpulmonary
obstruction is best imaged by
selective injection of contrast into the
morphologic left ventricle. In the
setting of VSD, adding 20 to 25 of
RAO will demonstrate to advantage
both the VSD and the left ventricular
outflow tract obstruction.

55. • The functional status of the left
AV valve is perhaps best
assessed by echocardiography and
color Doppler, but rightventricular
angiography will also add
information .
• The character of subaortic
stenosis, admittedly
uncommon, may best be
demonstrated by right ventricular
angiography. Varying degrees of
obliquity may be required to pro
le the small left ventricle or the
VA connection of double-outlet
RV.

56. • The pulmonary arteries and their
bifurcation are best imaged by a
selective injection of contrast into
the pulmonary arteries with
craniocaudal angulation.
• A degree of right or left anterior
obliquity will focus on the right or
left PA, respectively.
• The aorta and the coronary arteries
can be profiled by
aortography, filmed in the frontal
and lateral projections.
• The coronary arteries originate from
the posterior-facing sinuses, and
selective coronary angiography may
be necessary to obtain adequate
demonstration of the anatomy.

57. • When anatomical repair is planned, such
as the double-switch,procedure, coronary
angiography may be helpful in delineating
the anatomy of the coronary arteries.
• When there has been prior construction of
a systemic-to- pulmonary arterial shunt, or
the pulmonary trunk has been banded to
reduce the flow of blood to the lungs or to
train the morphologically left ventricle
haemodynamic and angiographic data is
required to demonstrate the anatomy of the
pulmonary arteries and to show whether
the morphologically left ventricle has been
adequately trained so that it can support
the systemic circulation.

58. • Medical Management
• Medical management involves the usual modalities for cardiac failure, such
as inhibition of angiotensin-converting enzymes, diuretics, and control of
arrhythmias with pacing to raise the heart rate when necessary.

59. Operative Indications of CC-TGA
The presence of corrected TGA is not an indication for a
reparative operation
WITHOUT ASSOCIATED DEFECTS
Complete heart block
-WITH ASSOCIATED DFECTS
1. Ventricular septal defect
2. VSD & Important PS
3. Left-sided tricuspid incompetence

60. • CHB
• Dual chamber AV sequential pacemeker is indicated in any
symptomatic patient with AV block.

61. • CORRECTIVE SURGICAL MANAGEMENT
• Overview — There has been a paradigm shift from
• conventional repair/Physiological Repair of the associated cardiac lesions
while maintaining the congenitally corrected atrioventricular and
ventriculoarterial discordance to an
• “anatomic” repair, which makes the morphologic left ventricle become the
systemic pump and the morphologic right ventricle the pulmonary
ventricle.

62. 1. Ventricle shape
Cylindric vs. crescent-shaped cavity
2. Contraction pattern
Concentric vs. bellow-like contraction
3. Pumping action
Pressure pump vs. low pressure-volume pump
4. Coronary artery supply
Two system vs. one system
5. Embryology
Primitive ventricle vs. bulbus cordis
6. Papillary muscles
Two papillary vs. small & numerous (septophylic)
Characteristics of Both Ventricles LV Vs RV
The long-term systemic workload results in progressive tricuspid regurgitation
that increases volume overload and contributes to ventricular dysfunction and
failure. Increase the vulnerability of this ventricle to ischemia, particularly
when hypertrophy is present

64. • Isolated L-TGA –
• the choice of anatomic repair is controversial.
• complex procedures that require substantial time on bypass .
• In contrast, there are data that show adults with isolated L-TGA without
anatomic repair are at-risk for systemic heart failure, although the risk is
lower than patients described above with associated lesions .
The final decision is individualized based on a review of the patient’s
potential for heart failure without anatomic correction versus the
potential complications of the anatomic repair, and the preference of the
family.

65. • Suggested guide for deciding surgical approach
• Pediatric patients with L-TGA and
– significant ventricular septal defect [VSD],
– left ventricular (LV) outflow tract obstruction, and/or
– Ebstein-like malformation of the tricuspid valve
• should be considered for anatomic repair as they are at greatest risk for
developing systemic heart failure with conventional repair.
•

66. • Patients who are diagnosed with L-TGA beyond childhood eventually
present with systemic ventricular dysfunction or failure, systemic tricuspid
valve regurgitation, or arrhythmias.
• When systemic tricuspid regurgitation is present, these adults should be
referred for systemic AV valve replacement before they have morphologic
right ventricular failure or progressive dysfunction (systemic right
ventricular EF less than 40 percent).
• PA banding has been found to improve systemic AV valve regurgitation in
select patients.
• Cardiac transplantation or ventricular assist device placement should be
considered in patients with persistent heart failure refractory to these
measures and medical management.

67. • conventional repair/Physiological Repair
• Associated cardiac anomalies can be repaired with this approach, albeit that
the morphologically right ventricle remains as the pump to the systemic
circulation.
– ventricular septal defects, if present, can be closed,
– obstruction within the left ventricular outflow tract can be relieved by
either resection or placement of a valved conduit, and the
– tricuspid valve, if leaking, can be repaired or replaced.

68. • ventricular septal defect
• Usually the VSD is perimembranous in position-
• NO right ventriculuotomy and no damage to systemic av valve
- incision in the right atrium,, through the morphologically mitral valve either
displacing septal leaflet or cutting the annulus .
• Some muscular outlet defects can be
– closed via the pulmonary trunk and the pulmonary valve.
• The conduction system passes in anterocephalad fashion around the pulmonary
outflow tract.
• To avoid damaging the conduction system, either continuous or interrupted
sutures are placed on the morphologically right ventricular margin of the defect
superiorly, and from the morphologically left ventricular side of the margin
inferiorly
• PA banding to prevent pulomonary overcirculation and PAH –May help for
anatomic repair in future.

69. • LVOTO
• Mostly subvalvular posteriorly located overlied by RV anteriorly.
• Conduction system runs on left ventricular side of septum- any tension on
septum can damage it.
• Incisions placed across the attachments of the pulmonary valvar leaflets
• the ventriculotomy is placed towards the apex of the ventricle
– careful resection of accessory tissue, or
– open pulmonary valvotomy, but in general
– a valved conduit is placed from the morphologically left ventricle to the
pulmonary arteries so as to relieve the obstruction.
• Valved conduits will not last forever, and most will need to be changed.
• It is wise, therefore, to close the pericardium with a membrane to protect
the heart during sternal re-entry at reoperations.

70. • Morphologically tricuspid valve abnormalities
• Repair or replacement of the morphologically tricuspid valve sometimes
has to be done as part of physiological repairs when there is severe
tricuspid valvar regurgitation.
• with problems of continuing cardiac failure, since often the
morphologically right ventricle is failing by the time such surgery is
entertained.
• In addition, particularly in younger patients where there is marked
dysplasia of the valvar leaflets, repair can be extremely difficult, if not
impossible.
• Under these circumstances, replacement may well be necessary.
• Difficulties are Similar to ebstein anamoly

71. Classic Operation of CC-TGA
1. Repair of ventricular septal defect
2. Repair of coexisting VSD & PS
· Extracardiac conduit
· Without extracardiac conduit
3. Correction of incompetent tricuspid valve
· Repair ( annuloplasty )
· Replacement
4. Fontan-type repair
Straddling, A-V canal , hypoplastic ventricle

72. • Outcome and complications —
• Although the early mortality is low,
• long-term outcome is poor --progressive systemic RV dysfunction and
heart failure.
• In a case series from a single center of 123 patients with L-TGA that
underwent conventional repair, postoperative survival rates at 1, 5, 10, and
15 years were 84, 75, 68, and 61 percent, respectively .
• Risk factors associated with a poorer outcome included
– tricuspid valve replacement,
– preoperative poor RV function,
– complete heart block after surgery,
– subvalvular pulmonary stenosis, and
– Ebstein-like malformation of the tricuspid valve.

73. • Anatomic repair —
• Associated lesions remains the major determinant regarding surgical
repair.
• The poor late outcome results associated with conventional repair of L-TGA
has led to anatomic correction to make the morphologic LV the systemic
pump and the morphologic RV the pulmonary ventricle.

74. 1. Morphologic LV that is prepared (ie, sufficiently hypertrophied or
―trained‖) to take over the workload of the systemic ventricle, thereby
minimizing the likelihood of postoperative LV failure.
2. Current LV/RV pressure ratio greater than 0.7
3. Unobstructed LV-PA & RV-Ao connections
4. Balanced ventricular & AV valve sizes
5. Septatable heart, without AV valve straddling
6. Translocatable coronary arteries
7. Competent mitral valve with good LV function
(Karl TR, et al. ATS 1997)
Proposed Patient Selection Criteria

75. • Anatomical Correction
• The current choice of surgical intervention for anatomic correction of the
ventricles is largely dependent on the
– presence of subpulmonary obstruction and the
– anatomy of the VSD:
• morphologically left ventricle is restored to pumping the systemic
circulation by
– double-switch operation-combining atrial and arterial switch
procedures, or
– atrial switch along with ventricular rerouting.

76. • Double -switch operation
– Where competent and non-stenotic valves.
• Atrial switch along with ventricular rerouting/ Senning-Rastelli procedure.
– Where there is pulmonary stenosis or atresia, usually in association
with a large ventricular septal defect, the atrial switch is combined with
tunnelling of the morphologically left ventricle to the aorta.
– A valved conduit is then placed from the morphologically right
ventricle to the pulmonary arteries.

77. • Pulmonary artery banding or left ventricular “training” —
• Not needed in significant PS/pulmonaryhypertension/unrestrictive VSD.
• In these patients, the LV is already functioning at pressure levels
consistent with what will be required as the systemic ventricle.
• However, in other patients in whom the LV is not initially ready to become
the systemic ventricle, PA banding is used to ―train‖ the LV.

78. • Pulmonary artery banding or left ventricular “training” —
• In L-TGA patients with a LV that is not ready to function as the systemic
ventricle, placement of a band on the pulmonary artery (PA) is used to
increase the afterload of the morphologic LV.
• This exposure to near systemic pressure increases the LV posterior wall
thickness (ie, left ventricular ―training‖).
• Altering the left and right ventricular pressure ratio may also reduce the
right ventricular sphericity and improve the geometry of the right ventricle
prior to anatomic correction .

79. • Although pediatric cardiac surgical centers use varying measurements to
determine if a morphologic LV is adequately prepared for the systemic
circulation, most published reports suggest a morphologic LV pressure of
66 to 80 percent of systemic pressure is sufficient.
• In addition, others recommend that normal LV mass and thickness for
systemic function using echocardiography and/or magnetic resonance
imaging be required prior to anatomic correction .
• Risk factors for failure of PA band retraining include
– mild LV dysfunction before banding,
– development of significant LV dilation and dysfunction, and
– postoperative development of tricuspid regurgitation .

80. • In several case series, the median time from PA banding to the double
switch procedure ranged from 2 to 14.5 months .
• Typically, PA banding appears to be more successful in patients less than
13 years of age, and the younger the patient, the shorter interval required
for training.
• Patients older than 16 years of age appear to be unlikely to achieve
sufficient LV function to proceed to anatomic correction.

81. • Pulmonary artery banding for Large ventricular septal defect —
• In infants with a large unrestrictive VSD, an increase in pulmonary blood
flow may result in heart failure in the first few weeks of life as the
pulmonary vascular resistance falls.
• The placement of a PA band can be considered in patients who are
refractory to medical management.
• Creating increased resistance to the pulmonary circuit will reduce
pulmonary blood flow, improve the symptoms of heart failure, and promote
weight gain.
• Promotion of growth is desired as anatomic surgical correction is easier to
perform in a larger infant.

82. • Double switch operation —
• The double switch (DS) operation
consists of an atrial switch
procedure that creates an intra-
atrial baffle (Mustard or Senning
procedure) and an arterial switch
operation (ASO).
• The intra-atrial baffle diverts the
deoxygenated systemic venous
return into the subpulmonary
ventricle and oxygenated
pulmonary venous return to the
subsystemic ventricle.
• The ASO involves transection of
both great arteries, and then
translocation of the vessels to the
opposite root similar to the ASO
procedure performed for D-TGA
requiring coronary artery transfer.

83. • Relocation of the pulmonary trunk may be achieved by transposing the
pulmonary arteries anterior to the reconstructed aorta, or they may be left in
posterior position.
• In general, if the aorta is more or less anterior to the pulmonary trunk, then
the pulmonary arteries are relocated anteriorly.
• If the arterial trunks are more side-by-side, then we leave the pulmonary
arteries behind the newly reconstructed aorta.
• At the end of the procedure, it is important to check on the reconstruction
using transoesphageal or epicardial echocardiography, confirming the
patency of the venous and arterial pathways as well as ensuring adequate
ventricular function

84. • After a DS procedure, normal concordance is established with systemic
deoxygenated blood baffled across the tricuspid valve into the morphologic
right ventricle and flow into the pulmonary artery.
• In addition, the oxygenated pulmonary venous return is baffled from the
left atrium across the mitral valve into the morphologic left ventricle and
then pumped across the neo-aorta to the systemic circulation

85. • This operation is a technically difficult and challenging procedure with a
long cardiopulmonary bypass time.
• Therefore, identifying the ideal surgical timing is a complex issue.
• Various centers report a median age at the time of surgery that ranges from
7 months to 3.2 years and a median weight of 9.6 to 14.7 kg.
• Early hospital mortality is reported to range from 0 to 7.4 percent, and
reported event-free survival rates are between 70 to 85 percent at 10 years .
• In addition, coronary artery transfer is required. As a result, in patients
undergoing this surgical intervention, delineating the coronary anatomy is
mandatory.

86. • Senning-Rastelli procedure —
• In patients with L-TGA that have a VSD and LV outflow tract
obstruction, the Senning-Rastelli (SR) procedure is typically used.
• In this intervention, the intra-atrial baffle (Senning tunnel) is created and a
baffle is placed in VSD so that the blood from the LV is directed into the
aorta, and a conduit is placed between the right ventricle and pulmonary
artery (Rastelli procedure).
• The Rastelli procedure requires a sizable and appropriately located VSD so
that the baffle can be placed to redirect blood flow into the aorta.
• The intermediate-term results show improved survival of this group
compared with the patients undergoing a double switch operation same
used for D-TGA, VSD, and LV outflow tract obstruction.
• Long-term, conduits become stenotic as they do not grow as the child
grows. As a result, patients who undergo a Senning-Rastelli procedure
require serial conduit replacements.

87. • Ventricular Rerouting Combined
with Atrial Redirection
• The atrial switch is performed in the
same manor as for the double-
switch procedure
• An incision is made in the
morphologically right
ventricle, permitting creation of an
intraventricular tunnel between the
ventricular septal defect and the
aorta.
• In creating this tunnel, care has to
be taken to avoid any subaortic
stenosis.
• The repair is completed by placing
a valved conduit from the right
ventriculotomy to the pulmonary
arteries.

88. • Outcome and complications — Because these procedures were initially
introduced in the 1990s, there are limited long-term outcome data.
Nevertheless, several case series have provided information regarding
mortality and morbidity.
• Mortality —
• The following case series demonstrate comparable mortality rates to that
seen with conventional repair. It remains to be seen if long-term survival
improves
• In a large case series of 113 patients from an English pediatric cardiac
surgical center of patients undergoing anatomic repair from 1991 to
2011, actuarial survivals at 1, 5, and 10 years were 88, 84, and 84 percent
in the DS group (n = 68), and 92, 92, and 77 percent in the SR group (n =
45), respectively .
• Early deaths occurred in five patients in the DS group, and no patients in
the SR group

89. • Morbidity —
• The complications associated with anatomic correction in patients with L-
TGA are primarily due to conduction abnormalities (ie, complete heart
block and arrhythmias), left ventricular dysfunction, and neo-aortic
regurgitation.
• In addition, some of the baffle-associated complications seen in patients
with D-TGA who undergo ASO repair may also occur in patients with L-
TGA who undergo DS operation.

90. • Conduction abnormalities —
• New onset complete heart block and atrial arrhythmias are common
complications postoperatively .
• In the previously mentioned English case series of 113 patients.
• After anatomic correction, pacemaker insertion was required in 10 of the
68 patients who underwent DS and in 5 of the 45 patients with SR
procedure. In this cohort, tachyarrhythmias were observed in four patients
preoperatively and developed in four patients postoperatively (three in the
DS group and one in the SR group).

91. • Left ventricular dysfunction — .
• Morphologic LV dysfunction -reported in 14 to 18 percent of patients .
• Due to the small numbers of patients, it is currently difficult to determine
with certainty the underlying cause or risk factors of postoperative LV
dysfunction.
• In the previously mentioned English case series, 16 of the 113 patients (14
percent) developed LV dysfunction postoperatively, all of whom were in
the DS group .

92. • Neo-aortic regurgitation —
• Patients who have undergone DS appear to be at greater risk for neo-aortic
regurgitation than patients who have undergone SR procedure.
• In the case series from England, 70 percent of patients after DS repair had
at least mild aortic insufficiency (AI) at follow-up, including six patients
with severe AI requing AVR.

93. • Risk factors for neo-aortic root dilation were previous pulmonary arterial
banding and ASO performed in a later era
• A change in surgical technique is a likely explanation for the association
between surgery in a more recent era with neo-aortic root dilation, possibly
related to the increased size of the coronary ―buttons‖ taken for the
translocation.
• In this current era, pulmonary arterial banding is very rare as complete
repairs are typically performed in the first week of life, thereby reducing
the frequency neo-aortic regurgitation.

94. • Coronary artery stenosis or insufficiency
• The incidence of coronary events continues to be bimodal with the majority
of events (89 percent) occurring in the first three months following the
ASO .
• These tend to be related to ―kinking‖ or other anatomic obstructions to
coronary perfusion. Unexplained ventricular dysfunction or poor
hemodynamics should prompt early evaluation of the coronaries in the
postoperative setting.
• Risk factors for the development of coronary events include type of
coronary anatomy (presence of a single coronary orifice ) and the
occurrence of a major intraoperative event (coronary translocation
difficulty, left ventricular dysfunction, cardiac arrest, or temporary
mechanical support at the end of the intervention).

95. • Baffle-associated complications —
• Although there are limited reports of baffle-associated complications in
patients with L-TGA undergoing anatomic repair, they have been reported
frequently in adult patients undergoing D-TGA surgical repair
• Obstruction at the right atrial and superior vena caval junction is a
recognized complication of the Mustard procedure. The clinical
presentation may include chylothorax, upper extremity edema, or facial
plethora.
• Pulmonary venous obstruction is a complication more commonly
associated with the Senning procedure. Pulmonary venous congestion may
be an early manifestation. Progressive obstruction may be seen later and
may present with symptoms of reactive airway disease.

96. • Reintervention —
• Surgical reintervention is common in patients who undergo either a SR
procedure or DS operation as illustrated by the following findings from the
previously mentioned English case series :
• In the SR group (n = 45), 34 reinterventions were performed in 16 patients
including 14 right ventricular-pulmonary artery conduit changes or
ballooning.
• In the DS group (n = 68), 41 reinterventions were performed in 13 patients
including six aortic valve replacements, and surgical and catheter
reinterventions of the Senning pathway in 14 patients.

97. • FOLLOW-UP CARE —
• Longitudinal follow-up care is required in all patients with levo- or left-
transposition of the great arteries (L-TGA) by a cardiologist with expertise
in congenital heart disease.
• Clinicians need to know the potential complications following the various
surgical repairs and in unoperated patients.
• Follow-up routine care includes focused history, physical examination, and
detailed imaging study by echocardiography and/or magnetic resonance
imaging (MRI).

98. • History —:
• Episodes of syncope or palpitations that may suggest an underlying
arrhythmia or complete heart block
• Increasing exercise intolerance suggestive of declining systemic ventricular
function or increasing pulmonary artery obstruction
• Exertional chest pain may suggest coronary artery insufficiency.
• Edema of the face and upper extremities suggest superior venal caval
obstruction due to a baffle complication seen in the Senning procedure
• Dyspnea may suggest systemic atrioventricular (AV) valve regurgitation or
systemic ventricular dysfunction in the adult patient that is unoperated

99. • Physical examination —
• Vital signs, particularly the pulse, to determine any irregularity that
suggests an underlying arrhythmia
• Cardiac auscultation to detect any murmur (eg, pulmonary stenosis, aortic
or tricuspid insufficiency) or gallop (eg, failure)
• Examination for signs of cardiac failure including pulmonary
congestion, peripheral edema, and hepatomegaly

100. • Tests — Routine testing includes electrocardiography and
echocardiography.
• Electrocardiography (ECG) is performed yearly to detect and diagnose
arrhythmias. ECG is essential to look for complete heart block as there is a
2 percent annual risk for the development of complete heart block
• Holter or event recorder monitoring may be useful in patients with a
history suggestive of arrhythmia.
• Routine echocardiography is used to assess ventricular function, detect
pulmonary artery stenosis, and evaluate competency of the neo-aortic
valve. Evaluation of the systemic and pulmonary venous baffles can also be
performed with echocardiography.
• Angiography remains the preferred modality to diagnose coronary artery
occlusions in patients who undergo the arterial switch operation

101. • Cardiac magnetic resonance imaging is an excellent tool to quantify
ventricular function.
• It should be used when evaluating adults who have not undergone
repair, and can be used to accurately assess left ventricular thickness and
function in those patients who have undergone PA banding.
• This diagnostic modality is also helpful in identifying fibrosis and scar
formation.

102. • Endocarditis prophylaxis —
• Prophylactic antibiotics for endocarditis are recommended for patients
who have surgical repairs that include the use of prosthetic material
(eg, heart valve), prior episode of endocarditis, and those with high-risk
lesions for endocarditis (eg, unrepaired cyanotic heart disease or with a
residual defect such as a patch margin VSD).

103. • PREGNANCY —
• In general, women with a systemic ventricular ejection fraction that is less
than 40 percent and/or have a New York Heart functional class III and IV
should be counseled against pregnancy as the added volume load of
pregnancy is typically not well tolerated.
• In a one study of 22 women with L-TGA, 50 of the 60 pregnancies resulted
in live births including one preterm birth at 29 weeks gestation. None of the
infants had congenital heart disease.
• There were no pregnancy-related deaths but one woman developed heart
failure due to worsening systemic atrioventricular valve regurgitation.
• In addition, one woman with 12 pregnancies resulting in 10 live births
subsequently developed endocarditis and heart failure