Congenitally Corrected Transposition Of Great Arteries (CC TGA)

DR.NILESH TAWADEJHRC MUMBAI

HISTORY OF CC TGA • More than century before Karl von Rokintansky applied the term

‘’corrected’’ for undescribed form of transposition of great arteries.

• End of 18 th century MATHEW BAILLE described a ‘singular malformation’

characterized by discordant origin of arterial trunks from the ventricular

mass

• 1957 – ANDERSON and co workers described the clinical manifestation of

the Rokintansky’s singular malformation

• And 4 yrs later SCHIEBER and co workers changed the term “corrected”

to “congenitally corrected” to clarify that correction was a gift of GOD and

not a gift of the surgeon

THE TERMS TO DEFINE

• Transposition- discordant origin of arterial trunks from the ventricular mass . Ao

from morpho Rt ventricle and PA from morpho Lt ventricle.

• D –loop – normal right word bend in developing straight heart tube of embryo ;

indicates that the sinus or inflow portion of morpho Rt ventricle is on right side of

morpho Lt ventricle

• L –loop- the sinus or inflow portion of the morpho Rt ventricle is to left of

morpho Lt ventricle

• Discordant loop – An L loop in situs solitus and D –loop in situs inversus

• Ventricular inversion – Atrioventricular discordance with Ventriculoarterial

concordance. Morpho Rt atrium is aligned with Lt ventricle from which aorta

arises and morpho Lt atrium aligned with Rt ventricle that gives rise to pulmonary

trunk.

TERMS TO DEFINE

Criss-cross hearts –

Atrioventricular connections are

not parallel (as in normal hearts )

but are angulated as much as 90 5.

It results from abnormal rotation of

ventricular mass around its long

axis and resulting in the

relationship that could not be

inferred from the inflow tracts.

Criss –cross hearts

CC TGA• It typically occurs in situs solitus (5 %

situs inversus )

• Prevalence 0.5 % of clinically diagnosed cardiac malformations and 1 in 13,000 live births

• Congenitally corrected transposition is characterized by chambers that are joined discordantly at Atrioventricular junction and ventricles that are joined discordantly at ventriculo- great arterial junction.

• This double discordance – AV and VA – physiologically corrects the discordance intrinsic to each.

EMBRYOLOGICAL BASIS • When the heart tube bends to the left in situs solitus , the

morphological right ventricle lies on left of morphological

left ventricle

• Ventriculo arterial discordance is less well defined on

embryological basis .

• Some researchers thoughts that developmental fault at

infundibular segment and some argues that fault lies at

arterial segment.

PHYSIOLOGICAL CONSEQUENCES • Depends on the functional adequacy of sub aortic morphological

right ventricle and co-existing mal formations.

• The thick walled sub aortic Rt ventricle is supplied by the concordant RCA which is designed to perfuse the thin walled low resistance right ventricle.

• So this inverted right ventricle has high prevalence of myocardial perfusion defects and abnormalities of regional wall motion.

• Ejection Fraction is considerably less than that of the normal sub

aortic left ventricle

• VSD , PS , abnormalities of left AV valve has considerable impact on the functioning of the inadequate inverted right ventricle .

Associated abnormalities • CC -TGA with no associated abnormalities are in fact the exception as 90 %

cases has abnormalities. Most common includes VSD , left ventricular

outflow tract obstruction and anomalies of left sided AV valve.

• VSD 80 % of necropsy cases , non restrictive perimembranous type due to

mal-alignment of atrial and ventricular septum Sub -arterial and muscular defects are unusual

• Pulmonary outflow obstruction 30-50% of cases , tissue tags are most common cause of obstruction ,

these tags are derived from membranous septum or mitral or pulmonary valve itself .

Obstruction is associated with large VSD in 80% of cases and without VSD IN remaining 20%.

Associated abnormalities • Abnormalities of left AV (tricuspid ) valve-

90% cases has anatomically abnormal valve but fairly

functions well in early life but age related increase in

regurgitation is seen.

Most common and important anatomical abnormality is

dysplasia of valve with or without of EBSTEIN’S like

anomaly and sometimes valve is stenotic.

Sometimes left and right AV valve can be straddling the

ventricular septum and it is important to identify them

preoperatively

Coronary artery pattern - Coronary artery and ventricular concordance

Coronaries shows mirror image distribution.

Both Coronaries arises from posterior sinuses and anterior one is non coronary

Largest pathological study from 56 specimen reported 76% incidence of relatively ‘normal’ pattern with the right and left coronaries originating from left and right facing sinuses respectively ..

RT SIDED COORONARY

ARTERY BIFURCATES IN TO

CIRCUMFLEX AND

ANTERIOR DESCENDING

BRANCHES

IT HAS MORPHOLOGY

LIKE LEFT CORONARY

ARTERY .

LEFT SIDED

CORONARY runs into

left AV grove and gives

marginal and

infundibular branches.

it has a morphology

like RCA

coronary anomalies

are common in CC -TGA

e.g especially like single

coronary artery

CLINICAL FEATURES • HISTORY –

M :F =1.5:1

It shows monogenic transmission as it occurs in the first degree relatives

Isolated CC-TGA has asymptomatic childhood but clinical problems starts arising in adulthood

If symptoms occurs in infanthood may be due to bradycardia reflecting high degree AV block, tachyarrhythmia, cyanosis and or CHF.

CHF due to large VSD or severe regurgitation in AV valve so clinical features suggestive of mitral regurgitation in neonate should prompt consideration of CC-TGA.

Older child may be referred to a pediatric for loud second heart sound in suspicion of pulmonary hypertension.(as aorta is placed left and anterior to)

CLINICAL FEATURES

• Patients may have angina pectoris which is attributed to a supply –

demand imbalance between a thick walled systemic right ventricle

and its blood supply from a morphological right coronary artery .

• Myocardial perfusion defects are prevalent due to this.

• VSD that accompanies CC TGA is typically non restrictive with

clinical course analogous to normally formed heart.

CLINICAL FEATURES • PHYSICAL EXAMINATION

Retarded Growth and Development are seen with large Ventricular Septal Defects and Congestive Heart Failure .

Cyanosis and Clubbing appear when pulmonary stenosis or pulmonary vascular disease with reversal of shunt of VSD.

• ARTERIAL PULSEWave form is normal , rate reflects bradycardia.

• JVPProlonged PR interval is recognized by an increase in the

interval between jugular A wave and carotid pulse and CHB may be identified by random cannon A waves

Precordial Movement And Palpation• Precordial movement is

influenced by ventricular septum which is vertical and facing forward.

• Rt ventricle forms the apex laterally and medial border is adjacent to left sternum

• so right ventricular impulse is accentuated with large AV regurg

• Left ventricle is behind the sternum so not palpated even in presence of PAH OR PS

• AORTIC component of second heart sound is palpated because of anterior position

STERNUM

AUSCULTATION• FIRST SOUND – soft due to prolonged PR

• SECOND SOUND –loud due to aortic valve is anterior mistaken for PAH.

• VSD- produces holosystoloic or decrescendo murmur in fourth LISC. May be associated with MDM left AV valve.

• Left AV valve regurg -generates systolic murmur analogous to MR and it radiates to left sternal edge rather than to axilla.

• murmur of PS is heard mid left sternal edge rather than at second LISC .

ELECTROCARDIOGRAM• Due to misaligned atrial and ventricular septum AV node and its connections

are different in CC TGA.

• Anomalous Anterior AV node is present with long bundle that penetrates fibrous annulus and descends into the anterior aspect of the ventricular septum

• This long bundle is well formed in young children but in beginning of adolescence this bundle starts replacing with fibrous tissue

• RBB and LBB are concordant with ventricles

• EBSTEINS malformation is associated with left sided accessory pathway that provides substrate for pre excitation .

ELECTROCARDIOGRAM• The P wave

Is normal in direction and configuration but broad notched P waves may be seen when left AV valve is regurgitant or large VSD with L R SHUNT.

• AV BLOCK- More than 75% pts exhibits varying degree of heart blocks

from PR prolongation to CHB, even in same pt block varies from time to time

CHB associated with narrow QRS complex duration.

ELECTROCARDIOGRAM• QRS complex

Activation of septum is in reverse direction as that of normal heart so Q wave will appear in right Precordial leads and will be absent in left Precordial leads even in presence of volume overload of systemic ventricle.

Left axis deviation is diagnostically important ; cause of this is abnormal location of AV NODE and its connection with ventricular conduction system .

• T wave In more than 80% of cases T waves are positive in all six Precordial

leads a distinctive feature attributed to the side by side relation ship of the inverted ventricle

ELECTROCARDIOGRAM

Absence of Q waves

Upright T waves

8 yr old boy with CCTGA large non restrictive VSD with left to right shunt

Broad notched P waves

Chest XRAY

• Narrow vascular pedicle

• ‘HUMP SHAPED’ appearance of

left cardiac silhouette of right

ventricle due to inverted

infundibulum.

• ‘Septal notch’ – which is subtle

indentation just above the

diaphragm corresponding to

inter-ventricular groove

ECHO CARDIOGRAPHY

• Echo examination of pt with complex AV AND VA connection

should begin with defining situs in abdomen .

• Sub costal views are important in identification of a case of CC TGA.

• First clue for presence of AV Discordance is Significant

malalignment between the atrial and ventricular septum.

• Look for features of right and left morphologic ventricles

• Short axis view at the level of aortic and pulmonary valves is very

useful in defining the anatomical position of aorta and pulmonary

artery.

ECHOCARDIOGRAPHY• LEFT VENTRICLE

Ovoid or ellipsoid shaped Fine Trabeculations AV valve that inserts into the

ventricular septum proximally than contra lateral valve

Bicommisural valve with fish mouth appearance

paired papillary muscle and chordae tendineae that inserts into free wall of LV

Continuity between AV valve and great artery

• RIGHT VENTRICLE Crescent shaped Coarse Trabeculations Distal insertion of AV valve

into the septum

Tricommissural valve

Multiple irregular papillary muscle with chordal attachment to ventricular septum

Discontinuity between AV valve and great artery

Surgical Care• Surgery is recommended only for symptomatic associated lesions and

when significant hemodynamic benefit is expected.• The altered location of a fragile conduction system and the mirror image

coronary anatomy may complicate surgical repair,• Ventricular septal defect closure is generally performed when symptoms of

CHF or failure to thrive do not respond to medical therapy or when pulmonary vascular pressures are increasing.

• Tricuspid valve replacement can be performed for severe tricuspid incompetence as repair of the dysplastic or displaced valve is not usually feasible.

• The atrial and ventricular double switch procedure is performed when significant pulmonic stenosis and a large ventricular septal defect are present.

• Feasibility of the repair depends on the location of the ventricular septal defect

• The atrial switch for L-transposition takes the form of the Senning or

Mustard procedure with additional repair of any ventricular septal

defect. The arterial switch operation is the most current procedure

available, generally performed within 2 weeks of birth

• In a study of 52 patients reported by Termignon et al, the operative

mortality rate of a classic repair of congenitally corrected

transposition of the great arteries and ventricular septal defect was

16% and the rate of complete heart block was 24% after the repair.

• Survival rates were 83% at 1 year and 55% at 5 years after the

repair

SUMMARY• Congenitally corrected transposition of the great arteries

without coexisting malformations is uncommon and initially can go unrecognized.

• The clinical picture is dominated by pathophysiology of associated cardiac anomalies.

• Ventricular septal defects are typically nonrestrictive and perimembranous and are analogous to comparable defects in hearts without ventricular inversion.

• Pulmonary stenosis regulates the left-to-right shunt through a ventricular septal defect.

• Long term follow up of conventional surgical approach is disappointing and has led to novel surgical approaches aimed at restoring AV and VA connections.