D-TGA Dr. Tahsin.N TRANSPOSITION Abnormal origin of the

D-TGA Dr. Tahsin.N TRANSPOSITION  Abnormal origin of the

D-TGA Dr. Tahsin.N TRANSPOSITION Abnormal origin of the Aorta and Pulmonary Artery from the ventricular complex Atrioventricular concordance with ventriculo-arterial discordance

Abnormal spatial relationship of the great arteries Results in two circulations in parallel Incidence & Prevalence 5% to 7% of all congenital cardiac malformations The incidence is reported to range from 20.1 to 30.5/100,000 live births

strong (60%70%) male preponderance Embryology Embryology 1. Spiral aortico-pulmonary septum forms but does not spiral or twist during its partitioning of the truncus arteriosus

a. Aorta arises from right ventricle b. Pulmonary trunk arises from the left ventricle 2. Result is two closed circuits a. Systemic unoxygenated repeatedly re-circulated b. Pulmonary - oxygenated - repeatedly re-circulated Embryology

The normal conus is subpulmonary, left-sided and anterior ; it prevents fibrous continuity between the pulmonary and tricuspid valve rings. In TGA, the infundibulum is usually subaortic, right-sided and anterior; it prevents fibrous continuity between the aortic and tricuspid valve rings and further results in abnormal pulmonary to mitral valve ring fibrous continuity.

Anatomy The common clinical type - situs solitus of the atria, concordant AV and discordant ventriculoarterial alignments complete TGA. TGA {S,D,D} - TGA with situs solitus (S) of the atria and viscera, usual (D) looping of the ventricles and an anterior and rightward (D) aorta.

Anatomy- Great artery relationship Situs solitus and intact ventricular septum - the aortic root is directly anterior or anterior and to the right of the pulmonary trunk in a slightly oblique relationship

Less commonly, the aorta may be positioned anterior and to the left or, rarely, posterior and to the right of the pulmonary trunk. Coronary Anatomy The two aortic sinuses of Valsalva adjacent to the aorticopulmonary septum that face the pulmonary artery contain the ostia of the coronary arteries in more than 99% of

cases Coronary anatomy Usual-66.9 CX from RCA-16.1 Single RCA-3.9 Single LCA-1.7 Inverted-2.4

Intramural LCA-2.1 Other-1.6 SA node artery Origin and proximal course of artery may be variable; reaches the sinus node by the interatrial groove on the anterior surface of the heart, occasionally with an intramyocardial course in the anterosuperior rim of the fossa ovalis.

It can be damaged easily during balloon atrial septostomy, during surgical septectomy or when this portion of the septum is widely excised as in the Mustard or Senning atrial switch operation. Anatomy - Coexisting Anomalies Nearly half of the hearts have no other anomaly except a PFO or a PDA.

The VSD is the most frequent coexisting anomaly-40% to 45%. - perimembranous (conoventricular 33%) - AV canal (inlet septum 5%) - muscular (27%) - malalignment (30%) - conal septal hypoplasia type (5%)

VSD The subaortic stenosis caused by the anterior malalignment of the infundibular septum is frequently associated with aortic arch hypoplasia, coarctation or even complete interruption of the aortic arch Posterior (leftward) malalignment is associated with varying degrees of LVOTOsubpulmonary stenosis, annular hypoplasia

or even pulmonary valvar atresia Subpulmonary Stenosis 25% [5%] Fixed -Circumferrential fibrous membrane /diaphragm - Fibromuscular ridge - Herniating tricuspid leaflet tissue - Anomalous MV septal attachments

- Tissue tags from membranous septum Dynamic-associated with SAM Subaortic Obstruction Rightward and anterior displacement of the infundibular septum Associated aortic arch anomalies

- hypoplasia - coarctation - interruption Asso. RV hypoplasia & tricuspid valve anomalies TV anomalies Nearly 31% Functionally imp 4%

Ratio of tricuspid to mitral anulus circumference is less than 1 in almost 50% of cases, whereas in normal hearts this ratio is always greater than 1 TV anomalies Straddling/overriding of chordae Overriding of the tricuspid annulus

Abnormal chordal atatchments Dysplasia Accessory tissue Double orifice MV anomalies Nearly 20% Functionally imp 4%

Cleft anterior mitral valve leaflet anomalous papillary muscles and chordae Straddling redundant tissue tags Juxtaposition of atrial appendages Both appendages or left + part of right are adjacent

2-6% Left > right -6x Female preponderance often additionally associated with major cardiac pathology, including dextrocardia, VSD, bilateral infundibulum, right ventricular hypoplasia and tricuspid stenosis or atresia. Imp in BAS

Bronchopulmonary Collateral Circulation Bronchopulmonary anastomotic channels > 30% of infants with TGA under 2 years of age Persistence of a significant bronchopulmonary collateral circulation after surgical repair - large enough left-to-right shunt CCF - warrant catheter embolization PBF

50% of the patients - greater proportion of blood flow to the right lung than normal due to rightward alignment of MPA associated with some degree of hypoplasia of the left pulmonary arterial vessels and is further manifested in the occasional reports of unilateral, always left-sided, pulmonary vein stenosis or hypoplasia.

PBF Postnatal Physiology of TGA Determinants of effective gas exchange Effective ventilation Effective Pulmonary circulation Pulmonary blood flow

Pulmonary vascular resistance Existence of a communication between pulmonary and systemic circuits Persistent fetal channel PFO or DA Abnormal channels ASD, VSD Effective delivery of oxygenated blood to the tissues Definition of shunts

Anatomical shunts Left to Right: Blood flowing from left sided chambers to the right sided chambers Right to Left: Blood flowing from right sided chambers to the left sided chambers

Definition of shunts Physiological shunts Left to right: The volume of oxygenated pulmonary venous return recirculated to pulmonary circulation (Qp Qep) Right to left shunt: The volume of systemic venous return that contributes to cardiac output (reentering the systemic circulation) without having passed through the pulmonary

circulation (Qs Qep) Definition of shunts Effective pulmonary blood flow (Qep): The volume of systemic venous return that is effectively oxygenated in the lungs Effective systemic blood flow (Qes):

The volume of oxygenated pulmonary venous return that enters the systemic circulation and perfuses the systemic capillary bed TGA: Atrial and Ventricular level shunts From LA to RA / LV to RV Anatomically left to right Physiologically, this

volume of oxygenated blood enters systemic circulation. Hence, they contribute to Qes = Effective Systemic Blood Flow

TGA: Atrial and Ventricular level shunts = Effective PBF From RA to LA/ RV to LV Anatomically, right to left shunt

Physiologically, this volume of systemic venous blood enters pulmonary circulation. Hence they contribute to Qep Recirculating

Oxy Blood Recirculating systemic blood TGA: Shunt at PDA level Aorta to PA flow:

Anatomically it is left to right Here the deoxygenated systemic venous blood enters pulmonary circulation. Hence, this volume contributes to Qep PA to Aorta flow: Anatomically it is right to left Here the oxygenated blood enters systemic circulation. Hence, this volume contributes to Qes Thus, the flow across the ductus is functionally opposite to that of

flow across ASD or VSD in TGA Systemic venous Pulmonar y venous return

return Anat R-L RIGHT Anat

L-R LEFT HEART HEART

Physi o R-L Physi o L-R BODY

LUNGS Unique feature Net inter-circulatory mixing volume is constant: net R-L, L-R, Qep and Qes are equal to each other Any major difference in the volumes would result in depletion of blood volume of one circulation at the expense of

overloading the other circulation Precise factors controlling intercirculatory exchange SPECULATIVE, MULTIPLE LOCAL PRESSURE GRADIENTS

Compliance of the cardiac chambers Phase of respiratory cycle Vascular resistances Heart rate

Volume of blood flow Flow across the communications Rules of the Heart With only ASD, the flow has to be bidirectional If the flow is only or predominantly left to right across the ASD, it suggests presence of additional shunt (VSD or PDA) Unrestrictive VSD - flow is bidirectional Except in the initial few days, PDA flow is always left to right

(Ao to PA). Presence of right to left flow across ductus may suggest the presence of coarctation of aorta Right to Left Shunt Systole

VSD Left to Right Shunt Diastole PDA Initially, bidirectional flow across the ductus Later, once the PVR falls, the flow essentially becomes aorta

to PA The pulmonary circulation becomes overloaded fast, especially if the PFO is restrictive Factors influencing systemic saturation Extent of inter-circulatory mixing and Total pulmonary blood flow High PBF results in increased oxygenated blood available in

the left sided chambers for mixing: higher systemic SO2 if there is good mixing Reduced PBF will result in low systemic SO2 in spite of adequate anatomic shunts Factors influencing systemic saturation If there is delay in the fall of PVR (PPHN), hypoxemia will persist despite adequate ASD

Need ECMO or urgent ASO Hypoxemia provokes a fall in SVR and increase the recirculating systemic volume Fall in SVR may deplete the pulmonary circulation further Role of bronchopulmonary collaterals Systemic arterial hypoxemia may stimulate development of bronchpulmonary collaterals

Usually in TGA with solely a restrictive inter-atrial communication Prolonged survival of such infants may be due to this extracardiac site of shunting/mixing History M:F 4:1;unless juxtaposition of atrial appendages Usually in multigravida-2X increase in > 3 pregnancies Familial recurrence-monogenic inheritance

Cyanosis As early as day 1 in pts with IVS(1st hr-56%;1st day-90%) More intense if associated PS/atresia Mild if associated non restrictive VSD PS often responsible for hypercyanotic spells-intense cyanosis, tachypnea, extreme irritability and hypothermia Squatting is rare

Reverse differrential cyanosis CHF In patients with a large PDA Large VSD Mortality 1st week-30%

1st month-50% 1st year-90% Depends on the degree of shunting Moderate PS improves survival Predilection for brain abscess but rare < 2 years Appearance Birth weight greater than normal

Reverse differential cyanosis Varicosities of scalp and arms Arterial Pulse Bounding pulse - due to large volume of highly unsaturated blood - Not due to PDA-since only systolic shunt from aorta to PA Diminished femoral pulses

- CoA - Subaortic stenosis-anterior and rightward displacement of septum Palpation Nomal in neonates RV impulse in patients with CHF LV impulse non restrictive VSD with low PVR

Palpable S2 A2 Auscultation Loud A2 LV S3-mildly cyanosed patients,increased PBF,LV failure RV S3-deeply cyanosed patients, increased systemic flow, RV failure

Auscultation Ejection click-pulmonary;does not decrease with inspiration Aortic-subaortic stenosisdilated aortic root MSM-aortic:hypervolemic and hyperkinetic circulation Pulmonary: valvular- after few weeks of birth, progressively increases Subvalvar dynamic obstruction-3rd LICS and radiates to the right

Auscultation VSD: absentholosystolicshortensabolished PDA: Systolic if large PDA since high PVR curtails diastolic flow Continuous if restrictive PDA Continuous murmurs may arise in large systemic arterial collaterals but rare

MDM may be heard across AV valves ECG Normal in first few days of life RAE-increased pressure(CHF)/volume (hypervolemic systemic circulation) LAE-large ASD,increased PBF RAD-occurs when LV volume overload is curtailed by

pulmonary vascular disease or PS ECG RVH - NR VSD +high PVR/PS BVH - NR VSD + low PVR

Right precordial T waves not inverted but rather distinctly taller than the left sided T waves CXR Absent thymic shadow after 12 hours of life Narrow vascular pedicle bcoz - AP orientation of great vessels Right aoric arch -11-16%

Egg on side appearance Juxtaposition-localised bulge along the mid left cardiac border which represents contiguous mass of the 2 appendages together PBF & Heart size inversely proportional ECHO

Diagnosis Detection & quantitation of shunt

Detection of outfow obstructions Asso anomalies Coronary Anatomy Post op Detection of Complications Cardiac catheterization in TGA Fallacies in application of Ficks Principle in

calculating shunts and flows in TGA Oxygen consumption is not normal, so assumed values are unreliable Arteriovenous oxygen differences may be very small, so magnitudes of errors in calculated values would be very large. Effect / contribution of Bronchopulmonary collaterals to PBF can result in overestimation.

TGA and PVOD Changes in Pulmonary Vascular Resistance Accelerated PVD is common With unrestrictive VSD, Grade 3 or 4 changes seen in 20% before 2 months and in 80% by 1 year Without VSD or PDA, it is seen in 6%, progression is slower than with VSD

The number of intra acinar pulmonary arteries are also shown to be decreased In TGA/ASD, regression of PVR occurs as in simple ASD but subsequently PVOD may develop rapidly. Reduced saturation shear stress

Increased hematocrit Increased PVOD Bronchial artery collaterals bring poorly saturated blood to pulmonary vessels

Short MPA Metabolism in TGA physiology Oxygen demands are high while delivery and uptake is poor at baseline Metabolic acidemia, lactic acidosis HYPOTHERMIA can KILL EXAGGERATING TISSUE HYPOXIA AND METABOLIC ACIDEMIA

Hypoglycemia Hyperinsulinemia Management Definitive Repair at three levels: the atrial level : Senning or Mustard Sx

ventricular level : Rastelli operation great artery level : arterial switch operation or Jatene operation Damus-Kaye-Stansel operation in conjunction with the Rastelli operation can be used in patients with VSD and subaortic stenosis Lecompte Operation-VSD+subpulmonary stenosis

Arterial switch operation (Jatene operation) Advantages physiologic correction fewer long-term complications Arrhythmias RV dysfunction baffle stenosis tricuspid regurgitation (TR).

Arterial switch operation (or Jatene operation) Pre requisite An LV that can support the systemic circulation after surgery The LV pressure should be near systemic levels at the time of surgery, or the switch should be performed shortly after birth (i.e., before 2 weeks of age).

In patients whose LV pressure is low, it can be raised by PA banding, either with or without a shunt, for 7 to 10 days (in cases of a rapid, two-stage switch operation) or for 5 to 9 months before undertaking the switch operation. LV pressure >85% and LV posterior wall thickness >4.5 mm appear to be satisfactory. Pre-op Coronary artery pattern amenable to transfer to the neoaorta

without distortion or kinking. Risk is high when the left main or LAD coronary artery passes anteriorly between the aorta and the PA. Pre-op The left ventricular inflow and outflow tracts must be free of significant structural abnormality. The right ventricular outflow tract should be free of significant

stenosis. Anatomic variants that may impact operative mortality include

An intramural course of a coronary artery A retropulmonary course of the left coronary artery Multiple VSDs Coexisting abnormalities of the aortic Straddling AV valves

Longer duration of global myocardial ischemic (cross-clamp) prolonged circulatory arrest times Complications PA stenosis at the site of reconstruction - 5% to 10% complete heart block - 5% to 10%. Aortic regurgitation (AR) late complication > 20% of patients especially PA banding

An important cause of AR may be unequal size of the pulmonary cusps that leads to eccentric coaptation Coronary artery obstruction myocardial ischemia, infarction, and even death. Atrial level Surgery Mustard operation: This oldest surgical technique redirects the

pulmonary and systemic venous return at the atrial level by using either a pericardial or a prosthetic baffle. Senning operation: This is a modification of the Mustard operation. It uses the atrial septal flap and the RA free wall to redirect the pulmonary and systemic venous return Complications

a.Obstruction to the pulmonary venous return (<5% of all cases) b.Obstruction to the systemic venous return (<5% of all cases) c.Residual intra-atrial baffle shunt (=20% of all cases) d.Tricuspid valve regurgitation (rare) e.Absence of sinus rhythm (>50% of all cases) and frequent supraventricular arrhythmias f.Depressed RV (i.e., systemic ventricular) function during exercise g.Sudden death attributable to arrhythmias (3% of survivors)

h.Pulmonary vascular obstructive disease Rastelli operation In patients with VSD and severe PS The LV is directed to the aorta by creating an intraventricular tunnel between the VSD and the aortic valve. A conduit is placed between the RV and the PA

Rastelli operation Complications conduit obstruction (especially in those containing porcine heterograft valves) complete heart block (rarely occurs). This conduit needs to be replaced as the child grows.

Medical Prostaglandin E1 infusion should be started to improve arterial oxygen saturation by reopening the ductus. This should be continued throughout the cardiac catheterization and until the time of surgery. Oxygen should be administered for severe hypoxia. Oxygen may help lower pulmonary vascular resistance and increase PBF, resulting in increased systemic arterial oxygen saturation.

Role of PGE1 in TGA Considerable benefit in first few days till PVR is elevated, especially if PFO is small Enables bidirectional shunting, improves mixing If valve of FO is competent, it would result in increased LA pressure and pulmonary edema Atrial Septostomy

Before surgery, cardiac catheterization and a balloon atrial septostomy (i.e., the Rashkind procedure) are often carried out to have some flexibility in planning surgery. a balloon-tipped catheter is advanced into the left atrium (LA) through the PFO. The balloon is inflated with diluted radiopaque dye and abruptly with-drawn to the right atrium (RA) under fluoroscopic or echo monitoring.

Atrial Septostomy For older infants and those for whom the initial balloon atrial septostomy was only temporarily successful, blade atrial septostomy may be performed. Following this, the balloon procedure can be repeated for a better result.

Pulmonary Artery Banding Transposition associated with large VSD without LVOTO To prevent Heart failure Pulmonary vascular disease Present Indications Presence of complex/multiple VSDs Coexisting medical conditions that cause a delay in surgery

To train LV before switch in TGA/IVS Systemic-Pulmonary Anastomosis TGA/VSD and severe LVOTO Operative mortality - as low as 5%. Reassessment of pulmonary vascular resistance D-TGA (Complete Transposition of Severe cyanosis in a large

newborn great arteries) Male preponderance (3:1)

Single S2 Signs of CHF ()

Usually no heart murmur Egg-shaped heart with narrow waist (on x-ray film)

ECG: Normal or RVH THANK U

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