Transposition of the Great Arteries

Francesca N. Delling, MDJanuary 11, 2009

Cardiac Tube

Complete Transposition of the Great Arteries

Ventriculoarterial discordance

Also known as d-TGA (d = dextroposition of the bulboventricular loop)

Aorta on the right and anterior

Complete Transposition of the Great Arteries

Systemic and pulmonary circulation run in parallel need for a communication between the two - ASD, VSD (most common), or PDA to support life

One of the most common cyanotic defects in the newborns

If circulatory mixing via PDA, its physiological closure abrupt cyanosis and deterioration need for Rashkind atrial balloon septostomy until definite surgery

Atrial switch procedures

Senning (1958): atrial baffle from autologous tissue to direct the venous return to the contralateral AV valve and ventricle

Atrial switch procedures Mustard: atrial septum is excised, baffle is created with synthetic material

Late complications of atrial switch procedures:Arrhythmias

Late development of both brady and tachyarrhythmias

Sinus node dysfunction common in adults

Series of 534 children by Gelatt et al (J Am Coll Cardiol.1997;29:194-201) - NSR in 77% at 5 years, 40% at 20 years - 11% needed PPM - 14% had atrial flutter - 16% had a late death (due to arrhythmias and myocardial failure)

Ventricular arrhythmias uncommon in the absence of severe ventricular dysfunction

Late complications of atrial switch procedures:Systemic Ventricular dysfunction and TR

RV is the systemic ventricle

TR secondary to annular dilatation (TVR not indicated) or damage at the time of VSD repair or endocarditis (TVR warranted)

Treatment of systemic ventricular dysfunction is challenging: - No convincing data of utility of ACE-inhibitors - Caution with the use of beta-blockers (AVB, bradycardia) - Two-stage repair surgery (pulmonary artery banding to “retrain” the LV, followed by baffle take-down and arterial switch) is extensive and LV failure occurs after pulmonary banding

Late complications of atrial switch procedures:Atrial baffle obstruction and leaks

Obstruction of SVC (with “SVC syndrome”) more common than IVC (hepatic congestion or cirrhosis). If significant stenosis, may need percutaneous balloon and stenting or even surgery

Pulmonary vein stenosis much less common but may cause PHTN

Late complications of atrial switch procedures:Pulmonary hypertension

Occurs in 7% of those who survive to adulthood

Cause unclear (in some cases: PV baffle obstruction)

Risk factors: age > 2, shunts at ventricular or great artery level before repair (Newfeld EA et al. Am J Cardiol.1974;34:539-543)

Comparison between atrial switch procedures

Senning better than Mustard 340 pts (124 Mustard vs. 215 Senning) Heart, 2004; 90:307-313

• Mortality– 82 deaths (24%)

» Senning showed trend to better mortality but not statistically significant

• Baffle Obstruction

– 15% - Mustard

– 1% - Senning

• Senning patients had better functional status

Atrial switch procedures and pregnancy

Pregnancy poses a significant volume load that may increase RV dimensions and is sometimes irreversible

Poses a definite risk of deterioration of functional class, even if pt is asymptomatic

Risk of congenital heart disease in the offspring, in the absence of a family history, is probably < 5% (Clarkson PM et al. J Am Coll Cardiol.1994;24:190-193)

Arterial switch procedure

Jatene 1976

Complications: coronary stenoses with sudden death or MI, RV outflow tract distortion, dilatation of neo-aortic root with AI

Used when d-TGA + large subaortic VSD and pulmonary stenosis

A patch directs blood from the LV through the VSD to the aorta (1)

PV is oversewn and a valved conduit is inserted from the RV to the PA to bypass the pulmonary stenosis (2)

Rastelli procedure

Advantages: LV functions as systemic ventricle

Disadvantages: - Conduit degeneration and stenosis, necessitating reoperation - Atrial and ventricular arrhythmias with sudden death - Possible RV and LV failure

Rastelli procedure (continued)

Echo: parasternal long-axis

Posterior pulmonary artery and anterior aorta aligned rather than in the usual crossing arrangement

Parasternal short-axis

Aorta is anterior and on the right

Parasternal short-axis base

4-chamber view

CMR: 4-chamber

LVOT

RV 2-chamber

Short axis

Congenitally corrected Transposition

RA enters the morphological LV PA, and left atrium communicates with morphological RV aorta

Congenitally corrected Transposition (continued)

Left-handed looping of the heart tube morphologic RV in levo-position AV discordance

Aortopulmonary septum fails to rotate 180 ventriculoarterial discordance (although blood flows in the normal directions, it passes through the “wrong” chamber)

Aorta anterior and to the left, great arteries may be side to side

Congenitally corrected Transposition (continued)

Because the TV always enters a morphological RV it too is on the left side in the systemic circulation and is termed systemic AV valve

AV concordance AV discordance

Associated anomalies

VSD (70%): if large (LR flow), pts present in infancy or childhood with congestive heart failure. Reversal of flow R L leads to desaturation

Pulmonary stenosis (40%), commonly subvalvular. Associated valvular PS also occurs

Abnormalities of the systemic (tricuspid) AV valve (90%) Ebstein’s anomaly: - apical displacement of valve BUT no “saillike” anterior leaflet

Congenitally corrected Transposition:

AV node and His have unusual position

Many have dual AV nodes

Conduction system is vulnerable to fibrosis 2% per year incidence of CHB

Conduction anomaliesCongenitally corrected Transposition:

Congenitally corrected Transposition:CXR

Levocardia Dextrocardia

Congenitally corrected Transposition:EKG

Ventriculuar excitation begins at the septal endocardium of the right sided LV

Congenitally corrected Transposition:Echocardiography

1. Hypertrophied RV on the left

2. Moderator Band

3. Apical attachment of the TV

Congenitally corrected Transposition:Echocardiography

Overriding great vessels

a. Aorta arises anteriorly and comes off the RV

b. PA arises posteriorly from the LV

Congenitally corrected Transposition:Echocardiography

anterior and leftward aorta

Congenitally corrected Transposition:

Cardiac cath: - hemodynamic assessment of associated anomalies- evaluation of systemic AV valve regurgitation and ventricular function

MRI: Defines ventricular function and volumes

Systemic ventricular failure and AV valve regurgitation

? Cause

Inherent vulnerability to failure- concordant coronary anatomy: morphological RV perfusedby single right coronary artery with limitations of perfusion-Acar et al. Heart 1999: 20 pts with L-TGA and ETT MIBI all 20 had perfusion defects at rest, 17 worsened with exercise

Controversy exists as to which comes first: AV valve regurgitation or ventricular failure

Systemic ventricular failure and AV valve regurgitation

PM implantation may precipitate deterioration in systemicventricular function and worsening of AV valve regurgitation

Congenitally corrected Transposition:Surgical repair

Two schools of thought:

– Classic approach – fix only the defects associated with the condition (VSD, systemic AV valve regurgitation)

– Newer approach is to restore the LV as the systemic ventricle (anatomical repair)

• Major advantage is drastically reduces risk of TR which is associated with RV failure and late sudden death

118 pt classical repair J Thorac Cardiovasc Surg 117 (1999), pp. 1190–

1203 – 15 % operative mortality

– 56% underwent reoperation within 20 yrs

– 48% survival rate at 20 years – CHF > 70%

Congenitally corrected Transposition:Classical repair

Congenitally corrected Transposition:Double switch operation

Venous Switch via Mustard or Senning

Great vessel Switch

Closure of VSD

Congenitally corrected TranspositionAnd VSD

A patch can be inserted to tunnel the LV flow into the aorta, and the morphological RV is connected to the pulmonary artery via conduit “Rastelli technique”

Before anatomic repair (either double switch or Rastelli) LV needs to be prepared to function as a

systemic ventricle pulmonary banding

Congenitally corrected Transposition:Anatomic repair

54 pt restoration of LV – J Thorac CV Surg. 2003;125:1229-41

– Early mortality 5.6 % (3 pts)

– Long term mortality:• 1 year – 94% survival

• 4 year – 90% survival

• 9 year – 90% Survival vs. Classic 60 – 83% (10 years)

Early mortality of 5% encouraging, but: - 7 pts with Rastelli needed repeat conduit, aortic valve replacementor transplantation.- Balloon angioplasty of baffle obstruction or pulmonary stenosis also needed

Need for re-intervention post anatomic repair confirmed by more recent paper by Sharma et al (J Thorac Cardiovasc Surg. 2009 Feb;137)

- 68 patients (31 Rastelli/atrial switch; 37 arterial switch/atrial rerouting)- early deaths, late re-operations, late deaths (LV dysfunction, tachyarrhytmias observed in both groups

Congenitally corrected Transposition:Anatomic repair

Pregnancy and C-TGA

Women with systemic EF <40% or significant systemic AVvalve regurgitation should be counseled against pregnancy

Series of Connolly et al ( J Am Coll Cardiol.1999;33:1962)

60 pregnancies 22 ♀ resulting in 50 live births (83%)• none of the offspring had congenital heart disease• no pregnancy related deaths • 1 woman with significant AV valve regurgitation • 1 had CHF

45 pregnancies 19 ♀ (Am J. Card. 1999;84:820-24)

• 27 live births; 12 miscarriages; 6 elective term

• 1 child with a congenital heart defect

• Mothers with 6 CV events–3 episodes of CHF

–2 Episodes of increasing cyanosis, one CVA

Antibiotic prophylaxis

Prophylaxis is reasonable in patients with CHD with the highest risk for adverse outcome from infective endocarditis

- patients with prosthetic valves- previous endocarditis- unrepaired and palliated CHD- repaired CHD within 6 months after the procedure- repaired CHD with residual defects at or adjacent to the site of a prosthetic patch or prosthetic device that inhibits endothelization

ACC/AHA guidelines for the management of adults with congenital heart disease. J Am Coll Cardiol. 2008 Dec 2;52(23):e1-121

References

Carole A. Warnes. Transposition of the great arteries. Circulation 2006;114:2699-2709.

Yale University School of Medicine. Congenital Heart Disease Echo Atlas. http://www.med.yale.edu/intmed/cardio/chd/

http://pediatriccardiology.uchicago.edu/MP/embryology/embryology.htm

Thank you