AUTHOR AND EDITOR INFORMATION

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• Medication
• Follow-up
• Miscellaneous
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INTRODUCTION

Section 2 of 11  

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• Introduction
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• Medication
• Follow-up
• Miscellaneous
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Background

Transposition of the great arteries (TGA) is the most common cyanotic congenital heart lesion that presents in neonates. The hallmark of TGA is ventriculoarterial discordance, in which the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle.

Although TGA was first described over 2 centuries ago, no treatment was available until the middle of the 20th century, with the development of surgical atrial septectomy in the 1950s and balloon atrial septostomy in the 1960s. These palliative therapies were followed by physiological procedures (atrial switch operation) and anatomic repair (arterial switch operation). Today, the survival rate for infants with TGA is greater than 90%.

The major anatomic classifications of TGA depend on the relationship of the great arteries to each other and/or the infundibular morphology. In approximately 60% of the patients, the aorta is anterior and to the right of the pulmonary artery (dextro-TGA [d-TGA]). However in a subset of patients, the aorta may be anterior and to the left of the pulmonary artery (levo-TGA [l-TGA]). In addition, most patients with TGA (regardless of the spacial orientation of the great arteries) have a subaortic infundibulum, an absence of subpulmonary infundibulum, and fibrous continuity between the mitral valve and the pulmonary valve. Despite these useful classifications, several exceptions are noted, and, hence, discordant ventriculoarterial connection is the only distinguishing characteristic that defines TGA.

From a practical standpoint, the presence or absence of associated cardiac anomalies defines the clinical presentation and surgical management of a patient with TGA. The primary anatomic subtypes are (1) TGA with intact ventricular septum, (2) TGA with ventricular septal defect, (3) TGA with ventricular septal defect and left ventricular outflow tract obstruction, and (4) TGA with ventricular septal defect and pulmonary vascular obstructive disease.

In approximately one third of patients with TGA, the coronary artery anatomy is abnormal, with a left circumflex coronary arising from the right coronary artery (22%), a single right coronary artery (9.5%), a single left coronary artery (3%), or inverted origin of the coronary arteries (3%) representing the most common variants.

Pathophysiology

The pulmonary and systemic circulations function in parallel, rather than in series. Oxygenated pulmonary venous blood returns to the left atrium and left ventricle but is recirculated to the pulmonary vascular bed via the abnormal pulmonary arterial connection to the left ventricle. Deoxygenated systemic venous blood returns to the right atrium and right ventricle where it is subsequently pumped to the systemic circulation, effectively bypassing the lungs. This parallel circulatory arrangement results in a deficient oxygen supply to the tissues and an excessive right and left ventricular workload. It is incompatible with prolonged survival unless mixing of oxygenated and deoxygenated blood occurs at some anatomic level.

The following are 3 common anatomic sites for mixing of oxygenated and deoxygenated blood in TGA:

• Atrial septal defect
• Ventricular septal defect
• Patent ductus arteriosus

One or all of these lesions can be present in concert with d-TGA, and the degree of arterial hypoxemia depends on the degree of anatomic mixing.

Frequency

United States

Despite its overall low prevalence, TGA is the most common etiology for cyanotic congenital heart disease in the newborn. This lesion presents in 5-7% of all patients with congenital heart disease. The overall annual incidence is 20-30 per 100,000 live births, and inheritance is multifactorial. TGA is isolated in 90% of patients and is rarely associated with syndromes or extracardiac malformations. This congenital heart defect is more common in infants of diabetic mothers.

Mortality/Morbidity

• The mortality rate in untreated patients is approximately 30% in the first week, 50% in the first month, and 90% by the end of the first year. With improved diagnostic, medical, and surgical techniques, the overall short-term and midterm survival rate exceeds 90%.
• Long-term complications are secondary to prolonged cyanosis and include polycythemia and hyperviscosity syndrome. These patients may develop headache, decreased exercise tolerance, and stroke.
• Thrombocytopenia is common in patients with cyanotic congenital heart disease leading to bleeding complications.
• Patients with a large ventricular septal defect, a patent ductus arteriosus, or both may have an early predilection for congestive heart failure, as pulmonary vascular resistance falls with increasing age. Heart failure may be mitigated in those patients with left ventricular outflow tract (pulmonary) stenosis.
• A small percentage (approximately 5%) of patients with TGA (and often a ventricular septal defect) develop accelerated pulmonary vascular obstructive disease and progressive cyanosis despite surgical repair or palliation. Long-term survival in this subgroup is particularly poor.

Race

No racial predilection is known.

Sex

TGA has a 60-70% male predominance.

Age

Patients with TGA usually present with cyanosis in the newborn period, but clinical manifestations and courses are influenced predominantly by the degree of intercirculatory mixing.

CLINICAL

Section 3 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

• Infants with transposition of the great arteries (TGA) are usually born at term, with cyanosis apparent within hours of birth.
• The clinical course and manifestations depend on the extent of intercirculatory mixing and the presence of associated anatomic lesions.
• • TGA with intact ventricular septum: Prominent and progressive cyanosis within the first 24 hours of life is the usual finding in infants.
  • TGA with large ventricular septal defect
  • • Infants may not initially manifest symptoms of heart disease, although mild cyanosis (particularly when crying) is often noted.
    • Signs of congestive heart failure (tachypnea, tachycardia, diaphoresis, and failure to gain weight) may become evident over the first 3-6 weeks as pulmonary blood flow increases.
  • TGA with ventricular septal defect and left ventricular outflow tract obstruction
  • • Infants often present with extreme cyanosis at birth, proportional to the degree of left ventricular (pulmonary) outflow tract obstruction.
    • The clinical history may be similar to that of an infant with tetralogy of Fallot.
  • TGA with ventricular septal defect and pulmonary vascular obstructive disease
  • • Progressively advancing pulmonary vascular obstructive disease can prevent this rare subgroup of patients from developing symptoms of congestive heart failure, despite a large ventricular septal defect.
    • Most often, patients present with progressive cyanosis, despite an early successful palliative procedure.

Physical

Newborns with TGA are usually well developed, without dysmorphic features. Physical findings at presentation depend on the presence of associated lesions.

• TGA with intact ventricular septum
• • Infants typically present with progressive central (perioral and periorbital) cyanosis.
  • Other than cyanosis, the physical examination is often unremarkable.
• TGA with large ventricular septal defect
• • Cyanosis may be mild initially, although it is usually more apparent with stress or crying.
  • Upon presentation, infants often have an increased right ventricular impulse, a prominent grade 3-4/6 holosystolic murmur, third heart sound, mid-diastolic rumble, and a gallop rhythm.
  • Hepatomegaly may be present.
• TGA with ventricular septal defect and left ventricular outflow tract obstruction
• • Cyanosis is prominent at birth, and the findings are similar to those of infants with tetralogy of Fallot.
  • A single, or narrowly split, diminished second heart sound and a grade 2-3/6 systolic ejection murmur may be present.
  • Hepatomegaly is rare.
• TGA with ventricular septal defect and pulmonary vascular obstructive disease
• • Progressive pulmonary vascular obstructive disease is not always evident from physical examination.
  • Cyanosis is usually present and can progress despite palliative therapy in the newborn period.
  • No murmur (despite the ventricular septal defect) or early short systolic ejection sounds are heard.
  • The second heart sound is often single, with increased intensity.
  • In later childhood or adolescence, a high-pitched, blowing, early decrescendo diastolic murmur of pulmonary insufficiency and a blowing apical murmur of mitral insufficiency are evident.

Causes

• Etiology for TGA is unknown and is presumed to be multifactorial.
• Embryology likely involves abnormal persistence of the subaortic conus with resorption or underdevelopment of the subpulmonary conus (infundibulum). This abnormality aligns the aorta anterior and superior with the right ventricle during development.

DIFFERENTIALS

Section 4 of 11  

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• Multimedia
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Other Problems to be Considered

Double-outlet right ventricle with malposed great arteries

WORKUP

Section 5 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Hyperoxia test (for cyanotic congenital heart disease)
• • In a patient with arterial hypoxemia, an arterial blood gas measurement is obtained on 100% oxygen for 10 minutes.
  • Pulmonary disease (not cyanotic congenital heart disease) is suspected if the partial pressure of oxygen increases to greater than 150 mm Hg with oxygen.

Imaging Studies

• Chest radiography
• • The chest radiograph may appear normal in newborns with transposition of the great arteries (TGA) and intact ventricular septum but may demonstrate the classic "egg on a string" appearance in approximately one third of patients.
  • With a ventricular septal defect, cardiomegaly usually occurs with increased pulmonary arterial vascular markings.
• Echocardiography
• • Echocardiographic images should be diagnostic of TGA by demonstrating the bifurcating pulmonary artery arising posteriorly from the left ventricle in the parasternal long-axis view.
  • The parasternal short-axis view shows the relationship of the great arteries to one another. The aorta is usually anterior and rightward of the pulmonary artery in cross-section.
  • Most associated anatomic lesions, including atrial septal defects, ventricular septal defects, and patent ductus arteriosus, are also diagnosed readily by echocardiography.
  • The coronary artery anatomy needs to be ascertained and may be abnormal in nearly one third of patients. The coronary artery origins and branching pattern are often delineated by echocardiography.

Procedures

• Cardiac catheterization
• • Diagnostic cardiac catheterization is usually reserved for the subgroup of patients for whom echocardiography does not adequately delineate the anatomy. Suspected coronary artery abnormalities and additional ventricular septal defects may be confirmed or better delineated by cardiac catheterization with angiography. In addition, cardiac catheterization may be necessary to improve left-to-right shunting.
  • Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.
  • Complications may include rupture of blood vessel, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.

TREATMENT

Section 6 of 11  

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Medical Care

• Initial treatment consists of maintaining ductal patency with continuous intravenous (IV) prostaglandin E₁ infusion to promote pulmonary blood flow, increase left atrial pressure, and promote left-to-right intercirculatory mixing at the atrial level. This is particularly important in patients with severe left ventricular outflow tract stenosis or atresia. Prostaglandin therapy may or may not benefit the patient with simple transposition of the great arteries (TGA) and an intact ventricular septum without left ventricular outflow tract obstruction.
• Cardiac catheterization, depending on the degree of restriction at the atrial septum and the timing of operative repair, is indicated for a balloon atrial septostomy in severely hypoxemic patients with an inadequate atrial level communication and insufficient mixing. The balloon atrial septostomy is used to increase the atrial level shunt and to improve mixing.
• For the ill neonate, metabolic acidosis should be corrected with fluid replacement and bicarbonate administration.
• Mechanical ventilation may be necessary if pulmonary edema develops in concert with severe hypoxemia.
• Ultimately, the patient requires surgical repair or palliation early in life.

Surgical Care

• Surgical approach depends on the age of the patient at presentation, the presence of associated congenital cardiac lesions, and the experience of the cardiothoracic surgeon with a given surgical technique. Most full-term neonates with uncomplicated TGA can undergo an arterial switch procedure in one operation, with minimal mortality.
• TGA with intact ventricular septum
• • The ideal operation is an arterial switch procedure.
  • • It represents an anatomic repair and establishes ventriculoarterial concordance.
    • This procedure should be performed when the infant is younger than 4 weeks, as the left ventricle may not be able to handle systemic pressure postoperatively if left too long in the low-pressure, low-resistance pulmonary circuit.
  • Rarely, however, depending on the particular coronary artery anatomy (eg, intramural coronary artery), coronary artery translocation may not be feasible, and an arterial switch is not recommended. In this subgroup, an atrial level switch (Senning or Mustard procedure) has lower surgical and short-term morbidity and mortality.
• TGA with ventricular septal defect
• • The preferred operation is an arterial switch procedure with ventricular septal defect closure.
  • If the ventricular septal defect is large and nonrestrictive and coronary artery anatomy makes an arterial switch operation inadvisable, a Rastelli-type intracardiac repair may be feasible.
  • With the Rastelli-type procedure, it may be preferable to wait until the infant is older and larger because of the need for a right ventricle–pulmonary artery conduit in the Rastelli operation.
  • If the infant has excessive congestive heart failure (with growth failure), it may be advisable to either proceed with reparative surgery or, if not feasible, band/ligate the main pulmonary artery and place an aortopulmonary shunt during the newborn period to restrict pulmonary blood flow.
• TGA with ventricular septal defect and left ventricular outflow tract obstruction
• • An arterial switch operation may not be feasible due to pulmonary (left ventricular outflow tract) stenosis or atresia.
  • If the ventricular septal defect is nonrestrictive and not too remote from the aorta, a Rastelli intracardiac repair could be possible.
  • Because the Rastelli procedure necessitates a conduit from the right ventricle to the pulmonary artery, delaying repair until the infant is older and larger may be preferable. In this case, placing an aortopulmonary shunt during the newborn period may be necessary to establish adequate pulmonary blood flow while waiting.
• TGA with ventricular septal defect and pulmonary vascular obstructive disease
• • These patients might not be appropriate surgical candidates because of the progressive increase in pulmonary vascular resistance.
  • This is a small subgroup of patients whose conditions are not often diagnosed until after a palliative or reparative procedure is performed.

Consultations

• Pediatric cardiologist
• Pediatric cardiothoracic surgeon

Diet

• Patients with TGA and a large ventricular septal defect who have not undergone repair may require increased caloric density during infancy (120-130 kcal/kg/d), particularly if they have significant congestive heart failure and poor weight gain.
• Following definitive repair, most patients do not need a special diet.

Activity

• No specific activity requirements are necessary.

MEDICATION

Section 7 of 11  

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Transposition of the great arteries (TGA) has no specific or recommended drug therapies. Newborn infants with TGA (particularly those with severe left ventricular outflow tract obstruction) may derive some initial benefit from alprostadil (ie, prostaglandin E₁) therapy. Patients with TGA and ventricular septal defect who have not undergone surgical repair, and some patients following complete repair, might potentially benefit from digoxin and diuretic therapy to improve systemic ventricular function and avoid fluid retention. All patients require antibiotic prophylaxis prior to dental and indicated surgical procedures in order to reduce the risk of subacute bacterial endocarditis. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.

Drug Category: Inotropic agents

These drugs increase the contractility of cardiac muscle in a dose-dependent manner (ie, positive inotropic effect).

Drug Category: Loop diuretics

These drugs inhibit electrolyte reabsorption in the thick ascending limb of the loop of Henle, thus promoting diuresis.

Drug Category: Prostaglandins

Temporary maintenance of patency of ductus arteriosus in neonates with ductal-dependent congenital heart disease.

FOLLOW-UP

Section 8 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

• Admit for preoperative testing and surgical interventions.
• Carefully monitor medication doses and side effects.
• Monitor adequacy of repair and palliation with periodic physical examinations and possibly echocardiograms.
• Periodic electrocardiograms and/or 24-hour Holter monitoring to monitor for atrial arrhythmias should be employed, particularly following atrial-level switch operation (ie, Senning or Mustard procedure).
• Controversy surrounds whether patients should undergo cardiac catheterization every few years following arterial switch operation because of the concern for long-term patency and normal function of the coronary arteries following surgical translocation. No specific recommendations for routine cardiac catheterization will be possible until more information is available, and treatment of coronary artery stenosis is still a matter of debate.

Further Outpatient Care

Evidence from the Boston Circulatory Arrest Trial suggests that neurodevelopmental outcomes for children with dextro transposition of the great arteries (d-TGA) who undergo arterial switch operation (and other complex neonatal operations) may not be normal and may require further investigation and follow-up.¹

In/Out Patient Meds

• Many patients do not require any specific medications. Possible discharge medications might include digoxin, furosemide, or both.
• All patients require preoperative and postoperative antibiotic prophylaxis for dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa. Antibiotic prophylaxis is also recommended for invasive respiratory tract procedures that involve incision or biopsy of the respiratory mucosa (eg, tonsillectomy, adenoidectomy). Antibiotic prophylaxis is not recommended for bronchoscopy unless the procedure involves incision of the respiratory tract mucosa. For invasive respiratory tract procedures to treat an established infection (eg, drainage of abscess, empyema), administer an antibiotic active against Streptococcus viridans. See the endocarditis prophylaxis guidelines that were recently revised by the American Heart Association (AHA) in the Medication section.²

Transfer

• Transfer may be required for specialized diagnostic, therapeutic, and surgical interventions.

Complications

• Congestive heart failure
• Arrhythmia
• Eisenmenger syndrome (irreversible and progressive pulmonary vascular obstructive disease)

Prognosis

• Prognosis depends on the specific anatomic substrate and type of surgical therapy employed (arterial switch operation, atrial switch operation, or Rastelli procedure).
• The overall survival rate following arterial switch operation is 90%.
• The overall mortality rate following an atrial level switch is low; however, long-term morbidity associated with systemic (right) ventricular dilatation and failure, systemic atrioventricular (tricuspid) valve regurgitation, and atrial bradyarrhythmias and tachyarrhythmias is significant.

Patient Education

• Family members should learn cardiopulmonary resuscitation (CPR).
• Educate family members about congenital heart disease.
• Obtain genetics counseling for future pregnancy, despite the relatively low risk of recurrence.
• For excellent patient education resources, visit eMedicine's Heart Center. Also, see eMedicine's patient education article Tetralogy of Fallot.

MISCELLANEOUS

Section 9 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to consider the diagnosis, particularly in a cyanotic newborn
• Failure to adequately delineate coronary artery anatomy preoperatively
• Failure to appropriately interpret diagnostic information, including echocardiography, x-rays, and oxygenation studies
• Complications of surgery, including death

MULTIMEDIA

Section 10 of 11  

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• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  This 2-dimensional echocardiogram (parasternal long-axis view) shows a patient with transposition of the great arteries and ventricular septal defect. The pulmonary artery arises from the posterior (left) ventricular, dives posteriorly, and bifurcates immediately into left and right branch pulmonary arteries. A large ventricular septal defect is present in the outlet septum.
	View Full Size Image
Media type:  Echo

Media file 2:  This 2-dimensional echocardiogram (apical 4-chamber view) shows a patient with transposition of the great arteries and ventricular septal defect. The anterior aorta arises from the right-sided right ventricle.
	View Full Size Image
Media type:  Echo

Media file 3:  This right ventricular angiogram shows a patient with transposition of the great arteries. The aorta arises directly from the right-sided anterior right ventricle (10° left anterior oblique [LAO]).
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Media type:  Angiogram

Media file 4:  This right ventricular angiogram shows a patient with transposition of the great arteries. The aorta arises directly from the right-sided anterior right ventricle (70° left anterior oblique [LAO]).
	View Full Size Image
Media type:  Angiogram

Media file 5:  This left ventricular angiogram shows a patient with transposition of the great arteries. The pulmonary artery arises directly from the left-sided posterior left ventricle (30° right anterior oblique [RAO]).
	View Full Size Image
Media type:  Angiogram

Media file 6:  This left ventricular angiogram shows a patient with transposition of the great arteries. The pulmonary artery arises directly from the left-sided posterior left ventricle (20° cranial).
	View Full Size Image
Media type:  Angiogram

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

1. Wypij D, Newburger JW, Rappaport LA, et al. The effect of duration of deep hypothermic circulatory arrest in infant heart surgery on late neurodevelopment: the Boston Circulatory Arrest Trial. J Thorac Cardiovasc Surg. Nov 2003;126(5):1397-403. [Medline].
2. Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. J Am Dent Assoc. Jun 2007;138(6):739-45, 747-60. [Medline]. [Full Text].
3. Aseervatham R, Pohlner P. A clinical comparison of arterial and atrial repairs for transposition of the great arteries: early and midterm survival and functional results. Aust N Z J Surg. Mar 1998;68(3):206-8. [Medline].
4. Horer J, Schreiber C, Dworak E, et al. Long-term results after the Rastelli repair for transposition of the great arteries. Ann Thorac Surg. Jun 2007;83(6):2169-75. [Medline].
5. Kampmann C, Kuroczynski W, Trubel H, et al. Late results after PTCA for coronary stenosis after the arterial switch procedure for transposition of the great arteries. Ann Thorac Surg. Nov 2005;80(5):1641-6. [Medline].
6. Kirjavainen M, Happonen JM, Louhimo I. Late results of Senning operation. J Thorac Cardiovasc Surg. Mar 1999;117(3):488-95. [Medline].
7. Neches WH, Park SC, Ettedgui, JA. Transposition of the great arteries. In: The Science and Practice of Pediatric Cardiology. Vol 1. 1998:1463-1503.
8. Paul MH, Wernovsky G. Transposition of the great arteries. In: Moss and Adams Heart Disease in Infants, Children, and Adolescents. Vol 2. 1995:1154-1224.
9. Pedra SR, Pedra CA, Abizaid AA, et al. Intracoronary ultrasound assessment late after the arterial switch operation for transposition of the great arteries. J Am Coll Cardiol. Jun 21 2005;45(12):2061-8. [Medline].
10. Planche C, Lacour-Gayet F, Serraf A. Arterial switch. Pediatr Cardiol. Jul-Aug 1998;19(4):297-307. [Medline].
11. Puley G, Siu S, Connelly M, et al. Arrhythmia and survival in patients >18 years of age after the mustard procedure for complete transposition of the great arteries. Am J Cardiol. Apr 1 1999;83(7):1080-4. [Medline].
12. Soongswang J, Adatia I, Newman C, et al. Mortality in potential arterial switch candidates with transposition of the great arteries. J Am Coll Cardiol. Sep 1998;32(3):753-7. [Medline].
13. Takeuchi D, Nakanishi T, Tomimatsu H, Nakazawa M. Evaluation of Right Ventricular Performance Long After the Atrial Switch Operation for Transposition of the Great Arteries Using the Doppler Tei Index. Pediatr Cardiol. Aug 17 2005;[Medline].
14. Wren C, Birrell G, Hawthorne G. Cardiovascular malformations in infants of diabetic mothers. Heart. Oct 2003;89(10):1217-20. [Medline].

Article Last Updated: Oct 19, 2007