Practice Essentials
Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital heart defect in which the heart twists abnormally during fetal development and the ventricles are reversed. Patients and/or their parents/guardians should receive pregnancy counseling, [1] education regarding infective endocarditis prophylaxis, as well as counseling about moderate and not heavy exercise routines. [2]
See the image below.
Subcostal view of a 1-year-old child with L-transposition of the great arteries, valvular and subvalvular pulmonic stenosis, and a moderate outlet ventriculoseptal defect (VSD). Note the ventriculoarterial discordance. Note the posterior, rightward position of the pulmonary artery. [PA = pulmonary artery, LV = left ventricle, RV = right ventricle].
Signs and symptoms
Symptoms usually reflect associated cardiac anomalies. The most common presenting features include the following:
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bradycardia related to high-degree AV heart block
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a single loud second heart sound, which is often palpable to the left of the sternum, arising from the anteriorly positioned aortic valve
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heart murmur due to associated ventricular septal defect, pulmonic stenosis, or tricuspid regurgitation
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cyanosis (only if there is an associated cardiac defect, such as pulmonary atresia or ventricular septal defect)
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heart failure
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tachyarrhythmia
See Clinical Presentation for more detail.
Diagnosis
This condition is usually diagnosed later in childhood or in early adult life when patients present with complete heart block or heart failure due to right ventricular decompensation or systemic tricuspid valve regurgitation.
Diagnosis may require some or all of the following tests:
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Echocardiogram
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Chest radiography
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Transesophageal echocardiography
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Cardiac MRI
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Electrocardiography
Echocardiogram and cardiac MRI are most commonly used in the diagnosis of CCTGA.
See Workup for more detail.
Management
Medical care
There is little evidence that established medical treatment options for left ventricle dysfunction (ACE inhibitors, beta-blockers, nitrates) produce similar outcomes for systemic right ventricles. Caution should be used with administration of beta-blockers, as complete heart block may be precipitated in these patients with known conduction system abnormalities. Ultimately, patients with failing systemic ventricular function may best be served by cardiac transplantation.
Surgical care
For patients who need surgery, the type of operation will vary according to the associated defects. There are several options available including the following:
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Ventricular septal defect closure (VSD) and insertion of a tube (conduit) between the heart and the lungs
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Tricuspid valve replacement
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Switch procedures, including double switch and the Senning-Rastelli procedure
Early pacemaker placement is recommended in the setting of complete heart block either during or after surgical intervention, or if any significant associated defect, such as cardiomegaly, decreased right ventricular function, symptomatic bradycardia, or heart failure, is present.
See Treatment and Medication for more detail.
Pathophysiology
Congenitally corrected transposition of the great vessels is a rare congenital heart defect associated with multiple cardiac morphologic abnormalities and conduction defects.
During embryologic development, left-handed looping of the heart tube results in atrioventricular (AV) discordance, and the aortopulmonary septum fails to rotate 180°, resulting in ventriculoarterial discordance. Blood flows in an effective sequence, hence the name corrected; however, the right ventricle supports the systemic circulation in this disorder.
Venous blood returns from the body into the right atrium before passing through the mitral valve into a morphological left ventricle. Blood then enters the lungs via the pulmonic valve into the main pulmonary artery. Pulmonary venous blood returns to the left atrium and then passes through the tricuspid valve to the morphological right ventricle, exiting to the aorta via the aortic valve. The aorta is positioned anterior and to the left of the pulmonary artery. In effect, the ventricles are transposed.
Etiology
Causes and exposures associated with congenitally corrected transposition of the great arteries have not been identified clearly.
A substantial number of patients with congenital heart disease have a deletion of chromosome band 22q11. These deletions have been associated with abnormalities of the pulmonary arteries and aortic arch or its major branches regardless of the intracardiac anatomy. [3] Rarely, these deletions are found in patients with transposition of the great vessels. In one series, none of 45 patients with transposition had the deletion.
Epidemiology
United States data
Data from the Baltimore-Washington Infant Study supported the fact that congenitally corrected transposition is a rare disorder. [4] As many as 40 infants per 100,000 live births are affected by congenitally corrected transposition of the great vessels; this is fewer than 1% of all congenital heart defects.
International data
This disorder is reported in 0.5% of patients with congenital heart disease, and the literature reports fewer than 1000 cases. Most pediatric cardiologists have seen multiple cases of congenitally corrected transposition of the great vessels; however, the true prevalence of the malformation is not known.
Prognosis
Patient prognosis depends on AV conduction, arrhythmias, structural abnormalities, and degree of hemodynamic disturbance. [5]
Sudden death may be related to the onset of complete heart block or atrial or ventricular arrhythmias.
Right ventricular failure can develop over time. This may be related to coronary perfusion mismatch as the right ventricle is supplied by a single coronary artery. In addition, differences in right and left ventricular fiber orientation, geometry, and microscopic structural features may play a role in early failure of the right ventricle when functioning as the systemic ventricle. Poor prognostic indicators include cyanosis, polycythemia, pulmonary vascular obstructive disease, tricuspid regurgitation, younger age at surgery, larger preoperative shunt size, and lower right ventricular ejection fraction. A multicenter series of 182 patients with congenitally corrected transposition of the great arteries demonstrated that 25% of patients without associated cardiac lesions and 67% of patients with other cardiac abnormalities developed congestive heart failure by age 45. [6]
Morbidity/mortality
Note the following:
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Ten-year survival rate ranges from 64-83% from the time of diagnosis and is dependent on associated anomalies.
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Freedom [7] reported an operative mortality rate of 6% and a 15-year actuarial survival rate of 48% in a cohort of patients with congenitally corrected transposition of the great vessels at the Hospital for Sick Children in Toronto.
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A median age at death of 40 years has been reported in both patients who have undergone operation and those who have not.
Complications
Major postoperative residual complications include contractile dysfunction of the systemic right ventricle, progressive tricuspid (systemic AV) regurgitation, complete heart block, atrial or ventricular arrhythmias, and infective endocarditis. Patients may develop conduit or homograph dysfunction postoperatively.
Systemic AV valve regurgitation is well described after surgery even when the valve has not been directly manipulated.
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Subcostal view of a 1-year-old child with L-transposition of the great arteries, valvular and subvalvular pulmonic stenosis, and a moderate outlet ventriculoseptal defect (VSD). Note the ventriculoarterial discordance. Note the posterior, rightward position of the pulmonary artery. [PA = pulmonary artery, LV = left ventricle, RV = right ventricle].
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Apical image revealing atrioventricular discordance. Note the pulmonary venous return into the left atrium, with sequential flow through the tricuspid valve to the right ventricle. The right ventricle is systemic. [LA = left atrium, RA = right atrium, LV = left ventricle, RV = right ventricle].
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Post-Rastelli repair with left ventricle to aortic baffle through a ventriculoseptal defect (VSD) complicated by subaortic stenosis.
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This image demonstrates a calcified pulmonary homograft anterior and adjacent to the chest wall (right ventricle to pulmonary artery bifurcation) with significant homograft stenosis and prior pulmonary valvular endocarditis (same patient as in Image 3).
