DOI:10.2214/AJR.05.0636
AJR 2007; 188:W428-W430
© American Roentgen Ray Society
Congenitally Corrected Transposition of the Great Arteries: Imaging with 16-MDCT
Donald S. Chang1,2,
Bruce M. Barack2,3,
Margaret H. Lee2,4 and
Hsin-Yi Lee2,3
1 Division of Cardiology, VA Greater Los Angeles Healthcare System, 11301
Wilshire Blvd. (111E), Los Angeles, CA 90073.
2 David Geffen School of Medicine at UCLA, Los Angeles, CA.
3 Imaging Service, VA Greater Los Angeles Healthcare System, Los Angeles,
CA.
4 Department of Radiology, Olive View-UCLA Medical Center, Sylmar, CA.
Received April 13, 2005;
accepted after revision June 24, 2005.
Address correspondence to D. S. Chang
(dchang{at}ucla.edu).
WEB This is a Web exclusive article.
Keywords: angiography • cardiac imaging • cardiovascular disease • congenital • CT
Introduction
Congenitally corrected transposition of the great arteries is a rare
form of congenital heart disease. It is characterized by atrioventricular and
ventriculoarterial discordance and is associated with a variety of
intracardiac defects. We present a case of an adult with congenitally
corrected transposition imaged with noninvasive techniques.
Case Report
A 43-year-old man with the diagnosis of congenitally corrected
transposition of the great arteries presented with one-block exertional
dyspnea; increasing fatigue; and occasional sharp, fleeting chest pains. He
had an unremarkable childhood until the onset of palpitations when he was 10
years old. At 17 years, he began experiencing chest ache symptoms. At 18
years, he underwent cardiac catheterization and was diagnosed with
congenitally corrected transposition of the great arteries. No coronary artery
stenosis was found. He continued to experience occasional sharp, fleeting
chest pains, which were self-resolved. He was asymptomatic during heavy
physical activity while working as a roofer. Pertinent medical history
included polysubstance abuse with cocaine, methamphetamines, marijuana, and
alcohol. On physical examination, he was normotensive. He had a laterally
displaced cardiac impulse and a grade 3/6 holosystolic murmur heard over the
precordium. His carotid pulses were normal.
Chest radiography revealed a prominent left upper cardiac border on the
posteroanterior radiograph with an inapparent aortic knob and pulmonary trunk
(Fig. 1A). On transthoracic
echocardiography, there was atrioventricular and ventriculoarterial
discordance. The patient's morphologic right ventricle had an ejection
fraction of 40% with moderate regurgitation of the tricuspid (systemic) valve.
An echocardiographic four-chamber view
(Fig. 1B) showed the tricuspid
valve inserting closer to the apex when compared with the mitral valve, along
with a moderator band and thick trabeculations in the morphologic right
ventricle on the left side of the heart. There was no ventricular septal
defect and no valvular or subvalvular pulmonic stenosis.
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Fig. 1B —43-year-old man with congenitally corrected transposition of great
arteries. Four-chamber view from transthoracic echocardiography shows
tricuspid valve inserting closer to apex compared with mitral valve, along
with moderator band and thick trabeculations in morphologic right ventricle
(MRV) on left side of heart. RA = right atrium, LA = left atrium, MLV =
morphologic left ventricle.
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Cardiac MRI, MR angiography, and coronary CT angiography were performed to
further evaluate cardiac morphology, cardiac function, and coronary anatomy,
respectively, given the patient's symptoms. Cardiac MRI was performed on a
1.5-T unit (Magnetom Sonata, Siemens Medical Solutions) with a phased-array
torso coil and corroborated the findings on echocardiography. A representative
coronal MR angiography examination (Fig.
1C) revealed an inverted aorta and anatomic right ventricular
outflow tract forming the left upper cardiac border. Coronary CT angiography
was performed with a 16-MDCT scanner (Aquilion 16, Toshiba Medical Systems)
with a retrospective ECG-gated protocol (section width, 0.5 mm; rotation time,
400 milliseconds; tube voltage, 120 kV; and tube current, 350 mA) after IV
administration of a nonionic contrast medium. Reconstructed images were then
processed on a separate workstation (Vitrea 2, Vital Images).
Maximum-intensity-projection (MIP) and 3D volume-rendered images were obtained
(Figs. 1D,
1E and
1F).
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Fig. 1C —43-year-old man with congenitally corrected transposition of great
arteries. Coronal MR angiography image shows that left upper cardiac border is
formed by inverted aorta and anatomic right ventricular outflow tract.
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Fig. 1D —43-year-old man with congenitally corrected transposition of great
arteries. Axial CT maximum-intensity-projection (MIP) image shows anterior,
right-sided aortic sinus giving rise to anterior descending coronary artery
(arrowhead), which courses along anterior interventricular groove
supplying morphologic left ventricle. Posterior aortic sinus gives rise to
right coronary artery (arrow), which courses along posterior
atrioventricular groove between left atrium and morphologic right ventricle
and, in turn, gives rise to infundibular and marginal branches supplying
morphologic right ventricle. LCC = left coronary cusp, RCC = right coronary
cusp, star = morphologic right ventricular outflow tract.
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Fig. 1E —43-year-old man with congenitally corrected transposition of great
arteries. Axial CT MIP image shows four chambers of heart. RA = right atrium,
LA = left atrium, MRV = morphologic right ventricle, MLV = morphologic left
ventricle. Of note, moderator bandlike structure in morphologic left ventricle
most likely represents anomalous papillary muscle.
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Fig. 1F —43-year-old man with congenitally corrected transposition of great
arteries. Three-dimensional volume-rendered image shows spatial relationship
of great arteries with ascending aorta anterior and to left of main pulmonary
artery. Anterior descending artery (short arrow) and circumflex
artery (arrowhead) arise from common left ventricular coronary artery
off of anterior aortic sinus. Right coronary artery (long arrow)
arises from posterior aortic sinus.
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Coronary CT angiography and MRI confirmed the diagnosis of congenitally
corrected transposition of the great arteries. Levocardia, atrial situs
solitus, and coronary-ventricular concordance were well shown.
The ascending aorta was anterior and to the left of the main pulmonary
artery. The noncoronary cusp was anterior and to the left of both the left and
right coronary cusps, which faced the right ventricular outflow tract. The
left coronary cusp was anterior to the right coronary cusp
(Fig. 1D). The left main
coronary artery arose from the left coronary cusp and divided into its two
characteristic branches, the anterior descending and circumflex coronary
arteries (Figs. 1D and
1F). The anterior descending
artery coursed in the anterior interventricular groove and supplied the
morphologic left ventricle, demonstrating coronary-ventricular concordance
(Fig. 1F). The circumflex
artery coursed in the anterior atrioventricular groove in the position
occupied by the right coronary artery in the normal heart.
The right coronary artery arose from the right coronary cusp and supplied
the infundibulum and the anterior, lateral, and posterior walls of the
morphologic right (systemic) ventricle. The right coronary artery continued in
the posterior atrioventricular groove, in the position occupied by the
circumflex branch of the left coronary artery in the normal heart, just
proximal to the crux. It gave rise to the posterior descending branch, which
coursed in the inferior interventricular groove. Thus, coronary-ventricular
concordance was again confirmed, and right coronary dominance was shown. The
size of the right coronary artery and its major branches was unusually large
in comparison with the dominant right coronary artery system in the normal
heart.
Discussion
Congenitally corrected transposition of the great arteries occurs in less
than 1% of all forms of congenital heart disease
[1]. The most common associated
intracardiac defects are ventricular septal defect and pulmonic stenosis
[2,
3]. Other associated lesions
include pulmonary atresia, tricuspid (systemic) valve regurgitation,
Ebsteinlike anomaly of the tricuspid valve, atrial septal defect, and
coarctation of the aorta [3].
There is a male predominance in patients who have significant associated
intracardiac defects [2]. Late
complications include systemic ventricular dysfunction, progressive systemic
atrioventricular valvular regurgitation, congestive heart failure, infective
endocarditis, and conduction abnormalities such as complete heart block,
Wolff-Parkinson-White syndrome, and supraventricular tachyarrhythmias such as
atrial fibrillation and atrial flutter
[1,
2,
4].
Complete heart block can develop at a rate of 2% per year
[1]. Patients undiagnosed until
adulthood usually have no associated anomalies and present due to an abnormal
chest radiograph or ECG. These patients are asymptomatic until right
ventricular dysfunction, tricuspid regurgitation, or complete heart block
develops. No treatment is required for patients with corrected transposition
who have no other defects because their life expectancy has been reported to
be near normal [5]. In our
case, no other significant intracardiac abnormalities were found and no
significant coronary artery stenosis was revealed by coronary CT angiography.
The right ventricular dysfunction is most likely due to the effect of systemic
pressures on the morphologic right ventricle along with tricuspid
regurgitation. Polysubstance abuse may also be a contributing factor.
Three main anatomic types of corrected transposition of the great arteries
have been described by Van Praagh and colleagues
[6]. Our patient has the S, L,
L type with situs solitus of the viscera and atria, L-loop ventricles, and
L-transposition of the great arteries. Embryologically, the ventral limb of
the left interventricular sulcus on the primary heart tube gives rise to a
left-sided crista supraventricularis, which determines, in part, the right
ventricular morphology of the left-sided ventricle. The dorsal limb spirals
toward the atrioventricular canal, giving rise to a malpositioned
interventricular septum, and displaces the embryonic right ventricle to the
left [7]. According to this
embryological explanation, the morphologic noncoronary cusp, usually posterior
and to the right, now rotates 120° clockwise to lie anterior and to the
left. Similarly, the left and right coronary cusps rotate 120° clockwise.
The formation of the coronary system occurs relatively late in cardiac
development before joining the aorta. After the positioning of the ventricles
has taken place, the coronary system forms by a complex vasculogenic pathway
and then joins the aorta.
The right ventricular muscle mass in a congenitally corrected transposition
of the great arteries is significantly increased in comparison with the right
ventricular muscle mass in the normal heart because it is subjected to
systemic pressures. This increased systemic pressure results in an increased
right ventricular workload, necessitating an increase in oxygen delivery. The
large size of the right coronary artery in our case may be explained as the
mechanism by which coronary blood flow is increased to supply the increased
oxygen demand.
The variation in coronary artery anomalies in congenitally corrected
transposition of the great arteries reported in the literature has been
ascribed to the rarity of this disorder and the subsequent small number of
patients in each reported series
[8]. Knowledge of the
presurgical coronary anatomy is important if an atrial and arterial switch
operation is contemplated because coronary anomalies are occasionally present
[9]. The coronary arteries
usually course to their respective ventricles. Significant coronary artery
abnormalities may affect the surgical approach, with unexpected anatomy being
associated with higher morbidity and mortality rates
[8].
During cardiac catheterization, there is a risk of inducing transient or
permanent complete heart block because the atrioventricular conduction system
originates from an anterosuperior communicating atrioventricular node, which
passes to the right of and anterior to the pulmonary valve, in the direct path
of a catheter during a right heart catheterization, with the conduction system
lying just below the pulmonic valve
[6]. A noninvasive imaging
method of determining coronary anomalies and their origin, course, and
distribution that could potentially supplant cardiac catheterization is
therefore highly desirable.
The newer noninvasive imaging techniques provide a safer method of
investigating congenital anomalies and also result in improved spatial
orientation of the vessels and chambers of the heart.
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Introduction
Case Report
