Keywords
ALCAPA - congenital heart disease - giant left atrium
Introduction
Anomalous origin of the left coronary artery (ALCAPA) from the pulmonary artery is
a rare congenital anomaly with coronary steal and myocardial ischemia. The left ventricular
dilatation leads to mitral regurgitation (MR) causing left atrial enlargement. We
report a rare case of giant left atrium (LA) in an infant with ALCAPA-mediated secondary
MR, which has been hitherto unreported.
Case Report
A 5-month-old female infant presented to the pediatric outpatient clinic due to poor
weight gain and recurring lower respiratory tract infections. Clinical signs suggested
features of left ventricular dysfunction. Cardiomegaly with splayed carina was observed
on chest radiography suggesting left atrial enlargement. A transthoracic echocardiography
showed dilated left ventricle (LV) with hyperechoic papillary muscles and severe MR.
Subsequently retrospective electrocardiogram (ECG) gated computed tomography angiography
(CTA) was performed, and images were reconstructed at 43% (best systole) and 74% (best
diastole) of the cardiac cycle. CTA done for anatomic delineation revealed ([Fig. 1]) an ALCAPA, a giant LA (measuring 51 mm × 49 mm) and dilated LV (measuring 45 mm
at the mid-cavity level in end diastole). The enlarged LA was seen splaying the inferior
vena cava and right atrium confluence with anterior displacement of the right atrium
([Fig. 2]). No other cardiovascular anomalies were detected. No significant intercoronary
collaterals were seen.
Fig. 1 (A–C) Computed tomography (CT) angiographic images show normal origin of right coronary
artery (RCA; black arrow) with aorta (Ao) and anomalous origin of the left coronary artery (LCA; white arrows) from the main pulmonary artery (MPA). LA, left atrium; LV, left ventricle.
Fig. 2 (A, B) Cinematic rendered computed tomography (CT) images show giant left atrium (LA) with
anterior displacement and splaying of the inferior vena cava (IVC) and right atrium
(RA). (C) CT angiographic (CTA) image depicts the giant LA. LV, left ventricle.
Discussion
ALCAPA is a rare entity first described by Brooks in 1885 wherein the left coronary
artery (LCA) arises from the pulmonary artery with an incidence of 1 in 300,000 births
with varied hemodynamic manifestations.[1] Embryologically, it may be attributed to abnormal septation of the conotruncus into
the aorta and pulmonary artery, or abnormal persistence of pulmonary arterial buds
together with involution of aortic buds.[2] Other notable rare anomalous coronary artery origin entities from pulmonary arteries
include anomalous origin of the right coronary artery from the pulmonary artery (ARCAPA),
anomalous origin of left circumflex artery from pulmonary artery (ACXAPA), and combined
right coronary artery and LCA origin from the pulmonary artery. ALCAPA patients present
with heart failure in early infantile period at around 3 to 4 months of age secondary
to decrease in pulmonary arterial pressure and if untreated, around 90% patients die
in first year of life. In fetal development, blood flow in the anomalous LCA primarily
moves from the pulmonary artery to the myocardium. However, after the initial neonatal
stage, the blood flow direction reverses, leading to left to right shunt. This shift
occurs because pulmonary resistance decreases naturally, and collateral vessels develop
gradually from the right coronary artery. Consequently, the LCA acts as a conduit,
ultimately leading to gradual myocardial ischemia and dysfunction in the LV.[3] Ischemic insult to the LV leads to secondary MR due to papillary muscle ischemia
and dilatation of the LV. Enlargement of the LA in cases of ALCAPA is attributed to
MR and also to intrinsic properties of the LA wall.[4]
[5] Giant LA associated with ALCAPA has been previously reported once in a 5-year-old
boy.[6] However, to the best of our knowledge, it has not been described in an infantile
age group. Other differential diagnosis of giant LA in infantile age group is idiopathic
congenital giant LA, rheumatic heart disease, left to right shunt lesions, and chronic
atrial fibrillation. Our case is unique as it describes early complications of ALCAPA
in an infant. Definite treatment for this condition is surgical intervention to establish
a two-coronary system. In surgical approaches, direct reimplantation of the coronary
artery into the aorta, also known as coronary button transfer, is used to correct
ALCAPA. Other techniques include transpulmonary baffling, or the Takeuchi procedure,
which helps in rerouting blood flow to the coronary arteries. The subclavian–left
coronary anastomosis, which involves connecting the subclavian artery to the LCA to
improve blood flow, can also be performed. Additionally, coronary artery bypass grafting
can be performed using a saphenous vein graft or the left internal mammary artery,
often with the ligation of the anomalous LCA to restore proper circulation. Cardiac
transplantation remains an option for patients who experience severe left ventricular
dysfunction and persistent heart failure, providing a last-resort solution for those
not responding to other treatments.[7] Our case underwent mitral valve repair with concomitant coronary button transfer
with reimplantation of the LCA to the aorta.
Magnetic resonance imaging (MRI) is a robust modality in evaluating patients with
ALCAPA with the added advantage of no exposure to ionizing radiation. MRI is particularly
helpful in anatomic delineation, functional cardiac assessment, myocardial characterization,
and flow assessment. Using CINE (cinematic) steady-state free precession (SSFP) sequences,
left ventricular function, mitral insufficiency, or MR, regional wall motion abnormalities
can be detected and quantified. First pass perfusion images can detect areas of perfusion
deficit, and late gadolinium enhancement (LGE) images can detect areas of myocardial
fibrosis secondary to infarct prompting the need for early surgical correction to
subdue risk of malignant arrhythmias. Advanced flow quantification sequences using
phase contrast imaging can be useful to quantity the degree of left to right shunt.
In cases of ALCAPA, it is imperative to look for coronary vascular origins, presence
or absence of inter coronary collaterals, any hypertrophied coronary artery segments,
features of left ventricular dysfunction, and presence of myocardial fibrosis.[8] In the postoperative period, serial echocardiography is indicated for left ventricular
functional assessment, and cross-sectional imaging such as CTA or MRI can be helpful
in evaluating reverse left ventricular remodeling and regression of intracoronary
collateral network.
This case underscores the importance of CTA in defining all the morphologic aspects
of ALCAPA that may be useful in planning surgical repair.
