The pathophysiological consequences of this anomaly are profound. In normal physiology, both coronary arteries arise from the high-pressure, oxygen-rich aortic root. In ALCAPA, however, the left coronary artery originates from the low-pressure pulmonary circulation. Following the postnatal decline in pulmonary arterial pressure and oxygen saturation, myocardial perfusion through the left coronary system becomes progressively inadequate. This results in chronic subendocardial ischemia, left ventricular dysfunction and varying degrees of mitral insufficiency secondary to papillary muscle ischemia³.

Clinical expression depends largely on the development of collateral vessels between the right and left coronary systems. In the absence of sufficient collateralization, most infants develop heart failure early in life and mortality rates remain extremely high without surgical correction. Contemporary advances in noninvasive cardiac imaging, particularly multislice CT coronary angiography, have substantially improved diagnostic accuracy and preoperative anatomical assessment.

Case Presentation

A one-year-old infant was referred to our tertiary paediatric cardiology centre for evaluation of persistent respiratory distress and failure to thrive. The child had been born at term following an uncomplicated pregnancy, with no antenatal suspicion of congenital heart disease. Over the preceding months, the parents had noted progressive feeding intolerance, excessive diaphoresis during crying and poor weight gain compared with age-matched peers.

On clinical examination, the infant appeared tachypnoeic with mild subcostal retractions. Peripheral pulses were palpable and symmetrical, though mild tachycardia was present. Cardiac auscultation revealed a grade III/VI systolic murmur best heard along the left parasternal border, radiating toward the apex. No cyanosis was observed, but signs of early congestive heart failure were clinically suspected.

Chest radiography (Figure 1) demonstrated cardiomegaly accompanied by increased pulmonary vascular markings suggestive of pulmonary congestion. Electrocardiography (Figure 2) revealed nonspecific ST-segment and T-wave abnormalities raising suspicion of myocardial ischemia. Transthoracic echocardiography (Figure 3) Transthoracic echocardiography provided crucial anatomical and functional information. The examination demonstrated marked dilatation of the left ventricle with globally reduced systolic function. The left ventricular walls appeared hypokinetic, particularly in the anterolateral segments. Increased echogenicity of the mitral papillary muscles was noted, a finding highly suggestive of ischemic injury and papillary muscle fibrosis, which correlated with the presence of mild-to-moderate mitral regurgitation on colour Doppler imaging. Careful assessment of the coronary origins revealed anomalous emergence of the left coronary artery from the main pulmonary artery rather than from the left aortic sinus. Colour Doppler interrogation showed retrograde flow from the left coronary system into the pulmonary artery, further supporting the diagnosis. The right coronary artery appeared dilated, reflecting compensatory increased flow and collateral development.

Figure 1: Frontal chest radiograph demonstrating cardiomegaly associated with pulmonary vascular congestion

Figure 2: Electrocardiogram Showing Left Ventricular Hypertrophy and Anterolateral Ischemic Changes in a One-Year-Old Infant with ALCAPA

Figure 3: Transthoracic echocardiography demonstrating left ventricular dilatation, hyperechogenic mitral papillary muscle and anomalous origin of the left coronary artery arising from the pulmonary artery

For comprehensive anatomical evaluation, a contrast-enhanced multislice CT coronary angiography was performed under controlled sedation using paediatric acquisition protocols.

Discussion

ALCAPA remains one of the most clinically consequential congenital coronary anomalies due to its direct impact on myocardial perfusion. In early infancy, pulmonary arterial pressures are relatively high, permitting antegrade perfusion of the left coronary artery⁴. However, as pulmonary vascular resistance decreases after birth, perfusion pressure falls and blood preferentially flows from the left coronary system into the pulmonary artery. This reversal produces myocardial ischemia and establishes a left-to-right shunt.

The clinical presentation in infancy typically reflects ischemic cardiomyopathy. Symptoms may include irritability, feeding difficulty, diaphoresis, tachypnoea and growth failure. Mitral regurgitation frequently develops secondary to papillary muscle dysfunction. Without intervention, mortality in the first year of life has historically exceeded 80-90 percent.

Survival beyond infancy depends on the extent of collateral circulation arising from the right coronary artery. In such cases, the RCA becomes enlarged and tortuous, as observed in our patient, while collateral vessels attempt to maintain myocardial perfusion^5,6. Nevertheless, even in survivors, the risk of malignant arrhythmias, infarction and sudden death persists.

Multislice CT coronary angiography has emerged as a cornerstone imaging modality in this context. Its high spatial resolution allows precise delineation of coronary origins, collateral pathways and associated anomalies within a single non-invasive acquisition. Compared with conventional angiography, CT offers rapid imaging with excellent anatomical detail, which is particularly advantageous in paediatric populations.

Juxtaposition of the atrial appendages represents an additional congenital morphological variant. It is most commonly associated with transposition of the great arteries and other conotruncal defects. Its coexistence with ALCAPA is unusual but surgically relevant, as it may influence operative orientation and exposure.

Definitive management of ALCAPA is surgical. The preferred technique involves reimplantation of the anomalous left coronary artery into the aorta, thereby restoring a dual coronary system. Early surgical correction is associated with substantial recovery of ventricular function and favourable long-term prognosis⁷.

Conclusions

Anomalous origin of the left coronary artery from the pulmonary artery is a rare but life-threatening congenital condition that requires a high index of suspicion, particularly in infants presenting with unexplained ventricular dysfunction or heart failure. Advanced imaging modalities, especially CT coronary angiography, enable accurate anatomical diagnosis and facilitate surgical planning. Early recognition and timely surgical repair remain the principal determinants of survival and myocardial recovery.

References

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2.                Hauser M. Congenital anomalies of the coronary arteries. Heart 2005;91:1240-1245.

3.                Dodge-Khatami A, Mavroudis C, Backer CL. Surgical therapy for ALCAPA. Ann Thorac Surg 2002;74:946-955.

4.                Kristensen T, Kofoed KF, Helqvist S, et al. ALCAPA presenting in adulthood. J Cardiothorac Surg 2008;3:1-2.

5.                Wesselhoeft H, Fawcett JS, Johnson AL. Anomalous origin of the left coronary artery from the pulmonary trunk. Circulation 1968;38:403-425.

6.                Charuzi Y, Spanos PK, Amplatz K, Edwards JE. Juxtaposition of the atrial appendages. Circulation 1973;47:620-627.

7.                Mesurolle B, Qanadli SD, Mignon F, Lacombe P. Coronary artery anomalies imaging. AJR Am J Roentgenol 2006;186:1202.