Coronary Arteries Anomalies by CT in Children With CHD

Congenital heart diseases (CHD) form an important spectrum of pediatric diseases causing significant morbidity and mortality. Due to inter-related embryology of the heart and development of the coronary arteries, there is a great variability in coronary artery patterns in patients with CHD \[1\].

The spectrum of coronary artery anomalies ranges from benign / incidental findings to significant cardiac morbidity in infancy or increased risk of cardiac sudden death in childhood or adolescence \[2\]. Abnormalities can be found in the coronary artery origin, course, and size or the number of vessels. Isolated anomalies of coronary artery origins, in those without structural heart disease, had an estimated incidence of 0.7% \[3\]. Coronary artery anomalies have a higher incidence in children with congenital heart disease, ranging from an incidence of 5% in those with coarctation \[4\] to 7% in tetralogy of Fallot \[5\] and up to 37% in single-ventricle physiologies \[6\]. Identifying these anomalies has become an important part of the preoperative evaluation to avoid inadvertent injury and has been shown to be effectively diagnosed with modern CT techniques compared to surgical visualization and catheter angiography \[6,7\]. System of coronary artery origin and branching is of great help to surgeons who dedicate their efforts to the treatment of congenital heart disease \[8\].

Coronary artery imaging in children is frequently challenging due to small size, high heart rates, and motion artifacts from cardiac pulsation, respiration, and the patients themselves, which results in technical or procedural difficulties \[9\].

Imaging modalities for evaluating coronary arteries in children include echocardiography, conventional invasive angiography, magnetic resonance imaging (MRI), and computed tomography (CT). Transthoracic echocardiography is widely used as the primary imaging approach. However, it is impaired by its limited ability to fully characterize coronary anatomy, by poor acoustic windows, and by operator dependency \[10\].

Magnetic resonance imaging (MRI), also provides information on cardiac anatomy and function, allowing 3-dimensional coronary artery imaging without the use of ionizing radiation.However, it is impaired by long acquisition time requiring prolonged patient cooperation, which may not be possible in children without general anesthesia, and bylimited spatial resolution which makes coronary evaluation beyond originassessment difficult \[11\].

Computed tomography (CT) angiography is often the firstline diagnostic modality of choice for noninvasive imaging of the coronary arteries in both adults and children. CT is rapidly acquired and can be performed in the setting of multiple support devices. Compared with cardiac MRI and transthoracic echocardiography, CT provides excellent spatial resolution with superior visualization of the entire course of the coronary arteries \[12\].

Recent advances in CT technology have allowed for dramatic decreases in radiation dose while maintaining theexcellent spatial resolution that allows for detailed anatomical evaluation \[13\].

Coronary artery abnormalities in children may be congenital or acquired. Congenital anomalies include a complex group of disorders occurring as isolated conditions or in the spectrum of congenital heart disease.Acquired coronary anomalies are mainly secondary to Kawasaki disease or surgery when congenital heart disease repair involves coronary manipulation. Increasing evidence is supporting the role of CT in general for coronary evaluation of these patients \[14,15\]. The Coronary artery anomalies are grouped under four subtypes, i.e. anomalies of origin and course, intrinsic anomalies of coronaries, anomalies of termination, and anomalous anastomotic vessels \[16\]. Coronary artery abnormalities are more common in patients with congenital heart disease. Even when clinically irrelevant, these lesions may become important as they may affect surgical repair. Unambiguous coronary artery imaging is therefore mandatory in this situation and, especially when echocardiography is not conclusive ,CT should be employed to avoid unnecessary invasive procedures, even in the neonatal period. The most common conditions to consider in this setting include tetralogy of Fallot and (dextro-)transposition of the great arteries\[17\].