Coronary Artery Disease in Children

Overview.

An anomalous aortic origin of the LMCA (AAOLCA) may originate from the right sinus of Valsalva or may arise as a single coronary artery with the RCA. Before bifurcating into the LAD and Cx arteries, the LMCA must travel toward the left by one of four routes: anterior to the right ventricular outflow tract (RVOT), within the interventricular septum beneath the RVOT (intraseptal), between the aorta and the pulmonary artery (interarterial), or posterior to the aorta. Similarly, an anomalous aortic origin of the RCA (AAORCA) may originate from the left sinus of Valsalva or as a single coronary with the LMCA. It typically has an interarterial course toward the right atrioventricular groove, although other routes are possible. While the anterior and posterior courses are considered clinically benign, the interarterial course ( Fig. 77.5 ) is associated with sudden cardiac death. This association was originally described in several autopsy series, with AAOLCA found more frequently than AAORCA. Several studies and case reports have subsequently established this association, with congenital coronary anomalies reported as the second-most common cause for sudden cardiac death in adolescent athletes.

The true prevalence of anomalous aortic origin of the coronary arteries is unknown. The majority of patients are asymptomatic and a major adverse cardiac event is often the initial presentation. Based on prior angiographic studies, the prevalence of AAOLCA with an interarterial course is estimated at 0.02% to 0.05% of the population, and the prevalence of AAORCA is estimated at 0.1%. Given that AAORCA appears to be three to five times more common than AAOLCA in the general population, the prior autopsy studies suggest that AAOLCA is a higher risk lesion.

The pathophysiology of sudden cardiac death has not been conclusively determined. Most patients with sudden cardiac death had no significant clinical findings or known premonitory symptoms. In about 30% of the cases, syncope or chest pain occurred within 2 years of death, but resting ECG and stress ECG have been reported as normal. The prevailing thought is that the risk of sudden cardiac death is increased with significant physical exertion, such as strenuous athletic activity. Presumed risk factors for a lethal arrhythmia are transient ischemia caused by inadequate coronary flow through a narrowed “intramural” lumen compressed by the aorta and pulmonary artery, a slitlike opening caused by an acute takeoff (<45 degrees) of the anomalous coronary artery, and the presence of an ostial ridge or flap that also occludes the ostium. An intramural lumen refers to a portion of the coronary artery where the tunica media is shared with the aortic wall and there is no interposed adventitial layer.

In addition to interarterial coronary arteries, sudden death has rarely been reported with AAOLCA arising from the noncoronary sinus without an interarterial course. In this configuration, the alignment of the LMCA origin and the anterior interventricular groove is such that the LMCA may have a more acute takeoff angle from the noncoronary sinus ( e-Fig. 77.6 ). This acute takeoff angle creates a narrowing at the ostium that is thought to be a factor leading to ischemia and sudden death.

Imaging.

In neonates and young children, echocardiography can delineate the coronary origins to suggest the anomalous coronary types previously discussed. In adolescents and young adults, the coronary arteries may not be adequately assessed with echocardiography. Confirmation of the diagnosis and detailed characterization of the high-risk features previously mentioned is better performed by CMRA and CCTA. In particular, the presence of an intramural course should be evaluated by cross-sectional imaging, as this is poorly characterized by echocardiography. Current data suggests the risk of sudden cardiac death is low before 10 years of age, and so many centers defer surgical intervention until after this age. Further cross-sectional imaging can likely be deferred in most routine cases until around 10 years of age. This has the benefit of avoiding sedation or anesthesia in the majority of cases. Depending on the expertise and equipment available to individual centers, CMRA can be considered the first test of choice to avoid radiation exposure. If CMRA is not feasible due to technical or diagnostic reasons, then CCTA presents an excellent choice. Diagnostic catheter angiography does not have much of a role for this indication.

Morphologic features considered clinically relevant are: ostial size/morphology (including the presence of an acute angle takeoff from the aorta, a slitlike origin, and the presence of an ostial ridge), interarterial narrowing suggestive of an intramural course, length of the intramural portion, location in relation to the sinotubular junction and aortic commissures, and coronary dominance. Determination of the intramural course can be difficult with CCTA and CMRA. Correlation with surgical pathology suggests that CCTA findings of a slitlike origin, an acute angle at vessel takeoff, and an elliptical cross-section with parallel course along the aortic root are related to an intramural coronary segment ( Fig. 77.7 ). Endoluminal views and volume rendered reconstructions are helpful for ostial characterization and surgical planning.

Treatment.

Although there is a strong association with sudden cardiac death, the absolute risk among individuals, particularly in the absence of participation in competitive sports, is unknown. There is marked practice variation among congenital heart surgery centers due to this uncertainty. Recent data from a multicenter registry by the Congenital Heart Surgeons Society involving 23 pediatric centers reported 52% of AAORCA and 67% of AAOLCA had undergone surgery at a median age of 12.6 years. The type of surgical repair is dependent on the coronary anatomy. In those with an intramural course, an unroofing procedure is the technique of choice. This involves incising the common wall between the aorta and intramural coronary. Aortic valve commissural resuspension may be necessary in cases where the intramural coronary courses behind the commissure. Direct reimplantation or creation of a neo-ostium and ostioplasty is performed when there are separate ostia and no significant intramural course. A pulmonary artery translocation can be performed in the case of a single coronary with evidence of coronary compression and/or ischemia. A bypass graft can be performed but has a very limited role due to concerns with competitive flow from the native coronary.