The term coronary derives from the Latin root coronarius, which means crown. Indeed, the coronary arteries sit on the heart as a crown, and they are the "crowning subject" of adult cardiology due to the prevalence of acquired coronary artery disease. Although less of a preeminent subject in pediatric cardiology, coronary artery anomalies, with and without concomitant structural congenital heart disease, are an important topic for the pediatric cardiologist. This chapter reviews echocardiography of congenital coronary artery anomalies of importance to the pediatric cardiologist. Material pertinent to all congenital coronary artery anomalies is presented first, followed by material particular to each important anomaly.
Developmental considerationsBefore the development of the coronary arteries, the loosely packed myocardium of the embryonic heart is nourished by sinusoids throughout the heart cavities. As the myocardium becomes more compact, veins, arteries and capillaries develop from these primitive sinusoids. Then, at around 32 days of gestation, subepicardial vascular networks develop; shortly thereafter, endothelial buds appear at the base of the truncus arteriosus. These two anlagen join to one another by around 45 days of gestation, and the definitive coronary arterial circulation is thus established.Controversy exists regarding the number of endothelial buds present at the base of the truncus arteriosus and the manner in which the two coronary anlagen (subepicardial vascular networks and endothelial buds) connect with one another. Abrikossoff originally described two endothelial buds that were "allotted" to the aorta by division of the truncus into aorta and pulmonary artery [1]. Hackensellner later suggested that there are endothelial buds in each of the six sinuses of Valsalva of the great arteries and that all but two of these ultimately involute [2]. The latter theory has better withstood subsequent investigation [3], but either theory may readily explain the multitude of coronary artery anomalies that exist. The method of involution and induction of the appropriate sinuses of Valsalva remains speculative [4].
Normal coronary anatomyThere are normally two major coronary arteries, which originate from the right and left aortic sinuses of Valsalva. These sinuses are small outpouchings of the aorta between the sinotubular junction and the aortic valve leaflets. There are normally three such sinuses; the third, or posterior, sinus of Valsalva, is usually devoid of a coronary artery orifice. It is thus called the noncoronary sinus of Valsalva.
The left coronary arteryThe left main coronary artery arises from the left sinus of Valsalva and courses only a short distance (<4 cm in the adult) before dividing into the left circumflex and left anterior descending coronary arteries (Fig. 29.1). The left circumflex coronary artery varies considerably in size depending on whether the posterior descending coronary artery is a branch of the right coronary artery (right-dominant coronary system) or a branch of the circu...
