Discussion
ARCAPA is an extremely rare congenital heart disease (CHD) firstly described by the Irish anatomist John Brooks in 1885 . Its incidence, based on coronary angiographic procedures, is estimated around 0.002%, but, given the usually asymptomatic behavior of this anomaly, its real prevalence in general population might be higher . Compared to the more common anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), ARCAPA is associated with lower mortality rate in infancy and childhood and has a bimodal age presentation with peaks near after birth or in the middle 40-60s . ARCAPA is often diagnosed incidentally and usually is an isolated lesion. Sometimes it is associated with other malformations : more often CHD (23.8%), less frequently extracardiac and genetic syndromes . As described, the most frequent associated CHDs are aorto-pulmonary window and ventricular septal defect , in rare cases aortic arch hypoplasia or patent ductus arteriosus with coronary fistulae . In 4% of cases ARCAPA has been found in patients with extracardiac lesions such as anal atresia, tracheoesophageal fistula, limb anomalies or other . Our case is the first described in a patient with CPAM. Historically, embryological origin of coronary anomalies is thought to be linked to defects in arterial septation, the same process that, around the 12th day of life, leads to the formation of aorta and pulmonary trunk from the common truncus arteriosus . Another theory advocates abnormal signaling in pathways that regulate implantation of the primary coronary plexus to the aorta or pulmonary trunk . Embryologic causes of CPAM, which results from the cessation of lung development during various stages of embryogenesis , seems to be different and not linked to those of coronary anomalies.
Pathology reports described the anomalous coronary artery made different for the normal coronaries: thin walled, dilated and/or vein-like . Precise origin of the abnormal vessel is not always described in literature reports but it can originate from any site off the pulmonary trunk wall: the anterior or posterior sinus of Valsalva, the anterior aspect of trunk, or more frequently distal to the pulmonary valve . In our case ARCAPA took-off from the medial wall of the pulmonary trunk, distal to the anterior Valsalva sinus. A web of small vessels (collaterals) nearby the ostium (as in our case) or stenosis of the origin of ARCAPA have been reported .