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 .