ARCAPA was first described by the Irish anatomist John Brooks in 1885 . The incidence of ARCAPA in patients undergoing coronary angiography was found to be 0.002% . The embryological basis of ARCAPA remains unclear while it is generally thought with malformation of coronary artery development during the fourth to sixth week of gestation . Aortopulmonary window is the most common cardiac lesions associated with ARCAPA, accounting for about one forth cases .
The patients with ARCAPA present variable clinical manifestations. According to previous review, about 38% of patients with ARCAPA were asymptomatic at the time of diagnosis. There is a bimodal distribution of the age at presentation as one peak centered near after birth and another peak centered around 40 to 60 years of age . The reason for such phenomenon could be explained by the pathophysiology of ARCAPA. Soon after birth in patients with ARCAPA, the high pulmonary pressure keeps antegrade perfusion with deoxygenated blood. Myocardial anoxia of RCA territory causes collateralization development between the left and right coronary systems. As pulmonary pressure decreases and collateralization develops, blood from left coronary system flows retrogradely into the pulmonary artery and results in “coronary steal” phenomenon . If collateralization has not sufficiently developed, the patients may present with symptoms of myocardial ischemia, which could explain the first peak of symptomatic patients near birth. Otherwise, left coronary system supplies adequate oxygenated blood to the entire heart and the patients survive and may grow up asymptomatically. However, single coronary system is more prone to atherosclerosis and left to right shunt is more prone to cardiac dysfunction which contribute to the second peak of symptomatic patients around 40 to 60 years of age.
Angiography is considered as the golden standard for the diagnosis of ARCAPA. Typical features of ARCAPA observed by angiography include retrograde flow though the RCA, extensive collateralization, dilated coronary system with increased flow as well as flow from RCA into pulmonary artery . Additionally, echocardiography and coronary CT angiography are of important diagnostic value because of improved technologies and their non-invasiveness. In our case, echocardiography showed the typical features of ARCAPA including dilated coronary arteries, extensive collateralization and increased coronary flow, which were finally confirmed by coronary CT angiography.
There is consensus about early intervention in patients with ARCAPA to prevent later complications such as cardiac dysfunction and myocardial ischemia. The aims of treatment are to eliminate the “coronary steal” and establish dual coronary system originating from the aorta . Three surgical strategies are commonly applied which are simple RCA ligation, RCA ligation with CABG and RCA reimplantation onto aorta. Simple RCA ligation usually took place in patients who were not deemed good candidates for CABG. The other two strategies could achieve both aims while RCA reimplantation is thought to provide higher patency rate compared with RCA ligation with CABG, although large long-term data are lacking . In our case, we had planned RCA ligation with CABG preoperatively. However, the huge mismatch between the luminal caliber of RCA and graft vessels made CABG technically difficult. Because of the complete cardiac arrest and sufficient collateralization, simple RCA ligation was thought acceptable without compromised myocardial perfusion. After eliminating the “coronary steal” phenomenon, the patient received good results as 5-year postoperative coronary CT angiography showed both left ventricle and coronary system decreased in size without evidence of myocardial ischemia.