Aortopulmonary collaterals in single-ventricle congenital heart disease: how much do they count?

Broadly defined, aortopulmonary collateral blood vessels (APCs) arise from the systemic arteries and supply blood to the pulmonary circulation. In the setting of acquired and congenital pulmonary and cardiac disease, the number and caliber of these vessels can increase and lead to a significant systemic-to-pulmonary shunt. APCs typically arise from the descending aorta, subclavian artery branches, and bronchial and intercostal arteries. Unlike normal bronchial arteries, they often supply flow to the terminal respiratory unit and do not necessarily travel in close proximity to the bronchial tree. Prominent APCs are associated with a variety of congenital heart diseases but are more prevalent with cyanotic lesions, particularly tetralogy of Fallot with pulmonary valve atresia. APCs are also commonly found in patients with singleventricle heart disease, and their extent may fluctuate with successive surgical procedures.1–4 The impact and assessment of APCs in patients with a functionally single ventricle is the focus of the discussion that follows.