Abstract 2604: Assessment of Coronary Artery Size and Vasodilator Function in Children Following Arterial Switch Operation
Coronary translocation and re-implantation during neonatal arterial switch operation (ASO) may affect coronary artery growth and function during childhood. The purpose of this study was (1) to assess coronary artery size using quantitative coronary angiography and, (2) to assess myocardial blood flow (MBF) and flow reserve (MFR) using cardiac positron emission tomography (PET) in intermediate survivors of ASO. We performed coronary angiography in 12 children with neonatal ASO at a median age of 11 years (range 7.6 –15.1 years) and measured diameters of their proximal left anterior descending (LAD), left circumflex (LCX) and posterior descending artery (PDA) branches. These patients then underwent cardiac PET imaging using [13N] ammonia to assess MBF in the corresponding coronary territories at rest and during intravenous adenosine hyperemia. The resting left ventricular function was normal in all patients. Six of the 12 children had a variation in coronary anatomy (LCX from right coronary artery in 4, LAD from right coronary artery in one and dual LAD in one). The coronary z scores for LAD, LCX and PDA diameters were −0.40 ± 0.57, −0.58 ± 0.84, and −0.28 ± 1.76 respectively. The z scores were within normal range (−2.0 to 2.0) for 32 of 36 coronary branches and < −2.0 for 2 PDA branches. One child with a small proximal LCX (z score = −2.38) and occluded distal LCX had compensatory dilation of PDA (z score =3.0). Basal MBF was normal and homogeneous in all LAD, LCX and PDA territories (0.97 ± 0.34, 0.93 ± 0.27 and 0.93 ± 0.23 ml/gm myocardial mass/min). Hyperemic MBF was normal (>2.5 ml/gm/min) for all coronary territories in 10 of 12 patients. As a result, their MFR (ratio of hyperemic and basal flow) was normal in all coronary territories (4.0 ± 0.8, 3.8 ± 0.6 and 4.0 ± 0.8 in LAD, LCX and PDA territories respectively). Two patients, one with dual LAD and one with LAD origin from the right coronary artery had generalized impairment of hyperemic MBF (<2.0 ml/gm/min) and abnormally low MFR (<2.5 in all of their coronary territories). Coronary growth and function appears to be normal in most children following ASO. Children with pre-operative anatomic LAD abnormalities may be at higher risk of impaired flow reserve during childhood.