Myocardial blood flow and cardiac sympathetic innervation in young adults late after arterial switch operation for transposition of the great arteries

Background: The arterial switch operation (ASO) for repair of transposition of the great arteries (TGA) requires transection of the great arterial trunks and re-implantation of the coronary arteries into the neoaortic root resulting in cardiac sympathetic denervation whichmay affectmyocardial blood flow(MBF) regulation. The aims of the present study were to evaluate sympathetic (re-)innervation in young adults after ASO and its impact on MBF. Methods: Twelve patients (age 22.5 +/- 2.6 years) after ASO for TGA in the neonatal period and ten healthy controls (age 22.0 +/- 1.7 years) were included. Positron emission tomography (PET) was used formeasuring cardiac sympathetic innervationwith [C-11]meta-hydroxyephedrine (mHED) and MBFwith [O-15]H2O PET at rest, during adenosine stimulation, and during sympathetic stimulation with cold pressor test. Cold pressor-induced MBF response capacity was calculated as maximal global MBF over peak rate-pressure product multiplied by 10'000. Results: Global [C-11]mHED uptake was significantly lower in patients compared to controls (7.0 +/- 2.3 versus 11.8 +/- 2.1%/min, p < 0.001). Global MBF was lower in patients compared to controls at rest and during adenosine-induced hyperemia (0.66 +/- 0.08 versus 0.82 +/- 0.15 ml/min/g, p = 0.005; 2.23 +/- 1.19 versus 3.36 +/- 1.04 ml/min/g, p= 0.030, respectively). Interestingly, MBF during cold pressor test did not differ between patients and controls (0.99 +/- 0.20versus 1.07 +/- 0.16ml/min/g, p= 0.330). However, cold pressor-induced MBF response capacitywas significantly lower for patients as compared to controls (1.09 +/- 0.35 versus 1.44 +/- 0.39 ml/g/10,000 mmHg, p= 0.040). Conclusions: With only partial sympathetic re-innervation of the coronary arteries, maximal dilator capacity of the coronary microvasculature and cold pressor-induced MBF response capacity remain substantially impaired in young adults after ASO compared to healthy controls. (C) 2019 Elsevier B.V. All rights reserved.