Adenosine stress myocardial perfusion scintigraphy in pediatric patients after arterial switch operation

CONTEXT: Arterial switch operation (ASO) has become the established treatment for correction of transposition of great arteries (TGA). Despite the immediate correction of abnormal hemodynamics, acute and delayed complications related to the coronaries may cause morbidity and mortality. AIMS: We evaluated the incidence of perfusion abnormalities and safety of adenosine by stress–rest myocardial perfusion single-photon emission computed tomography (SPECT) [myocardial perfusion scintigraphy (MPS)] using Tc-99m Sestamibi (MIBI) in asymptomatic children post-ASO. SETTINGS AND DESIGN: Prospective study. MATERIALS AND METHODS: We conducted a prospective, single-institutional study where stress–rest MPS was performed on 10 children of age between 1.25 and 6 years. Two of the patients had additional ventricular septal defect, one patient had left ventricular outflow tract obstruction, and another had Taussig–Bing anomaly. All the patients underwent corrective surgery as a single-stage procedure at the age of 176 ± 212 days (range 9-560 days). Adenosine was administered at a rate of 140 μg/kg/min intravenously as continuous infusion for duration of 6 min. STATISTICAL ANALYSIS USED: All the continuous variables were summarized as mean ± standard deviation, or range and median. Mann–Whitney test for unpaired data and Wilcoxon Rank test for paired samples were used. RESULTS: The average increase in heart rate over the basal heart rate after adenosine stress was 59.7 ± 17.0%. No acute or remote complications were observed in any case. None of the patients demonstrated myocardial perfusion defects, either at rest or after adenosine stress. CONCLUSIONS: MPS post-adenosine induced vasodilatation is safe and feasible in patients of ASO for transposition of great arteries. One-stage repair, implantation of excised coronary buttons within neo-aortic sinus, and minimal or no mobilization of proximal coronaries may eliminate the occurrence of perfusion defects in patients of corrected TGA.