Simultaneous assessment of myocardial glucose metabolism and contractile function by gated F-18-deoxyglucose positron emission tomography in infants after arterial switch operation for d-transposition of the great arteries

Abstract

The arterial switch operation is now the treatment of choice for anatomic correction of dextro-transposition of the great arteries (d-TGA) in infancy. Early and late morbidity and mortality are related in part to impaired coronary perfusion due to stenosis, compression, kinking, or occlusion of the transferred coronary arteries. To guide further therapy in these patients, evaluation of myocardial viability in akinetic or hypokinetic regions is required. F-18-deoxyglucose positron emission tomography (FDG-PET) is well-established for the investigation of myocardial viability in adults. However, there are no reports about the impact of FDG-PET in infants. We applied ECG-triggered (7–12 gates) PET using a 30-min protocol for complete assessment of the metabolic and functional status of the myocardium in five infants with suspected or confirmed myocardial injury after the arterial switch operation. Left ventricular (LV) dysfunction was present in four infants. Coronary angiography revealed stenosis or occlusion of one or more coronary vessels in three patients. F-18-FDG (5–7 Mbq/kg) was injected after stimulation of glycolysis. Gated data acquisition was started 30 minutes after injection for a 20-min emission period, followed by a 10-min transmission. Glucose metabolism, wall motion, and wall thickening were evaluated visually and quantitatively from parametric 3-D images generated by a new software for wall delineation. In one infant with severely impaired LV function, PET demonstrated viable myocardium in hypokinetic regions except for a small non-transmural infarction in the apex, providing an objective indication for surgical revascularization. Another infant with severe stenosis of the left coronary artery showed no metabolic abnormality and was scheduled for coronary angioplasty. A third patient with kinking of the left and right coronary arteries had a large transmural defect corresponding to an apical and anterior infarction. These preliminary results suggest that myocardial viability and contractile function can be assessed simultaneously by gated FDG-PET in order to guide further therapy in infants with coronary stenosis or occlusion.