In a previous issue of Heart, Verttukattil and colleagues presented a study of intrapulmonary arteriovenous shunting after a superior cavopulmonary anastomosis using radionuclide labelled albumin microspheres.1 Their study is unusual. Despite there being long established indications for radionuclide imaging in congenital heart disease,2 such investigations are not often performed. Equally they are not often used in research studies. Why are they not more widely used? There are many reasons. Some are shared with acquired heart disease, where the use of nuclear cardiology varies greatly between different centres. Cultural and economic reasons have been used to explain these differences in use. There are certainly differences between use in Europe and North American centres.3 There are particular factors that apply to congenital heart disease. Perhaps most importantly investigation of congenital heart disease is focused much more on structural rather than functional abnormalities. Radionuclide imaging has little to contribute in this regard. Cardiologists looking after patients with congenital heart disease use structural imaging, chiefly echocardiography andx ray angiography, and now increasingly magnetic resonance imaging, on a daily basis. When functional information is needed they tend to stick to the techniques they know. The cardiologist who feels that M mode (one dimensional) echocardiography tells him or her all they need to know about a patient's ventricular function is unlikely to consider radionuclide imaging despite the evidence of its value.4

There are other factors at play. The majority of diagnosis of congenital heart disease takes place in childhood, predominantly in very young children. Radionuclide imaging is, albeit minimally, invasive and uses ionising radiation. Paediatric cardiologists are naturally and properly reluctant to expose children to investigations involving intravenous cannulation and radiation without good reasons. The radiation dose from paediatric nuclear medicine procedures is low, certainly compared to cineangiography,5 but …