ABSTRACT

As a result of improvement in radionuclide imaging modalities, the modulation of functional and electrophysiological characteristics of the heart by the autonomic nervous system has been the focus of cardiovascular research. Cardiac neuronal functional disorders are associated with various cardiac diseases, including congestive heart failure, ischemia, arrhythmia, and some types of cardiomyopathy. In vivo characterization of neuronal function in the myocardium based on radionuclide imaging is thought as a unique method. In recent decades, trials canalized toward assessing sympathetic innervation of the heart led to advances of radiotracers for single-photon emission computed tomography and positron emission tomography imaging. Nuclear cardiac imaging has allowed physicians the opportunity to assess non-invasively myocardial adrenergic innervation, via highly specific tracers such as I-123 metaiodobenzylguanidine and C-11 meta-hydroxyephedrine. In particular, SPECT imaging has been shown to allow the combined evaluation of regional myocardial perfusion and adrenergic innervation in the same imaging session, making possible the localization and quantitation of myocardial scar and the evaluation of the presence and spreading of denervated, though viable myocardium (i.e. innervation/perfusion mismatch). In clinical practice, sympathetic innervation imaging has been used in assessing prognosis, risk of ventricular arrhythmias and sudden death, and prediction of response to cardiac resynchronization therapy in patients with heart failure.