Metabolic tissue characterization in the failing heart by positron emission tomography.

Congestive heart failure represents an important clinical issue which can benefit from newer imaging approaches. Use of radiolabelled pharmaceuticals allow for functional tissue characterization in patients with impaired left ventricular function. Assessment of regional myocardial perfusion and metabolism with either SPECT or PET methods provide accurate detection of tissue viability. Several studies have indicated the utility of these imaging approaches for improved selection of patients for revascularization. The combination of functional measurements with echocardiography and metabolic tissue characterization with PET allows for the non-invasive measurement of cardiac efficiency. The effect of various therapeutic interventions can be objectively assessed by a work-metabolic index. Finally, autonomic innervation of the heart plays an important role in the modulation of the haemodynamic performance of the failing heart. New imaging approaches using radiolabelled catecholamine analogues or receptor antagonists have been used to identify the integrity of myocardiac pre- and post-synaptic sympathetic innervation. Imaging results in patients with dilated cardiomyopathy not only demonstrated a down-regulation of beta-receptor density, but also an abnormal pre-synaptic neuronal function, which may result into impaired regulation of extraneuronal catecholamine concentration. Thus, advanced scintigraphic imaging approaches may improve our diagnostic and prognostic workup in patients with congestive heart failure and may provide objective endpoints for the assessment of therapy.