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 pharma ceuticals allow for functional tissue characterization in patients wit h impaired left ventricular function. Assessment of regional myocardia l perfusion and metabolism with either SPECT or PET methods provide ac curate detection of tissue viability. Several studies have indicated t he utility of these imaging approaches for improved selection of patie nts for revascularization. The combination of functional measurements with echocardiography and metabolic tissue characterization with PET a llows for the non-invasive measurement of cardiac efficiency. The effe ct of various therapeutic interventions can be objectively assessed by a work-metabolic index. Finally, autonomic innervation of the heart p lays an important role in the modulation of the haemodynamic performan ce of the failing heart, New imaging approaches using radiolabelled ca techolamine analogues or receptor antagonists have been used to identi fy the integrity of myocardic pre- and post-synaptic sympathetic inner vation. Imaging results in patients with dilated cardiomyopathy not on ly demonstrated a down-regulation of beta-receptor density, but also a n abnormal pre-synaptic neuronal function, which may result into impai red regulation of extraneuronal catecholamine concentration. Thus, adv anced scintigraphic imaging approaches may improve our diagnostic and prognostic workup in patients with congestive heart failure and may pr ovide objective endpoints for the assessment of therapy.