Reversibility of intrathoracic lipotoxicity in obesity after bariatric surgery: use of magnetic resonance imaging.

Intrathoracic lipotoxicity is the consequence of increased accumulation and biological activity of various fat deposits in obesity, more specifically epicardial (“fat around the heart”) and intramyocardial fat (“fat within the myocardium”). Epicardial fat is located in close proximity to the coronary arteries within the visceral pericardial layer (in contrast to the paracardial or mediastinal fat outside the pericardial layer). The epicardial fat originates embryologically from specific mesothelial cells with a vascular supply from the coronary arteries (1). Epicardial adipose tissue appears to be biologically active by excreting paracrine and vasocrine factors that influence local and distant locations. Bioactive molecules like adiponectin are secreted by the epicardial fat and are transported to the myocardium and coronary endothelium through diffusion in the interstitial fluid and via the vasa vasorum. Adiponectin modulates the crosstalk between adipose tissue and the vasculature by inducing nitric oxide production (2). Epicardial fat volume and adiponectin have been shown to be associated with coronary vasoreactivity of coronary microcirculation and coronary atherosclerosis (2).