The endothelium is a continuous layer of cells that coats the interior walls of arteries, capillaries, and veins. It has an essential regulatory role in hemostatic function, vascular tone, inflammation, and platelet activity. Endothelial dysfunction is characterized by a shift to a proinflammatory and prothrombic state, and it could have a bidirectional relationship with heart failure (HF). Due to neurohormonal activation and shear stress, HFrEF may promote endothelial dysfunction, increase ROS synthesis, and reduce nitric oxide production. Different studies have also shown that endothelium function is damaged in HFpEF because of a systemic inflammatory state. Some clinical trials suggest that drugs that have an effect on endothelial dysfunction in patients with HF or cardiovascular disease may be a therapeutic option. The aim of this review is to highlight the pathogenetic correlation between endothelial dysfunction and heart failure and the related potential therapeutic options.

Endocarditis is a condition associated with high mortality and still often represents a diagnostic challenge due to the variability of its clinical manifestations. The 2023 ESC Guidelines for the management of endocarditis incorporate, within the modified Duke’s criteria, new imaging modalities elaborated and published by the International Society for Cardiovascular Infectious Diseases (ISCVID): 18F-Fluorodeoxyglucose Positron Emission Tomography (18F-FDG-PET)/Cardiac Computed Tomography (CT). This technique combines the advantages of whole-body 18F-FDG-PET with the spatial resolution of CT, offering good sensitivity and specificity (0.74—CI 0.70–0.77 and 0.88—CI 0.86–0.91, respectively) for all cases of endocarditis, with improved performance, particularly in prosthetic valve endocarditis, positioning itself as a promising tool in this field. This chapter aims to review the role of 18F-FDG-PET)/CT in comparison with other imaging techniques, highlighting its potential use as an important diagnostic method in different clinical settings of endocarditis.