epicardial

Epicardial is an anatomical term describing structures related to the epicardium, the thin serous membrane that envelops the heart. The epicardium is the visceral layer of the serous pericardium and constitutes the outer surface of the heart, continuous with the parietal pericardium at the great vessels. It covers the myocardium and, together with the underlying myocardium, forms the heart’s outer coating.

The epicardial surface contains small nerve fibers and the coronary arteries and veins as they course in the pericardial space. A distinct layer of adipose tissue, known as epicardial adipose tissue (EAT), lies between the visceral pericardium and the myocardium. EAT is metabolically active and can secrete inflammatory mediators that may influence coronary atherosclerosis and myocardial function in certain conditions.

Developmentally, the epicardium derives from the serous pericardium and contributes cells to the coronary vasculature and stromal components of the heart during embryogenesis.

Clinical relevance: Epicardial involvement is primarily discussed in the context of pericardial disease; epicarditis is rare, with pericarditis being the more common inflammatory condition affecting the serous pericardium. The epicardium is accessible in certain cardiac procedures, such as epicardial mapping or ablation for arrhythmias. Imaging techniques, including echocardiography, computed tomography, and magnetic resonance imaging, can measure epicardial fat thickness, which correlates with metabolic and cardiovascular risk.

In sum, epicardial refers to the outer surface of the heart and associated tissues, particularly the epicardium and its adipose component, with relevance to anatomy, physiology, and clinical practice.