Endothelial dysfunction and cardiovascular disease

The endothelium, by area alone, is one of the largest organs in the body comprised of up to trillion cells, weighing over 1 kg, and covering nearly 3 m2 in a 70 kg male.1,2 Moreover, it interacts with nearly every system in the body, and has been implicated in end organ diseases of systems such as neurologic, renal, hepatic, vascular, dermatologic, immunologic, and of course cardiac. The endothelium is a single vessel layer standing as the ultimate layer between blood and vascular supply to other tissues, and serving multiple purposes. The first and foremost is a hemostatic balance between thrombosis and anticoagulation via a careful series of checks and balances discussed below. Additionally, the endothelium regulates vascular tone, carefully balancing vasoconstriction and vasodilation to provide adequate perfusion pressure to target organs. Other functions include regulation of angiogenesis, wound healing, smooth muscle cell proliferation, fibrosis, and inflammation. Factors that adversely affect the endothelium include common cardiovascular risk factors such as tobacco use, obesity, age, hypertension, hyperlipidemia, physical inactivity, and poor dietary habits. Alternatively, factors that positively impact the function of the endothelium are, essentially, beneficial lifestyle habits opposite to those mentioned above such as increased physical activity, dietary habits which include anti-inflammatory and anti-oxidant foods, and some pharmaceutical agents such as L-Arginine. Presently there is no guideline directive – either pro or con – to routinely include endothelial function testing in cardiovascular disease (CVD) risk assessment.3–5