The word "stenosis" is a Greek word that means narrowing. In terms of the cardiovascular system, stenosis is a process where blood vessels narrow due to deposits on the vascular walls. Most often, these substances have a lipid code; the most known representative of such lipids is cholesterol. In fact, arterial stenosis is a particular manifestation of atherosclerosis. But unlike the latter, stenosis is local in its nature.

Stenosis can exert a highly negative effect: vessel constriction inhibits the blood flow and thus some parts of the body lack oxygen and nutrients.

Formation of stenosis is also associated with endothelial dysfunction—i.e. impaired vasodilation and impaired synthesis of nitric monoxide, a powerful antiatherogenic substance.

Severe arterial stenosis is accompanied by the formation of atherosclerotic plaques, which over time may completely block the blood flow in the vessel. If a blood clot detaches for some reason, the chance of an ischemic stroke increases dramatically.

In Russia, arterial stenosis is usually diagnosed with the help of invasive procedures where diagnostic probes are inserted inside the patient's vessels. This involves injecting chemicals that mimic physical activity (to test vasodilation).

Such stenosis diagnostics procedures are very hazardous: the mortality rate of some testing procedures may go up to 1%.