Vascular stiffness

The decisive factor in assessing vascular stiffness is the sign in front the number. If the number is negative, arteries have kept their elasticity. The higher the negative percentage of stiffness, the better the state of large arteries.

Normal values of this indicator are age-specific. In the cohort of people 18 to 35 years old, the values from -40% to -5% are considered good. For people older than 40 years, the safe range is from -5% to 5%. All positive values are typical for people older than 55 years. Of course, aging is irreversible and it inevitably leads to a gradual increase in vascular stiffness. But regardless of your age, you should keep your stiffness index low by living a healthy life.

To evaluate the index correctly, be sure to set the patient's real age before testing.

Vascular elasticity and stiffness are inverse values. Vascular stiffness grows when cholesterol and similar substances deposit on arterial walls (see atherosclerosis and stenosis).

After the heart pushes a portion of blood into the vessels, a pulse wave–called a direct pulse wave–travels through the aorta. Since the circulatory system is closed, the wave is reflected back from the bifurcation point (the place where the vessels diverge into the legs). A reflected wave is called a backward wave. Depending on the vascular wall elasticity, the time after which the reflected wave will get back to the starting point may vary. The later the wave returns, the more elastic the arteries.

Undoubtedly, this return time depends on the distance the wave travels. You need to know the patient's height, since its value helps accurately calculate the distance between the heart and the place where the pulse wave is reflected. Therefore, the vascular stiffness index is measured in meters per second by the following formula: [Distance (meters) / [Reflected wave return time (seconds)].

vascular stiffness index

For normal vascular elasticity, this index is 5-8 m/s; but when arterial wall stiffness is high, its value may reach 14 m/s. Arterial stiffness depends significantly on the patient's age, for elderly people have less elastin in the aortic wall. Arterial pressure also affects this parameter: stiffness grows as pressure increases.

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