Arterial Stiffness index measurement test

Increased arterial stiffness is associated with an increased risk of cardiovascular events such as heart attack and stroke. Arteries stiffen as a result of age and as a result of plaque buildup or atherosclerosis.

This is a non invasive test used to assess the stiffness (hardening) of the arteries. Increased arterial stiffness and the reduced elasticity in the blood vessels occurs with increasing age but is exponentially worse with other risk factors to heart disease.

When the heart contracts it generates a pulse or energy wave that travels through the circulation. The velocity or speed of travel of this pulse wave (pulse wave velocity) is related to the stiffness of the arteries.

The Heart Fit Clinic offers this screening test as part of our
assessment phase which can also include the
Carotid Intima Media Thickness (IMT).

Stiffness Index (SI)

When the heart beats, it produces a pressure wave, known as pulse wave (PW). The PW travels at certain speed, pulse wave velocity (PWV).The speed of the PWV is measured in meters per seconds (m/s). The speed of the PW is determines by the stiffness of the arteries. The more flexible the artery, the slower is the PWV.

Reflection Index (RI)

RI is a measure of the percentage of the pressure wave (PW) that is reflected back from a point where the artery narrows or bifurcates.

An easy way to think of this is, imagine you drop a stone into a pond, you see the waves moving towards to edge of the pond. When a wave reaches the side of the pond it is reflected back towards it’s origin. If the pond has a number of streams the pressure waves will continue to travel along these streams. However where the stream narrows or is restricted the pressure wave is again reflected back.

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