Angioscan Electronics AngioScan-01, Руководство пользователя

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AngioScan Medical Tests 37
© 2014 AngioScan-Electronics LLC
Stiffness index = L (m) / T (s), where
L - length of the aorta (calculated automatically from the patient’s height);
T - the time between the maximum amplitudes of the direct and reflected pulse waves.
Stiffness index score is based on the determination of the time interval between the early (direct) and
late (reflected) systolic waves.
This original pulse wave signal is transformed mathematically in order to
obtain its high-frequency components.
The physiological significance of the stiffness index is to evaluate the velocity of the pulse wave from the
heart to the site of pulse wave reflection.
With the increase in the stiffness of the large resistive vessels,
especially in the aorta, the pulse wave velocity increases, which is reflected in the increase in the
stiffness index.
When the aorta is elastic, the stiffness index in the range of 5 to 8 m/c, and in cases of
increasing the rigidity of the aortic wall can be up to 14 m/c.
Stiffness index is highly dependent on the age of the patient. In elderly patients, the walls of blood
vessels undergo the process of fibrosis (Table).
Also, this parameter has a significant influence of the
blood pressure. In patients with high blood pressure, the stiffness index increases.
Age, years
Average pressure, mm Hg 21 - 40 41 - 54 55 - 69
67 - 86 6,7 ± 0,37 7,3 ± 1,74 9,7 ± 2,11
87 - 95 7,0 ± 0,92 8,1 ± 1,57 10,0 ± 1,38
96 - 117 7,2 ± 1,25 8,7 ± 1,40 10,4 ± 1,79
Note: The mean arterial pressure is calculated with the formula:
DBP + 1/3 (SBP - DBP), where
DBP - diastolic blood pressure,
SBP - systolic blood pressure.
Stiffness index correlates well with the pulse wave velocity (PWV, pulse wave velocity) [Millasseau et al.