Hemodynamics
of
Large Arteries
121
reason, this formula has been used to obtain blood flow from the
measurement
of
pressure gradient.
The
second is the equation
of
continuity to describe
the
incompressibility of the fluid:
(4.5.2)
or that blood flow velocity gradient is related to the rate of change in
cross-sectional area of the blood vessel.
In
a cylindrical blood vessel,
the cross-sectional area
A,
is related to its inner lumen radius r, as
properties of the vessel wall
The third equation is the equation of state to describe the elastic
dr
-=k
dP
where
k
is a constant.
From this set of equations, the wave equation is obtained as:
Which gives the wave velocity
(4.5.3)
(4.5.4)
(4.5.5)
This equation also provides a means to obtain pulse wave velocity from
the simultaneous measurements of pressure and diameter. Define
Young’s modulus
of
elasticity
as:
(4.5.6)
