Hernodynamics
of
Large Arteries
95
and phase,
$",
superimposed on a
DC
component or mean
blood
pressure:
N
p(t)
=
+
Cpn
sin(nwt
+
4n)
(4.2.1)
n=l
w=2$
(4.2.2)
where f
(Hz)
is
the number of heart beats per second.
Similar
The relations for the pressure and flow pulse waveforms expressed as
equations can be written for the flow waveform.
magnitude and phase are, for the nth harmonic:
(4.2.3)
(4.2.4)
The ratio
of
pressure to flow
is,
therefore,
The vascular impedance obtained for the nth harmonic
is
therefore
(4.2.6)
where the magnitude of impedance
is
simply the ratio
of
the pressure
amplitude to the flow amplitude for the nth harmonic:
and the phase lag
(4.2.7)
en
=
4n
-
Fn
(4.2.8)
