Hernodynamics
of
Large Arteries
133
In diastole, when inflow is zero, as in the case when diastolic aortic
flow equals zero, then
0
=
C dPldt
+
P&
(4.5.5 5)
or
dP/P
7
-dt&C
(4.5.56)
This equation states that the rate
of
diastolic aortic pressure drop is
dependent on both the compliance
of
the arterial system and the
peripheral
resistance.
Both
of
which also
determine the
flow.
Integration
of
both sides
of
equation (4.5.56) gives us
In P
=
t/RsC
(4.5.5
7)
(4.5.5
8)
valid for the diastolic period, or t
=
fd.
U,
td
ts
\I
r.
m
/I
>
t(sec)
Fig.
4.5.3:
Illustration of the measured aortic pressure pulse waveform. The systolic
pressure, diastolic pressure, end-systolic pressure and mean blood pressure are also
shown. The approximate exponential decay of diastolic pressure through the diastolic
period (td) from the end of the systolic period (ts) is seen.
