90
Dynamics
of
the
Vascular
System
First, the pressure pulse increases and the flow pulse decreases in
amplitude progressively. The mean blood pressure declines slowly in
arteries, but dramatically
so
in the arteriolar beds. Secondly, the rate of
rise of the pressure (dp/dt) in early systole increases and the wavefront
becomes steeper, while that of the flow wave behaves in just the opposite
manner.
Thirdly, the incisura, or dicrotic notch, due to aortic valve
closure, is more rounded as the pressure wave propagates towards the
periphery and the diastolic pressure wave becomes more accentuated.
These features are seen from Fig.
4.2.1.
These observed changes are
related to the functional aspects of the arterial system. Consequently,
considerable diagnostic information can be derived from the accurate
measurements and analysis of pressure and flow pulse contours.
Fig.
4.2.1
:
Pressure
and flow waveforms in the ascending, thoracic and abdominal aortas,
as well
as
the femoral and saphenous arteries. The progressive increases in pulse pressure
and decreases in pulsatile
flow
magnitudes
are
seen.
From Nichols and O’Rourke
(1998).
