244
Dynamics
of
the Vascular System
loop control of cardiac assistance. To arrive at this goal it was shown that
model studies are important, because they predict either the open-loop or
closed-loop quantitative behavior of hemodynamic parameters.
A
microprocessor-based controller to implement real-time automation
of pump time using an
IABP
was developed by Zelano et al.
(1985,
1990).
The system sensed atrial P-waves, R-waves, and second heart
sounds, and operated in an open loop mode. The results of experiments
on dogs with this device indicate that automatic control of
IABP
in an
open loop mode yields equivalent increases in cardiac output, coronary
blood flow, with reduced resistance, and decreases in end diastolic
pressure and ventricular oxygen consumption when compared to normal
control adjustment by
a
certified balloon pump technician.
A
closed-loop
control algorithm however would be more desirable.
Improvement in the dynamics
of
the assisted circulation can be
valuable once the design of assist devices is refined and the control
strategies are better defined. To this end, the understanding of the
dynamics of the natural vascular system is
a
necessary step to the
appreciation of the overall function
of
the circulation.
