Biomedical Engineering Reference
In-Depth Information
Fig. 9.5
Refinements of one-electrode pacemaker using the refinement chart
the current time control of the pacemaker, is stored in variable
tic
; a safe pacing in-
terval is
Pace_Int
in which the pacemaker should not be paced.
In the next refinement (Figs.
9.5
(B),
9.6
(B)) step
pacing
is refined by
sensing
,
corresponding to the activity of the heart, when sensing period is not under refrac-
tory period (
RF
2
). In the first refinement of two-electrode pacemaker, sensors are
introduced in both chambers. In Fig.
9.5
(B) of one-electrode, sensing is represented
by transitions
Sensor ON
and
Sensor OFF
, while in Fig.
9.6
(B) of two-electrode,
sensing is represented by transitions
Sensor ON Atria
,
Sensor ON Ventricle
,
Sen-
sor OFF Atria
and
Sensor OFF ventricle
. This refinement introduces: the state of
pacemaker sensor (on/off), is modelled by a boolean flag
Pacemaker_Sensor
.The
pacemaker's actuator and sensor are synchronising to each other under the real-time
constraints. The block diagrams (Figs.
9.5
(B),
9.6
(B)) represent the
threshold
refine-
ment, that is a measuring unit which measures a stimulation threshold voltage value
of the heart and a pulse generator for delivering stimulation pulses to the heart. The
2
RF: Atria Refractory Period (ARP) or Ventricular Refractory Period (VRP).
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