Biomedical Engineering Reference
In-Depth Information
inv 1
:
ConductionNodeState
ConductionNode
BOOL
inv 2
:
CConductionTime
ConductionNode
0 .. 300
inv 3
:
CConductionSpeed
ConductionPath
0 .. 500
inv 4
:
HeartState
BOOL
In the abstract specification of the heart model, there are three events, namely
HeartOK to represent a normal state of the heart, HeartKO to express abnormal state
of the heart and HeartConduction to update the value of each landmark node of the
conduction network in terms of visited landmark nodes ( ConductionNodeState ), im-
pulse propagation intervals ( CConductionTime ) and impulse propagation velocities
( CConductionSpeed ).
The event HeartOK specifies a set of required conditions for a normal state of the
heart system. The first guard grd 1 states that all landmark nodes should be visited
in a single cycle of impulse propagation. The second guard states that the current
impulse propagation time of each landmark node should lie within the pre-specified
range of the impulse propagation times. The final guard states that the current im-
pulse propagation velocity of each path should lie between pre-defined impulse
propagation velocities. If all guards are satisfied then the heart state indicates the
normal condition as being TRUE .
EVENT HeartOK
WHEN
grd1
:∀
i
·
i
ConductionNode
ConductionNodeState(i)
=
TRUE
grd2
:∀
i
·
i
ConductionNode
CConductionTime(i)
ConductionTime(i)
grd3
:∀
i, j
·
i
j
ConductionPath
CConductionSpeed(i
j)
ConductionSpeed(i
j)
THEN
act1 : HeartState := TRUE
END
The event HeartKO specifies as an opposite set of guards to those for the normal
state of the heart system to specify abnormal conditions of the heart. These guards
state that if any landmark node is not visited in a single cycle of the impulse propa-
gation, or if any the current impulse propagation time of any landmark node does not
lie within the pre-specified range of the impulse propagation times, or if the current
impulse propagation velocity of any path does not lie within the pre-defined range
of impulse propagation velocities, then the heart system is in an abnormal state rep-
resents by its normal condition being FALSE . Different kinds of heart diseases affect
the electrical impulse propagation time and velocity in the heart system [ 24 ]. These
changes affect the actual heart rhythm and help to identify the possible abnormal
behaviours of the heart.
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