Biomedical Engineering Reference
In-Depth Information
8.5.5 Refinement 3: Perturbation in the Conduction
It introduces a set of possible blocks in the heart conducting system. These blocks
can occur in the conduction network and give trouble in electrical impulse propa-
gation. A set of landmark nodes partition the different regions for all possible heart
blocks. For introducing the heart blocks, we introduce an enumerated set
Heart-
BlockSets
in a new context model as a static property of the heart system.
axm
1
:
partition(HeartBlockSets,
{
SA
_
nodal
_
blocks
}
,
{
AV
_
nodal
_
blocks
}
,
{
Infra
_
Hisian
_
blocks
}
,
{
LBBB
_
blocks
}
,
{
RBBB
_
blocks
}
,
{
None
}
)
To model the heart block system, we define a variable
HeartBlocks
as
Heart
-
Blocks
HeartBlockSets
. New events are introduced to show different kinds of heart
blocks during impulse propagation into the conduction network. Events are
Heart-
Conduction_Block_A_B_C
to formalise the sinoatrial (SA) nodal block,
Heart-
Conduction_Block_B
to represent atrioventricular (AV) nodal block,
HeartConduc-
tion_Block_B_D
to specify Infra-Hisian block,
HeartConduction_Block_D_E_G
to
present Left bundle branch block, and
HeartConduction_Block_D_F_H
to specify
the Right bundle branch block.
Conduction disturbance in the heart during which an impulse formed within the
sinus node (A) is blocked or delayed from depolarising the atria. There are different
kinds of SA blocks [
24
,
30
]. To model SA block, we introduce an event
HeartCon-
duction_Block_A_B_C
, which formalises the SA block. In this event, guard (
grd
1)
represents that the landmark nodes (A or C) are not visited means FALSE state,
or the current impulse propagation time of B and C nodes are not lain within the
standard range, or the current impulse propagation velocity of the pairs
A
∈
→
B
and
A
C
are not lain within the standard range. When a guard is triggered, then
actions of this event state that the heart state is FALSE, and the heart block is a
sinoatrial (SA) nodal block.
→
EVENT HeartConduction
_
Block
_
A
_
B
_
C Refines HeartKO
WHEN
grd1
:
(ConductionNodeState(A)
=
FA L S E )
∨
(ConductionNodeState(C)
=
FA L S E )
∨
(CConductionTime(B)
∈
ConductionTime(B))
∨
(CConductionTime(C)
∈
ConductionTime(C))
∨
(CConductionSpeed(A
→
B)
∈
ConductionSpeed(A
→
B))
∨
(CConductionSpeed(A
→
C)
∈
ConductionSpeed(A
→
C))
THEN
act1
:
HeartState
:=
FA L S E
act2
:
HeartBlocks
:=
SA
_
nodal
_
blocks
END
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