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Chapter 2
•
Cardiovascular Care
Permanent Pacemaker Systems
Permanent pacemakers are fully
implanted in the body and connected
to the heart by one or two electrode
leads. The pacemaker is powered by
solid-state lithium batteries, which
usually last 5 to 10 years. Pacemakers
are programmable, there operating
characteristics can be changed by a
programmer that transmits specific
electromagnetic signals through the
skin.
Permanent Pacemaker
Pacemaker lead in external
jugular vein
Pacemaker lead tunneled
subcutaneously between
pacemaker and external
jugular vein
Generator placed beneath
skin in pectoral region
Tip of wire (electrode) lodged
in apex of right ventricle
Biventricular Pacemaker
A biventricular pacemaker uses three leads: one to pace the right atrium,
one to pace the right ventricle, and one to pace the left ventricle. The left
ventricular lead is placed in the coronary sinus. Both ventricles are paced at
the same time, causing them to contract simultaneously, improving cardiac
output.
Subclavian vein
Generator
Right atrial lead
Right atrium
Left ventricular lead
(in coronary sinus)
Left ventricle
Right ventricular lead
Right ventricle
Understanding
Pacemaker Codes
First Letter
The first letter of a pacemaker
code identifies the heart chambers
that are paced:
V
=
Ventricle
A
=
Atrium
D
=
Dual (ventricle and atrium)
O
=
None
Second Letter
The second letter signifies the heart
chamber where the pacemaker
senses the intrinsic activity:
V
=
Ventricle
A
= Atrium
D
= Dual
O
= None
Third Letter
The third letter shows the
pacemaker’s response to the
intrinsic electrical activity it senses
in the atrium or ventricle.
T
=
Triggers pacing
I
=
Inhibits pacing
D
=
Dual (can be triggered or
inhibited depending on the
mode and where intrinsic
activity occurs)
O
=
None (the pacemaker doesn’t
change its mode in response
to sensed activity)
Fourth Letter
The fourth letter signifies the
rate modulation ability of the
pacemaker (attempt to replicate
the ability of a normal heart to
increase heart rate in response to
metabolic demand).
R
=
Rate modulated
O
=
None
Fifth Letter
The fifth letter designates the
location of multisite pacing.
V
=
Ventricle
A
=
Atrium
D
=
Dual
O
=
None