Intensive Care: Learning Packages Intensive Care Unit
Pacemaker Learning Package LH_ICU2016_Learning_Package_Pacemaker_Learning_Package
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How do pacemakers work?
The pacemaker essentially does two things :
it senses the patient’s own rhythm using a “sensing circuit”,
It sends out electrical signals using an “output circuit”.
If the patient’s intrinsic rhythm becomes too slow or goes away
completely, the electronic pacemaker senses that, and starts sending
out signals along the wires leading from the pacing box to the heart
muscle.
The signals, if they’re “capturing” properly, provide a regular electrical
stimulus, making the heart contract at a rate fast enough to maintain
the patient’s blood pressure.
Pacemakers are not simply applied to the patient and turned on; we
must tell the pacemaker how to pace the heart.
The goal of pacing the heart is to maximize cardiac output. There are
two determinants of cardiac output; stroke volume and heart rate.
Pacemakers use the sensing and output circuits and then determine
the heart rate by timing and intervals
How do pacemakers determine heart rate? Before being able to understand pacemaker codes, it is necessary to have
an understanding of pacemaker timing.
INTERVALS AND TIMING Cardiac devices calculate everything in terms of intervals, from one event to
the next.The pacemaker does not keep track of how many beats the heart
has in a minute, it simply determines how long it has been since the last beat
has occurred.
Liverpool Hospital
Intensive Care: Learning Packages Intensive Care Unit
