Pacemakers and
Implanted Defibrillators
Mike Harlan
History
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Pacemakers
– It is believed that Dr. Albert Hyman was inventor of first
pacemaker
– First fully functional wearable pacemaker developed in 1957
– First implanted pacemaker 1960
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ICD’s
– First implantable ICD developed by Michel Mirowski, first used in
a human in 1980
– FDA approved use of ICD’s in 1985
Artificial Pacemakers
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An internal artificial pacemaker is a
small battery-operated device that
helps the heart beat in a regular
rhythm
An electrode is placed next to the
heart wall, and small electrical
charges travel through the wire to
the heart (usually the right side),
causing it to contract.
Most modern pacemakers have a
sensing device that turns the
pacemaker off when the natural
heartbeat is above a certain level
Types of Pacemakers
Fixed-rate – fires continuously at a preset rate
 Demand – contain a sensing device, fire only
when heart rate drops below a set rate
 Dual-chambered – stimulates the atria first and
then the ventricle
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Pacemaker Indications
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Absolute Indications
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Sick sinus rhythm
Symptomatic sinus bradycardia
Tachy-brady syndrome
Atrial Fibrillation with slow ventricular response
Third Degree Heart Block
Chronotropic incompetence
Prolonged QT syndrome
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Relative Indications
– Cardiomyopathy
– Severe refractory neurocardiogenic syncope
– Paroxysmal atrial fibrillation
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Results of a recent study showed that pt’s with
pacemakers had a one-year recurrence rate of
syncope of 19%, compared to 60% of pt’s in the
control group
Pacemaker Complications
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Infection
Thrombophlebitis
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Pacemaker Syndrome
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Blood clot causes inflammation in vein
Phenomenon where a pt. feels worse after
pacemaker placement and presents with
progressive worsening of symptoms of CHF
Failure to output
Failure to capture
Failure to sense correctly
Internal Cardiac Defibrillators
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ICD’s have wires connecting to one or more heart
chambers. The wires monitor heart rhythm and deliver
shocks to the heart when abnormal rhythm is sensed.
Single chamber ICD’s – wires connect to one or both
ventricles
Dual-chamber ICD’s – wires connect to both an atrium
and a ventricle
Wires of an ICD connect to small metal box that contains
a battery, pulse generator, and computer
ICD’s are indicated for pt’s with hx of life-threatening
ventricular tachyarrhythmias or VF
A recent study showed that pt’s that received an ICD
had a 31% reduction in mortality rate.
ICD complications
Most common problem
is that they shock when
not needed. This can
damage the heart or
trigger an irregular
heartbeat
 Swelling, bruising, or
infection after surgery
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Treatment of pt’s with pacemakers or ICD’s
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The presence of a pacemaker or ICD does not alter the
emergency treatment of patients
Defibrillation, cardioversion, and pacing can be
performed on pt’s with pacemakers or ICD’s
– Try to place pads a safe distance (10cm) from a
pacemaker or ICD if possible, but don’t delay
treatment
– A magnet can be placed over the pulse generator to
reset the pacemaker to a predetermined rate. This is
indicated if a pt. has a runaway pacemaker
References
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Bledsoe B, Porter R, Cherry R. Essentials of Paramedic
Care. Second Edition. Prentice Hall; 2007
http://emedicine.medscape.com/article/780825-print
http://www.nhlbi.nih.gov/health/dci/Diseases/icd.html
http://emedicine.medscape.com/article/162245-overview
Gregoratos G, Indications and Recommendations for
Pacemaker Therapy. American Family Physician, 2005