Transcript Cardiac Pacemaker System

Cardiac Pacemaker System
Presented by:
Wong Shin Shin (KEU 98038)
McCartney Dandot (KEU 97010)
Scope of presentation
• Introduction
• A prelude: normal heart activity
• Pacemakers: its past history
– Conception of idea
– Invention process
– Clinical prototyping
• Pacemakers: Current development
• Pacemakers: its future trend
• Comment and conclusion
Introduction
• A pacemaker system is a device capable of
generating artificial pacing impulses and
delivering them to the heart.
• It consists of a pulse generator and
appropriate electrodes.
• In the past few years electronic pacemaker
systems have become extremely important in
saving and sustaining the lives of cardiac
patients whose normal pacing function of the
heart have been impaired.
Normal heart activity
Why need the pacemakers?
• Sometimes a heart's natural rhythm is
interrupted or becomes irregular- bradycardia
– The heart's natural pacemaker sends out electrical
impulses too slowly due to a diseased SA node.
– Or, the electrical impulses may be blocked along
the pathway through the heart, -"heart block."
– Symptoms: dizziness, extreme fatigue, shortness
of breath, or fainting spells.
• A pacemaker stimulates the heart muscle with
precisely timed discharges of electricity that
cause the heart to beat in a manner very
similar to a naturally occurring heart rhythm.
Pacemakers: its past history
Conception of idea
• Cloroform was popular in the late 1980s, but
when it was used, occasional respiratory and
cardiac arrest occurred, as an occasional
complication of cloroform anesthesia
• To restart the heart, Green in the United
Kingdom [1872] applied the output of a 300V
battery using hand-held electrodes applied to
the base of the neck and the lower left chest.
• Interestingly, the electrode applied to the
lower left chest stimulated the ventricles. The
other electrode applied to the base of the
neck delivered current to the phrenic nerve
and twitched the diaphragm, causing a brisk
inspiratory motion.
Invention process
• In 1882, Ziemssen in Germany applied
cardiac pacing to a 42-year-old woman who
had a large defect in the anterior left chest
wall following resection of an enchondroma.
• The heart was only covered by skin, on which
Ziemssen placed electrodes.
• Using induction-coil shocks, he paced the
heart with a stimulus frequency higher than
that of the normal heart rate.
Clinical prototyping
• Dr. Rune Elmqvist designed the world's first
implantable pacemaker. It included a pulse
generator delivering about two volts with an
impulse period of two milliseconds. The
original transistors showed large leakage
currents and were found not suitable.
• Problems of the early pacemakers: breakage
of electrode wires, short battery life, the need
for surgery for pacemaker and lead
implantation
• Chardack [1961] described a durable
electrode wire made from the alloy that is
used in the escapement spring of watches. It
was sutured to the epicardium, and a
thoracotomy was required.
• Within a year, Lillehei et al. [1960] reported the
use of right ventricular catheter electrodes with
an external pacemaker to pace 66 patients. The
pacemaker was built by Earl Bakken, a
biomedical engineer, the founder of Medtronic
Inc. in 1949, which soon became the pioneer
pacemaker company.
• The pacemaker manufactured is called the
Greatbatch-Chardack pacemaker. It consisted of
a transistor oscillator and an amplifier energized
by 10 mercury-zinc cells. The 10 cells and
electronic circuitry were potted in epoxy and
covered by a double shell of Silastic. The
electrode used was about the size of a postage
stamp
Earl's first wearable, battery-powered, transistorized
cardiac pacemaker
Invention process (cont.)
From Earl E. Bakken's Book "One Man's
Full life"
"Back at the garage, I dug out a back issue of Popular Electronics
magazine in which I recalled seeing a circuit for an electronic,
transistorized metronome. The circuit transmitted clicks through a
loudspeaker; the rate of the clicks could be adjusted to fit the music. I
simply modified that circuit and placed it, without the loudspeaker, in a
four-inch-square, inch-and-thick metal box with terminals and switches
on the outside - and that, as they say, was that. "
Schematic drawing of
a pacemaker
The pulse
generator
houses the
battery and the
circuitry, which
generates the
stimulus and
senses
electrical
activity.
The lead is
an
insulated
wire that
carries the
stimulus
from the
generator
to the heart
and relays
intrinsic
cardiac
signals
back to the
generator
A closer look at the pacemaker
The programmer is a telemetry
device used to provide two-way
communication between the
generator and the clinician. It
can alter the therapy delivered
by the pacemaker and retrieve
diagnostic data that are
essential for optimally titrating
that therapy.
Pacemaker today
Pacemaker: Current Development
• Comprise of 3 distinct components:
• Pulse generator
• Lead
• Programmer
• Come in different shapes and sizes
• Small and lightweight (~22-50gms)
• Depending upon patient’s heart condition,
physician will prescribe the number of
chambers to be paced and type of pacing
Number of Chambers
• A single-chamber pacemaker paces either
the right atrium or the right ventricle, with
one lead. Most common is the right
ventricle.
• A dual-chamber pacemaker paces both the
right atrium and right ventricle of the heart
with two pacing leads. Most common type
of pacemaker implanted today.
Single-chamber pacemaker
• Correct a slow or
unsteady heartbeat,
resulted from “heart
block”.
• Pacemaker lead will
ensure that the heart's
ventricles contract
rhythmically and fully.
A single-chamber
pacemaker placed in the
right ventricle of the heart
Single-chamber pacemaker model
available from Medtronic
• Rate responsive
• It has one or two
sensors that detect
changes in the heart
rate needs.
• It then adjust the heart
rate accordingly
Medtronic Kappa SR,
Series 400
Dual-chamber pacemaker
•
•
•
A dual-chamber
pacemaker with
two pacing leads
Senses both atrial and
ventricular activity to see if
pacing is needed
When pacing does occur, the
contraction of the atria is
followed closely by a
contraction in the ventricles
Resulting in timing that
mimics the heart's natural way
of working.
Dual–chamber pacemaker model
available from Medtronic
• Rate responsive
• It has one or two
sensors that detect
changes in the heart
rate needs.
• It then adjust the heart
rate accordingly
Medtronic Kappa DR,
Series 400
Rate-Responsive Pacemaker
• A rate-responsive pacemaker uses a or a
combination of special sensor(s):
– activity sensor
– minute ventilation sensor
• that recognizes body changes and helps the
heartbeat speed up or slow down to meet patient
body's changing needs for blood.
• It mimics patient heart's natural function.
• The physician has many options in programming
the pacemaker to respond to the patient normal
activities as illustrated in the next slide.



A normal heart rhythm slows down or speeds up
many times during the day.
The heart beats slower while resting or sleeping.
Exercise or emotional excitement make heart
beat faster because, in an excited state, the body
requires greater amounts of blood to be
circulated.
Successes of the Pacemaker
• Successfully implanted, since the late 1950s.
• More than 2 million people have been
benefited
• The development of new pacing
technologies since 1985 has opened the
door for significant improvements in
pacemaker wearers' quality of life
• by permitting greater tolerance for exercise
and participation in new activities.
Case study on the success of
Medtronic Kappa 400 Series
• One year after receiving a single sensor (minute
ventilation), single chamber pacemaker, a 69-year-old
patient was still having symptoms when exercising
• After implanting the Medtronic Kappa 400 Series
pacemaker, the patient was able to resume his
previous exercise regimen of rock climbing and
exercising at a gym.
• The integrated dual sensors (activity and minute
ventilation) of the Medtronic Kappa 400 Series
pacemakers provide heart rate support proportional to
a patient's metabolic demands.
Pacemakers: its future trend
• In future generations,
– developments in the field of microprocessor
technology will most likely lead to greater
flexibility in the self-adjustment of rate, output,
and the overall sensitivity of pacemakers.
– The continued innovation of programmability
and telemetry will increase the diagnostic
capabilities of pacemakers.
– Systems are being developed which can
facilitate storing of patient details and which can
diagnose
rhythm
disturbances
using
sophisticated algorithms.
– Sensors will be combined with electrogram
analysis to differentiate between physiological
and pathological alterations in hemodynamics
so that appropriate adjustments can be initiated.
Pacemakers: its future trend (cont.)
• Pacemaker technology that is self-adjusting will evolve
that can differentiate arrhythmias and initiate the
appropriate pacing modality.
• Progress in battery technology will reduce generator
size further without effects on longevity.
• Generator microprocessors will permit more flexible
programming of algorithms that will satisfy the patient's
changing requirements.
• A pacemaker may be reprogrammed or experience a
change in the sensing or pacing thresholds after a
shock from a defibrillator.
• In future generations, it is important that the pacemaker
be able to protect itself from excessive energy and
shocks caused by a defibrillator.
Comment and conclusion
• A pacemaker system is a device that sends
periodic impulses to the heart to restore the
rhythm of the heart.
• Early devices provided only single-chamber,
asynchronous, nonprogrammable pacing
coupled with questionable reliability and
longevity.
• Today, advanced electronics afford dualchamber multiprogrammability, diagnostic
functions, rate response, data collection, and
exceptional reliability, and lithium-iodine
power sources extend longevity to upward of
10 years.
Comment and conclusion (cont.)
• Such features have evidently improved the
management of patients with cardiac
problems such as bradycardia.
• The new diagnostic function can aid
clinicians to diagnose and keep track with
patient’s development.
• Continual advances in a number of clinical,
scientific, and engineering disciplines have
so expanded the use of pacing that it now
provides cost-effective benefits to an
estimated 350,000 patients worldwide each
year.
That’s all for our presentation…
Thank you very much for your
attention!