Cardiac Pacemaker System

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Cardiac Pacemaker System

• Presented by
• Wong Shin Shin (KEU 98038)
• McCartney Dandot (KEU 97010)

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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

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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.

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Normal heart activity
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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.

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Pacemakers its past historyConception 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.

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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.

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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.

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• 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

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Earl's first wearable, battery-powered,
transistorized cardiac pacemaker
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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. "

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Schematic drawing of a pacemaker
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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.
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Pacemaker today
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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 patients heart condition,
  physician will prescribe the number of chambers
  to be paced and type of pacing

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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.

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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
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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
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Dual-chamber pacemaker

• 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.

A dual-chamber pacemaker with two pacing leads
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Dualchamber 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
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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.

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• 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.

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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.

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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.

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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.

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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.

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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 dual-chamber
  multiprogrammability, diagnostic functions, rate
  response, data collection, and exceptional
  reliability, and lithium-iodine power sources
  extend longevity to upward of 10 years.

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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 patients
  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.

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Thats all for our presentation

• Thank you very much for your
• attention!