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Proceedings of The 20th World Multi-Conference on Systemics, Cybernetics and Informatics (WMSCI 2016)
PACEMAKER: An Insight Into the Artificial Heart Rhythm
Lubna Moin
Department of Engineering, Faculty of Electronics and Power Engineering, PNEC, National University of Sciences and
Technology, Islamabad, Pakistan
Vali Uddin
Department of Engineering, Faculty of Engineering Science and Technology Hamdard University, Karachi, Pakistan
Bhawany Shankar Chowdhry
Department of Engineering, Faculty of Engineering Science and Technology, Mehran University, Jamshooro, Pakistan
and
Attaullah Y. Memon
Department of Engineering, Faculty of Electronics and Power Engineering, PNEC, National University of Sciences and
Technology, Islamabad, Pakistan
70-80 times per minute building up the heart beat. Figure 1
illustrates the conduction system of the heart.
ABSTRACT
A pacemaker is a small battery powered device, which paces the
heart by sending an electrical impulse, to cause rhythmical
contraction of the heart muscle. Since the first artificial
pacemaker was introduced in 1932, much has changed and will
continue to change in future. The complexity and reliability of
modern pacemakers has increased significantly, mainly due to
development in the integrated circuit design. This paper
basically will discuss the electronic perspective of the
pacemakers, the advancements done in this regard and the
ongoing research to make it more competent, capable and
useful.
Keywords:
Cardiac
pacemaker,
integrated
electrocardiograph, biological pacemakers.
circuits,
Figure 1: Heart Conduction System [1]
The figure 2 drawn below illustrates a single heart beat. As
shown below the atrial depolarization gives rise to P wave. The
PR interval is due to the delay at AV node. It is measured from
the beginning of the P wave to the beginning of the QRS
complex. The QRS represent the rapid depolarization of the
right and the left ventricle. The ST segment delineates the
depolarization of the ventricles.
1. INTRODUCTION
The heart is bestowed with certain specialized cells meant for
two main purposes. First purpose is to provoke the rhythmical
electrical impulses that can cause co-ordinated contraction of
heart muscles. Second objective is the proper guidance of the
conduction of these impulses rapidly through the whole heart.
Under normal conditions the atria contracts about 1/6 th of a
second before the ventricular contraction, allowing the filling of
the ventricle for further pumping. An added importance of this
system is that it allows both the ventricles to contract
proximately at the same time which is necessary for compelling
pressure of the ventricles. These specialized cells are present in
Sinoatrial SA node present in the right atrium. The signal
generated in the cells of the SA node is conducted toward left
atrium through Bachman Bundle. The signals from SA node
travels downwards through Atrioventricular AV node. The AV
node transfers the signal to the ventricles in the form of HIS
Bundles and Purkinje Fibers. So the SA node, Bachman
Bundles, HIS Bundles and Purkinje Fibers together form the
conduction system of the heart. The signal generated in the cells
of the SA node is conducted toward left atrium and to AV node.
SA node is made up of a group of cells called myocytes. These
cells contract due to depolarization and repolarization at rate of
Figure 2: Typical Electrocardiogram [1]
Lastly the ventricular contraction is depicted by R wave. The
repolarization of ventricle is portrayed by T wave. All these
waves have different voltage peaks and duration as shown in
table 1 below
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Proceedings of The 20th World Multi-Conference on Systemics, Cybernetics and Informatics (WMSCI 2016)
Peak
Table 1: ECG Voltage Levels
Av. Voltage
Duration
P
0.25mv
R-P 488ms
R
1.6mv
R-R 833ms
T
0.1mv-0.5mv
R-T 145ms
It was noticed by a Canadian electrical engineer John Hopps
while investigating the upshots of radio frequency in 1941 that
if the heart abdicate generating pulses due to fall in temperature,
it can be proceeded to beat artificially using mechanical and
electrical stimulations.
This research confesses the evolution of the first cardiac
defibrillation machine in 1949. Hayman was the scientist who
designed the first experimental pacemaker in 1932. Hyman‟s
pacemaker was powered by a hand-wound spring driven
generator that provided 6 minutes of pace making without
rewinding. The block diagram of his pacemaker is given in
figure 5, shown below.
2. ARTIFICIAL PACEMAKER
Speed control
The pacemaker, or sinoatrial node, is responsible for controlling
heart rate. The cells of SA node are self firing cells. The
depolarization and repolarization action is analogous to the
relaxation oscillator if compared to electronic devices which is
used to produce a periodic flash from the source of light.
When the natural pacemaker does not function properly, the
heart can suffer from arrhythmias such as bradycardia (heart
pumps too slow), tachycardia (heart pumps too fast), or
irregular heartbeats. The most common way of taking care of
these conditions is by use of an artificial pacemaker that is
implanted with the heart, shown in figure 3. Artificial
pacemakers are the electronic devices that stimulate the heart by
generating electrical impulses to restore or maintain the normal
rhythm. The implanted pacemaker can send out an electrical
impulse similar to the one a natural pacemaker. It can control
the impulses sent out per minute with a computer chip and
circuitry [2].
Hand Crank
Winds up
Spring motor
Magneto-generator
Drives
Impulse control
Current
Drives
;
Interrupter Disc
Stimulus
Pulsed
current
Heart (Right Atrium)
Needle Electrode
Figure 5: Block diagram of Hyman‟s pacemaker [4]
The first implantable pacemaker was invented by Dr. Rune
Elmqvist in the year 1958. Later in 1959 engineer Wilson
Greatbatch and the cardiologist W.M Chardack developed first
fully implantable pacemaker. Engineer Wilson Greatbatch
while modeling an oscillator to record heart sounds negligently
fitted a wrong value resistor in his circuit. The whole circuitry
began output a pulse with a steady pace, just like a beating
heart. This was the discovery of the first implantable rhythm
maker. This pacemaker basically consists of a blocking
oscillator. A blocking oscillator is a simple configuration of
discrete electronic components which produce a free running
(moving smooth and uninterrupted), signal and consist of only a
resistor, a transformer and one amplifying transistor. It is shown
in figure 6 below. Here the target of blocking oscillator is to
produce a narrow pulse. The transistor of the blocking oscillator
is normally cut-off between non conduction phase of pulses and
conducting during the time that a pulse is generated. The
operation of the blocking oscillator during a single cycle can be
classified into three phases, turn on period, pulse period and
relaxation period. Such a pacemaker is also named
asynchronous pacemakers
Figure 3: Pacemaker and leads
Functionally, a pacemaker comprises at least three parts: a
electrical pulse generator, a power source (battery) and an
electrode (lead) system as indicated in figure 4 [3].
Power
Source
Pulse
Generator
Electrodes
Figure 4: Basic pacemaker functional block diagram
3. FIRST IMPLANTABLE PACEMAKER
Figure 6: Circuitry of first implantable pacemaker
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Proceedings of The 20th World Multi-Conference on Systemics, Cybernetics and Informatics (WMSCI 2016)
4. DEMAND PACEMAKER
Because they are set at fixed value and do not change with
demand of the patient. The rate of asynchronous
pacemaker may be altered by the physician, but once set it will
continue to generate an electric pulse at regular intervals. Most
are set at 70 to 75 beats per minute.
Later in 1964 Berkovits invented a demand pacemaker.
Demand pacemaker provides electrical impulses only in the
absence of natural heart beat. Other important aspect of the
demand pacemaker is the life span of the battery because it is
only activated when pacing stimulus is needed [27].
Fig 7: Block diagram of demand pacemaker [30]
The demand pacemakers are designed by adding a sensing
amplifier to the asynchronous pacemakers so that it can detect
congenital heart activity. This synchronous pacemaker has rate
responsive pacing modalities in respect to physiological
situations and pathological conditions [27].
Injecting a gene TB-18 into the heart can convert heart muscle
cells to pacemaker cells that can initiate a heartbeat. This
method could be useful for certain patients, such as those who
develop infections from electronic pacemakers and need to have
the devices temporarily removed, or with life-threatening heart
disorders who cannot have an electronic pacemaker implanted.
So far this technique is applied on animals and now the research
of inducing this gene into human body is in progress [26].
5. LEADLESS PACEMAKER
The entire pacemaker discussed above follow a surgical
cleavage in the chest under the collar base where the pacemaker
enduringly placed in a pocket inside the skin. The surgeon then
embeds leads from pacemaker through the veins into the right
ventricle. These leads convey electrical pulses that expedite the
heart to beat normally [28].
Contradictory to the Conventional pacemakers, leadless pace
meters are placed directly into the heart without any surgical
cleavage and passing on leads. The leadless pace meter are
much minor in size. It is a less invasive approach. It consists of
a pulse generator that includes a battery and a steroid eluding
electrode that sends the pulses to the heart whenever it senses
irregular heartbeats.
7. CONCLUSIONS
Artificial pacemakers are the electronic devices that stimulate
the heart by generating electrical impulses to restore or maintain
the normal rhythm. It controls the pumping action of the heart
restoring the communication between the atria and ventricles;
therefore it increases the survival capacity tremendously. It is
used to meet the challenge of branchardia, tachyarrhythmia. It
has the sensor which itself maintains the level of periodic
signal. It basically performs the following function:




Stimulate cardiac depolarization
Sense intrinsic cardiac function
Respond to increased metabolic demand by providing
rate responsive pacing
Provide diagnostic information stored by the
pacemaker
The pacemaker technology is an active area of research. The
field is developing each year, starting from a lab setup of huge
pacemaker to the implantable lead pacemaker. Then the lead
less pacemakers arrived and now the biological pacemakers are
making their approach. There is also some risk or
disadvantages. Sometimes the risk factor arises due to high
threshold of cardiac excitation, battery failure or
electromagnetic interference. Sometimes the air on bubble
occurs in the space between lungs and chest wall. The
perforation of the heart might also take place. But new
Figure 8: Leadless Pacemaker [29]
6. BIOLOGICAL PACEMAKERS
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researches are in progress to overcome the stated problems
regarding artificial pacemaker.
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8. ACKNOWLEDGEMENTS
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I am very grateful to Dr. Faisal Qadir of The National Institute
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