On the nanoscale (1-100 nm), viscosity dominates inertia, and the extremely high degree of thermal noise in the environment makes conventional directed motion all but impossible, because the forces impelling these motors in the desired direction are minuscule when compared to the random forces exerted by the environment. Brownian motors operate specifically to utilise this high level of random noise to achieve directed motion, and as such are only viable on the nanoscale.
The concept of Brownian motors is a recent one, having only been coined in 1995 by Peter Hänggi, but the existence of such motors in nature may have existed for a very long time and help to explain crucial cellular processes that require movement at the nanoscale, such as protein synthesis and muscular contraction. If this is the case, Brownian motors may have implications for the foundations of life itself.
In more recent times, humans have attempted to apply this
knowledge of natural Brownian motors to solve human problems. The
applications of Brownian motors are most obvious in nanorobotics due to its inherent reliance on directed motion.
History
20th century
This
is a simulation of the Brownian motion of a big particle (dust
particle) that collides with a large set of smaller particles (molecules
of a gas) which move with different velocities in different random
directions.
The term “Brownian motor” was originally invented by Swiss theoretical physicist Peter Hänggi in 1995.[3]
The Brownian motor, like the phenomenon of Brownian motion that
underpinned its underlying theory, was also named after 19th century
Scottish botanist Robert Brown, who, while looking through a microscope at pollen of the plantClarkia pulchella
immersed in water, famously described the random motion of pollen
particles in water in 1827. In 1905, almost eighty years later, theoretical physicistAlbert Einstein published a paper where he modeled the motion of the pollen as being moved by individual water molecules,[6] and this was verified experimentally by Jean Perrin in 1908, who was awarded the Nobel Prize in Physics in 1926 "for his work on the discontinuous structure of matter".[7] These developments helped to create the fundamentals of the present theories of the nanoscale world.
Nanoscience has traditionally long remained at the intersection of the physical sciences of physics and chemistry, but more recent developments in research increasingly position it beyond the scope of either of these two traditional fields.
21st century
In 2002, a seminal paper on Brownian motors published in the American Institute of Physics magazine Physics Today, "Brownian motors", by Dean Astumian and Peter Hänggi.
There, they proposed the then novel concept of Brownian motors and
posited that "thermal motion combined with input energy gives rise to a
channeling of chance that can be used to exercise control over
microscopic systems". Astumian and Hänggi provide in their paper a copy
of Wallace Stevens' 1919 poem, The Place of the Solitaries to elegantly illustrate, from an abstract perspective, the ceaseless nature of noise.
Inspired
by the fascinating mechanism by which proteins move in the face of
thermal noise, many physicists are working to understand molecular
motors at a mesoscopic scale. An important insight from this work is
that, in some cases, thermal noise can assist directed motion by
providing a mechanism for overcoming energy barriers. In those cases,
one speaks of “Brownian motors.” In this article, we focus on several
examples that bring out some prominent underlying physical concepts that
have emerged. But first we note that poets, too, have been fascinated
by noise; see box 1.
...
In the microscopic world, “There must be no cessation / Of motion, or of
the noise of motion” (box 1). Rather than fighting it, Brownian motors
take advantage of the ceaseless noise to move particles efficiently and
reliably.
— Dean Astumian and Peter Hänggi, "Brownian Motors"
A year after the Astumian-Hänggi paper, David Leigh's organic chemistry group reported the first artificial molecular Brownian motors. In 2007 the same team reported a Maxwell's Demon-inspired molecular information ratchet.
Another important demonstration of nanoengineering and nanotechnology was the building of a practical artificial Brownian motor by IBM in 2018. Specifically, an energy landscape was created by accurately shaping a nanofluidic slit, and alternate potentials and an oscillating electric field were then used to “rock” nanoparticles to produce directed motion. The experiment successfully made the nanoparticles
move along a track in the shape of the outline of the IBM logo, and
serves as an important milestone in the practical use of Brownian motors
and other elements at the nanoscale.
The Sydney Nanoscience Hub, a AU$150 million purpose-built facility for nanoscale research and education.
Nanoscience research within the
Swiss Nanoscience Institute (SNI) is focused on areas of potential
benefit to the life sciences, sustainability, and information and
communications technologies. The aim is to explore phenomena at a
nanoscale and to identify and apply new pioneering principles. This
involves researchers immersing themselves in the world of individual
atoms and molecules. At this level, the classical disciplines of
physics, biology and chemistry merge into one. Interdisciplinary
collaboration between different branches of science and institutions is
thus a key element of the SNI’s day-to-day work.
— Swiss Nanoscience Institute, The University of Basel Website
Theory
The ratchet model serves as a theoretical underpinning of the Brownian motor.
The thermal noise on the nanoscale is so great that moving in a particular direction is as difficult as “walking in a hurricane” or “swimming in molasses”. The theoretical operation of the Brownian motor can be explained by ratchet theory, wherein strong random thermal fluctuations are allowed to move the particle in the desired direction, while energy is expended to counteract forces that would produce motion
in the opposite direction. This motion can be both linear and
rotational. In the biological sense and in the extent to which this
phenomenon appears in nature, this exists as chemical energy is sourced from the molecule adenosine triphosphate (ATP).
Because Brownian motors rely on the random nature of thermal noise to achieve directed motion, they are stochastic in nature, in that they can be analysed statistically but not predicted precisely.
Researchers have made significant advances in terms of examining these organic processes to gain insight into their inner workings. For example, molecular Brownian motors in the form of several different types of protein exist within humans. Two common biomolecular Brownian motors are ATP synthase, a rotary motor, and myosin II, a linear motor. The motor protein ATP synthase produces rotational torque that facilitates the synthesis of ATP from Adenosine diphosphate (ADP) and inorganic phosphate (Pi) through the following overall reaction:
Proteins acting as Brownian motors inside human cells
ATP Synthase
Myosin II
Kinesin
Applications
Nanorobotics
The relevance of Brownian motors to the requirement of directed motion in nanorobotics has become increasingly apparent to researchers from both academia and industry.
Artificial replication of Brownian motors are informed by and
differ from nature, and one specific type is the photomotor, wherein the
motor switches states due to pulses of light and generates directed motion. These photomotors, in contrast to their natural counterpartsˇ, are inorganic and possess greater efficiency and average velocity, and are thus better suited to human use than existing alternatives, such as organic protein motors.
Currently, one of the six current "Grand Challenges" of the University of Sydney Nano Institute is to develop nanorobotics for health, a key aspect of which is a “nanoscale parts foundry” that can produce nanoscale Brownian motors for “active transport around the body”. The Institute predicts that among the implications of this research is a "paradigm shift" in healthcare "away from the "break-fix" model to a focus on prevention and early intervention," such as in the case with heart disease:
The molecular-level changes in
early heart disease occur on the nanoscale. To detect these changes, we
are building nanoscale robots, smaller than cells, that will navigate
the body. This will enable us to see inside even the narrowest blood
vessels, to detect the fatty deposits (atherosclerotic plaque) that
signal the start of arterial blockage and allow treatment before the
disease progresses.
The impact of this project will be extensive. It will improve health
outcomes for all Australians with heart disease and reduce healthcare
costs. It has potential to benefit other health challenges, including
cancer, dementia and other neurodegenerative diseases. It will provide a
world-class collaborative environment to train the next generation of
Australian researchers, driving innovation and development of new
industries and jobs in Australia.
Professor Paul Bannon, an adult cardiothoracic surgeon of international standing and leading medical researcher, summarises the benefits of nanorobotics in health.
If I could miniaturise myself
inside the body... I could detect early, treatable damage in your
coronary arteries when you are 25 years old and thus avoid your
premature death.
Transgenerational design is the practice of making products and environments compatible with those physical and sensoryimpairments associated with human aging and which limit major activities of daily living. The term transgenerational design was coined in 1986, by Syracuse University industrial design professor James J. Pirkl to describe and identify products and environments that accommodate, and appeal to, the widest spectrum of those who would use them—the young, the old, the able, the disabled—without penalty to any group.
The transgenerational design concept emerged from his federally funded design-for-aging research project, Industrial design Accommodations: A Transgenerational Perspective. The project's two seminal 1988 publications provided detailed information about the aging process; informed and sensitized industrial design
professionals and design students about the realities of human aging;
and offered a useful set of guidelines and strategies for designing
products that accommodate the changing needs of people of all ages and
abilities.
Overview
The
transgenerational design concept establishes a common ground for those
who are committed to integrating age and ability within the consumer
population. Its underlying principle is that people, including those who
are aged or impaired, have an equal right to live in a unified society.
Transgenerational design practice recognizes that human aging is a continuous, dynamic process that starts at birth and ends with death, and that throughout the aging process, people normally experience occurrences of illness, accidents and declines in physical and sensory abilities that impair one's independence and lifestyle.
But most injuries, impairments and disabilities typically occur more
frequently as one grows older and experiences the effects of senescence (biological aging). Four facts clarify the interrelationship of age with physical and sensory vulnerability:
young people become old
young people can become disabled
old people can become disabled
disabled people become old
Within each situation, consumers expect products and services to
fulfill and enhance their lifestyle, both physically and symbolically.
Transgenerational design focuses on serving their needs through what
Cagan and Vogel call "a value oriented product development process".
They note that a product is "deemed of value to a customer if it offers
a strong effect on lifestyle, enabling features, and meaningful
ergonomics" resulting in products that are "useful, usable, and desirable" during both short and long term use by people of all ages and abilities.
Transgenerational design is "framed as a market-aware response to
population aging that fulfills the need for products and environments
that can be used by both young and old people living and working in the
same environment".
Benefits
Transgenerational
design benefits all ages and abilities by creating a harmonious bond
between products and the people that use them. It satisfies the psychological, physiological, and sociological factors desired—and anticipated—by users of all ages and abilities:
Transgenerational design addresses each element and accommodates the
user—regardless of age or ability—by providing a sympathetic fit and
unencumbered ease of use. Such designs provide greater accessibility by
offering wider options and more choices, thereby preserving and
extending one's independence, and enhancing the quality of life for all ages and abilities—at no group's expense.
responding to the widest range of individual differences
helping people remain active and independent
adapting to changing sensory and physical needs
maintaining one's dignity and self-respect
enabling one to choose the appropriate means to accomplish activities of daily living
History
Transgenerational design emerged during the mid-1980s coincident with the conception of universal design, an outgrowth of the disability rights movement and earlier barrier-free concepts. In contrast, transgenerational design grew out of the Age Discrimination Act of 1975,
which prohibited "discrimination on the basis of age in programs and
activities receiving Federal financial assistance", or excluding,
denying or providing different or lesser services on the basis of age.
The ensuing political interest and debate over the Act's 1978
amendments, which abolished mandatory retirement at age 65, made the
issues of aging a major public policy concern by injecting it into the mainstream of societal awareness.
Background
At the start of the 1980s, the oldest members of the population, having matured during the great depression, were being replaced by a generation of Baby Boomers, steadily reaching middle age and approaching the threshold of retirement. Their swelling numbers signaled profound demographic changes ahead that would steadily expand the aging population throughout the world.
Advancements in medical research were also changing the image of old age—from a social problem of the sick, poor, and senile, whose solutions depend on public policy—to the emerging reality of an active aging population having vigor, resources, and time to apply both.
Responding to the public's growing awareness, the media, public
policy, and some institutions began to recognize the impending
implications. Time and Newsweek devoted cover stories to the "Greying of America". Local radio stations began replacing their rock-and-roll formats with music targeted to more mature tastes. The Collegiate Forum (Dow Jones & Co., Inc.) devoted its Fall 1982 issue entirely to articles on the aging work force. A National Research Conference on Technology and Aging, and the Office of Technological Assessment of the House of Representatives, initiated a major examination of the impact of science and technology on older Americans”.
In 1985, the National Endowment for the Arts, the Administration on Aging, the Farmer's Home Administration, and the Department of Housing and Urban Development
signed an agreement to improve building, landscape, product and graphic
design for older Americans, which included new research applications
for old age that recognized the potential for making products easier to use by the elderly, and therefore more appealing and profitable.
Development
In 1987, recognizing the implications of population aging, Syracuse University’s Department of Design, All-University Gerontology Center, and Center for Instructional Development initiated and collaborated on an interdisciplinary project, Industrial Design Accommodations: A Transgenerational Perspective. The year-long project, supported by a Federal grant, joined the knowledge base of gerontology with the professional practice of industrial design.
The project defined "the three aspects of aging as physiological, sociological, and psychological; and divided the designer’s responsibility into aesthetic, technological, and humanistic concerns".
The strong interrelationship between the physiological aspects of aging and industrial design's humanistic
aspects established the project's instructional focus and categorized
the physiological aspects of aging as the sensory and physical factors
of vision, hearing, touch, and movement. This interrelationship was translated into a series of reference tables, which related specific physical and sensory factors of aging, and were included in the resulting set of design guidelines to:
sensitize designers and design students to the aging process
provide them with appropriate knowledge about this process
accommodate the changing needs of our transgenerational population
The project produced and published two instructional manuals—one for instructors and one for design professionals—each
containing a detailed set of "design guidelines and strategies for
designing transgenerationalproducts". Under terms of the grant,
instructional manuals were distributed to all academic programs of
industrial design recognized by the National Association of Schools of Art and Design (NASAD).
Chronology
1988: The term ‘transgenerational design’ first appears to have been publicly recognized and acknowledged by the Bristol-Myers
Company in its annual report, which stated, "The trend towards
transgenerational design seems to be catching on in some fields", noting
that “transgenerational design has the added advantage of circumventing
the stigmatizing label of being ‘old’ ”.
1989: The results of the 1987 Federal grant project were first presented at the national conference, Exploration: Technological Innovations for an Aging Population, supported in part by the American Association of Retired Persons (AARP) and the National Institute on Aging.
The proceedings focused “on current efforts to address the impact of
technology and an aging population, identification of high impact issues
and problems, innovative ideas, and potential solutions”.
Also in 1989 Design News, the Japanese design magazine, introduced “the new concept of transgenerational design
(for) coping with the needs of an aging population and its strategy”,
stating that “the impact will soon be felt by all global institutions”
and “alter the present course of industrial design practice and
education”.
1990: The OXO company introduced the first group of 15 Good Grips
kitchen tools to the U.S. Market. “These ergonomically-designed,
transgenerational tools set a new standard for the industry and raised
the bar to consumer expectation for comfort and performance”.
Sam Farber, OXOs founder, stated that “population trends demand
transgenerational products, products that will be useful to you
throughout the course of your life” because “it extends the life of a
product and its materials by anticipating the whole experience of the
user”.
1991: The Fall issue of the Design Management Journal
addressed the issue of “Responsible Design” and introduced the
transgenerational design concept in the article, “Transgenerational
Design: A Strategy Whose Time Has Arrived”. The article presented a
description, the rationale, and examples of early transgenerational
products, and offered “insights on the rationale and benefits of such a
transgenerational approach”.
1993: The September–October issue of ‘’AARP
The Magazine’’ exposed the transgenerational design concept to the
readers in a featured article, “This Bold House”, describing the
concept, details, and benefits of a transgenerational house. The article
noted that “easy-grip handles, flat thresholds, and adjustable-height
vanities are just the beginning in the world’s most accessible house,”
providing families of all ages and abilities with “what they will want
and need their whole lives”.
In November, the transgenerational design concept was introduced in
presentations to the European design community at the international
symposiums, “Designing for Our Future Selves”, held at the Royal College of Art in London and the Netherlands Design Institute in Rotterdam.
1994: The book, Transgenerational Design: Products for an Aging Population
(Pirkl 1994), may be regarded as the prime mover of the widespread
acceptance and practice of the transgenerational design concept. It
presented the first specialized content and photographic examples of
transgenerational products and environments, offering “practical
strategies in response to population aging, along with case study examples based on applying a better understanding of age-related capabilities”. It introduced the transgenerational design concept to the international design and gerontology
communities, broadening the conventional idea of “environmental
support” to include the product environment, sparking scholarly
discussions and comparisons with other emerging concepts: (universal design, design for all, inclusive design, and gerontechnology).
1995: The transgenerational design concept was presented at
the first of the ‘’International Guest Lecture Series by World
Experts’’, sponsored by the European Design for Aging Network (DAN) held consecutively at five international symposiums, “Designing for Our Future Selves”: Royal College of Art, London, November 15; Eindhoven University of Technology, Eindhoven, November 16–19; The Netherlands Design Institute, Amsterdam, November 21; University of Art and Design, Helsinki, November 23–25; and National College of Art and Design, Dublin, November 26–29.
2000: “The Transgenerational House: A Case Study in
Accessible Design and Construction” was presented in June at ‘’Designing
for the 21st Century: An International Conference on Universal
Design’’, held at the Rhode Island College of Art and Design,
Providence, RI.
2007:Architectural Graphic Standards, published by the American Institute of Architects and commonly referred to as the “architects bible”, presented a “Transgenerational House” case study in its "Inclusive Design"
section. Described as an “intricate exploration in how the execution of
detailed thought can create a living environment that serves the young
and old alike, across generations”, the study includes plans for the
room layout, kitchen, laundry, master bath, adjustable-height vanity,
and roll-in shower.
2012: The proliferation of transgenerational design has
diminished the tendency to associate age and disability with deficit,
decline and incompetence by providing a market-aware response to
population aging and the need for living and work environments used by
young and old people living and working in the same environment.
Continuing to emerge as a growing strategy for developing products,
services and environments that accommodate people of all ages and
abilities, "transgenerational design has been adopted by major
corporations, like Intel, Microsoft and Kodak”
who are “looking at product development the same way as designing
products for people with visual, hearing and physical impairments,” so
that people of any age can use them.
Discussions between designers and marketers are indicating that
successful transgenerational design “requires the right balance of
upfront research work, solid human factors analysis, extensive design
exploration, testing and a lot of thought to get it right”, and that
“transgenerational design is applicable to any consumer products
company—from appliance manufacturers to electronics companies, furniture
makers, kitchen and bath and mainstream consumer products companies”.
The primary purpose of a pacemaker is to maintain an adequate heart rate, either because the heart's natural pacemaker is not fast enough, or because there is a block
in the heart's electrical conduction system. Modern pacemakers are
externally programmable and allow a cardiologist to select the optimal
pacing modes for individual patients. Most pacemakers are on demand, in
which the stimulation of the heart is based on the dynamic demand of the
circulatory system. Others send out a fixed rate of impulses.
An ECG in a person with a single-chamber pacemaker to the atrium. Note the circle around one of the sharp electrical spikes in the position where the P wave would be expected.An ECG of a person with a dual-chamber pacemaker
Percussive pacing
Percussive
pacing, also known as transthoracic mechanical pacing, is the use of
the closed fist, usually on the left lower edge of the sternum over the right ventricle in the vena cava, striking from a distance of 20 – 30 cm to induce a ventricular beat (the British Journal of Anaesthesia
suggests this must be done to raise the ventricular pressure to
10–15 mmHg to induce electrical activity). This is an old procedure used
only as a life-saving means until an electrical pacemaker is brought to
the patient.
Transcutaneous pacing (TCP), also called external pacing, is
recommended for the initial stabilization of hemodynamically significant
bradycardias
of all types. The procedure is performed by placing two pacing pads on
the patient's chest, either in the anterior/lateral position or the
anterior/posterior position. The rescuer selects the pacing rate, and
gradually increases the pacing current (measured in mA) until electrical
capture (characterized by a wide QRS complex with a tall, broad T wave on the ECG)
is achieved, with a corresponding pulse. Pacing artifact on the ECG and
severe muscle twitching may make this determination difficult. External
pacing should not be relied upon for an extended period of time. It is
an emergency procedure that acts as a bridge until transvenous pacing or
other therapies can be applied.
ECG
rhythm strip of a threshold determination in a patient with a temporary
(epicardial) ventricular pacemaker. The epicardial pacemaker leads were
placed after the patient collapsed during aortic valve surgery. In the first half of the tracing, pacemaker stimuli at 60 beats per minute result in a wide QRS complex with a right bundle branch block pattern. Progressively weaker pacing stimuli are administered, which results in asystole
in the second half of the tracing. At the end of the tracing,
distortion results from muscle contractions due to a (short) hypoxic seizure. Because decreased pacemaker stimuli do not result in a ventricular escape rhythm, the patient can be said to be pacemaker-dependent and needs a definitive pacemaker.
Temporary epicardial pacing is used during open heart surgery should
the surgical procedure create atrio-ventricular block. The electrodes
are placed in contact with the outer wall of the ventricle (epicardium)
to maintain satisfactory cardiac output until a temporary transvenous
electrode has been inserted.
Transvenous pacing, when used for temporary pacing, is an alternative
to transcutaneous pacing. A pacemaker wire is placed into a vein, under
sterile conditions, and then passed into either the right atrium or
right ventricle. The pacing wire is then connected to an external
pacemaker outside the body. Transvenous pacing is often used as a bridge
to permanent pacemaker placement. It can be kept in place until a
permanent pacemaker is implanted or until there is no longer a need for a
pacemaker and then it is removed.
Right
atrial and right ventricular leads as visualized under x-ray during a
pacemaker implant procedure. The atrial lead is the curved one making a U
shape in the upper left part of the figure.
Permanent transvenous pacing
Permanent
pacing with an implantable pacemaker involves transvenous placement of
one or more pacing electrodes within a chamber, or chambers, of the
heart, while the pacemaker is implanted under the skin below the
clavicle. The procedure is performed by incision of a suitable vein into
which the electrode lead
is inserted and passed along the vein, through the valve of the heart,
until positioned in the chamber. The procedure is facilitated by fluoroscopy
which enables the physician to view the passage of the electrode lead.
After satisfactory lodgement of the electrode is confirmed, the opposite
end of the electrode lead is connected to the pacemaker generator.
There are three basic types of permanent pacemakers, classified according to the number of chambers involved and their basic operating mechanism:
Single-chamber pacemaker. In this type, only one pacing lead is placed into a chamber of the heart, either the atrium or the ventricle.
Dual-chamber pacemaker. Here, wires are placed in two
chambers of the heart. One lead paces the atrium and one paces the
ventricle. This type more closely resembles the natural pacing of the
heart by assisting the heart in coordinating the function between the
atria and ventricles.
Biventricular pacemaker. This pacemaker has three wires
placed in three chambers of the heart. One in the atrium and two in
either ventricle. It is more complicated to implant.
Rate-responsive pacemaker. This pacemaker has sensors that
detect changes in the patient's physical activity and automatically
adjust the pacing rate to fulfill the body's metabolic needs.
The pacemaker generator is a hermetically sealed device containing a power source, usually a lithium battery,
a sensing amplifier which processes the electrical manifestation of
naturally occurring heart beats as sensed by the heart electrodes, the computer logic for the pacemaker and the output circuitry which delivers the pacing impulse to the electrodes.
Most commonly, the generator is placed below the subcutaneous fat
of the chest wall, above the muscles and bones of the chest. However,
the placement may vary on a case-by-case basis.
The outer casing of pacemakers is so designed that it will rarely be rejected by the body's immune system. It is usually made of titanium, which is inert in the body.
Leadless pacing
Leadless
pacemakers are devices that are as small as a capsule and are small
enough to allow the generator to be placed within the heart, therefore
avoiding the need for pacing leads.
As pacemaker leads can fail over time, a pacing system that avoids
these components offers theoretical advantages. Leadless pacemakers can
be implanted into the heart using a steerable catheter fed into the femoral vein via an incision in the groin.
Modern pacemakers usually have multiple functions. The most basic
form monitors the heart's native electrical rhythm. When the pacemaker
wire or "lead" does not detect heart electrical activity in the chamber –
atrium or ventricle – within a normal beat-to-beat time period – most
commonly one second – it will stimulate either the atrium or the
ventricle with a short low voltage pulse. If it does sense electrical
activity, it will hold off stimulating. This sensing and stimulating
activity continues on a beat by beat basis and is called "demand
pacing". In the case of a dual-chamber device, when the upper chambers
have a spontaneous or stimulated activation, the device starts a
countdown to ensure that in an acceptable – and programmable – interval,
there is an activation of the ventricle, otherwise again an impulse
will be delivered.
The more complex forms include the ability to sense and/or stimulate both the atrial and ventricular chambers.
The revised NASPE/BPEG generic code for antibradycardia pacing
I
II
III
IV
V
Chamber(s) paced
Chamber(s) sensed
Response to sensing
Rate modulation
Multisite pacing
O = None
O = None
O = None
O = None
O = None
A = Atrium
A = Atrium
T = Triggered
R = Rate modulation
A = Atrium
V = Ventricle
V = Ventricle
I = Inhibited
V = Ventricle
D = Dual (A+V)
D = Dual (A+V)
D = Dual (T+I)
D = Dual (A+V)
From this the basic ventricular "on demand" pacing mode is VVI or
with automatic rate adjustment for exercise VVIR – this mode is suitable
when no synchronization with the atrial beat is required, as in atrial
fibrillation. The equivalent atrial pacing mode is AAI or AAIR which is
the mode of choice when atrioventricular conduction is intact but the sinoatrial node of the natural pacemaker is unreliable – sinus node disease (SND) or sick sinus syndrome. Where the problem is atrioventricular block
(AVB) the pacemaker is required to detect (sense) the atrial beat and
after a normal delay (0.1–0.2 seconds) trigger a ventricular beat,
unless it has already happened – this is VDD mode and can be achieved
with a single pacing lead with electrodes in the right atrium (to sense)
and ventricle (to sense and pace). These modes AAIR and VDD are unusual
in the US but widely used in Latin America and Europe.
The DDDR mode is most commonly used as it covers all the options though
the pacemakers require separate atrial and ventricular leads and are
more complex, requiring careful programming of their functions for
optimal results.
Automatic pacemakers are designed to be over-ridden by the
heart's natural rate at any moment that it gets back to a non-pathologic
normal sinus rhythm and can reinitiate influencing the electric activity in the heart when the pathologic event happens again. A "ventricular-demand pacemaker" produces a narrow vertical spike on the ECG, just before a wide QRS. The spike of an "atrial-demand pacemaker" appears just before the P wave.
Comparably, a Triggered Pacemaker is activated immediately
after an electrical activity is commenced in the heart tissue by
itself. A "ventricular triggered pacemaker" produces the impulse just
after a pulse is created in the ventricular tissue and it appears as a
simultaneous spike with QRS. An "atrial triggered pacemaker" is the mode
in which an impulse is produced immediately after an electrical event
in the atrium. It appears as a discharge following the p wave but prior to the QRS which is commonly widened.
Biventricular pacing
Three
leads can be seen in this example of a cardiac resynchronization
device: a right atrial lead (solid black arrow), a right ventricular
lead (dashed black arrow), and a coronary sinus lead (red arrow). The
coronary sinus lead wraps around the outside of the left ventricle,
enabling pacing of the left ventricle. Note that the right ventricular
lead in this case has two thickened aspects that represent conduction
coils and that the generator is larger than typical pacemaker
generators, demonstrating that this device is both a pacemaker and a
cardioverter-defibrillator, capable of delivering electrical shocks for
dangerously fast abnormal ventricular rhythms.
Cardiac resynchronization therapy (CRT) is used for people with heart failure in whom the left and right ventricles do not contract simultaneously (ventricular dyssynchrony),
which occurs in approximately 25–50% of heart failure patients. To
achieve CRT, a biventricular pacemaker (BVP) is used, which can pace
both the septal and lateral walls of the left ventricle. By pacing both sides of the left ventricle, the pacemaker can resynchronize the ventricular contractions.
CRT devices have at least two leads, one passing through the vena cava and the right atrium into the right ventricle to stimulate the septum, and another passing through the vena cava and the right atrium and inserted through the coronary sinus
to pace the epicardial wall of the left ventricle. Often, for patients
in normal sinus rhythm, there is also a lead in the right atrium to
facilitate synchrony with the atrial contraction. Thus, the timing
between the atrial and ventricular contractions, as well as between the
septal and lateral walls of the left ventricle can be adjusted to
achieve optimal cardiac function.
CRT devices have been shown to reduce mortality and improve
quality of life in patients with heart failure symptoms; a LV ejection
fraction less than or equal to 35% and QRS duration on EKG of 120 ms or
greater.
Biventricular pacing alone is referred to as CRT-P (for pacing).
For selected patients at risk of arrhythmias, CRT can be combined with
an implantable cardioverter-defibrillator
(ICD): such devices, known as CRT-D (for defibrillation), also provide
effective protection against life-threatening arrhythmias.
Conduction System Pacing
Conventional placement of ventricular leads in or around the tip or apex
of the right ventricle, or RV apical pacing, can have negative effects
on heart function. It has been associated with increased risk of atrial fibrillation, heart failure, weakening of the heart muscle and potentially shorter life expectancy. His bundle pacing
(HBP) leads to a more natural or perfectly natural ventricular
activation and has generated strong research and clinical interest. By
stimulating the His–Purkinje
fiber network directly with a special lead and placement technique, HBP
causes a synchronized and therefore more effective ventricular
activation and avoids long-term heart muscle disease. HBP in some cases
can also correct bundle branch block patterns.
Advancements in function
Posteroanterior and lateral chest radiographs
of a pacemaker with normally located leads in the right atrium (white
arrow) and right ventricle (black arrowhead), respectively
A major step forward in pacemaker function has been to attempt to
mimic nature by utilizing various inputs to produce a rate-responsive
pacemaker using parameters such as the QT interval, pO2 – pCO2 (dissolved oxygen or carbon dioxide levels) in the arterial-venous system, physical activity as determined by an accelerometer, body temperature, ATP levels, adrenaline,
etc.
Instead of producing a static, predetermined heart rate, or intermittent
control, such a pacemaker, a 'Dynamic Pacemaker', could compensate for
both actual respiratory loading and potentially anticipated respiratory
loading. The first dynamic pacemaker was invented by Anthony Rickards of
the National Heart Hospital, London, UK, in 1982.
Dynamic pacemaking technology could also be applied to future artificial hearts.
Advances in transitional tissue welding would support this and other
artificial organ/joint/tissue replacement efforts. Stem cells may be of
interest in transitional tissue welding.
Many advancements have been made to improve the control of the
pacemaker once implanted. Many of these have been made possible by the
transition to microprocessor controlled pacemakers. Pacemakers that control not only the ventricles but the atria
as well have become common. Pacemakers that control both the atria and
ventricles are called dual-chamber pacemakers. Although these
dual-chamber models are usually more expensive, timing the contractions
of the atria to precede that of the ventricles improves the pumping
efficiency of the heart and can be useful in congestive heart failure.
Rate responsive pacing allows the device to sense the physical
activity of the patient and respond appropriately by increasing or
decreasing the base pacing rate via rate response algorithms.
The DAVID trials have shown that unnecessary pacing of the right ventricle can exacerbate heart failure
and increases the incidence of atrial fibrillation. The newer
dual-chamber devices can keep the amount of right ventricle pacing to a
minimum and thus prevent worsening of the heart disease.
Considerations
Insertion
A pacemaker may be implanted whilst a person is awake using local anesthetic to numb the skin with or without sedation, or asleep using a general anesthetic. An antibiotic is usually given to reduce the risk of infection.
Pacemakers are generally implanted in the front of the chest in the
region of the left or right shoulder. The skin is prepared by clipping
or shaving any hair over the implant site before cleaning the skin with a
disinfectant such as chlorhexidine.
An incision is made below the collar bone and a space or pocket is
created under the skin to house the pacemaker generator. This pocket is
usually created just above the pectoralis major muscle (prepectoral), but in some cases the device may be inserted beneath the muscle (submuscular). The lead or leads are fed into the heart through a large vein guided by X-ray imaging (fluoroscopy). The tips of the leads may be positioned within the right ventricle, the right atrium, or the coronary sinus, depending on the type of pacemaker required.
Surgery is typically completed within 30 to 90 minutes. Following
implantation, the surgical wound should be kept clean and dry until it
has healed. Some movements of the shoulder within a few weeks of
insertion carry a risk of dislodging the pacemaker leads.
The batteries within a pacemaker generator typically last 5 to 10
years. When the batteries are nearing the end of life, the generator is
replaced in a procedure that is usually simpler than a new implant.
Replacement involves making an incision to remove the existing device,
disconnecting the leads from the old device and reconnecting them to a
new generator, reinserting the new device and closing the skin.
Periodic pacemaker checkups
Two types of remote monitoring devices used by pacemaker patients
Once the pacemaker is implanted, it is periodically checked to ensure
the device is operational and performing appropriately; the device can
be checked as often as is deemed necessary. Routine pacemaker checks are
typically done in-office every six months, though will vary depending
upon patient/device status and remote monitoring availability. Newer
pacemaker models can also be interrogated remotely, with the patient
transmitting their pacemaker data using a transmitter at home connected
to a cellular telephone network.
During in-office follow-up, diagnostic tests may include:
Sensing: the ability of the device to "see" intrinsic cardiac activity (atrial and ventricular depolarization).
Impedance: A test to measure lead integrity. Large and/or sudden
increases in impedance can indicate a lead fracture, while large and/or
sudden decreases in impedance can be caused by insulation failure.
Threshold amplitude: The minimum voltage (generally in hundredths of
volts) required in order to pace the atrium or ventricle connected to
the lead.
Threshold duration: The time that the device requires at the preset
amplitude to reliably pace the atrium or ventricle connected to the
lead.
Percentage of pacing: The percentage of time that the pacemaker has
been actively pacing since the previous device interrogation, which
shows how dependent the patient is on the device.
Estimated battery life at current rate: As modern pacemakers are
"on-demand" and only pace when necessary, battery lifespan is affected
by how much the pacemaker is utilized. Other factors affecting battery
life include programmed output and algorithms (features) that use
battery power.
Any events that were stored since the last follow-up, in particular arrhythmias such as atrial fibrillation.
These are typically stored based on specific criteria set by the
physician and specific to the patient. Some devices have the
availability to display intracardiac electrograms showing the onset of
an event as well as the event itself, which helps to diagnose its cause
or origin.
Magnetic fields, MRIs, and other lifestyle issues
A
patient's lifestyle is usually not modified to any great degree after
the insertion of a pacemaker. There are a few activities that are
unwise, such as full-contact sports and exposure of the pacemaker to
intense magnetic fields.
The pacemaker patient may find that some types of everyday
actions need to be modified. For instance, the shoulder harness of a
vehicle seatbelt
may be uncomfortable if it falls across the pacemaker insertion site.
Women will not be able to wear bras for a while after the operation, and
later might have to wear bras with wide shoulder straps.
For some sports and physical activities, special pacemaker
protection can be worn to prevent possible injuries, or damage to the
pacemaker leads.
Pacemakers may be affected by magnetic or electromagnetic fields, and ionising and acoustic radiation.
However, a 2013 study found that "The overall risk of clinically
significant adverse events related to EMI (electromagnetic interference)
in recipients of CIEDs (cardiovascular implantable electronic devices)
is very low. Therefore, no special precautions are needed when household
appliances are used. Environmental and industrial sources of EMI are
relatively safe when the exposure time is limited and distance from the
CIEDs is maximized. The risk of EMI-induced events is highest within the
hospital environment."
The study lists and tabulates (in Table 2) many sources of
interference, and many different potential effects: damage to circuitry,
asynchronous pacing, etc. Some sources of hazard in older devices have
been eliminated in newer ones.
Activities involving strong magnetic fields should be avoided. This includes activities such as arc welding with certain types of equipment, and maintaining heavy equipment that may generate strong magnetic fields. Some medical procedures, particularly magnetic resonance imaging (MRI), involve very strong magnetic fields or other conditions that may damage pacemakers.
However, many modern pacemakers are specified to be MR conditional or MRI conditional, safe to use during MRI subject to certain conditions. The first to be so specified was the Medtronic Revo MRI SureScan, approved by the US FDA in February 2011, which was the first to be specified as MR conditional.
There are several conditions to use of MR Conditional pacemakers,
including certain patients' qualifications and scan settings. An MRI
conditional device has to have MRI settings enabled before a scan, and
disabled afterwards.
As of 2014 the five most commonly used cardiac pacing device
manufacturers (covering more than 99% of the US market) made
FDA-approved MR-conditional pacemakers.
The use of MRI may be ruled out by the patient having an older, non-MRI
Conditional pacemaker, or by having old pacing wires inside the heart,
no longer connected to a pacemaker.
A 2008 US study found
that the magnetic field created by some headphones used with portable
music players or cellphones may cause interference if placed very close
to some pacemakers.
In addition, according to the American Heart Association,
some home devices have the potential to occasionally inhibit a single
beat. Cellphones do not seem to damage pulse generators or affect how
the pacemaker works.
It is recommended that objects containing magnets, or generating a
significant magnetic field, should not be in close proximity to a
pacemaker. Induction cooktops, in particular, can pose a risk.
Before medical procedures, the patient should inform all medical
personnel that they have a pacemaker. Having a pacemaker does not imply
that a patient requires the use of antibiotics to be administered before procedures such as dental work.
End-of-life care and pacemaker deactivation
A panel of the Heart Rhythm Society,
a US specialist organization based in Washington, DC, deemed that it
was legal and ethical to honor requests by patients, or by those with
legal authority to make decisions for patients, to deactivate implanted
cardiac devices. Lawyers say that the legal situation is similar to
removing a feeding tube, though as of 2010 there was no legal precedent
involving pacemakers in the United States. A patient in many
jurisdictions (including the US) is deemed to have a right to refuse or
discontinue treatment, including a pacemaker that keeps them alive.
Physicians have a right to refuse to turn it off, but are advised by the
HRS panel that they should refer the patient to a physician who will.
Some patients consider that hopeless, debilitating conditions, such as
severe strokes or late-stage dementia, can cause so much suffering that
they would prefer not to prolong their lives with supportive measures.
Privacy and security
Security
and privacy concerns have been raised with pacemakers that allow
wireless communication. Unauthorized third parties may be able to read
patient records contained in the pacemaker, or reprogram the devices, as
has been demonstrated by a team of researchers.
The demonstration worked at short range; they did not attempt to
develop a long range antenna. The proof of concept exploit helps
demonstrate the need for better security and patient alerting measures
in remotely accessible medical implants.
In response to this threat, Purdue University and Princeton University
researchers have developed a prototype firewall device, called MedMon,
which is designed to protect wireless medical devices such as pacemakers
and insulin pumps from attackers.
Complications
Complications from having surgery to implant a pacemaker are uncommon (each 1-3% approximately), but could include: infection where the pacemaker is implanted or in the bloodstream; allergic reaction to the dye or anesthesia
used during the procedure; swelling, bruising or bleeding at the
generator site, or around the heart, especially if the patient is taking
blood thinners, elderly, of thin frame or otherwise on chronic steroid use.
A possible complication of dual-chamber artificial pacemakers is
'pacemaker-mediated tachycardia' (PMT), a form of reentrant tachycardia.
In PMT, the artificial pacemaker forms the anterograde (atrium to
ventricle) limb of the circuit and the atrioventricular (AV) node forms
the retrograde limb (ventricle to atrium) of the circuit. Treatment of PMT typically involves reprogramming the pacemaker.
Another possible complication is "pacemaker-tracked tachycardia," where a supraventricular tachycardia such as atrial fibrillation or atrial flutter is tracked by the pacemaker and produces beats from a ventricular lead.
This is becoming exceedingly rare as newer devices are often programmed
to recognize supraventricular tachycardias and switch to non-tracking
modes.
It is important to consider leads as a potential nidus for thromboembolic
events. The leads are small-diameter wires from the pacemaker to the
implantation site in the heart muscle, and are usually placed
intravenously through the subclavian vein
in order to access the right atrium. Placing a foreign object within
the venous system in such a manner may disrupt blood-flow and allow for
thrombus formation. Therefore, patients with pacemakers may need to be
placed on anti-coagulation therapy to avoid potential life-threatening
thrombosis or embolus.
Sometimes leads will need to be removed. The most common reason
for lead removal is infection; however, over time, leads can degrade due
to a number of reasons such as lead flexing.
Changes to the programming of the pacemaker may overcome lead
degradation to some extent. However, a patient who has several pacemaker
replacements over a decade or two in which the leads were reused may
require lead replacement surgery.
Lead replacement may be done in one of two ways. Insert a new set
of leads without removing the current leads (not recommended as it
provides additional obstruction to blood flow and heart valve function)
or remove the current leads and then insert replacements. The lead
removal technique will vary depending on the surgeon's estimation of the
probability that simple traction will suffice to more complex
procedures. Leads can normally be disconnected from the pacemaker
easily, which is why device replacement usually entails simple surgery
to access the device and replace it by simply unhooking the leads from
the device to replace and hooking the leads to the new device. The
possible complications, such as perforation of the heart wall, come from
removing the lead{s} from the patient's body.
The free end of a pacemaker lead is actually implanted into the
heart muscle with a miniature screw or anchored with small plastic hooks
called tines. The longer the leads have been implanted (starting from a
year or two), the more likely that they will have additional
attachments to the patient's body at various places in the pathway from
device to heart muscle, since the body tends to incorporate foreign
devices into tissue. In some cases, for a lead that has been inserted
for a short amount of time, removal may involve simple traction to pull
the lead from the body. Removal in other cases is typically done with a
laser or cutting device which threads like a cannula with a cutting edge
over the lead and is moved down the lead to remove any organic
attachments with tiny cutting lasers or similar device.
Pacemaker lead malposition in various locations has been
described in the literature. Treatment varies, depending on the location
of the pacer lead and symptoms.
Another possible complication called twiddler's syndrome
occurs when a patient manipulates the pacemaker and causes the leads to
be removed from their intended location and causes possible stimulation
of other nerves.
Overall life expectancy with pacemakers is excellent, and mostly
depends upon underlying diseases, presence of atrial fibrillation, age
and sex at the time of first implantation.
Other devices
Sometimes devices resembling pacemakers, called implantable cardioverter-defibrillators
(ICDs) are implanted. These devices are often used in the treatment of
patients at risk from sudden cardiac death. An ICD has the ability to
treat many types of heart rhythm disturbances by means of pacing, cardioversion, or defibrillation. Some ICD devices can distinguish between ventricular fibrillation and ventricular tachycardia
(VT), and may try to pace the heart faster than its intrinsic rate in
the case of VT, to try to break the tachycardia before it progresses to
ventricular fibrillation. This is known as fast-pacing, overdrive pacing, or anti-tachycardia pacing
(ATP). ATP is only effective if the underlying rhythm is ventricular
tachycardia, and is never effective if the rhythm is ventricular
fibrillation.
NASPE / BPEG Defibrillator (NBD) code – 1993
I
II
III
IV
Shock chamber
Antitachycardia pacing chamber
Tachycardia detection
Antibradycardia pacing chamber
O = None
O = None
E = Electrogram
O = None
A = Atrium
A = Atrium
H = Hemodynamic
A = Atrium
V = Ventricle
V = Ventricle
V = Ventricle
D = Dual (A+V)
D = Dual (A+V)
D = Dual (A+V)
Short form of the NASPE/BPEG Defibrillator (NBD) code
ICD-S
ICD with shock capability only
ICD-B
ICD with bradycardia pacing as well as shock
ICD-T
ICD with tachycardia (and bradycardia) pacing as well as shock
History
In 1958, Arne Larsson
(1915–2001) became the first to receive an implantable pacemaker. He
had 26 devices during his life and campaigned for other patients needing
pacemakers.
Origin
In 1889, John Alexander MacWilliam reported in the British Medical Journal (BMJ) of his experiments in which application of an electrical impulse to the human heart in asystole caused a ventricular
contraction and that a heart rhythm of 60–70 beats per minute could be
evoked by impulses applied at spacings equal to 60–70/minute.
In 1926, Mark C Lidwill of the Royal Prince Alfred Hospital of Sydney, supported by physicist Edgar H. Booth of the University of Sydney,
devised a portable apparatus which "plugged into a lighting point" and
in which "One pole was applied to a skin pad soaked in strong salt
solution" while the other pole "consisted of a needle insulated except
at its point, and was plunged into the appropriate cardiac chamber".
"The pacemaker rate was variable from about 80 to 120 pulses per minute,
and likewise the voltage variable from 1.5 to 120 volts". In 1928, the apparatus was used to revive a stillborn infant at Crown Street Women's Hospital in Sydney, whose heart continued "to beat on its own accord", "at the end of 10 minutes" of stimulation.
In 1932, American physiologist Albert Hyman,
with the help of his brother, described an electro-mechanical
instrument of his own, powered by a spring-wound hand-cranked motor.
Hyman himself referred to his invention as an "artificial pacemaker",
the term continuing in use to this day.
An apparent hiatus in the publication of research conducted between the early 1930s and World War II may be attributed to the public perception of interfering with nature by "reviving the dead".
For example, "Hyman did not publish data on the use of his pacemaker in
humans because of adverse publicity, both among his fellow physicians,
and due to newspaper reporting at the time. Lidwell may have been aware
of this and did not proceed with his experiments in humans".
A number of innovators, including Paul Zoll, made smaller but still bulky transcutaneous pacing devices from 1952 using a large rechargeable battery as the power supply.
In 1957, William L. Weirich published the results of research performed at the University of Minnesota.
These studies demonstrated the restoration of heart rate, cardiac
output and mean aortic pressures in animal subjects with complete heart block through the use of a myocardial electrode.
In 1958 Colombian doctor Alberto Vejarano Laverde and Colombian electrical engineer Jorge Reynolds Pombo constructed an external pacemaker, similar to those of Hopps and Zoll, weighing 45 kg and powered by a 12 volt car lead–acid battery,
but connected to electrodes attached to the heart. This apparatus was
successfully used to sustain a 70-year-old priest, Gerardo Florez.
The development of the silicontransistor
and its first commercial availability in 1956 was the pivotal event
that led to the rapid development of practical cardiac pacemaking.
Wearable
In 1958, engineer Earl Bakken of Minneapolis, Minnesota, produced the first wearable external pacemaker for a patient of C. Walton Lillehei.
This transistorized pacemaker, housed in a small plastic box, had
controls to permit adjustment of pacing heart rate and output voltage
and was connected to electrode leads which passed through the skin of the patient to terminate in electrodes attached to the surface of the myocardium of the heart.
In the UK in the 1960s, Lucas Engineering in Birmingham was asked by Mr Abrams of The Queen Elizabeth Hospital
to produce a prototype for a transistorised replacement for the
electro-mechanical product. The team was headed by Roger Nolan, an
engineer with the Lucas Group Research Centre. Nolan designed and
created the first blocking oscillator and transistor-powered pacemaker.
This pacemaker was worn on a belt and powered by a rechargeable sealed
battery, enabling users to live a more-normal life.
One of the earliest patients to receive this Lucas pacemaker
device was a woman in her early 30s. The operation was carried out in
1964 by South African cardiac surgeon Alf Gunning, a student of Christiaan Barnard. This pioneering operation took place under the guidance of cardiac consultant Peter Sleight at the Radcliffe Infirmary in Oxford and his cardiac research team at St George's Hospital in London.
Implantable
Illustration of implanted cardiac pacemaker showing locations of cardiac pacemaker leads
The first clinical implantation into a human of a fully implantable pacemaker was on October 8, 1958, at the Karolinska Institute in Solna, Sweden, using a pacemaker designed by inventor Rune Elmqvist and surgeon Åke Senning (in collaboration with Elema-Schönander AB, later Siemens-Elema AB), connected to electrodes attached to the myocardium of the heart by thoracotomy.
The device failed after three hours. A second device was then implanted
which lasted for two days. The world's first implantable pacemaker
patient, Arne Larsson,
went on to receive 26 different pacemakers during his lifetime. He died
in 2001, at the age of 86, outliving the inventor and the surgeon.
In 1959, temporary transvenous pacing was first demonstrated by Seymour Furman and John Schwedel, whereby the catheter electrode was inserted via the patient's basilic vein.
In February 1960, an improved version of the Swedish Elmqvist design was implanted by Doctors Orestes Fiandra and Roberto Rubio in the Casmu 1 Hospital of Montevideo,
Uruguay. This pacemaker, the first implanted in the Americas, lasted
until the patient died of other ailments, nine months later. The early
Swedish-designed devices used batteries recharged by an induction coil
from the outside.
Implantable pacemakers constructed by engineer Wilson Greatbatch entered use in humans from April 1960 following extensive animal testing. The Greatbatch innovation varied from the earlier Swedish devices in using primary cells (a mercury battery) as the energy source. The first patient lived for a further 18 months.
The first use of transvenous pacing in conjunction with an implanted pacemaker was by Parsonnet in the United States,Lagergren in Sweden and Jean-Jacques Welti in France in 1962–63.
The transvenous, or pervenous, procedure involved incision of a vein into which was inserted the catheter electrode lead under fluoroscopic guidance, until it was lodged within the trabeculae of the right ventricle. This became the method of choice by the mid-1960s.
Cardiothoracic surgeon Leon Abrams and medical engineer Ray Lightwood developed and implanted the first patient-controlled variable-rate heart pacemaker in 1960 at the University of Birmingham.
The first implant took place in March 1960, with two further implants
the following month. These three patients made good recoveries and
returned to a high quality of life. By 1966, 56 patients had undergone
implantation with one surviving for over 5+1⁄2 years.
Lithium battery
The first lithium-iodide cell-powered pacemaker. Invented by Anthony Adducci and Art Schwalm. Cardiac Pacemakers Inc. 1972
The preceding implantable devices all suffered from the unreliability
and short lifetime of the available primary cell technology, mainly the
mercury battery. In the late 1960s, several companies, including ARCO in the US, developed isotope-powered pacemakers, but this development was overtaken by the development in 1971 of the lithium iodide cell by Wilson Greatbatch. Lithium-iodide or lithium anode cells became the standard for pacemaker designs.
A further impediment to the reliability of the early devices was the diffusion of water vapor from body fluids through the epoxy
resin encapsulation, affecting the electronic circuitry. This
phenomenon was overcome by encasing the pacemaker generator in a
hermetically sealed metal case, initially by Telectronics of Australia in 1969, followed by Cardiac Pacemakers, Inc. of St. Paul, Minnesota in 1972. This technology, using titanium as the encasing metal, became the standard by the mid-1970s.
On July 9, 1974, Manuel A. Villafaña and Anthony Adducci, the founders of Cardiac Pacemakers, Inc. (Guidant),
manufactured the world's first pacemaker with a lithium anode and a
lithium-iodide electrolyte solid-state battery. Lithium-iodide or
lithium anode cells increased the life of pacemakers from one year to as
long as eleven years, and has become the standard for pacemaker
designs. They began designing and testing their implantable cardiac
pacemaker powered by a new longer-life lithium battery in 1971. The
first patient to receive a CPI pacemaker emerged from surgery in June
1973.
Intra-cardial
In
2013, several firms announced devices that could be inserted via a leg
catheter rather than invasive surgery. The devices are roughly the size
and shape of a pill, much smaller than the size of a traditional
pacemaker. Once implanted, the device's prongs contact the muscle and
stabilize heartbeats. Development of this type of device was continuing. In November 2014, Bill Pike of Fairbanks, Alaska, received a Medtronic Micra pacemaker in Providence St Vincent Hospital in Portland, Oregon. D. Randolph Jones was the EP doctor. Also in 2014, St. Jude Medical Inc.
announced the first enrollments in the company's leadless Pacemaker
Observational Study evaluating the Nanostim leadless pacing technology.
The Nanostim pacemaker received European CE marking in 2013. Post-approval implant trials were carried out in Europe.
The European study was stopped after reports of six perforations that
led to two patient deaths. After investigations, St Jude Medical
restarted the study. In the United States, this therapy had not been approved by the FDA as of 2014.
While the St Jude Nanostim and the Medtronic Micra are single-chamber
pacemakers, it was anticipated that leadless dual-chamber pacing for
patients with atrioventricular block would become possible with further
development.
Reusable pacemakers
Worldwide
each year, in a simple procedure to avoid explosions, thousands of
pacemakers are removed from bodies to be cremated. Pacemakers with
significant remaining battery life are potentially life-saving devices
for people in low- and middle-income countries (LMICs). The Institute of Medicine, a US non-governmental organization,
has reported that inadequate access to advanced cardiovascular
technologies is a major contributor to cardiovascular disease morbidity
and mortality in LMICs. Ever since the 1970s, multiple studies worldwide
have reported on the safety and efficacy of pacemaker reuse. As of 2016,
widely acceptable standards for safe pacemaker and ICD reuse had not
been developed, and there continued to be legal and regulatory barriers
to widespread adoption of medical device reuse.
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