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A cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural pacemaker of the
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

heart
), is a medical device that generates electrical impulses delivered by
electrode An electrode is an electrical conductor In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, a ...

electrode
s to cause the heart muscle chambers (the upper, or
atriaAtria may refer to: *Atrium (heart) The atrium (Latin ātrium, “entry hall”) is the upper chamber through which blood enters the Ventricle (heart), ventricles of the heart. There are two atria in the human heart – the left atrium receives bloo ...
and/or the lower, or ventricles) to contract and therefore pump blood; by doing so this device replaces and/or regulates the function of the
electrical conduction system of the heart The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node to cause contraction of the heart muscle. The Cardiac pacemaker, pacemaking signal generated in the sinoatrial node travels through the right ...

electrical conduction system of the heart
. The primary purpose of a pacemaker is to maintain an adequate
heart rate Heart rate is the speed of the heartbeat Heartbeat or heartbeats may refer to: Physiology *Cardiac cycle, of the heart *Contraction of the cardiac muscle, muscles of the heart, or a perceived effect of it, such as: **Heart sounds, the noises gene ...

heart rate
, either because the heart's natural pacemaker is not fast enough, or because there is a
block Block or blocked may refer to: Arts, entertainment and media Broadcasting * Block programming, the result of a programming strategy in broadcasting * W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 t ...

block
in the heart's electrical conduction system. Modern pacemakers are externally programmable and allow a cardiologist, particularly a cardiac electrophysiologist to select the optimal pacing modes for individual patients. Modern devices are demand pacemakers, in which the stimulation of the heart based on the dynamic demand of the
circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ system is a biological system A biological system is a complex network Network and networking may refer to: Arts, entertai ...
. A specific type of pacemaker called a
defibrillator Defibrillation is a treatment for life-threatening cardiac dysrhythmia Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. The heart rate tha ...

defibrillator
combines pacemaker and defibrillator functions in a single implantable device, which should be called a defibrillator, for clarity. Others, called biventricular pacemakers have multiple electrodes stimulating differing positions within the lower heart chambers to improve synchronization of the ventricles, the lower chambers of the heart.


Methods of pacing


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 The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, human lung, lungs, and major blood vessels from in ...
over the
right ventricle A ventricle is one of two large chambers toward the bottom of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood ...
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

Transcutaneous pacing (TCP), also called external pacing, is recommended for the initial stabilization of hemodynamically significant
bradycardia Bradycardia is a condition typically defined wherein an individual has a resting heart rateHeart rate is the speed of the heartbeat measured by the number of contractions (beats) of the heart The heart is a muscle, muscular Organ (anatom ...
s 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 The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing; in other words, it's the main spike seen on an E ...

QRS complex
with a tall, broad
T wave Normal T wave In electrocardiography, the T wave represents the repolarization of the Ventricle (heart), ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the ''absolute refractory period (ph ...
on the
ECG Electrocardiography is the process of producing an electrocardiogram (ECG or EKG). It is an electrogram of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood ...

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.


Epicardial pacing (temporary)

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 (temporary)

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.


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 inside the skin under the clavicle. The procedure is performed by incision of a suitable vein into which the electrode
lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate h ...
is inserted and passed along the vein, through the valve of the heart, until positioned in the chamber. The procedure is facilitated by
fluoroscopy Image:Normal barium swallow animation.gif, A barium swallow exam taken via fluoroscopy. Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical i ...

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 Chambers may refer to: Places Canada: *Chambers Township, Ontario United States: *Chambers County, Alabama *Chambers, Arizona, an unincorporated community in Apache County *Chambers, Nebraska *Chambers, West Virginia *Chambers Township, Holt Coun ...
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 A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers, but as technology advanced it applied to a larger category ...
device containing a power source, usually a
lithium battery Lithium batteries are primary batteries that have metallic lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the Symbol (chemistry), symbol Li and atomic number 3. It is a soft, silvery-white alkal ...

lithium battery
, a sensing amplifier which processes the electrical manifestation of naturally occurring heart beats as sensed by the heart electrodes, the
computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, programs. These ...

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 The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as Tumor immunology, cancer cells and objects such ...
. It is usually made of
titanium Titanium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical ele ...

titanium
, which is inert in the body.


Leadless pacing

Leadless pacemakers are devices that 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 In the human body The human body is the structure of a Human, human being. It is composed of many different types of Cell (biology), cells that together create Tissue (biology), tissues and subsequently organ systems. They ensure homeostasi ...
via an incision in the groin.


Basic function

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. 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 natural pacemaker the
sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is a group of Cell (biology), cells known as pacemaker cells, located in the wall of the atrium (heart), right atrium of the heart. These cells can produce an electric ...
is unreliable – sinus node disease (SND) or
sick sinus syndrome Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms ( arrhythmias) usually caused by a malfunction of the sinus node, the heart's primary pacemaker. Tachycardia-bradycardia syndrome is a varia ...
. Where the problem is
atrioventricular block Atrioventricular block (AV block) is a type of heart block that occurs when the electrical signal traveling from the atria, or the upper chambers of the heart, to ventricles, or the lower chambers of the heart, is impaired. Normally, the sinoatri ...
(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 Electrocardiography is the process of producing an electrocardiogram (ECG or EKG). It is an electrogram of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood ...

ECG
, just before a wide
QRS The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing; in other words, it's the main spike seen on an E ...
. The spike of an "
atrial The atrium (Latin ātrium, “entry hall”) is the upper chamber through which blood enters the ventricles of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood ...
-demand pacemaker" appears just before the
P wave A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves Seismic waves are waves The United States Naval Reserve (Women's Reserve), better known as the WAVES (for Women Acc ...
. 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

Cardiac resynchronization therapy (CRT) is used for people with
heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mo ...
in whom the left and right ventricles do not contract simultaneously (
ventricular dyssynchronyIn cardiology, ventricular dyssynchrony is a difference in the timing, or lack of synchrony, of contractions in different ventricle (heart), ventricles in the heart. Large differences in timing of contractions can reduce cardiac efficiency and is cor ...
), 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 A ventricle is one of two large chambers toward the bottom of the heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the Unite ...
. 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 The atrium (Latin ātrium, “entry hall”) is the upper chamber through which blood enters the ventricles of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood ...
into the
right ventricle A ventricle is one of two large chambers toward the bottom of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood ...
to stimulate the
septum In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...
, and another passing through the ''vena cava'' and the right atrium and inserted through the
coronary sinus The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers less-oxygenated blood to the right atrium, as do the superior vena cava, superior and inferior v ...
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, 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 An implantable cardioverter-defibrillator (ICD) or automated implantable cardioverter defibrillator (AICD) is a device implantable inside the body, able to perform cardioversion Cardioversion is a medical procedure A medical procedure is a ...

implantable cardioverter-defibrillator
(ICD): such devices, known as CRT-D (for defibrillation), also provide effective protection against life-threatening arrhythmias.


His bundle 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. Indeed, it has been associated with increased risk of
atrial fibrillation Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm (arrhythmia) characterized by the rapid and irregular beating of the atrial chambers of the heart. It often begins as short periods of abnormal beating, which become longer or cont ...

atrial fibrillation
,
heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mo ...
, 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 fiber network directly with a special lead and placement technique, HBP causes a synchronized and therefore more effective ventricular activation and avoid long term heart muscle disease. HBP in some cases can also correct
bundle branch block A bundle branch block is a defect of the bundle branches or fascicles in the electrical conduction system of the heart The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node to cause contraction ...

bundle branch block
patterns.


Advancements in function

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 The QT interval is a measurement made on an electrocardiogram Electrocardiography is the process of producing an electrocardiogram (ECG or EKG). It is a graph of voltage Voltage, electric potential difference, electromotive force emf, ...

QT interval
, pO2 – pCO2 (dissolved
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
or
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
levels) in the arterial-venous system, physical activity as determined by an
accelerometer An accelerometer is a tool that measures proper acceleration In relativity theory, proper acceleration is the physical acceleration (i.e., measurable acceleration as by an accelerometer) experienced by an object. It is thus acceleration relative ...

accelerometer
,
body temperature Thermoregulation is the ability of an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a sy ...
,
ATP ATP may refer to: Companies and organizations * Association of Tennis Professionals * American Technical Publishers * ', a Danish pension * Armenia Tree Project * Association for Transpersonal Psychology * ATP architects engineers office * ATP ...

ATP
levels,
adrenaline Adrenaline, also known as epinephrine, is a hormone A hormone (from the Greek participle , "setting in motion") is any member of a class of signaling molecules in multicellular organisms, that are transported to distant organs to regulate p ...

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 heart An artificial heart is a device that replaces the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxyge ...
s. 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 A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip ...

microprocessor
controlled pacemakers. Pacemakers that control not only the ventricles but the
atriaAtria may refer to: *Atrium (heart) The atrium (Latin ātrium, “entry hall”) is the upper chamber through which blood enters the Ventricle (heart), ventricles of the heart. There are two atria in the human heart – the left atrium receives bloo ...
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 Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mo ...
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 A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general ane ...
to numb the skin with or without
sedation Sedation is the reduction of irritability Irritability is the excitatory ability that living organisms In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, B ...
, or asleep using a
general anesthetic General anaesthetics (or anesthetics, see spelling differences Despite the various English dialects Dialect The term dialect (from Latin , , from the Ancient Greek word , , "discourse", from , , "through" and , , "I speak") is used in ...
. 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 Chlorhexidine (CHX) (commonly known by the salt Salt is a mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specifi ...

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 The pectoralis major () is a thick, fan-shaped or triangular convergent muscle, situated at the chest of the human body. It makes up the bulk of the chest muscles Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs ...

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 Fluoroscopy () is an imaging technique that uses X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation In physics Physics is the natural science that studies matter, ...

fluoroscopy
). The tips of the leads may be positioned within the
right ventricle A ventricle is one of two large chambers toward the bottom of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped bloo ...
, the
right atrium The atrium (Latin ātrium, “entry hall”) is the upper chamber through which blood enters the ventricles of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood ...
, 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. Care should be taken to avoid excessive movement of the shoulder within the first few weeks to reduce the 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

Once the pacemaker is implanted, it is periodically checked to ensure the device is operational and performing appropriately. Depending on the frequency set by the following physician, the device can be checked as often as is 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 an at-home transmitter connected to their geographical cellular network. This data can then be accessed by the technician through the device manufacturer's web portal. At the time of in-office follow-up, the device will be interrogated to perform diagnostic testing. These tests 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 be indicative of a lead fracture while large and/or sudden decreases in impedance can signify a breach in lead insulation. * Threshold amplitude: The minimum amount of energy (generally in hundredths of volts) required in order to pace the atrium or ventricle connected to the lead. * Threshold duration: The amount of time that the device requires at the preset amplitude to reliably pace the atrium or ventricle connected to the lead. * Percentage of pacing: Defines how dependent the patient is on the device, the percentage of time that the pacemaker has been actively pacing since the previous device interrogation. * Estimated battery life at current rate: As modern pacemakers are "on-demand", meaning that they only pace when necessary, device longevity is affected by how much it is utilized. Other factors affecting device longevity include programmed output and algorithms (features) causing a higher level of current drain from the battery. * Any events that were stored since the last follow-up, in particular
arrhythmias Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the heartbeat Heartbeat or heartbeats may refer to: Physiology *Cardiac cycle, of the heart *Contraction of the cardiac muscle, muscles of the ...
such as
atrial fibrillation Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm (arrhythmia) characterized by the rapid and irregular beating of the atrial chambers of the heart. It often begins as short periods of abnormal beating, which become longer or cont ...

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 of the onset of the event as well as the event itself. This is especially helpful in diagnosing the cause or origin of the event and making any necessary programming changes.


Magnetic fields, MRIs, and other lifestyle issues

A patient's lifestyle is usually not modified to any great degree after insertion of a pacemaker. There are a few activities that are unwise such as full contact sports and activities that involve 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 A seat belt (also known as a safety belt, or spelled seatbelt) is a vehicle safety Automotive safety is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisio ...

seatbelt
may be uncomfortable if the harness should fall across the pacemaker insertion site. If the patient does wish to practice any type of sport or physical activity, special pacemaker protection can be worn to prevent possible physical injuries or damage to the pacemaker leads. Any kind of an activity that involves intense electro-magnetic fields should be avoided. This includes activities such as
arc welding Arc welding is a welding Welding is a process that joins materials, usually s or s, by using high to melt the parts together and allowing them to cool, causing . Welding is distinct from lower temperature metal-joining techniques such as ...
possibly, with certain types of equipment, or maintaining heavy equipment that may generate intense magnetic fields (such as a
magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging Medical imaging is the technique and process of imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of a ...
(MRI) machine). However, in February 2011 the FDA approved a new pacemaker device from
Medtronic Medtronic plc is an American-Irish registered medical device company that primarily operates in the United States. Medtronic has an operational and executive headquarters in Minneapolis, Minnesota in the US. In 2015, Medtronic acquired Irish– ...
called the Revo MRI SureScan which was the first to be labeled as for MRI use. There are several limitations to its use including certain patients' qualifications and scan settings. An MRI conditional device has to be reprogrammed right before and right after MRI scanning. All the 5 most common cardiac pacing device manufacturers (covering more than 99% of the US market) now have FDA-approved MR-conditional pacemakers. A 2008 US study has found that the magnetic field created by some headphones included with portable music players or cell phones, when placed within inches of pacemakers, may cause interference. In addition, according to the
American Heart Association The American Heart Association (AHA) is a nonprofit organization A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collectiv ...
, some home devices have a remote potential to cause interference by occasionally inhibiting a single beat. Cellphones available in the United States (less than 3 watts) do not seem to damage pulse generators or affect how the pacemaker works. Having a pacemaker does not imply that a patient requires the use of
antibiotic An antibiotic is a type of antimicrobial An antimicrobial is an agent that kills microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an organism () is any organic, life, living system t ...
s to be administered before procedures such as dental work. The patient should inform all medical personnel that he or she has a pacemaker. The use of MRI may be ruled out by the patient having a pacemaker manufactured before MRI conditional devices became common, or by the patient having old pacing wires abandoned inside the heart, no longer connected to their pacemaker.


Turning off the pacemaker

A panel of The Heart Rhythm Society, a specialist organization based in Washington, DC found 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 there is currently no legal precedent involving pacemakers in the United States of America. A patient in the United States is thought to have a right to refuse or discontinue treatment, including a pacemaker that keeps him or her 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 believe that hopeless, debilitating conditions, like those brought on by severe strokes or late-stage dementia, can cause so much suffering that they would prefer not to prolong their lives with supportive measures, such as cardiac devices.


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 Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical or dental specialty that uses operative manual and instrumental techniques on a person to investigate or t ...
to implant a
pacemaker A cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural pacemaker of the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the cir ...
are uncommon (each 1-3 % approximately), but could include: infection where the pacemaker is implanted or in the bloodstream;
allergic reaction Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, i ...

allergic reaction
to the dye or
anesthesia Anesthesia or anaesthesia (from Greek "without sensation") is a state of controlled, temporary loss of sensation or awareness that is induced for medical purposes. It may include some or all of Analgesic, analgesia (relief from or prevention o ...
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
steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes which alter membrane fluidity; and ...
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 Supraventricular tachycardia (SVT) is an umbrella term for arising from the . This is in contrast to the other group of fast heart rhythms - , which start within the . There are four main types of SVT: , , (PSVT) and . The symptoms of SVT incl ...
such as
atrial fibrillation Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm (arrhythmia) characterized by the rapid and irregular beating of the atrial chambers of the heart. It often begins as short periods of abnormal beating, which become longer or cont ...

atrial fibrillation
or
atrial flutter Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the c ...
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. Sometimes the leads, which are small diameter wires, from the pacemaker to the implantation site in the heart muscle 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.Transvenous Lead Extraction: Heart Rhythm Society Expert Consensus on Facilities, Training, Indications, and Patient Management
Author: Bruce L. Wilkoff, MD. Coauthor(s): Charles J. Love, MD, FHRS, Charles L. Byrd, MD, Maria Grazia Bongiorni, MD, Roger G. Carrillo, MD, FHRS, George H. Crossley, III, MD, FHRS, Laurence M. Epstein, MD, Richard A. Friedman, MD, MBA, FHRS, Charles E. H. Kennergren, MD, PhD, FHRS, Przemyslaw Mitkowski, MD, Raymond H. M. Schaerf, MD, FHRS, Oussama M. Wazni, MD
Changes to 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 a 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 from the patient's body. The other end of a pacemaker lead is actually implanted into the heart muscle with a miniature screw or anchored with small plastic hooks called tines. In addition, the longer the leads have been implanted starting from a year or two, the more likely that they will have attachments to the patient's body at various places in the pathway from device to heart muscle, since the human 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. Depending on the location of the pacer lead and symptoms treatment varies. Another possible complication called 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.


Other devices

Sometimes devices resembling pacemakers, called
implantable cardioverter-defibrillator An implantable cardioverter-defibrillator (ICD) or automated implantable cardioverter defibrillator (AICD) is a device implantable inside the body, able to perform cardioversion Cardioversion is a medical procedure A medical procedure is a ...

implantable cardioverter-defibrillator
s (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 Cardioversion is a medical procedure A medical procedure is a course of action intended to achieve a result in the delivery of healthcare. A medical procedure with the intention of determining, measuring, or diagnosing a patient condition or para ...

cardioversion
, or
defibrillation Defibrillation is a treatment for life-threatening cardiac dysrhythmia Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. The heart rate tha ...
. Some ICD devices can distinguish between ventricular fibrillation and
ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a type of regular, fast heart rate that arises from improper electrical activity in the ventricles of the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pump ...
(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.


History


Origin

In 1889,
John Alexander MacWilliam John Alexander MacWilliam (31 July 1857 – 13 January 1937), a physiologist at the University of Aberdeen , mottoeng = The fear of the Lord is the beginning of wisdom , established = , type = Public research university Ancient univers ...
reported in the ''
British Medical Journal ''The BMJ'' is a weekly peer-reviewed medical trade journal, published by the trade union A trade union (or a labor union in American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English ...
'' (BMJ) of his experiments in which application of an electrical impulse to the human heart in
asystole Asystole is the absence of ventricular contractions in the context of a lethal heart arrhythmia (in contrast to an induced asystole on a cooled patient on a heart-lung machine and general anesthesia during surgery necessitating stopping the heart) ...

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 The Royal Prince Alfred Hospital (abbreviated RPAH or RPA) is a major public teaching hospital in Sydney, Australia, located on Missenden Road in Camperdown, New South Wales, Camperdown. It is a teaching hospital of the Central Clinical School o ...
of Sydney, supported by physicist Edgar H. Booth of the
University of Sydney The University of Sydney (USYD, or informally Sydney Uni) is a public In public relations Public relations (PR) is the practice of managing and disseminating information from an individual or an organization An organization, ...

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 Stillbirth is typically defined as fetus, fetal death at or after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without vital signs, signs of life. A stillbirth can result in the feeling of Guilt (emotion), guilt ...
infant at Crown Street Women's Hospital, Sydney whose heart continued "to beat on its own accord", "at the end of 10 minutes" of stimulation. In 1932, American physiologist
Albert HymanAlbert Salisbury Hyman (1893 - 1972), a Harvard-trained New York cardiologist, together with his brother Charles, constructed in 1930-1932 an electro-mechanical device which was one of the earliest artificial pacemakers. The device was, reportedly, t ...
, 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 Hiatus may refer to: *Hiatus (linguistics), the lack of a consonant separating two vowels in separate syllables *Hiatus (television), a break of several weeks or more in television scheduling *Hiatus (anatomy), a natural fissure in a structure *Hi ...
in publication of research conducted between the early 1930s and
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
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".


Transcutaneous

In 1950, Canadian electrical engineer John Hopps designed and built the first external pacemaker based upon observations by cardio-thoracic surgeons Wilfred Gordon Bigelow and John Callaghan at Toronto General Hospital, although the device was first tested on a dog at the University of Toronto's Banting Institute. A substantial external device using vacuum tube technology to provide transcutaneous pacing, it was somewhat crude and painful to the patient in use and, being powered from an AC wall socket, carried a potential hazard of electric shock, electrocution of the patient and inducing ventricular fibrillation. 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 silicon transistor and its first commercial availability in 1956 was the pivotal event that led to 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 Lead (electronics), leads which passed through the skin of the patient to terminate in electrodes attached to the surface of the myocardium of the heart. One of the earliest patients to receive this Lucas pacemaker device was a woman in her early 30s in an operation carried out in 1964 at the Radcliffe Infirmary in Oxford by cardiac surgeon Alf Gunning from South Africa and later Professor Gunning who was a student of Christiaan Barnard. This pioneering operation was carried out 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. Sleight later became Professor of Cardiovascular Medicine at Oxford University.


Implantable

The first clinical implantation into a human of a fully implantable pacemaker was in 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 as well as 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 in Montevideo, Uruguay in the Casmu 1 Hospital by Doctors Orestes Fiandra and Roberto Rubio. That device lasted until the patient died of other ailments, nine months later. The early Swedish-designed devices used rechargeable batteries, which were charged by an induction coil from the outside. It was the first pacemaker implanted in America. 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 (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 Fluoroscopy, fluoroscopic guidance, until it was lodged within the trabeculae of the right ventricle. This method was to become 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 Birmingham University. 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 years.


Lithium battery

The preceding implantable devices all suffered from the unreliability and short lifetime of the available primary cell technology which was mainly that of the mercury battery. In the late 1960s, several companies, including ARCO in the USA, developed Atomic battery, isotope-powered pacemakers, but this development was overtaken by the development in 1971 of the lithium iodide button cell, cell battery by Wilson Greatbatch. Lithium-iodide or lithium anode cells became the standard for future pacemaker designs. A further impediment to reliability of the early devices was the diffusion of water vapour from the 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 Minneapolis in 1972. This technology, using Titanium#Medical, titanium as the encasing metal, became the standard by the mid-1970s. On July 9, 1974, Manuel A. Villafaña and Anthony Adducci founders of Cardiac Pacemakers, Inc. (Guidant) in St. Paul, Minnesota, manufactured the world's first pacemaker with a lithium anode and a lithium-iodide electrolyte solid-state battery.


Intra-cardial

In 2013, multiple 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. Engineers and scientists are currently working on this type of device. In November 2014 a patient, 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. In 2014 also 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 CE marking in 2013. The post-approval implants have occurred in Europe. The European study was recently stopped, after there were reports of six perforations that led to two patient deaths. After investigations St Jude Medical restarted the study. But in the United States this therapy is still not approved by the FDA. While the St Jude Nanostim and the Medtronic Micra are just single-chamber pacemakers it is anticipated that leadless dual-chamber pacing for patients with atrioventricular block will become possible with further development.


Reusable pacemakers

Thousands of pacemakers are removed by funeral home personnel each year all over the world. They have to be removed postmortem from bodies that are going to be cremated to avoid explosions. It is a fairly simple procedure that can be carried out by a mortician. Pacemakers with significant battery life are potentially life-saving devices for people in low and middle income countries (LMICs). The National Academy of Medicine, Institute of Medicine, a United States non-governmental organization, has reported that inadequate access to advanced cardiovascular technologies is one of the major contributors to cardiovascular disease morbidity and mortality in LMICs. Ever since the 1970s, multiple studies all over the world have reported on the safety and efficacy of pacemaker reuse. , widely acceptable standards for safe pacemaker and ICD reuse have not been developed, and there continue to be legal and regulatory barriers to widespread adoption of medical device reuse.


Manufacturers

Current and prior manufacturers of implantable pacemakers * Biotronik (Germany) * Boston Scientific (USA) * Guidant (USA) (now owned by Boston Scientific) * Intermedics (USA) * Lepu Medical (China) * Medico (Italy) *
Medtronic Medtronic plc is an American-Irish registered medical device company that primarily operates in the United States. Medtronic has an operational and executive headquarters in Minneapolis, Minnesota in the US. In 2015, Medtronic acquired Irish– ...
(USA) * Sorin Group (Italy) (merged with Cyberonics to form LivaNova) * St. Jude Medical (USA) (now owned by Abbott Laboratories)


See also

* Biological pacemaker * Button cell * Electrical conduction system of the heart * Implantable cardioverter-defibrillator * Infective endocarditis * Pacemaker syndrome


References


External links


Detecting and Distinguishing Cardiac Pacing Artifacts


* [https://web.archive.org/web/20100925001511/http://escardio.org/communities/EHRA/education/webinars/Pages/welcome.aspx Current indications for CRT-P and CRT-D: Webinar from the European Heart Rhythm Association (EHRA)] {{DEFAULTSORT:Artificial Pacemaker 1959 introductions Cardiac electrophysiology Embedded systems Implants (medicine) Neuroprosthetics Prosthetics Cybernetics Biomedical engineering Medical devices Australian inventions Colombian inventions