A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker The cells that create these rhythmical impulses are called pacemaker cells, and they directly control the heart rate. Artificial devices also called pacemakers can be used after damage to the body's intrinsic conduction system to produce these impulses synthetically) is a medical device A medical device is a product which is used for medical purposes in patients, in diagnosis, therapy or surgery. If applied to the body, the effect of the medical device is primarily physical, in contrast to pharmaceutical drugs, which exert a biochemical effect. Specific regional definitions of medical device vary slightly as detailed below. The which uses electrical impulses, delivered by electrodes An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit . The word was coined by the scientist Michael Faraday from the Greek words elektron (meaning amber, from which the word electricity is derived) and hodos, a way contacting the heart muscles, to regulate the beating of the heart The heart of a vertebrate is composed of cardiac muscle, an involuntary striated muscle tissue which is found only within this organ. The average human heart, beating at 72 beats per minute, will beat approximately 2.5 billion times during a lifetime . It weighs on average 250 g to 300 g in females and 300 g to 350 g in males. The primary purpose of a pacemaker is to maintain an adequate heart rate The pulse rates can also be measured at any point on the body where an artery's pulsation is transmitted to the surface - often as it is compressed against an underlying structure like bone - by pressuring it with the index and middle finger. The thumb should not be used for measuring another person's heart rate, as its strong pulse may interfere, either because the heart's native pacemaker The sinoatrial node is the impulse generating (pacemaker) tissue located in the right atrium of the heart, and thus the generator of sinus rhythm. It is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. These cells are modified cardiac myocytes. Though they possess some contractile filaments, is not fast enough, or there is a block in the heart's electrical conduction system The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node of the heart to be propagated to (and stimulate) the myocardium (Cardiac muscle). The myocardium contracts after stimulation. It is the ordered stimulation of the myocardium that allows efficient contraction of the heart, thereby allowing. Modern pacemakers are externally programmable and allow the cardiologist Cardiology is a specialty dealing with disorders of the heart and blood vessels. The field includes diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians specializing in this field of medicine are called cardiologists. Cardiologists should not be to select the optimum pacing modes for individual patients. Some combine a pacemaker and defibrillator An implantable cardioverter-defibrillator is a small battery-powered electrical impulse generator which is implanted in patients who are at risk of sudden cardiac death due to ventricular fibrillation. The device is programmed to detect cardiac arrhythmia and correct it by delivering a jolt of electricity. In current variants, the ability to in a single implantable device. Others have multiple electrodes stimulating differing positions within the heart to improve synchronisation Synchronization or synchronisation is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time. Systems operating with all their parts in synchrony are said to be synchronous or in sync. Some systems may be only approximately synchronized, or of the lower chambers In the heart, a ventricle is a heart chamber which collects blood from an atrium and pumps it out of the heart of the heart.

Contents

History

The first implantable pacemaker. In 1958, Arne Larsson (1915-2001) became the first to receive an implantable pacemaker. He had a total of 26 devices during his life and campaigned for other patients needing pacemakers.

In 1889, J A McWilliam reported in the British Medical Journal of his experiments in which application of an electrical impulse to the human heart in asystole In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow. Asystole is one of the conditions required for a medical practitioner to certify death 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.[1]

In 1926, Dr Mark C Lidwell of the Royal Prince Alfred Hospital of Sydney, supported by physicist Edgar H Booth of the University of Sydney The University of Sydney is the oldest university in Australia. It was established in Sydney in 1850. It is a member of Australia's "Group of Eight" universities that are highly ranked in terms of their research performance. In 2008, the University had 46,054 students and 3,081 (full-time equivalent) academic staff making it the second, 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, Sydney whose heart continued "to beat on its own accord", "at the end of 10 minutes" of stimulation.[2][3]

In 1932, American physiologist Albert Hyman, working independently, 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.[4][5]

An apparent hiatus in publication of research conducted between the early 1930s and World War II World War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all of the great powers, organized into two opposing military alliances: the Allies and the Axis. The war involved the mobilization of over 100 million military personnel, making it the most widespread war in history 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".[3]

An external pacemaker was designed and built by the Canadian electrical engineer John Hopps in 1950 based upon observations by cardio-thoracic surgeon Wilfred Gordon Bigelow at Toronto General Hospital The Toronto General Hospital , is a part of the University Health Network, and a major teaching hospital in downtown Toronto, Ontario. It is located in the Discovery District, directly north of the Hospital for Sick Children, across Gerrard Street West, and east of Princess Margaret Hospital and Mount Sinai Hospital, across University Avenue. They . A substantial external device using vacuum tube In electronics, a vacuum tube, electron tube , thermionic valve, or valve (elsewhere, especially in Britain) is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space. Some special function vacuum tubes are filled with low-pressure gas: these are so-called technology to provide transcutaneous pacing Transcutaneous pacing is a temporary means of pacing a patient's heart during a medical emergency. It is accomplished by delivering pulses of electric current through the patient's chest, which stimulates the heart to contract, it was somewhat crude and painful to the patient in use and, being powered from an AC wall socket, carried a potential hazard of electrocution of the patient by inducing ventricular fibrillation Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them tremble rather than contract properly. Ventricular fibrillation is a medical emergency. If the arrhythmia continues for more than a few seconds, blood circulation will cease, and sudden cardiac death.

A number of innovators, including Paul Zoll, made smaller but still bulky transcutaneous pacing Transcutaneous pacing is a temporary means of pacing a patient's heart during a medical emergency. It is accomplished by delivering pulses of electric current through the patient's chest, which stimulates the heart to contract devices in the following years using a large rechargeable battery as the power supply.[6]

In 1957, Dr. William L. Weirich published the results of research performed at the University of Minnesota The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 51,141 students in 2008-2009. These studies demonstrated the restoration of heart rate, cardiac output and mean aortic pressures in animal subjects with complete heart block A heart block is a disease in the electrical system of the heart. This is opposed to coronary artery disease, which is disease of the blood vessels of the heart. While coronary artery disease can cause angina or myocardial infarction (heart attack), heart block can cause lightheadedness, syncope (fainting), and palpitations through the use of a myocardial electrode. This effective control of postsurgical heart block proved to be a significant contribution to decreasing mortality Death is the state of terminated life. The term "death" refers to both to the event of life's termination and to the state of lack of life. The true nature of the latter has for millennia been a central concern of the world's religious traditions and of philosophical enquiry. Many religions maintain faith in either some kind of afterlife of open heart surgery Cardiac surgery is surgery on the heart and/or great vessels performed by a cardiac surgeon. Frequently, it is done to treat complications of ischemic heart disease , correct congenital heart disease, or treat valvular heart disease created by various causes including endocarditis. It also includes heart transplantation in this time period.[7]

The development of the silicon Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855. A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. As the eighth most common element in the universe by mass, silicon very rarely occurs as the pure free element in nature, but is transistor In electronics, a transistor is a semiconductor device commonly used to amplify or switch electronic signals. A transistor is made of a solid piece of a semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing and its first commercial availability in 1956 was the pivotal event which led to rapid development of practical cardiac pacemaking.

In 1957, engineer Earl Bakken of Minneapolis, Minnesota, produced the first wearable external pacemaker for a patient of Dr. C. Walton Lillehei Clarence Walton Lillehei , was an American surgeon who pioneered open-heart surgery, as well as numerous techniques, equipment and prostheses for cardiothoracic surgery. This transistorised 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 Cardiac muscle is a type of involuntary striated muscle found in the walls of the heart, specifically the myocardium. Cardiac muscle cells are known as cardiac myocytes . Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. The cells that comprise cardiac muscle are sometimes seen as intermediate of the heart.

The first clinical implantation into a human of a fully implantable pacemaker was in 1958 at the Karolinska University Hospital in Solna, Sweden, using a pacemaker designed by Rune Elmqvist and surgeon Åke Senning, connected to electrodes attached to the myocardium Cardiac muscle is a type of involuntary striated muscle found in the walls of the heart, specifically the myocardium. Cardiac muscle cells are known as cardiac myocytes . Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. The cells that comprise cardiac muscle are sometimes seen as intermediate of the heart by thoracotomy Thoracotomy is an incision into the chest. It is performed by a surgeon, and, rarely, by emergency physicians, to gain access to the thoracic organs, most commonly the heart, the lungs, the esophagus or thoracic aorta, or for access to the anterior spine such as is necessary for access to tumors in the spine. 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[8].

In 1959, temporary transvenous pacing was first demonstrated by Furman et al. in which the catheter In medicine a catheter is a tube that can be inserted into a body cavity, duct or vessel. Catheters thereby allow drainage, injection of fluids or access by surgical instruments. The process of inserting a catheter is catheterization. In most uses a catheter is a thin, flexible tube ; in some uses, it is a larger, solid tube. ("hard" electrode was inserted via the patient's basilic vein.[9]

In February 1960, an improved version of the Swedish Elmqvist design was implanted in Montevideo Montevideo is the largest city, the capital and chief port of Uruguay. Montevideo is the only city in the country with a population over 1,000,000. According to Mercer Human Resource Consulting, Montevideo provides the highest quality of life in Latin America. It is the seat of the Roman Catholic Archdiocese of Montevideo, Uruguay Uruguay, officially the Oriental Republic of Uruguay , is a country located in the southeastern part of South America. It is home to 3.46 million people, of whom 1.7 million live in the capital Montevideo and its metropolitan area. An estimated 94.6% of the population are of mostly European descent in the Casmu Hospital by Doctors Fiandra and Rubio. That device lasted until the patient died of other ailments, 9 months later. The early Swedish-designed devices used rechargeable batteries, which were charged 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 Animal testing / animal experimentation is the use of non-human animals in scientific experimentation. It is estimated that 50 to 100 million vertebrate animals worldwide — from zebrafish to non-human primates — are used annually. Although much larger numbers of invertebrates are used and the use of flies and worms as model organisms is very. The Greatbatch innovation varied from the earlier Swedish devices in using primary cells (mercury battery A mercury battery is a non-rechargeable electrochemical battery, a primary cell. Due to the content of mercury, and the resulting environmental concerns, the sale of mercury batteries is banned in many countries. Both ANSI and IEC have withdrawn standards for mercury batteries. Mercury batteries were made in button types for watches and) 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 USA [10][11][12], Lagergren in Sweden[13][14] and Jean-Jaques Welti in France[15] in 1962-63. The transvenous, or pervenous, procedure involved incision of a vein into which was inserted the catheter In medicine a catheter is a tube that can be inserted into a body cavity, duct or vessel. Catheters thereby allow drainage, injection of fluids or access by surgical instruments. The process of inserting a catheter is catheterization. In most uses a catheter is a thin, flexible tube ; in some uses, it is a larger, solid tube. ("hard" electrode lead under 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.

World's first Lithium-iodide cell powered pacemaker. Cardiac Pacemakers Inc. 1972

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 A mercury battery is a non-rechargeable electrochemical battery, a primary cell. Due to the content of mercury, and the resulting environmental concerns, the sale of mercury batteries is banned in many countries. Both ANSI and IEC have withdrawn standards for mercury batteries. Mercury batteries were made in button types for watches and.

In the late 1960s, several companies, including ARCO in the USA, developed isotope powered pacemakers, but this development was overtaken by the development in 1970 of the lithium-iodide cell 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 Epoxy or polyepoxide is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives resin encapsulation affecting the electronic circuitry. This phenomenon was overcome by encasing the pacemaker generator in an hermetically sealed metal case, initially by Telectronics Telectronics Pty Ltd was an Australian company best known for its role in developing the pacemaker. In 1988 the business was acquired by Pacific Dunlop. However, legal claims resulting from the sale of faulty pacemaker electrode leads inherited by the company in acquisition of Cordis Corporation of Miami led to eventual sale of the assets of the of Australia in 1969 followed by Cardiac Pacemakers Inc of Minneapolis in 1972. This technology, using titanium as the encasing metal, became the standard by the mid-1970s.

Others who contributed significantly to the technological development of the pacemaker in the pioneering years were Bob Anderson of Medtronic Medtronic, Inc. , based in Minneapolis, Minnesota Minneapolis, J.G (Geoffrey) Davies of St George's Hospital London, Barouh Berkovits and Sheldon Thaler of American Optical, Geoffrey Wickham of Telectronics Telectronics Pty Ltd was an Australian company best known for its role in developing the pacemaker. In 1988 the business was acquired by Pacific Dunlop. However, legal claims resulting from the sale of faulty pacemaker electrode leads inherited by the company in acquisition of Cordis Corporation of Miami led to eventual sale of the assets of the Australia, Walter Keller of Cordis Corp. of Miami, Hans Thornander who joined previously mentioned Rune Elmquist of Elema-Schonander in Sweden, Janwillem van den Berg of Holland and Anthony Adducci of Cardiac Pacemakers Inc.(Guidant

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 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 Anesthesia suggests this must be done to raise the ventricular pressure to 10 - 15mmhg 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.[16]

Transcutaneous Pacing

Main article: Transcutaneous pacing Transcutaneous pacing is a temporary means of pacing a patient's heart during a medical emergency. It is accomplished by delivering pulses of electric current through the patient's chest, which stimulates the heart to contract

Transcutaneous pacing (TCP), also called external pacing, is recommended for the initial stabilization of hemodynamically significant bradycardias Bradycardia , as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min 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 Electrocardiography is the recording of the electrical activity of the heart over time via skin electrodes. It is a noninvasive recording produced by an electrocardiographic device. The etymology of the word is derived from electro, because it is related to electrical activity, cardio, Greek for heart, graph, a Greek root meaning "to write&) is achieved, with a corresponding pulse. Pacing artifact on the ECG Electrocardiography is the recording of the electrical activity of the heart over time via skin electrodes. It is a noninvasive recording produced by an electrocardiographic device. The etymology of the word is derived from electro, because it is related to electrical activity, cardio, Greek for heart, graph, a Greek root meaning "to write& 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)

Main article: Epicardial

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.

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 The aortic valve is one of the valves of the heart. It lies between the left ventricle and the aorta 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 During a right bundle branch block, the right ventricle is not directly activated by impulses travelling through the right bundle branch. The left ventricle however, is still normally activated by the left bundle branch and these impulses travel through the left ventricle's myocardium to the right ventricle and activate the right ventricle pattern. Progressively weaker pacing stimuli are administered, which results in asystole In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow. Asystole is one of the conditions required for a medical practitioner to certify death in the second half of the tracing. At the end of the tracing, distortion results from muscle contractions due to a (short) hypoxic seizure An epileptic seizure is a transient symptom of excessive or synchronous neuronal activity in the brain. It can manifest as an alteration in mental state, tonic or clonic movements, convulsions, and various other psychic symptoms . The medical syndrome of recurrent, unprovoked seizures is termed epilepsy, but seizures can occur in people who do not. Because decreased pacemaker stimuli do not result in a ventricular escape rhythm In cardiology a ventricular escape beat is a self-generated electrical discharge initiated by, and causing contraction of, the ventricles of the heart; normally the heart rhythm is begun in the atria of the heart and is subsequently transmitted to the ventricles. The ventricular escape beat follows a long pause in ventricular rhythm and acts to, the patient can be said to be pacemaker-dependent and needs a definitive pacemaker.

Transvenous Pacing (temporary)

Main article: Transvenous pacing

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 pacing

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 pacing with an implantable pacemaker involves transvenous placement of one or more pacing electrodes within a chamber, or chambers, of the heart. 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 Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an x-ray source and fluorescent screen between which a patient is placed. However, modern fluoroscopes couple the screen to an x- which enables the physician or cardiologist 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:[17]

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. The whole thing will not be rejected, and will be encapsulated by scar tissue, in the same way a piercing is.[citation needed]

Basic function

Modern pacemakers usually have multiple functions. The most basic form monitors the heart's native electrical rhythm. When the pacemaker fails to sense a heartbeat within a normal beat-to-beat time period, it will stimulate the ventricle of the heart with a short low voltage pulse. This sensing and stimulating activity continues on a beat by beat basis.

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[18]
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)

Biventricular Pacing (BVP)

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 2 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.

A biventricular pacemaker, also known as CRT (cardiac resynchronization therapy) is a type of pacemaker that can pace both the septal and lateral walls of the left ventricle. By pacing both sides of the left ventricle, the pacemaker can resynchronize a heart whose opposing walls do not contract in synchrony, which occurs in approximately 25-50 % of heart failure patients. CRT devices have at least two leads, one in the right ventricle to stimulate the septum, and another inserted through the coronary sinus to pace the lateral 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 msec or greater.[19][20][21] CRT can be combined with an implantable cardioverter-defibrillator (ICD).[22]

Advancements in function

X-ray image of installed pacemaker showing wire routing

One unrealized advancement in pacemaker function could mimic nature by utilizing various bodily input parameters such as CO2 - O2 at in arterial-vein system, body temperature, ATP levels, Adrenaline, etc. Instead of producing a static, predetermined heart rate, or intermittent control, a Dynamic Pacemaker could compensate for both actual respiratory loading and potentially anticipated respiratory loading. A Dynamic Pacemaker would require sensory technology for which heart-rate regulation parameters must first be acutely identified. 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 or may not be of interest to transitional tissue welding.

When first invented, pacemakers controlled only the rate at which the heart's two largest chambers, the ventricles, beat.

Many advancements have been made to enhance the control of the pacemaker once implanted. Many of these enhancements 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[23] have shown that unnecessary pacing of the right ventricle can lead to heart failure and an increased 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.

Patient considerations

Insertion

Wound left after a Pacemaker Implant

A pacemaker is typically inserted into the patient through a simple surgery using a local anesthetic. The patient is usually given a drug for relaxation, and an antibiotic to prevent infection.[24] An incision is made in the left shoulder area below the collar bone where the pacemaker is actually housed in the patient's body. The lead or leads (the number of leads varies depending on the type of pacemaker) are fed into the heart through a large vein using a fluoroscope to monitor the progress of lead insertion. A temporary drain may be installed and removed the following day. The actual surgery may take about an hour.

The patient should exercise reasonable care about the wound as it heals.

Following surgery there is a followup session during which the pacemaker is checked using a "programmer" that can communicate with the device and allows a health care professional to evaluate the system's integrity and determine the settings such as pacing voltage output.

Pacemaker Patient Identification Card

International Pacemaker Patient Identification Cards carry information such as; patient data (between others, symptom primary, ECG, aetiology), pacemaker center (doctor, hospital), IPG (rate, mode, date of implantation, MFG, type) and lead [25][26].

Living with a pacemaker

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. 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 (6) months, though will vary depending upon patient/device status and remote monitoring availability.

At the time of in-office follow-up, the device will be interrogated to perform diagnostic testing. These tests include:

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.

An additional aspect of the in-office check is to examine any events that were stored since the last follow-up. 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.

Lifestyle Considerations

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 may be uncomfortable if the harness should fall across the pacemaker insertion site.

Any kind of an activity that involves intense magnetic fields should be avoided. This includes activities such as arc welding possibly, with certain types of equipment[27], or maintaining heavy equipment that may generate intense magnetic fields.

A 2008 U.S. study has found[28] that the magnets in some portable music player headphones may interfere with pacemakers when placed in close proximity.

Some medical procedures may require the use of antibiotics to be administered before the procedure. The patient should inform all medical personnel that the patient does have a pacemaker. Some standard medical procedures such as the use of Magnetic resonance imaging (MRI) may be ruled out by the patient having a pacemaker.

In addition, according to the American Heart Association, there are other devices that cause risk with patients that have pacemakers, such as:

• anti-theft systems which are also known as electronic article surveillance (EAS) • metal detectors for security • cell phones • extracorporeal shock-wave lithotripsy (ESWL) • radiofrequency ablation (RFA) • short-wave or microwave diathermy • therapeutic radiation • transcutaneous electric nerve stimulation (TENS)

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.[29] 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.[29]

Other devices with pacemaker function

Main article: Implantable cardioverter-defibrillator

Sometimes devices resembling pacemakers, called ICDs (implantable cardioverter-defibrillators) 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.

NASPE / BPEG Defibrillator (NBD) code - 1993[30]
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[30]
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

See also

References

  1. ^ McWilliam JA (1889). "Electrical stimulation of the heart in man". Br Med J 1: 348–50. doi:10.1136/bmj.1.1468.348. . Partial quote in "Electrical Stimulation of the Heart in Man - 1889", Heart Rhythm Society, Accessed May 11, 2007.
  2. ^ Lidwell M C, "Cardiac Disease in Relation to Anaesthesia" in Transactions of the Third Session, Australasian Medical Congress, Sydney, Australia, Sept. 2-7 1929, p 160.
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  8. ^ Success Stories : Larsson, Arne : St. Jude Medical
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  15. ^ Jean Jaques Welti:Biography, Heart Rhythm Foundation
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  19. ^ Cleland JG, Daubert JC, Erdmann E, et al. (2005). "The effect of cardiac resynchronization on morbidity and mortality in heart failure". N. Engl. J. Med. 352 (15): 1539–49. doi:10.1056/NEJMoa050496. PMID 15753115. http://content.nejm.org/cgi/content/full/352/15/1539.
  20. ^ Bardy GH, Lee KL, Mark DB, et al. (2005). "Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure". N. Engl. J. Med. 352 (3): 225–37. doi:10.1056/NEJMoa043399. PMID 15659722. http://content.nejm.org/cgi/pmidlookup?view=short&pmid=15659722&promo=ONFLNS19.
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  24. ^ de Oliveira JC, Martinelli M, D'Orio Nishioka SA, et al. (2009). "Efficacy of antibiotic prophylaxis prior to the implantation of pacemakers and cardioverter-defibrillators: Results of a large, prospective, randomized, double-blinded, placebo-controlled trial". Circ Arrhythmia Electrophysiol 2: 29–34. doi:10.1161/CIRCEP.108.795906.
  25. ^ European Pacemaker Patient Identification card
  26. ^ Eucomed
  27. ^ "Testing of work environments for electromagnetic interference (Pacing Clin Electrophysiol. 1992) - PubMed Result". www.ncbi.nlm.nih.gov. http://www.ncbi.nlm.nih.gov/pubmed/1279591. Retrieved on 2008-11-10.
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External links

Health Science – Medicine - Surgery - Cardiac surgery procedures (ICD-9-CM V3 35-37)
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Congenital heart disease Atrial septostomy - Blalock-Taussig shunt - Fontan procedure - Norwood procedure - Rastelli procedure - Kawashima procedure - Mustard procedure
Conduction system Maze procedure (Cox maze and minimaze) - Pacemaker insertion

Categories: American inventions | Australian inventions | Cardiac electrophysiology | Embedded systems | Implants | Neuroprosthetics | Prosthetics

 

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