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Cardiac arrest is a sudden loss of
blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory system is controlled by homeostasis, homeostatic mechanisms of autoregulation, just as hydraul ...
resulting from the failure 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
to pump effectively. Signs include
loss of consciousness Unconsciousness is a state which occurs when the ability to maintain an awareness of self and environment is lost. It involves a complete, or near-complete, lack of responsiveness to people and other environmental stimulus A stimulus is somethin ...

loss of consciousness
and abnormal or absent breathing. Some individuals may experience
chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in the shoulder, arm, upper abdomen, or jaw, along with na ...
,
shortness of breath Shortness of breath (SOB), also known as dyspnea (BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codificat ...
, or
nausea Nausea is a diffuse sensation of unease and discomfort, often perceived as an urge to vomiting, vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, upper abdomen, or ...

nausea
before cardiac arrest. If not treated within minutes, it typically leads to
death Death is the permanent, irreversible cessation of all biological functions that sustain a living Living or The Living may refer to: Common meanings *Life, a condition that distinguishes organisms from inorganic objects and dead organi ...

death
. The most common cause of cardiac arrest is
coronary artery disease Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the heart muscle Cardiac muscle (also called heart muscle or myocardium) i ...
. Less common causes include major
blood loss Bleeding, also known as a hemorrhage, haemorrhage, or simply blood loss, is blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an organism to survi ...

blood loss
, lack of oxygen, very low potassium,
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 . A number of inherited disorders may also increase the risk including
long QT syndrome Long QT syndrome (LQTS) is a condition in which repolarization of the heart after a Cardiac cycle, heartbeat is affected. It results in an increased risk of an cardiac arrhythmia, irregular heartbeat which can result in Syncope (medicine), faintin ...
. The initial heart rhythm is most often
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
. The diagnosis is confirmed by finding no
pulse In medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge) ...

pulse
. While a cardiac arrest may be caused by
heart attack A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

heart attack
or heart failure, these are not the same. Prevention includes not smoking, physical activity, and maintaining a healthy weight. Treatment for cardiac arrest includes immediate
cardiopulmonary resuscitation Cardiopulmonary resuscitation (CPR) is an emergency procedure An emergency procedure is a plan of actions to be conducted in a certain order or manner, in response to a specific class of reasonably foreseeable emergency, a situation that poses ...
(CPR) and, if a
shockable rhythm 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 ...
is present,
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 ...
. Among those who survive,
targeted temperature management Targeted temperature management (TTM) previously known as therapeutic hypothermia or protective hypothermia is an active treatment that tries to achieve and maintain a specific body temperature in a person for a specific duration of time in an ef ...
may improve outcomes. An
implantable cardiac 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 by which an abnormally fa ...
may be placed to reduce the chance of death from recurrence. In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
, approximately 535,000 cases occur a year. About 13 per 10,000 people (326,000 or 61%) experience cardiac arrest outside of a hospital setting, while 209,000 (39%) occur within a hospital. Cardiac arrest becomes more common with age. It affects males more often than females. The percentage of people who survive out of hospital cardiac arrest with treatment by emergency medical services is about 8%. Many who survive have significant
disability A disability is any condition that makes it more difficult for a person to do certain activities or effectively interact with the world around them (socially or materially). These conditions, or impairments, may be Cognitive disability, cogn ...

disability
. However, many American television programs have portrayed unrealistically high survival rates of 67%.


Signs and symptoms

Cardiac arrest is not preceded by any warning symptoms in approximately 50 percent of people. For those who do experience symptoms, they will be non-specific, such as new or worsening
chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in the shoulder, arm, upper abdomen, or jaw, along with na ...
,
fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
, blackouts,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo Vertigo is a condition where a person has the sensation of moving or of surrounding objects moving when they are not. Often it feels like a spinnin ...

dizziness
,
shortness of breath Shortness of breath (SOB), also known as dyspnea (BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codificat ...
,
weakness Weakness is a symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressu ...
and
vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilat ...

vomiting
. When cardiac arrest occurs, the most obvious sign of its occurrence will be the lack of a palpable
pulse In medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge) ...

pulse
in the victim. Also, as a result of loss of cerebral perfusion (blood flow to the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
), the victim will rapidly lose
consciousness Consciousness, at its simplest, is sentience or awareness of internal and external existence. Despite millennia of analyses, definitions, explanations and debates by philosophers and scientists, consciousness remains puzzling and controversial ...

consciousness
and will stop breathing. The main criterion for diagnosing a cardiac arrest, as opposed to
respiratory arrest Respiratory arrest is caused by apnea Apnea (BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codification ...
, which shares many of the same features, is lack of
circulation Circulation may refer to: Science and technology * Atmospheric circulation, the large-scale movement of air * Circulation (physics), the path integral of the fluid velocity around a closed curve in a fluid flow field * Circulatory system, a biolo ...
; however, there are a number of ways of determining this.
Near-death experience A near-death experience (NDE) is a profound personal experience associated with death or impending death which researchers claim share similar characteristics. When positive, such experiences may encompass a variety of sensations including deta ...
s are reported by 10 to 20 percent of people who survived cardiac arrest. Certain types of prompt intervention can often reverse a cardiac arrest, but without such intervention, death is all but certain. In certain cases, cardiac arrest is an anticipated outcome of a serious illness where death is expected.


Causes

Sudden cardiac arrest (SCA) and sudden cardiac death (SCD) occur when the heart abruptly begins to beat in an abnormal or irregular rhythm (
arrhythmia Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the is irregular, too fast, or too slow. The that is too fast – above 100 beats per minute in adults – is called , and a heart rate that i ...
). Without organized electrical activity in the heart muscle, there is no consistent contraction of the ventricles, which results in the heart's inability to generate an adequate
cardiac output Cardiac output (CO), also known as heart output denoted by the symbols Q, or \dot Q_ , is a term used in cardiac physiologyCardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; Ca ...
(forward pumping of blood from heart to rest of the body). There are many different types of
arrhythmias 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 rateHeart rate is the speed of the heartbeat measured by the number of contraction ...
, but the ones most frequently recorded in SCA and SCD are
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) or
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
(VF). Less common causes of dysrhythmias in cardiac arrest include
pulseless electrical activity Pulseless electrical activity (PEA) refers to cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not. Pulseless electrical activity is found initially in about 55% of people in cardiac arrest. U ...
(PEA) or
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
. Such rhythms are seen when there is prolonged cardiac arrest, progression of ventricular fibrillation, or due to efforts such as defibrillation to resuscitate the person. Sudden cardiac arrest can result from cardiac and non-cardiac causes including the following:


Coronary artery disease

Coronary artery disease Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the heart muscle Cardiac muscle (also called heart muscle or myocardium) i ...
(CAD), also known as
ischemic heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), Ischemia, ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the myocardium, heart muscle due to build-up of plaque (atherosclero ...
, is responsible for 62 to 70 percent of all SCDs. CAD is a much less frequent cause of SCD in people under the age of 40. Cases have shown that the most common finding at postmortem examination of sudden cardiac death (SCD) is chronic high-grade
stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular Organ (anatomy), organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture) ...
of at least one segment of a major coronary artery, the arteries that supply the heart muscle with its blood supply.


Structural heart disease

Structural heart diseases not related to CAD account for 10% of all SCDs. Examples of these include: cardiomyopathies (
hypertrophic __NOTOC__ Hypertrophy (, from Greek ὑπέρ "excess" + τροφή "nourishment") is the increase in the volume of an organ or tissue due to the enlargement of its component cells Cell most often refers to: * Cell (biology), the functional bas ...
, dilated, or arrythmogenic), cardiac rhythm disturbances, congenital coronary artery anomalies,
myocarditis Myocarditis, also known as inflammatory cardiomyopathy, is inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is ...
,
hypertensive heart disease Hypertensive heart disease includes a number of complications of high blood pressure Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term Disease, medical condition in which the blood pressure in the artery, arter ...
, and
congestive 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 mos ...
.
Left ventricular hypertrophy Left ventricular hypertrophy (LVH) is of the of the left of the , that is, left-sided . Causes While ventricular hypertrophy as a reaction to and , it is most frequently referred to as a pathological reaction to , or . It is one aspect of . ...
is thought to be a leading cause of SCD in the adult population. This is most commonly the result of longstanding
high blood pressure Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank ...

high blood pressure
which has caused secondary damage to the wall of the main pumping chamber of the heart, 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 ...
. A 1999 review of SCDs in the United States found that this accounted for over 30% of SCDs for those under 30 years. A study of military recruits age 18-35 found that this accounted for over 40% of SCDs. Congestive heart failure increases the risk of SCD fivefold.


Inherited arrhythmia syndromes

Arrhythmias that are not due to structural heart disease account for 5 to 10% of sudden cardiac arrests. These are frequently caused by
genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome In the fields of molecular biology Molecular biology is the branch of biology Biology is the natural science that studies life and li ...
s that lead to abnormal heart rhythms. The genetic
mutation 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 mechan ...
s often affect specialised proteins known as
ion channel Ion channels are pore-forming membrane protein Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane ...

ion channel
s that conduct electrically charged particles across the
cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane A biological membrane, biomembrane or cell membrane is a selectively permeable membra ...

cell membrane
, and this group of conditions are therefore often referred to as
channelopathies Channelopathies are diseases caused by disturbed function of ion channel subunits or the proteins that regulate them. These diseases may be either congenital (often resulting from a mutation or mutations in the encoding genes) or acquired (often re ...
. Examples of these inherited arrhythmia syndromes include
Long QT syndrome Long QT syndrome (LQTS) is a condition in which repolarization of the heart after a Cardiac cycle, heartbeat is affected. It results in an increased risk of an cardiac arrhythmia, irregular heartbeat which can result in Syncope (medicine), faintin ...
,
Brugada Syndrome Brugada syndrome (BrS) is a genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome In the fields of molecular biology and genetics, a genome is all genetic information of an orga ...
,
Catecholaminergic polymorphic ventricular tachycardia Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited genetic disorder that predisposes those affected to potentially life-threatening abnormal heart rhythms or Heart arrhythmia, arrhythmias. The arrhythmias seen in CPVT ...
, and
Short QT syndrome Short QT syndrome (SQT) is a very rare genetic disease of the electrical system 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, common ...
. Other conditions that promote arrhythmias but are not caused by genetic mutations include Wolff-Parkinson-White syndrome. Long QT syndrome, a condition often mentioned in young people's deaths, occurs in one of every 5000 to 7000 newborns and is estimated to be responsible for 3000 deaths each year compared to the approximately 300,000 cardiac arrests seen by emergency services.Sudden Cardiac Death
These conditions are a fraction of the overall deaths related to cardiac arrest but represent conditions which may be detected prior to arrest and may be treatable.


Non-cardiac causes

SCA due to non-cardiac causes accounts for the remaining 15 to 25%. The most common non-cardiac causes are
trauma Trauma most often refers to: *Major trauma, in physical medicine, severe physical injury caused by an external source *Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic injur ...
, major
bleeding Bleeding, also known as a hemorrhage, haemorrhage, or simply blood loss, is blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally ...

bleeding
(
gastrointestinal bleeding Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the Human gastrointestinal tract, gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a sho ...
,
aortic rupture Aortic rupture is the rupture or breakage of the aorta The aorta ( ) is the main and largest artery An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, br ...

aortic rupture
, or
intracranial hemorrhage Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull The skull is a bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. Bones p ...
),
hypovolemic shock Hypovolemic shock is a medical emergency and an advanced form of hypovolemia due to insufficient amounts of blood and/or fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied shea ...
,
overdose A drug overdose (overdose or OD) is the ingestion Ingestion is the consumption of a substance by an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system t ...

overdose
,
drowning Drowning is a type of suffocation Asphyxia or asphyxiation is a condition of deficient supply of oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Grou ...

drowning
, and
pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain p ...

pulmonary embolism
. Cardiac arrest can also be caused by poisoning (for example, by the ), or through electrocution, lightning.


Mnemonic for reversible causes

"Hs and Ts" is the name for a mnemonic used to aid in remembering the possible treatable or reversible causes of cardiac arrest. ; Hs * Hypovolemia – A lack of blood volume * Hypoxia – A lack of
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
* ions (
Acidosis Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term ''acidemia'' describes th ...

Acidosis
) – An abnormal pH in the body * Hyperkalemia or Hypokalemia – Both increased or decreased
potassium Potassium is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, b ...

potassium
can be life-threatening. * Hypothermia – A low
core body temperature Normal human body-temperature (normothermia, euthermia) is the typical temperature range found in humans. The normal human body temperature range is typically stated as . Human body temperature varies. It depends on gender, age, time of day, exe ...
* or – Low or high blood glucose ; Ts * Tablets or Toxins such as drug overdose * Cardiac Tamponade – Fluid building up around the heart * Tension pneumothorax – A collapsed lung * (
Myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

Myocardial infarction
) – Heart attack * (
Pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain p ...

Pulmonary embolism
) – A blood clot in the lung * Traumatic cardiac arrest


Children

In children, the most common cause of cardiopulmonary arrest is shock or
respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise i ...

respiratory failure
that has not been treated, rather than a
heart arrhythmia 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 rateHeart rate is the speed of the heartbeat measured by the number of contraction ...
. When there is a cardiac arrhythmia, it is most often
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
or
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 ...
, in contrast to
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
or
tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (s ...
as seen in adults. Other causes can include drugs such as
cocaine Cocaine (from , from , ultimately from Quechuan languages, Quechua: ''kúka'') is a tropane alkaloid and stimulant drug obtained primarily from the leaves of two coca species native to South America, ''Erythroxylum coca'' and ''Erythroxylu ...
,
methamphetamine Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug use, recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disord ...

methamphetamine
, or overdose of medications such as antidepressants in a child who was previously healthy but is now presenting with a dysrhythmia that has progressed to cardiac arrest.


Risk factors

The risk factors for SCD are similar to those of coronary artery disease and include age, cigarette smoking, high blood pressure, high cholesterol, lack of
physical exercise Exercise is any bodily activity that enhances or maintains physical fitness Physical fitness is a state of health Health is a state of physical, mental and social well-being Well-being, also known as ''wellness'', ''prudential valu ...
,
obesity Obesity is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. ...

obesity
,
diabetes Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorder A metabolic disorder is a disorder that negatively alters the body's processing and distribution of macronutrients such as proteins, fats, and carbohydrate ...

diabetes
, and
family history Genealogy (from el, γενεαλογία ' "study of family trees") is the study of families In human society, family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinit ...
. A prior episode of sudden cardiac arrest also increases the risk of future episodes.
Air pollution Air pollution is the presence of substances in the atmosphere that are harmful to the health of humans and other Outline of life forms, living beings, or cause damage to the climate or to materials. There are different types of air pollutants, ...

Air pollution
is also associated with the risk of cardiac arrest. Current cigarette smokers with coronary artery disease were found to have a two to threefold increase in the risk of sudden death between ages 30 and 59. Furthermore, it was found that former smokers’ risk was closer to that of those who had never smoked.


Mechanism

The mechanism responsible for the majority of sudden cardiac deaths is
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
. Structural changes in the diseased heart as a result of inherited factors (mutations in ion-channel coding genes for example) cannot explain the suddenness of SCD. Also, sudden cardiac death could be the consequence of and
bradyarrhythmia Bradycardia is a condition typically defined wherein an individual has a resting heart rate of under 60 beats per minute (BPM) in adults, although some studies use a heart rate of less than 50 BPM. Bradycardia typically does not cause symptoms u ...
s.


Diagnosis

Cardiac arrest is synonymous with
clinical death Clinical death is the medical term Medical terminology is language used to precisely describe the human body including its components, processes, conditions affecting it, and procedures performed upon it. Medical terminology is used in the field of ...

clinical death
. Historical information and a physical exam diagnosis cardiac arrest, as well as provides information regarding the potential cause and the prognosis. The history should aim to determine if the episode was observed by anyone else, what time the episode took place, what the person was doing (in particular if there was any trauma), and involvement of drugs. The physical examination portion of diagnosis cardiac arrest focuses on the absence of a pulse clinically. In many cases lack of is the
gold standard A gold standard is a monetary system A monetary system is a system by which a government provides money in a country's economy. Modern monetary systems usually consist of the national treasury, the mint (facility), mint, central bank, the cen ...
for diagnosing cardiac arrest, as lack of a pulse (particularly in the peripheral pulses) may result from other conditions (e.g. shock), or simply an error on the part of the rescuer. Nonetheless, studies have shown that rescuers often make a mistake when checking the carotid pulse in an emergency, whether they are healthcare professionals or lay persons. Owing to the inaccuracy in this method of diagnosis, some bodies such as the European Resuscitation Council (ERC) have de-emphasised its importance. The Resuscitation Council (UK), in line with the ERC's recommendations and those of the American Heart Association, have suggested that the technique should be used only by healthcare professionals with specific training and expertise, and even then that it should be viewed in conjunction with other indicators such as
agonal respiration Agonal respiration, gasping respiration or agonal breathing is a distinct abnormal pattern of breathing and brainstem reflex characterized by gasping, labored breathing, accompanied by strange vocalizations and myoclonus. Possible causes include c ...
. Various other methods for detecting circulation have been proposed. Guidelines following the 2000 International Liaison Committee on Resuscitation (ILCOR) recommendations were for rescuers to look for "signs of circulation", but not specifically the pulse. These signs included coughing, gasping, colour, twitching, and movement. However, in face of evidence that these guidelines were ineffective, the current recommendation of ILCOR is that cardiac arrest should be diagnosed in all casualties who are unconscious and not breathing normally. Another method is to use molecular autopsy or postmortem molecular testing which uses a set of molecular techniques to find the ion channels that are cardiac defective. Other physical findings can help determine the potential cause of the cardiac arrest.


Classifications

Clinicians classify cardiac arrest into "shockable" versus "non-shockable", as determined by 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
rhythm. This refers to whether a particular class of
cardiac dysrhythmia 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 ...
is treatable using
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 ...
. The two "shockable" rhythms are
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
and pulseless ventricular tachycardia while the two "non-shockable" rhythms are
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
and
pulseless electrical activity Pulseless electrical activity (PEA) refers to cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not. Pulseless electrical activity is found initially in about 55% of people in cardiac arrest. U ...
.


Prevention

With positive outcomes following cardiac arrest unlikely, an effort has been spent in finding effective strategies to prevent cardiac arrest. With the prime causes of cardiac arrest being
ischemic heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), Ischemia, ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the myocardium, heart muscle due to build-up of plaque (atherosclero ...
, efforts to promote a
healthy diet A healthy diet is a diet Diet may refer to: Food * Diet (nutrition) In nutrition, diet is the sum of food consumed by a person or other organism. The word diet often implies the use of specific intake of nutrition for #Health, health or #We ...
,
exercise Exercise is any bodily activity that enhances or maintains physical fitness Physical fitness is a state of health Health is a state of physical, mental and social well-being Well-being, also known as ''wellness'', ''prudential value ...

exercise
, and
smoking cessation Smoking cessation, usually called quitting smoking or stopping smoking, is the process of discontinuing tobacco smoking Tobacco smoking is the practice of burning tobacco village in Xanthi, Greece Tobacco is the common name of sever ...
are important. For people at risk of heart disease, measures such as
blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physics, a force is an influence that can change the motion (physics), motion of an Physical object, object. A force can cause an object with mas ...

blood pressure
control,
cholesterol Cholesterol is any of a class of certain organic compound, organic molecules. A cholesterol is a sterol (or chemical modification, modified steroid), a type of lipid. Cholesterol is biosynthesis, biosynthesized by all animal Cell (biology)#Euk ...

cholesterol
lowering, and other medico-therapeutic interventions are used. A
Cochrane review Cochrane (previously known as the Cochrane Collaboration) is a British international charitable organisation formed to organise medical research findings to facilitate evidence-based Evidence-based practice (EBP) is the idea that occupation ...
published in 2016 found moderate-quality evidence to show that blood pressure-lowering drugs do not appear to reduce sudden cardiac death.


Code teams

In medical parlance, cardiac arrest is referred to as a "code" or a "crash". This typically refers to "code blue" on the
hospital emergency codes Hospital emergency codes are coded messages often announced over a public address system of a hospital A hospital is a health care institution providing patient treatment with specialized medical and nursing staff and medical equipment. The be ...
. A dramatic drop in vital sign measurements is referred to as "coding" or "crashing", though coding is usually used when it results in cardiac arrest, while crashing might not. Treatment for cardiac arrest is sometimes referred to as "calling a code". People in general wards often deteriorate for several hours or even days before a cardiac arrest occurs. This has been attributed to a lack of knowledge and skill amongst ward-based staff, in particular, a failure to carry out measurement of the
respiratory rate The respiratory rate is the rate at which breathing File:X-ray video of a female American alligator (Alligator mississippiensis) while breathing - pone.0004497.s009.ogv, upright=1.4, X-ray video of a female American alligator while breathing. ...
, which is often the major predictor of a deterioration and can often change up to 48 hours prior to a cardiac arrest. In response to this, many hospitals now have increased training for ward-based staff. A number of "early warning" systems also exist which aim to quantify the person's risk of deterioration based on their
vital signs Vital signs (also known as vitals) are a group of the four to six most important that indicate the status of the body’s (life-sustaining) functions. These measurements are taken to help assess the general physical health of a person, give clu ...
and thus provide a guide to staff. In addition, specialist staff are being used more effectively in order to augment the work already being done at ward level. These include: * Crash teams (or code teams) – These are designated staff members with particular expertise in resuscitation who are called to the scene of all arrests within the hospital. This usually involves a specialized cart of equipment (including
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 ...
) and drugs called a "" or "crash trolley". * Medical emergency teams – These teams respond to all emergencies, with the aim of treating the people in the acute phase of their illness in order to prevent a cardiac arrest. These teams have been found to decrease the rates of in-hospital cardiac arrest and improve survival. * Critical care outreach – As well as providing the services of the other two types of team, these teams are also responsible for educating non-specialist staff. In addition, they help to facilitate transfers between intensive care/high dependency units and the general hospital wards. This is particularly important, as many studies have shown that a significant percentage of patients discharged from critical care environments quickly deteriorate and are re-admitted; the outreach team offers support to ward staff to prevent this from happening.


Implantable cardioverter defibrillator

An
implantable cardioverter defibrillator An implantable cardioverter-defibrillator (ICD) or automated implantable cardioverter defibrillator (AICD) is a device implant (medicine), implantable inside the body, able to perform cardioversion, defibrillation, and (in modern versions) car ...

implantable cardioverter defibrillator
(ICD) is a battery-powered device that monitors electrical activity in the heart and when an arrhythmia or asystole is detected is able to deliver an electrical shock to terminate the abnormal rhythm. ICDs are used to prevent sudden cardiac death (SCD) in those that have survived a prior episode of sudden cardiac arrest (SCA) due to ventricular fibrillation or ventricular tachycardia (
secondary prevention Preventive healthcare, or prophylaxis, consists of measures taken for disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental health and efficienc ...
). ICD's are also used prophylactically to prevent sudden cardiac death in certain high risk patient populations (
primary prevention Preventive healthcare, or prophylaxis, consists of measures taken for disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental health and efficiency ...
). Numerous studies have been conducted on the use of ICDs for the secondary prevention of SCD. These studies have shown improved survival with ICD's compared to the use of anti-arrhythmic drugs. ICD therapy is associated with a 50%
relative risk reduction In epidemiology, the relative risk reduction (RRR) or efficacy is the relative decrease in the risk of an adverse event in the exposed group compared to an unexposed group. It is computed as (I_u - I_e) / I_u, where I_eis the incidence in the expo ...
in death caused by an arrhythmia and a 25% relative risk reduction in all cause mortality. Primary prevention of SCD with ICD therapy for high-risk patient populations has similarly shown improved survival rates in a number of large studies. The high-risk patient populations in these studies were defined as those with severe ischemic cardiomyopathy (determined by a reduced left ventricular ejection fraction (LVEF)). The LVEF criteria used in these trials ranged from less than or equal to 30% in MADIT-II to less than or equal to 40% in MUSTT.


Diet

Marine-derived omega-3 polyunsaturated fatty acids (PUFAs) have been promoted for the prevention of sudden cardiac death due to their postulated ability to lower
triglyceride A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester An ester is a derived from an (organic or inorganic) in which at least one –OH group is replaced by an –O– () group, as in the substitution reaction of a an ...

triglyceride
levels, prevent
arrhythmia Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the is irregular, too fast, or too slow. The that is too fast – above 100 beats per minute in adults – is called , and a heart rate that i ...
s, decrease
platelet aggregation Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a s ...
, and lower blood pressure. However, according to a recent systematic review, omega-3 PUFA supplementation are not being associated with a lower risk of sudden cardiac death.


Management

Sudden cardiac arrest may be treated via attempts at resuscitation. This is usually carried out based upon basic life support, advanced cardiac life support (ACLS), pediatric advanced life support (PALS), or neonatal resuscitation program (NRP) guidelines.


Cardiopulmonary resuscitation

Early
cardiopulmonary resuscitation Cardiopulmonary resuscitation (CPR) is an emergency procedure An emergency procedure is a plan of actions to be conducted in a certain order or manner, in response to a specific class of reasonably foreseeable emergency, a situation that poses ...
(CPR) is essential to surviving cardiac arrest with good neurological function. It is recommended that it be started as soon as possible with minimal interruptions once begun. The components of CPR that make the greatest difference in survival are chest compressions and defibrillating shockable rhythms. After defibrillation, chest compressions should be continued for two minutes before a rhythm check is again done. This is based on a compression rate of 100-120 compressions per minute, a compression depth of 5–6 centimeters into the chest, full Cardiopulmonary resuscitation, chest recoil, and a ventilation rate of 10 breath ventilations per minute. Correctly performed bystander CPR has been shown to increase survival; however, it is performed in less than 30% of out of hospital arrests . If high-quality CPR has not resulted in return of spontaneous circulation and the person's heart rhythm is 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
, discontinuing CPR and pronouncing the person's death is reasonable after 20 minutes. Exceptions to this include certain cases with hypothermia or who have drowning, drowned. Some of these cases should have longer and more sustained CPR until they are nearly Normothermia, normothermic. Longer durations of CPR may be reasonable in those who have cardiac arrest while in hospital. Bystander CPR, by the lay public, before the arrival of EMS also improves outcomes. Either a bag valve mask or an advanced airway may be used to help with breathing particularly since vomiting and regurgitation are common, particularly in out-of-hospital cardiac arrest (OHCA). If this occurs, then modification to existing oropharyngeal suction may be required, such as the use of Suction Assisted Laryngoscopy Airway Decontamination. High levels of oxygen are generally given during CPR. Tracheal intubation has not been found to improve survival rates or neurological outcome in cardiac arrest and in the prehospital environment may worsen it. Endotracheal tube and supraglottic airways appear equally useful. When done by EMS 30 compressions followed by two breaths appear better than continuous chest compressions and breaths being given while compressions are ongoing. For bystanders, CPR which involves only chest compressions results in better outcomes as compared to standard CPR for those who have gone into cardiac arrest due to heart issues. Mechanical chest compressions (as performed by a machine) are no better than chest compressions performed by hand. It is unclear if a few minutes of CPR before defibrillation results in different outcomes than immediate defibrillation. If cardiac arrest occurs after 20 weeks of pregnancy someone should pull or push the uterus to the left during CPR. If a pulse has not returned by four minutes emergency Cesarean section is recommended.


Defibrillation

Defibrillation is indicated if a shockable rhythm is present. The two shockable rhythms are
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
and pulseless ventricular tachycardia. In children 2 to 4 J/Kg is recommended. In addition, there is increasing use of public access defibrillation. This involves placing an automated external defibrillator in public places, and training staff in these areas how to use them. This allows defibrillation to take place prior to the arrival of emergency services and has been shown to lead to increased chances of survival. Some defibrillators even provide feedback on the quality of CPR compressions, encouraging the lay rescuer to press the person's chest hard enough to circulate blood. In addition, it has been shown that those who have arrests in remote locations have worse outcomes following cardiac arrest.


Medications

, medications other than epinephrine (medication), epinephrine (adrenaline), while included in guidelines, have not been shown to improve survival to hospital discharge following out-of-hospital cardiac arrest. This includes the use of atropine, lidocaine, and amiodarone. Epinephrine in adults, as of 2019, appears to improve survival but does not appear to improve neurologically normal survival. It is generally recommended every five minutes. Vasopressin overall does not improve or worsen outcomes compared to epinephrine. The combination of epinephrine, vasopressin, and methylprednisolone appears to improve outcomes. Some of the lack of long-term benefit may be related to delays in epinephrine use. While evidence does not support its use in children, guidelines state its use is reasonable. Lidocaine and amiodarone are also deemed reasonable in children with cardiac arrest who have a shockable rhythm. The general use of sodium bicarbonate or calcium is not recommended. The use of calcium in children has been associated with poor neurological function as well as decreased survival. Correct dosing of medications in children is dependent on weight. To minimize time spent calculating medication doses, the use of a Broselow tape is recommended. The 2010 guidelines from the American Heart Association no longer contain the recommendation for using atropine in
pulseless electrical activity Pulseless electrical activity (PEA) refers to cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not. Pulseless electrical activity is found initially in about 55% of people in cardiac arrest. U ...
and
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
for want of evidence for its use. Neither lidocaine nor amiodarone, in those who continue in
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 ...
or
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
despite defibrillation, improves survival to hospital discharge but both equally improve survival to hospital admission. Thrombolytics when used generally may cause harm but may be of benefit in those with a confirmed
pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain p ...

pulmonary embolism
as the cause of arrest. Evidence for use of naloxone in those with cardiac arrest due to opioids is unclear but it may still be used. In those with cardiac arrest due to local anesthetic, lipid emulsion may be used.


Targeted temperature management

Cooling adults after cardiac arrest who have a return of spontaneous circulation (ROSC) but no return of consciousness improves outcomes. This procedure is called
targeted temperature management Targeted temperature management (TTM) previously known as therapeutic hypothermia or protective hypothermia is an active treatment that tries to achieve and maintain a specific body temperature in a person for a specific duration of time in an ef ...
(previously known as therapeutic hypothermia). People are typically cooled for a 24-hour period, with a target temperature of . There are a number of methods used to lower the body temperature, such as applying ice packs or cold-water circulating pads directly to the body, or infusing cold saline. This is followed by gradual rewarming over the next 12 to 24 hrs. Recent meta-analysis found that the use of therapeutic hypothermia after out-of-hospital cardiac arrest is associated with improved survival rates and better neurological outcomes.


Do not resuscitate

Some people choose to avoid aggressive measures at the end of life. A do not resuscitate order (DNR) in the form of an advance health care directive makes it clear that in the event of cardiac arrest, the person does not wish to receive
cardiopulmonary resuscitation Cardiopulmonary resuscitation (CPR) is an emergency procedure An emergency procedure is a plan of actions to be conducted in a certain order or manner, in response to a specific class of reasonably foreseeable emergency, a situation that poses ...
. Other directives may be made to stipulate the desire for intubation in the event of
respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise i ...

respiratory failure
or, if comfort measures are all that are desired, by stipulating that healthcare providers should "allow natural death".


Chain of survival

Several organizations promote the idea of a chain of survival. The chain consists of the following "links": * Early recognition If possible, recognition of illness before the person develops a cardiac arrest will allow the rescuer to prevent its occurrence. Early recognition that a cardiac arrest has occurred is key to survival for every minute a patient stays in cardiac arrest, their chances of survival drop by roughly 10%. * Early CPR improves the flow of blood and of oxygen to vital organs, an essential component of treating a cardiac arrest. In particular, by keeping the brain supplied with oxygenated blood, chances of neurological damage are decreased. * Early defibrillation is effective for the management of
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricular ...

ventricular fibrillation
and pulseless
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 ...
* Early advanced care * Early post-resuscitation care which may include percutaneous coronary intervention If one or more links in the chain are missing or delayed, then the chances of survival drop significantly. These protocols are often initiated by a Code Blue (emergency code), code blue, which usually denotes impending or acute onset of cardiac arrest or
respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise i ...

respiratory failure
, although in practice, code blue is often called in less life-threatening situations that require immediate attention from a physician.


Other

Resuscitation with extracorporeal membrane oxygenation devices has been attempted with better results for in-hospital cardiac arrest (29% survival) than out-of-hospital cardiac arrest (4% survival) in populations selected to benefit most. Cardiac catheterization in those who have survived an out-of-hospital cardiac arrest appears to improve outcomes although high quality evidence is lacking. It is recommended that it is done as soon as possible in those who have had a cardiac arrest with ST elevation due to underlying heart problems. The precordial thump may be considered in those with witnessed, monitored, unstable ventricular tachycardia (including pulseless VT) if a defibrillator is not immediately ready for use, but it should not delay CPR and shock delivery or be used in those with unwitnessed out of hospital arrest.


Prognosis

The overall chance of survival among those who have cardiac arrest outside hospital is poor, at 10%. Among those who have an out-of-hospital cardiac arrest, 70% occur at home and their survival rate is 6%. For those who have an in-hospital cardiac arrest, the survival rate is estimated to be 24%. Among children rates of survival are 3 to 16% in North America. For in hospital cardiac arrest survival to discharge is around 22%. However, some may have neurological injury that can range from mild memory problems to coma. Prognosis is typically assessed 72 hours or more after cardiac arrest. Rates of survival are better in those who someone saw collapse, got bystander CPR, or had either ventricular tachycardia or ventricular fibrillation when assessed. Survival among those with Vfib or Vtach is 15 to 23%. Women are more likely to survive cardiac arrest and leave hospital than men. A 1997 review found rates of survival to discharge of 14% although different studies varied from 0 to 28%. In those over the age of 70 who have a cardiac arrest while in hospital, survival to hospital discharge is less than 20%. How well these individuals are able to manage after leaving hospital is not clear. A study of survival rates from out-of-hospital cardiac arrest found that 14.6% of those who had received resuscitation by paramedics survived as far as admission to hospital. Of these, 59% died during admission, half of these within the first 24 hours, while 46% survived until discharge from hospital. This reflects an overall survival following cardiac arrest of 6.8%. Of these 89% had normal brain function or mild neurological disability, 8.5% had moderate impairment, and 2% had major neurological disability. Of those who were discharged from hospital, 70% were still alive four years later.


Epidemiology

Based on death certificates, sudden cardiac death accounts for about 15% of all deaths in Western countries. In the United States 326,000 cases of out of hospital and 209,000 cases of in hospital cardiac arrest occur among adults a year. The lifetime risk is three times greater in men (12.3%) than women (4.2%) based on analysis of the Framingham Heart Study. However this gender difference disappeared beyond 85 years of age. Around half of these individuals are younger than 65 years of age. In the United States during pregnancy cardiac arrest occurs in about one in twelve thousand deliveries or 1.8 per 10,000 live births. Rates are lower in Canada.


Society and culture


Names

In many publications the stated or implicit meaning of "sudden cardiac death" is sudden
death Death is the permanent, irreversible cessation of all biological functions that sustain a living Living or The Living may refer to: Common meanings *Life, a condition that distinguishes organisms from inorganic objects and dead organi ...

death
from cardiac causes. However, sometimes physicians call cardiac arrest "sudden cardiac death" even if the person survives. Thus one can hear mentions of "prior episodes of sudden cardiac death" in a living person. In 2006 the American Heart Association presented the following definitions of sudden cardiac arrest and sudden cardiac death: "Cardiac arrest is the sudden cessation of cardiac activity so that the victim becomes unresponsive, with no normal breathing and no signs of circulation. If corrective measures are not taken rapidly, this condition progresses to sudden death. Cardiac arrest should be used to signify an event as described above, that is reversed, usually by CPR and/or defibrillation or cardioversion, or cardiac pacing. Sudden cardiac death should not be used to describe events that are not fatal".


Slow code

In some medical facilities, the resuscitation team may purposely respond slowly to a person in cardiac arrest, a practice known as "slow code", or may fake the response altogether for the sake of the person's family, a practice known as "show code". This is generally done for people for whom performing CPR will have no medical benefit. Such practices are ethically controversial, and are banned in some jurisdictions.


References


External links


The Center for Resuscitation Science at the Hospital of the University of Pennsylvania
{{DEFAULTSORT:Cardiac Arrest Cardiac arrhythmia Medical emergencies Causes of death Wikipedia medicine articles ready to translate RTTEM