Cardiac arrest
Cardiac arrest, also known as sudden cardiac arrest, is when the heart suddenly and unexpectedly stops beating.[11][1] As a result, blood cannot properly circulate around the body and there is diminished blood flow to the brain and other organs. When the brain does not receive enough blood, this can cause a person to lose consciousness. Coma and persistent vegetative state may result from cardiac arrest. Cardiac arrest is also identified by a lack of central pulses and abnormal or absent breathing.[1]
For other uses, see Cardiac arrest (disambiguation).Cardiac arrest
Cardiopulmonary arrest, circulatory arrest, sudden cardiac arrest (SCA)[1]
If reversed, coma, persistent vegetative state, post-cardiac arrest syndrome; if not reversed, death
The risk of onset increases with age[3]
Coronary artery disease, congenital heart defect, major blood loss, lack of oxygen, electrical injury, very low potassium, heart failure, myocardial infarction
Not smoking, physical activity, maintaining a healthy weight, healthy eating[5]
13 per 10,000 people per year (outside hospital in the US)[9]
> 425,000 per year (U.S.)[10]
Cardiac arrest and resultant hemodynamic collapse often occur due to arrhythmias (irregular heart rhythms). Ventricular fibrillation and ventricular tachycardia are most commonly recorded.[12] However, as many incidents of cardiac arrest occur out-of-hospital or when a person is not having their cardiac activity monitored, it is difficult to identify the specific mechanism in each case.
Structural heart disease, such as coronary artery disease, is a common underlying condition in people who experience cardiac arrest. The most common risk factors include age and cardiovascular disease.[13] Additional underlying cardiac conditions include heart failure and inherited arrhythmias. Additional factors that may contribute to cardiac arrest include major blood loss, lack of oxygen, electrolyte disturbance (such as very low potassium), electrical injury, and intense physical exercise.[14]
Cardiac arrest is diagnosed by the inability to find a pulse in an unresponsive patient.[4][1] The goal of treatment for cardiac arrest is to rapidly achieve return of spontaneous circulation using a variety of interventions including CPR, defibrillation, and/or cardiac pacing. Two protocols have been established for CPR: basic life support (BLS) and advanced cardiac life support (ACLS).[15]
If return of spontaneous circulation is achieved with these interventions, then sudden cardiac arrest has occurred. By contrast, if the person does not survive the event, this is referred to as sudden cardiac death. Among those whose pulses are re-established, the care team may initiate measures to protect the person from brain injury and preserve neurological function.[16] Some methods may include airway management and mechanical ventilation, maintenance of blood pressure and end-organ perfusion via fluid resuscitation and vasopressor support, correction of electrolyte imbalance, EKG monitoring and management of reversible causes, and temperature management. Targeted temperature management may improve outcomes.[17][18] In post-resuscitation care, an implantable cardiac defibrillator may be considered to reduce the chance of death from recurrence.[5]
Per the 2015 American Heart Association Guidelines, there are approximately 535,000 incidents of cardiac arrest annually (about 13 per 10,000 people).[9] Of these, 326,000 (61%) experience cardiac arrest outside of a hospital setting, while 209,000 (39%) occur within a hospital.[9]
Cardiac arrest becomes more common with age and affects males more often than females.[11] Twice as many black men die from a cardiac arrest as white men. Asian and Hispanic people are not as frequently affected as white people.[11]
Signs and symptoms[edit]
Cardiac arrest is not preceded by any warning symptoms in approximately 50 percent of people.[19] For individuals who do experience symptoms, the symptoms are usually nonspecific to the cardiac arrest.[20] For example, new or worsening chest pain, fatigue, blackouts, dizziness, shortness of breath, weakness, or vomiting.[20][11]
When cardiac arrest is suspected by a layperson (due to signs of unconsciousness, abnormal breathing, and/or no pulse) it should be assumed that the victim is in cardiac arrest. Bystanders should call emergency medical services (such as 911 or 112) and initiate CPR.
Risk factors[edit]
Major risk factors for cardiac arrest include age and underlying cardiovascular disease. A prior episode of sudden cardiac arrest increases the likelihood of future episodes.[21] A 2021 meta-analysis assessing the recurrence of cardiac arrest in out-of-hospital cardiac arrest survivors identified that 15% of survivors experienced a second event, most often in the first year.[22] Furthermore, of those who experienced recurrence, 35% had a third episode.[22]
Additional significant risk factors include cigarette smoking, high blood pressure, high cholesterol, history of arrhythmia, lack of physical exercise, obesity, diabetes, family history, cardiomyopathy, alcohol use, and possibly caffeine intake.[23][24][25][26] 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.[19][13] A statistical analysis of many of these risk factors determined that approximately 50% of all cardiac arrests occur in 10% of the population perceived to be at greatest risk, due to aggregate harm of multiple risk factors, demonstrating that cumulative risk of multiple comorbidities exceeds the sum of each risk individually.[27]
Prevention[edit]
Primary prevention[edit]
With the lack of positive outcomes following cardiac arrest, efforts have been spent finding effective strategies to prevent cardiac arrest events. The approach to primary prevention promotes a healthy diet, exercise, limited alcohol consumption, and smoking cessation.[5]
Exercise is an effective preventative measure for cardiac arrest in the general population but may be risky for those with pre-existing conditions.[69] The risk of a transient catastrophic cardiac event increases in individuals with heart disease during and immediately after exercise.[69] The lifetime and acute risks of cardiac arrest are decreased in people with heart disease who perform regular exercise, perhaps suggesting the benefits of exercise outweigh the risks.[69]
A 2021 study found that diet may be a modifiable risk factor for a lower incidence of sudden cardiac death.[70] The study found that those who fell under the category of having "Southern diets" representing those of "added fats, fried food, eggs, organ and processed meats, and sugar‐sweetened beverages" had a positive association with an increased risk of cardiac arrest, while those deemed following the "Mediterranean diets" had an inverse relationship regarding the risk of cardiac arrest.[70] According to a 2012 review published, omega-3 PUFA supplementation is not associated with a lower risk of sudden cardiac death.[71]
A Cochrane review published in 2016 found moderate-quality evidence to show that blood pressure-lowering drugs do not reduce the risk of sudden cardiac death.[72]
Prognosis[edit]
The overall rate of survival among those who have OHCA is 10%.[134][135] Among those who have an OHCA, 70% occur at home, and their survival rate is 6%.[136][137] For those who have an in-hospital cardiac arrest (IHCA), the survival rate one year from at least the occurrence of cardiac arrest is estimated to be 13%.[138] For IHCA, survival to discharge is around 22%.[139][79] Those who survive to return of spontaneous circulation and hospital admission frequently present with post-cardiac arrest syndrome, which usually presents with neurological injury that can range from mild memory problems to coma.[79] One-year survival is estimated to be higher in people with cardiac admission diagnoses (39%) when compared to those with non-cardiac admission diagnoses (11%).[138]
A 1997 review found rates of survival to discharge of 14%, although different studies varied from 0 to 28%.[140] In those over the age of 70 who have a cardiac arrest while in hospital, survival to hospital discharge is less than 20%.[141] How well these individuals manage after leaving the hospital is not clear.[141]
The global rate of people who were able to recover from OHCA after receiving CPR has been found to be approximately 30%, and the rate of survival to discharge from the hospital has been estimated at 9%.[142] Survival to discharge from the hospital is more likely among people whose cardiac arrest was witnessed by a bystander or emergency medical services, who received bystander CPR, and who live in Europe and North America.[142] Relatively lower survival to hospital discharge rates have been observed in Asian countries.[142]
Prognosis is typically assessed 72 hours or more after cardiac arrest.[143] Rates of survival are better in those who had someone witness their collapse, received bystander CPR, and/or had either V-fib or V-tach when assessed.[144] Survival among those with V-fib or V-tach is 15 to 23%.[144] Women are more likely to survive cardiac arrest and leave the hospital than men.[145] Hypoxic ischemic brain injury is a concerning outcome for people suffering a cardiac arrest.[146] Most improvements in cognition occur during the first three months following cardiac arrest, with some individuals reporting improvement up to one year post-cardiac arrest.[146] 50 – 70% of cardiac arrest survivors report fatigue as a symptom.[146]
Epidemiology[edit]
North America[edit]
The risk of cardiac arrest varies with geographical region, age, and gender. The lifetime risk is three times greater in men (12.3%) than women (4.2%) based on analysis of the Framingham Heart Study.[147] This gender difference disappeared beyond 85 years of age.[148] Around half of these individuals are younger than 65 years of age.[149]
Based on death certificates, sudden cardiac death accounts for about 20% of all deaths in the United States.[150][151] In the United States, approximately 326,000 cases of out-of-hospital and 209,000 cases of IHCA occur among adults annually, which works out to be an incidence of approximately 110.8 per 100,000 adults per year.[9][79][150]
In the United States, during-pregnancy cardiac arrest occurs in about one in twelve-thousand deliveries or 1.8 per 10,000 live births.[86] Rates are lower in Canada.[86]
Society and culture[edit]
Names[edit]
In many publications, the stated or implicit meaning of "sudden cardiac death" is sudden death from cardiac causes.[152] Some 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.[153]
In 2021, the American Heart Association clarified that "heart attack" is often mistakenly used to describe cardiac arrest. While a heart attack refers to death of heart muscle tissue as a result of blood supply loss, cardiac arrest is caused when the heart's electrical system malfunctions. Furthermore, the American Heart Association explains that "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".[154]
Slow code[edit]
A "slow code" is a slang term for the practice of deceptively delivering sub-optimal CPR to a person in cardiac arrest, when CPR is considered to have no medical benefit.[155] A "show code" is the practice of faking the response altogether for the sake of the person's family.[156]
Such practices are ethically controversial[157] and are banned in some jurisdictions. The European Resuscitation Council Guidelines released a statement in 2021 that clinicians are not suggested to participate/take part in "slow codes".[155] According to the American College of Physicians, half-hearted resuscitation efforts are deceptive and should not be performed by physicians or nurses.[158]
Children[edit]
In children, the most common cause of cardiac arrest is shock or respiratory failure that has not been treated.[28] Cardiac arrhythmias are another possible cause. Arrhythmias such as asystole or bradycardia are more likely in children, in contrast to ventricular fibrillation or tachycardia as seen in adults.[28]
Additional causes of sudden unexplained cardiac arrest in children include hypertrophic cardiomyopathy and coronary artery abnormalities.[159] In childhood hypertrophic cardiomyopathy, previous adverse cardiac events, non-sustained ventricular tachycardia, syncope, and left ventricular hypertrophy have been shown to predict sudden cardiac death.[160] Other causes can include drugs, such as cocaine and methamphetamine, or overdose of medications, such as antidepressants.[28]
For management of pediatric cardiac arrest, CPR should be initiated if suspected. Guidelines provide algorithms for pediatric cardiac arrest management. Recommended medications during pediatric resuscitation include epinephrine, lidocaine, and amiodarone.[161][79][80] However, the use of sodium bicarbonate or calcium is not recommended.[80][162] The use of calcium in children has been associated with poor neurological function as well as decreased survival.[28] Correct dosing of medications in children is dependent on weight, and to minimize time spent calculating medication doses, the use of a Broselow tape is recommended.[28]
Rates of survival in children with cardiac arrest are 3 to 16% in North America.[161]