Arrhythmia
Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow.[2] A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia.[2] Some types of arrhythmias have no symptoms.[1] Symptoms, when present, may include palpitations or feeling a pause between heartbeats.[1] In more serious cases, there may be lightheadedness, passing out, shortness of breath, chest pain, or decreased level of consciousness.[1] While most cases of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure.[2][3] Others may result in sudden death.[3]
For other uses, see Arrhythmia (disambiguation).Arrhythmia
Cardiac arrhythmia, cardiac dysrhythmia, irregular heartbeat, heart arrhythmia
Older age[4]
Problems with the electrical conduction system of the heart[2]
Millions[4]
Arrhythmias are often categorized into four groups: extra beats, supraventricular tachycardias, ventricular arrhythmias and bradyarrhythmias.[3] Extra beats include premature atrial contractions, premature ventricular contractions and premature junctional contractions.[3] Supraventricular tachycardias include atrial fibrillation, atrial flutter and paroxysmal supraventricular tachycardia.[3] Ventricular arrhythmias include ventricular fibrillation and ventricular tachycardia.[3][7] Bradyarrhythmias are due to sinus node dysfunction or atrioventricular conduction disturbances.[8] Arrhythmias are due to problems with the electrical conduction system of the heart.[2] A number of tests can help with diagnosis, including an electrocardiogram (ECG) and Holter monitor.[5]
Many arrhythmias can be effectively treated.[2] Treatments may include medications, medical procedures such as inserting a pacemaker, and surgery.[6] Medications for a fast heart rate may include beta blockers, or antiarrhythmic agents such as procainamide, which attempt to restore a normal heart rhythm.[6] This latter group may have more significant side effects, especially if taken for a long period of time.[6] Pacemakers are often used for slow heart rates.[6] Those with an irregular heartbeat are often treated with blood thinners to reduce the risk of complications.[6] Those who have severe symptoms from an arrhythmia or are medically unstable may receive urgent treatment with a controlled electric shock in the form of cardioversion or defibrillation.[6]
Arrhythmia affects millions of people.[4] In Europe and North America, as of 2014, atrial fibrillation affects about 2% to 3% of the population.[9] Atrial fibrillation and atrial flutter resulted in 112,000 deaths in 2013, up from 29,000 in 1990.[10] However, in most recent cases concerning the SARS-CoV‑2 pandemic, cardiac arrhythmias are commonly developed and associated with high morbidity and mortality among patients hospitalized with the COVID-19 infection, due to the infection's ability to cause myocardial injury.[11] Sudden cardiac death is the cause of about half of deaths due to cardiovascular disease and about 15% of all deaths globally.[12] About 80% of sudden cardiac death is the result of ventricular arrhythmias.[12] Arrhythmias may occur at any age but are more common among older people.[4] Arrhythmias may also occur in children; however, the normal range for the heart rate varies with age.[3]
Signs and symptoms[edit]
The term cardiac arrhythmia covers a very large number of very different conditions.
The most common symptom of arrhythmia is an awareness of an abnormal heartbeat, called palpitations. These may be infrequent, frequent, or continuous. Some of these arrhythmias are harmless (though distracting for patients) but some of them predispose to adverse outcomes. Arrhythmias also cause chest pain and shortness of breath.
Some arrhythmias do not cause symptoms and are not associated with increased mortality. However, some asymptomatic arrhythmias are associated with adverse events. Examples include a higher risk of blood clotting within the heart and a higher risk of insufficient blood being transported to the heart because of a weak heartbeat. Other increased risks are of embolization and stroke, heart failure, and sudden cardiac death.
If an arrhythmia results in a heartbeat that is too fast, too slow, or too weak to supply the body's needs, this manifests as lower blood pressure and may cause lightheadedness, dizziness, syncope, loss of consciousness, coma, persistent vegetative state, or brain death due to insufficient supply of blood and oxygen to the brain.[20]
Some types of arrhythmia result in cardiac arrest, or sudden death.
Medical assessment of the abnormality using an electrocardiogram is one way to diagnose and assess the risk of any given arrhythmia.
Research[edit]
Arrhythmias due to medications have been reported since the 1920s with the use of quinine.[34] In the 1960s and 1970s problems with antihistamines and antipsychotics were discovered.[34] It was not until the 1980s that the underlying issue, QTc prolongation was determined.[34] Osborn waves on electrocardiogram (ECG) are frequent during targeted temperature management (TTM) after cardiac arrest, particularly in patients treated with 33 °C.[35] Osborn waves are not associated with increased risk of ventricular arrhythmia, and may be considered a benign physiological phenomenon, associated with lower mortality in univariable analyses.[35]