<unk> s, also known as cardiac<unk> s, heart<unk> s, or dysrhythmias,<unk> e irregularities in the heartbeat, including when it is too fast or too slow. A heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a heart rate that is too slow – below 60 beats per minute – is called bradycardia. Some types of<unk> s have no symptoms. Symptoms, when present, may include palpitations or feeling a pause between heartbeats. In more serious cases, there may be lightheadedness, passing out, shortness of breath or chest pain. While most cases of<unk> <unk> e not serious, some predispose a person to complications such as stroke or heart failure. Others may result in sudden death.<unk> s<unk> e often categorized into four groups: extra beats, supraventricular tachycardias, ventricular<unk> s and bradyarrhythmias. Extra beats include premature atrial contractions, premature ventricular contractions and premature junctional contractions. Supraventricular tachycardias include atrial fibrillation, atrial flutter and paroxysmal supraventricular tachycardia. Ventricular<unk> s include ventricular fibrillation and ventricular tachycardia. Bradyarrhythmias<unk> e due to sinus node dysfunction or atrioventricular conduction disturbances.<unk> s<unk> e due to problems with the electrical conduction system of the heart. A number of tests can help with diagnosis, including an electrocardiogram (ECG) and Holter monitor. Many<unk> s can be effectively treated. Treatments may include medications, medical procedures such as inserting a pacemaker, and surgery. Medications for a fast heart rate may include beta blockers, or antiarrhythmic agents such as procainamide, which attempt to restore a normal heart rhythm. This latter group may have more significant side effects, especially if taken for a long period of time. Pacemakers<unk> e often used for slow heart rates. Those with an irregular heartbeat<unk> e often treated with blood thinners to reduce the risk of complications. Those who have severe symptoms from an<unk>  or<unk> e medically unstable may receive urgent treatment with a controlled electric shock in the form of cardioversion or defibrillation.<unk>  affects millions of people. In Europe and North America, as of 2014, atrial fibrillation affects about 2% to 3% of the population. Atrial fibrillation and atrial flutter resulted in 112,000 deaths in 2013, up from 29,000 in 1990. However, in most recent cases concerning the SARS-CoV‑2 pandemic, cardiac<unk> s<unk> e 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. Sudden cardiac death is the cause of about half of deaths due to cardiovascular disease and about 15% of all deaths globally. About 80% of sudden cardiac death is the result of ventricular<unk> s.<unk> s may occur at any age but<unk> e more common among older people.<unk> s may also occur in children; however, the normal range for the heart rate varies with age.
Arrhythmia
Drowning
Proarrhythmia
Atrial fibrillation
Hypsarrhythmia
Reflex syncope  Reflex syncope  1
Cardiovascular drift
Myocardial infarction