|
Bradycardia
Bradycardia, also called bradyarrhythmia, is a resting heart rate under 60 beats per minute (BPM). While bradycardia can result from various pathological processes, it is commonly a physiological response to cardiovascular conditioning or due to asymptomatic type 1 atrioventricular block. Resting heart rates of less than 50 BPM are often normal during sleep in young and healthy adults and athletes. In large population studies of adults without underlying heart disease, resting heart rates of 45–50 BPM appear to be the lower limits of normal, dependent on age and sex. Bradycardia is most likely to be discovered in the elderly, as age and underlying cardiac disease progression contribute to its development. Bradycardia may be associated with symptoms of fatigue, dyspnea, dizziness, confusion, and syncope due to reduced blood flow to the brain. The types of symptoms often depend on the etiology of the slow heart rate, classified by the anatomical location of a dysfunctio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resting Heart Rate
Heart rate is the frequency of the heartbeat measured by the number of contractions of the heart per minute (''beats per minute'', or bpm). The heart rate varies according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide. It is also modulated by numerous factors, including (but not limited to) genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease/illness, as well as the interaction between these factors. It is usually equal or close to the pulse rate measured at any peripheral point. The American Heart Association states the normal resting adult human heart rate is 60–100 bpm. An ultra-trained athlete would have a resting heart rate of 37–38 bpm. '' Tachycardia'' is a high heart rate, defined as above 100 bpm at rest. '' Bradycardia'' is a low heart rate, defined as below 60 bpm at rest. When a human sleeps, a heartbeat with rates around 40–50 bpm is common and co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinus Bradycardia
Sinus bradycardia is a sinus rhythm with a reduced rate of electrical discharge from the sinoatrial node, resulting in a bradycardia, a heart rate that is lower than the normal range (60–100 beats per minute for adult humans). Signs and symptoms The decreased heart rate can cause a decreased cardiac output resulting in symptoms such as lightheadedness, dizziness, hypotension, vertigo, and syncope. The slow heart rate may also lead to atrial, junctional, or ventricular ectopic rhythms. Bradycardia is not necessarily problematic. People who practice sports may have sinus bradycardia, because their trained hearts can pump enough blood in each contraction to allow a low resting heart rate. Sinus bradycardia can also be an adaptive advantage; for example, diving seals may have a heart rate as low as 12 beats per minute, helping them to conserve oxygen during long dives. Sinus bradycardia is a common condition found in both healthy individuals and those who are considered well- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinus Node Dysfunction
Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms (arrhythmias) usually caused by a malfunction of the sinus node, the heart's primary pacemaker. Tachycardia-bradycardia syndrome is a variant of sick sinus syndrome in which the arrhythmia alternates between fast and slow heart rates. Signs and symptoms Often sinus node dysfunction produces no symptoms, especially early in the disease course. Signs and symptoms usually appear in more advanced disease and more than 50% of patients will present with syncope or transient near-fainting spells as well as bradycardias that are accompanied by rapid heart rhythms, referred to as tachycardia-bradycardia syndrome Other presenting signs or symptoms can include confusion, fatigue, palpitations, chest pain, shortness of breath, headache, and nausea. Patients can also present with symptoms of congestive heart failure, stroke or transient ischemic attacks due to the abnormal rhythm. Com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Blocker
Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms ( arrhythmia), and to protect the heart from a second heart attack after a first heart attack ( secondary prevention). They are also widely used to treat high blood pressure, although they are no longer the first choice for initial treatment of most people. Beta blockers are competitive antagonists that block the receptor sites for the endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline) on adrenergic beta receptors, of the sympathetic nervous system, which mediates the fight-or-flight response. Beta-adrenergic receptors are found on cells of the heart muscles, smooth muscles, airways, arteries, kidneys, and other tissues that are part of the sympathetic nervous system and lead to stress responses, especially when they are stimulated by epinephrine (adrenaline). Beta blockers interfere with the binding to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syncope (medicine)
Syncope , commonly known as fainting or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain, typically from low blood pressure. There are sometimes symptoms before the loss of consciousness such as lightheadedness, sweating, pale skin, blurred vision, nausea, vomiting, or feeling warm. Syncope may also be associated with a short episode of muscle twitching. Psychiatric causes can also be determined when a patient experiences fear, anxiety, or panic; particularly before a stressful event, usually medical in nature. When consciousness and muscle strength are not completely lost, it is called presyncope. It is recommended that presyncope be treated the same as syncope. Causes range from non-serious to potentially fatal. There are three broad categories of causes: heart or blood vessel related; reflex, also known as neurally mediated; and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcutaneous Pacing
Transcutaneous pacing (TCP), also called external pacing, is a temporary means of pacing a patient's heart during a medical emergency. It should not be confused with defibrillation (used in more serious cases, in ventricular fibrillation and other shockable rhythms) using a manual or automatic defibrillator, though some newer defibrillators can do both, and pads and an electrical stimulus to the heart are used in transcutaneous pacing and defibrillation. Transcutaneous pacing is accomplished by delivering pulses of electric current through the patient's chest, which stimulates the heart to contract. The most common indication (medicine), indication for transcutaneous pacing is an abnormally slow heart rate. By convention, a heart rate of fewer than 60 beats per minute in the adult patient is called bradycardia. Not all instances of bradycardia require medical treatment. Normal heart rate varies substantially between individuals, and many athletes in particular have a relatively slow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoprenaline
Isoprenaline, also known as isoproterenol and sold under the brand name Isuprel among others, is a sympathomimetic medication which is used in the treatment of acute bradycardia (slow heart rate), heart block, and rarely for asthma, among other indications. It is used by injection into a vein, muscle, fat, or the heart, by inhalation, and in the past under the tongue or into the rectum. Side effects of isoprenaline include rapid heart beat, heart palpitations, and arrhythmias, among others. Isoprenaline is a selective agonist of the β-adrenergic receptors, including both the β1- and β2-adrenergic receptors. By activating these receptors, it increases heart rate and the force of heart contractions. Chemically, isoprenaline is a synthetic catecholamine and is the ''N''-isopropyl analogue of norepinephrine (noradrenaline) and epinephrine (adrenaline). Isoprenaline was one of the first synthetic sympathomimetic amines and was the first selective β-adrenergic rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athletic Heart Syndrome
Athletic heart syndrome (AHS) is a non-pathological condition commonly seen in sports medicine in which the human heart is enlarged, and the resting heart rate is lower than normal. The athlete's heart is associated with physiological cardiac remodeling as a consequence of repetitive cardiac loading. Athlete's heart is common in athletes who routinely exercise more than an hour a day, and occurs primarily in endurance athletes, though it can occasionally arise in heavy weight trainers. The condition is generally considered benign, but may occasionally hide a serious medical condition, or may even be mistaken for one. Signs and symptoms Athlete's heart most often does not have any physical symptoms, although an indicator would be a consistently low resting heart rate. Athletes with AHS often do not realize they have the condition unless they undergo specific medical tests, because athlete's heart is a normal, physiological adaptation of the body to the stresses of physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronotropic Incompetence
Chronotropic incompetence (CI) is the inability of heart rate to increase as expected in response to exercise. The condition can be defined in different ways and occurs in various diseases. Sufferers have a higher risk of cardiovascular disease and early death. Definition In healthy people, cardiac output during exercise increases via a rise in both heart rate and stroke volume. When the heart rate does not rise sufficiently, this can lead to exercise intolerance. CI can be detected using a cardiopulmonary exercise test. People with CI have a higher risk of cardiovascular disease and early death. There are different ways to define CI. One common threshold is not being able to reach 80% of age-predicted maximal heart rate (APMHR), which is said to be 220 – age. Another definition is not being able to reach 80% of the expected heart rate reserve, that is, the difference between the individual's resting heart rate and APMHR. Incidence Chronotropic incompetence occurs in vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagus Nerve
The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibers and serves as a major pathway that connects the brain to various organs, including the heart, lungs, and digestive tract. As a key part of the parasympathetic nervous system, the vagus nerve helps regulate essential involuntary functions like heart rate, breathing, and digestion. By controlling these processes, the vagus nerve contributes to the body's "rest and digest" response, helping to calm the body after stress, lower heart rate, improve digestion, and maintain homeostasis. The vagus nerve consists of two branches: the right and left vagus nerves. In the neck, the right vagus nerve contains approximately 105,000 fibers, while the left vagus nerve has about 87,000 fibers, according to one source. However, other sources report sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given intravenously or by injection into a muscle. Eye drops are also available which are used to treat uveitis and early amblyopia. The intravenous solution usually begins working within a minute and lasts half an hour to an hour. Large doses may be required to treat some poisonings. Common side effects include dry mouth, abnormally large pupils, urinary retention, constipation, and a fast heart rate. It should generally not be used in people with closed-angle glaucoma. While there is no evidence that its use during pregnancy causes birth defects, this has not been well studied so sound clinical judgment should be used. It is likely safe during breastfeeding. It is an antimuscarinic (a type of anticholinergic) that works by inhibit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark Ages, Dark Ages (), the Archaic Greece, Archaic or Homeric Greek, Homeric period (), and the Classical Greece, Classical period (). Ancient Greek was the language of Homer and of fifth-century Athens, fifth-century Athenian historians, playwrights, and Ancient Greek philosophy, philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Homeric Greek, Epic and Classical periods of the language, which are the best-attested periods and considered most typical of Ancient Greek. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
