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Arrhythmia
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<h2 id="classification">Classification</h2> <p>Arrhythmia may be classified by rate (<a href="/facts/Tachycardia/ycmyzP7q">tachycardia</a>, <a href="/facts/Bradycardia/70msP5HD">bradycardia</a>), mechanism (automaticity, re-entry, triggered) or duration (isolated <a href="/facts/Premature_heart_beat/AaWAG4Ax">premature beats</a>; couplets; runs, that is 3 or more beats; non-sustained = less than 30 seconds or sustained = over 30 seconds). </p><p>Arrhythmias are also classified by site of origin: </p> <h3>Atrial arrhythmia</h3> <ul><li><a href="/facts/Sinus_bradycardia/hFwvnGwu">Sinus bradycardia</a></li> <li><a href="/facts/Sinus_arrhythmia/1lPTx57s">Sinus arrhythmia</a></li> <li><a href="/facts/Sinus_tachycardia/2wudlhKv">Sinus tachycardia</a></li> <li><a href="/facts/Premature_atrial_contraction/ISPIoqjx">Premature atrial contractions (PACs)</a></li> <li><a href="/facts/Wandering_pacemaker/np5hxxhQ">Wandering atrial pacemaker</a></li> <li><a href="/facts/Atrial_tachycardia/IqvkJg72">Atrial tachycardia</a></li> <li><a href="/facts/Multifocal_atrial_tachycardia/zBDqK5BX">Multifocal atrial tachycardia</a></li> <li><a href="/facts/Supraventricular_tachycardia/oAVgMc5Y">Supraventricular tachycardia (SVT)</a></li> <li><a href="/facts/Atrial_flutter/VbmJJ4Dk">Atrial flutter</a></li> <li><a href="/facts/Atrial_fibrillation/Rzkq1tmN">Atrial fibrillation (Afib)</a></li> <li><a href="/facts/AV_nodal_reentrant_tachycardia/FVl8M9b2">AV nodal reentrant tachycardia</a></li></ul> <h3>Junctional arrhythmia</h3> <ul><li><a href="/facts/AV_nodal_reentrant_tachycardia/FVl8M9b2">AV nodal reentrant tachycardia</a></li> <li><a href="/facts/Junctional_rhythm/FMW5t7FG">Junctional rhythm</a></li> <li><a href="/facts/Junctional_tachycardia/0S7Ffw5z">Junctional tachycardia</a></li> <li><a href="/facts/Premature_junctional_contraction/Mnm0R8bf">Premature junctional contraction</a></li></ul> <h3>Ventricular arrhythmia</h3> <ul><li><a href="/facts/Premature_ventricular_contraction/5jqhoQnl">Premature ventricular contractions</a> (PVCs), sometimes called ventricular extra beats (VEBs) <ul><li>Premature ventricular beats occurring after every normal beat are termed <a href="/facts/Ventricular_bigeminy/ngzUU0KD">ventricular bigeminy</a></li> <li>PVCs that occur at intervals of 2 normal beats to 1 PVC, or 1 normal beat to 2 PVCs, are termed "PVCs in trigeminy"<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a></li> <li>Groups of three premature ventricular beats are called triplets and are considered a brief run of <a href="/facts/Non-sustained_ventricular_tachycardia/UrRmY5Q6">non-sustained ventricular tachycardia</a> (NSVT); if the grouping lasts for more than 30 seconds, it is considered sustained <a href="/facts/Ventricular_tachycardia/UrRmY5Q6">ventricular tachycardia</a> (VT).<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a></li></ul></li> <li><a href="/facts/Accelerated_idioventricular_rhythm/JBcmsSm2">Accelerated idioventricular rhythm</a></li> <li><a href="/facts/Ventricular_tachycardia/UrRmY5Q6">Monomorphic ventricular tachycardia</a></li> <li><a href="/facts/Polymorphic_ventricular_tachycardia/UrRmY5Q6">Polymorphic ventricular tachycardia</a></li> <li><a href="/facts/Ventricular_fibrillation/7rCnI7zf">Ventricular fibrillation</a></li> <li><a href="/facts/Torsades_de_pointes/dsdr4HPF">Torsades de pointes</a></li> <li><a href="/facts/Arrhythmogenic_right_ventricular_dysplasia/1drYtI96">Arrhythmogenic right ventricular dysplasia</a></li> <li><a href="/facts/Re-entry_ventricular_arrhythmia/wRxwARF3">Re-entry ventricular arrhythmia</a></li></ul> <h3>Heart blocks</h3> <p>These are also known as <a href="/facts/Atrioventricular_node/rRMrQror">AV</a> blocks, because the vast majority of them arise from pathology at the <a href="/facts/Atrioventricular_node/rRMrQror">atrioventricular node</a>. They are the most common causes of bradycardia: </p> <ul><li><a href="/facts/First-degree_heart_block/XY4r0EeP">First-degree heart block</a>, which manifests as PR prolongation</li> <li><a href="/facts/Second-degree_heart_block/enfWr7br">Second-degree heart block</a> <ul><li><a href="/facts/Type_1_Second_degree_heart_block/enfWr7br">Type 1 Second degree heart block</a>, also known as <a href="/facts/Mobitz_I/enfWr7br">Mobitz I</a> or <a href="/facts/Wenckebach/dm5YgWfB">Wenckebach</a></li> <li><a href="/facts/Type_2_Second_degree_heart_block/enfWr7br">Type 2 Second degree heart block</a>, also known as <a href="/facts/Mobitz_II/enfWr7br">Mobitz II</a></li></ul></li> <li><a href="/facts/Third-degree_heart_block/04nIpVRF">Third-degree heart block</a>, also known as <a href="/facts/Complete_heart_block/04nIpVRF">complete heart block</a></li></ul> <p>First, second, and third-degree blocks also can occur at the level of the sinoatrial junction. This is referred to as <a href="/facts/Sinoatrial_block/ud6lv8vo">sinoatrial block</a> typically manifesting with various degrees and patterns of <a href="/facts/Sinus_bradycardia/hFwvnGwu">sinus bradycardia</a>. </p> <h3>Sudden arrhythmic death syndrome</h3> <p><a href="/facts/Sudden_arrhythmic_death_syndrome/VpSC80u0">Sudden arrhythmic death syndrome</a> (SADS), is a term used as part of <i>sudden unexpected death syndrome</i> to describe sudden <a href="/facts/Death/VJmq29qm">death</a> because of <a href="/facts/Cardiac_arrest/HIAm9AWX">cardiac arrest</a> occasioned by an arrhythmia in the presence or absence of any structural heart disease on autopsy. The most common cause of sudden death in the US is <a href="/facts/Coronary_artery_disease/szCt0nVx">coronary artery disease</a> specifically because of poor oxygenation of the heart muscle, that is <a href="/facts/Myocardial_ischemia/szCt0nVx">myocardial ischemia</a> or a <a href="/facts/Myocardial_infarction/xoGw0qcG">heart attack</a><a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a> Approximately 180,000 to 250,000 people die suddenly of this cause every year in the US. SADS may occur from other causes. There are many inherited conditions and heart diseases that can affect young people which can subsequently cause sudden death without advance symptoms.<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> </p><p>Causes of SADS in young people include <a href="/facts/Viral_myocarditis/ypoBJ4Pp">viral myocarditis</a>, <a href="/facts/Long_QT_syndrome/kX1NAAUh">long QT syndrome</a>, <a href="/facts/Brugada_syndrome/DJAI2fzg">Brugada syndrome</a>, <a href="/facts/Catecholaminergic_polymorphic_ventricular_tachycardia/ybbXGBcw">Catecholaminergic polymorphic ventricular tachycardia</a>, <a href="/facts/Hypertrophic_cardiomyopathy/NmPkh1rh">hypertrophic cardiomyopathy</a> and <a href="/facts/Arrhythmogenic_right_ventricular_dysplasia/1drYtI96">arrhythmogenic right ventricular dysplasia</a>.<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a><a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a> </p> <h3>Fetal arrhythmia</h3> <p>Arrhythmias may also occur in the <a href="/facts/Fetus/evocHd0Y">fetus</a>.<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a> The normal heart rate of the fetus is between 110 and 160 beats per minute. Any rhythm beyond these limits is abnormal and classed as a fetal arrhythmia. These are mainly the result of premature atrial contractions, usually give no symptoms, and have little consequence. However, around one percent of these will be the result of significant structural damage to the heart.<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> </p> <h2 id="signs-and-symptoms">Signs and symptoms</h2> <p>The term cardiac arrhythmia covers a very large number of very different conditions. </p><p>The most common symptom of arrhythmia is an awareness of an abnormal heartbeat, called <a href="/facts/Palpitation/2wACMY49">palpitations</a>. These may be infrequent, frequent, or continuous. Some of these arrhythmias are harmless (though <a href="/facts/Distracting/wW6WuND7">distracting</a> for patients) but some of them predispose to adverse outcomes. Arrhythmias also cause <a href="/facts/Chest_pain/QFUzPBsT">chest pain</a> and <a href="/facts/Shortness_of_breath/1jBfFzxU">shortness of breath</a>. </p><p>Some arrhythmias do not cause symptoms and are not associated with increased mortality. However, some asymptomatic arrhythmias <i>are</i> 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 <a href="/facts/Embolization/zPNry9cY">embolization</a> and stroke, heart failure, and sudden cardiac death. </p><p>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, <a href="/facts/Coma/N9oQ7g7R">coma</a>, <a href="/facts/Persistent_vegetative_state/EkAyEEU3">persistent vegetative state</a>, or brain death due to insufficient supply of blood and oxygen to the brain.<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> </p><p>Some types of arrhythmia result in <a href="/facts/Cardiac_arrest/HIAm9AWX">cardiac arrest</a>, or sudden death. </p><p>Medical assessment of the abnormality using an <a href="/facts/Electrocardiogram/YpVswJ0W">electrocardiogram</a> is one way to diagnose and assess the risk of any given arrhythmia. </p> <h2 id="mechanism">Mechanism</h2> <p>Cardiac arrhythmia are caused by one of two major mechanisms. The first of arrhythmia is a result of enhanced or abnormal <a href="/facts/Cardiac_action_potential/CJu2rTR8">impulse</a> formation originating at the <a href="/facts/Cardiac_pacemaker/j4Rn2Gfm">pacemaker</a> or the <a href="/facts/Bundle_of_His/B8RgFvlR">His</a>-<a href="/facts/Purkinje_fibers/3Xcjlhnp">Purkinje</a> network. The second is due to re-entry conduction disturbances.<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a> </p> <h2 id="diagnostic">Diagnostic</h2> <p>Cardiac arrhythmia is often first detected by simple but nonspecific means: <a href="/facts/Auscultation/mmICf6XP">auscultation</a> of the heartbeat with a <a href="/facts/Stethoscope/DrKjH4x1">stethoscope</a>, or feeling for peripheral <a href="/facts/Pulse/Bg8EUcWL">pulses</a>. These cannot usually diagnose specific arrhythmia but can give a general indication of the heart rate and whether it is regular or irregular. Not all the electrical impulses of the heart produce audible or palpable beats; in many cardiac arrhythmias, the premature or abnormal beats do not produce an effective pumping action and are experienced as "skipped" beats. </p><p>The simplest <i>specific</i> diagnostic test for assessment of heart rhythm is the <a href="/facts/Electrocardiogram/YpVswJ0W">electrocardiogram</a> (abbreviated ECG or EKG).<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a><a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a> A <a href="/facts/Holter_monitor/CskFhGLn">Holter monitor</a> is an EKG recorded over a 24-hour period, to detect arrhythmias that may happen briefly and unpredictably throughout the day. </p><p>A more advanced study of the heart's electrical activity can be performed to assess the source of the <a href="/facts/Cardiac_aberration/b1qERrYF">aberrant</a> heart beats. This can be accomplished in an <a href="/facts/Electrophysiology_study/76sKKGgw">electrophysiology study</a>, an <a href="/facts/Endovascular_procedure/r6n1y8sU">endovascular procedure</a> that uses a catheter to "listen" to the electrical activity from within the heart, additionally if the source of the arrhythmias is found, often the abnormal cells can be ablated and the arrhythmia can be permanently corrected. <i>Transesophageal atrial stimulation</i> (TAS) instead uses an electrode inserted through the <a href="/facts/Esophagus/XWa7WoWn">esophagus</a> to a part where the distance to the posterior wall of the <a href="/facts/Left_atrium/eYNg8Vw2">left atrium</a> is only approximately 5–6 mm (remaining constant in people of different age and weight).<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a> Transesophageal atrial stimulation can differentiate between <a href="/facts/Atrial_flutter/VbmJJ4Dk">atrial flutter</a>, <a href="/facts/AV_nodal_reentrant_tachycardia/FVl8M9b2">AV nodal reentrant tachycardia</a> and orthodromic <a href="/facts/Atrioventricular_reentrant_tachycardia/RoB307mr">atrioventricular reentrant tachycardia</a>.<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a> It can also evaluate the risk in people with <a href="/facts/Wolff%25E2%2580%2593Parkinson%25E2%2580%2593White_syndrome/2V6sl7yb">Wolff–Parkinson–White syndrome</a>, as well as terminate <a href="/facts/Supraventricular_tachycardia/oAVgMc5Y">supraventricular tachycardia</a> caused by <a href="/facts/Cardiac_arrhythmia/ooEpr46Q">re-entry</a>.<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a> </p> <h3>Differential diagnosis</h3> <h4>Normal electrical activity</h4> <p class="note">Main article: <a href="/facts/Electrical_conduction_system_of_the_heart/AouErvDx">Electrical conduction system of the heart</a></p> <p>Each heartbeat originates as an electrical impulse from a small area of tissue in the right <a href="/facts/Atrium_(heart)/eYNg8Vw2">atrium</a> of the heart called the <a href="/facts/Sinoatrial_node/KIGaek8u">sinus node or sinoatrial node (SA node)</a>. The impulse initially causes both atria to contract, then activates the <a href="/facts/Atrioventricular_node/rRMrQror">atrioventricular node (AV node)</a>, which is normally the only electrical connection between the atria and the <a href="/facts/Ventricle_(heart)/FCzV1xm7">ventricles</a> (main pumping chambers). The impulse then spreads through both ventricles via the <a href="/facts/Bundle_of_His/B8RgFvlR">bundle of His</a> and the <a href="/facts/Purkinje_fibers/3Xcjlhnp">Purkinje fibers</a> causing a synchronized contraction of the heart muscle and, thus, the pulse. </p><p>In adults, the normal resting heart rate ranges from 60 to 90 beats per minute. The resting heart rate in children is much faster. In athletes, however, the resting heart rate can be as slow as 40 beats per minute, and be considered normal. </p><p>The term <a href="/facts/Respiratory_sinus_arrhythmia/lletUWQR">sinus arrhythmia</a><a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a> refers to a normal phenomenon of alternating mild acceleration and slowing of the heart rate that occurs with breathing in and out respectively. It is usually quite pronounced in children and steadily decreases with age. This can also be present during <a href="/facts/Meditation/8KjW0lHy">meditation</a> breathing exercises that involve deep inhaling and breath holding patterns.<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a> </p> <h4>Bradycardias</h4> <p>A slow rhythm (less than 60 beats/min) is labelled <a href="/facts/Bradycardia/70msP5HD">bradycardia</a>. This may be caused by a slowed signal from the sinus node (sinus bradycardia), by a pause in the normal activity of the sinus node (sinus arrest), or by blocking of the electrical impulse on its way from the atria to the ventricles (AV block or heart block). Heart block comes in varying degrees and severity. It may be caused by reversible poisoning of the AV node (with drugs that impair conduction) or by irreversible damage to the node. Bradycardias may also be present in the normally functioning heart of endurance athletes or other well-conditioned persons. Bradycardia may also occur in <a href="/facts/Ictal_bradycardia/jQldXQw1">some types of seizures</a>. </p> <h4>Tachycardias</h4> <p>In adults and children over 15, resting heart rate faster than 100 beats per minute is labeled <a href="/facts/Tachycardia/ycmyzP7q">tachycardia</a>. Tachycardia may result in palpitation; however, tachycardia is not <i>necessarily</i> an arrhythmia. Increased heart rate is a normal response to physical exercise or emotional stress. This is mediated by the <a href="/facts/Sympathetic_nervous_system/hs8psNRd">sympathetic nervous system</a> on the <a href="/facts/Sinus_node/KIGaek8u">sinus node</a> and called sinus tachycardia. Other conditions that increase sympathetic nervous system activity in the heart include ingested or injected substances, such as <a href="/facts/Caffeine/Hx6E2QC5">caffeine</a> or <a href="/facts/Amphetamines/KlmrodPb">amphetamines</a>, and an overactive thyroid gland (<a href="/facts/Hyperthyroidism/H9Eqmbgk">hyperthyroidism</a>) or <a href="/facts/Anemia/AgEPPmg8">anemia</a>. </p><p>Tachycardia that is not sinus tachycardia usually results from the addition of abnormal impulses to the normal <a href="/facts/Cardiac_cycle/b93n3ecF">cardiac cycle</a>. Abnormal impulses can begin by one of three mechanisms: automaticity, re-entry, or triggered activity. A specialized form of re-entry which is both common and problematic is termed fibrillation. </p><p>Although the term "tachycardia" has been known for over 160 years, bases for the classification of arrhythmias are still being discussed. </p> <h4>Heart defects</h4> <p>Congenital heart defects are structural or electrical pathway problems in the heart that are present at birth. Anyone can be affected by this because overall health does not play a role in the problem. Problems with the electrical pathway of the heart can cause very fast or even deadly arrhythmias. <a href="/facts/Wolff%25E2%2580%2593Parkinson%25E2%2580%2593White_syndrome/2V6sl7yb">Wolff–Parkinson–White syndrome</a> is due to an extra pathway in the heart that is made up of electrical muscle tissue. This tissue allows the electrical impulse, which stimulates the heartbeat, to happen very rapidly. Right <a href="/facts/Ventricular_outflow_tract/5dpafByD">ventricular outflow tract</a> tachycardia is the most common type of ventricular tachycardia in otherwise healthy individuals. This defect is due to an electrical node in the right ventricle just before the pulmonary artery. When the node is stimulated, the patient will go into ventricular tachycardia, which does not allow the heart to fill with blood before beating again. <a href="/facts/Long_QT_syndrome/kX1NAAUh">Long QT syndrome</a> is another complex problem in the heart and has been labeled as an independent factor in mortality. There are multiple methods of treatment for these including cardiac ablations, medication treatment, or lifestyle changes to have less stress and exercise. </p> <h4>Automaticity</h4> <p class="note">Main article: <a href="/facts/Automatic_tachycardia/mtIhrLQH">Automatic tachycardia</a></p> <p>Automaticity refers to a <a href="/facts/Cardiac_muscle/oMqU4Sdu">cardiac muscle</a> cell firing off an impulse on its own. All of the cells in the heart have the ability to initiate an <a href="/facts/Action_potential/Sz8yCRqx">action potential</a>; however, only some of these cells are designed to routinely trigger heartbeats. These cells are found in the conduction system of the heart and include the SA node, AV node, Bundle of His, and Purkinje fibers. The <a href="/facts/Sinoatrial_node/KIGaek8u">sinoatrial node</a> is a single specialized location in the atrium that has a higher automaticity (a faster pacemaker) than the rest of the heart and, therefore, is usually responsible for setting the heart rate and initiating each heartbeat. </p><p>Any part of the heart that initiates an impulse without waiting for the sinoatrial node is called an <a href="/facts/Cardiac_ectopy/9JxUpWsI">ectopic</a> focus and is, by definition, a pathological phenomenon. This may cause a single premature beat now and then, or, if the <a href="/facts/Ectopic_focus/KTEkwLPX">ectopic focus</a> fires more often than the sinoatrial node, it can produce a sustained abnormal rhythm. Rhythms produced by an ectopic focus in the atria, or by the <a href="/facts/Atrioventricular_node/rRMrQror">atrioventricular node</a>, are the least dangerous dysrhythmias; but they can still produce a decrease in the heart's pumping efficiency because the signal reaches the various parts of the heart muscle with different timing than usual and can be responsible for poorly coordinated contraction. </p><p>Conditions that increase automaticity include <a href="/facts/Sympathetic_nervous_system/hs8psNRd">sympathetic nervous system</a> stimulation and <a href="/facts/Hypoxia_(medical)/JWV04G89">hypoxia</a>. The resulting heart rhythm depends on where the first signal begins: If it is the sinoatrial node, the rhythm remains normal but rapid; if it is an ectopic focus, many types of dysrhythmia may ensue. </p> <h4>Re-entry</h4> <p>Re-entrant arrhythmias occur when an electrical impulse recurrently travels in a tight circle within the heart, rather than moving from one end of the heart to the other and then stopping.<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a><a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a> </p><p>Every cardiac cell can transmit <a href="/facts/Autowave/QPATWNmk">impulses of excitation</a> in every direction but will do so only once within a short time. Normally, the <a href="/facts/Action_potential/Sz8yCRqx">action potential</a> impulse will spread through the heart quickly enough that each cell will respond only once. However, if there is some essential heterogeneity of <a href="/facts/Refractory_period_(physiology)/mu1rMsNe">refractory period</a> or if conduction is abnormally slow in some areas (for example in heart damage) so the myocardial cells are unable to activate the fast sodium channel, part of the impulse will arrive late and potentially be treated as a new impulse. Depending on the timing, this can produce a sustained abnormal circuit rhythm. </p><p>As a sort of <i>re-entry</i>, vortices of excitation in the myocardium (<a href="/facts/Autowave/QPATWNmk">autowave vortices</a>) are considered to be the main mechanism of life-threatening cardiac arrhythmias.<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a> In particular, the <a href="/facts/Autowave_reverberator/eGPAHEFL">autowave reverberator</a> is common in the thin walls of the atria, sometimes resulting in <a href="/facts/Atrial_flutter/VbmJJ4Dk">atrial flutter</a>. Re-entry is also responsible for most <a href="/facts/Paroxysmal_supraventricular_tachycardia/8oRvtjr5">paroxysmal supraventricular tachycardia</a>, and dangerous <a href="/facts/Ventricular_tachycardia/UrRmY5Q6">ventricular tachycardia</a>. These types of re-entry circuits are different from <a href="/facts/WPW/2V6sl7yb">WPW</a> syndromes, which utilize abnormal conduction pathways. </p><p>Although <a href="/facts/Omega-3_fatty_acid/X72Ynqov">omega-3 fatty acids</a> from <a href="/facts/Fish_oil/01zGCKh3">fish oil</a> can be protective against arrhythmias, they can facilitate re-entrant arrhythmias.<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a> </p> <h4>Fibrillation</h4> <p>When an entire chamber of the heart is involved in multiple micro-re-entry circuits and is, therefore, quivering with chaotic electrical impulses, it is said to be in fibrillation. </p><p>Fibrillation can affect the atrium (<a href="/facts/Atrial_fibrillation/Rzkq1tmN">atrial fibrillation</a>) or the ventricle (<a href="/facts/Ventricular_fibrillation/7rCnI7zf">ventricular fibrillation</a>): ventricular fibrillation is imminently life-threatening. </p> <ul><li>Atrial fibrillation affects the upper chambers of the heart, known as the <a href="/facts/Atrium_(heart)/eYNg8Vw2">atria</a>. Atrial fibrillation may be due to serious underlying medical conditions and should be evaluated by a <a href="/facts/Physician/qJ3woFvG">physician</a>. It is not typically a medical emergency.</li> <li>Ventricular fibrillation occurs in the <a href="/facts/Ventricle_(heart)/FCzV1xm7">ventricles</a> (lower chambers) of the heart; it is always a medical emergency. If left untreated, <a href="/facts/Ventricular_fibrillation/7rCnI7zf">ventricular fibrillation</a> (VF, or V-fib) can lead to death within minutes. When a heart goes into V-fib, effective pumping of the blood stops. V-fib is considered a form of <a href="/facts/Cardiac_arrest/HIAm9AWX">cardiac arrest</a>. An affected individual will not survive unless <a href="/facts/Cardiopulmonary_resuscitation/0LNkmTVf">cardiopulmonary resuscitation</a> (CPR) and <a href="/facts/Defibrillation/Y51xTGj8">defibrillation</a> are provided immediately.</li></ul> <p>CPR can prolong the survival of the <a href="/facts/Brain/EKla9NkJ">brain</a> in the lack of a normal pulse, but defibrillation is the only intervention that can restore a healthy heart rhythm. Defibrillation is performed by applying an electric shock to the heart, which resets the cells, permitting a normal beat to re-establish itself. </p> <h4>Triggered beats</h4> <p>Triggered beats occur when problems at the level of the ion channels in individual heart cells result in abnormal propagation of electrical activity and can lead to a sustained abnormal rhythm. They are relatively rare and can result from the action of anti-arrhythmic drugs, or after <a href="/facts/Depolarization/qGX8lFXE">depolarizations</a>. </p> <h2 id="management">Management</h2> <p>The method of cardiac rhythm management depends firstly on whether the affected person is stable or unstable. Treatments may include physical maneuvers, medications, electricity conversion, or electro- or cryo-cautery. </p><p>In the United States, people admitted to the hospital with cardiac arrhythmia and conduction disorders with and without complications were admitted to the intensive care unit more than half the time in 2011.<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> </p> <h3>Physical maneuvers</h3> <p>Several physical acts can increase parasympathetic nervous supply to the heart, resulting in blocking of electrical conduction through the AV node. This can slow down or stop several arrhythmias that originate above or at the AV node (see main article: <a href="/facts/Supraventricular_tachycardia/oAVgMc5Y">supraventricular tachycardias</a>). Parasympathetic nervous supply to the heart is via the <a href="/facts/Vagus_nerve/cKQR0rLm">vagus nerve</a>, and these maneuvers are collectively known as <a href="/facts/Vagal_maneuver/NAfKzYLP">vagal maneuvers</a>. </p> <h3>Antiarrhythmic drugs</h3> <p class="note">Main article: <a href="/facts/Antiarrhythmic_agents/RJPHtxKr">Antiarrhythmic agents</a></p> <p>There are many classes of antiarrhythmic medications, with different mechanisms of action and many different individual drugs within these classes. Although the goal of drug therapy is to prevent arrhythmia, nearly every antiarrhythmic drug has the potential to act as a <a href="/facts/Pro-arrhythmic/rMxRDHMj">pro-arrhythmic</a>, and so must be carefully selected and used under medical supervision. </p> <h3>Other drugs</h3> <p>Several groups of drugs slow conduction through the heart, without actually preventing an arrhythmia. These drugs can be used to "rate control" a fast rhythm and make it physically tolerable for the patient. </p><p>Some arrhythmias promote blood clotting within the heart and increase the risk of embolus and stroke. <a href="/facts/Anticoagulant/cARpjm0G">Anticoagulant</a> medications such as <a href="/facts/Warfarin/kMnH6tb0">warfarin</a> and <a href="/facts/Heparin/4lxSm2pB">heparins</a>, and anti-platelet drugs such as <a href="/facts/Aspirin/opMK4qLk">aspirin</a> can reduce the risk of clotting. </p> <h3>Electricity</h3> <p>Arrhythmias may also be treated electrically, by applying a shock across the heart – either externally to the chest wall, or internally to the heart via implanted electrodes.<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a> </p><p><a href="/facts/Cardioversion/xkhcA9a8">Cardioversion</a> is either achieved pharmacologically or via the application of a shock <i>synchronized</i> to the underlying heartbeat. It is used for the treatment of supraventricular tachycardias. In elective cardioversion, the recipient is usually sedated or lightly <a href="/facts/Anesthesia/b3MKVn8E">anesthetized</a> for the procedure. </p><p><a href="/facts/Defibrillation/Y51xTGj8">Defibrillation</a> differs in that the shock is not synchronized. It is needed for the chaotic rhythm of ventricular fibrillation and is also used for pulseless ventricular tachycardia. Often, more electricity is required for defibrillation than for cardioversion. In most defibrillation, the recipient has lost consciousness so there is no need for sedation. </p><p>Defibrillation or cardioversion may be accomplished by an <a href="/facts/Implantable_cardioverter-defibrillator/b5U5lH8K">implantable cardioverter-defibrillator</a> (ICD). </p><p>Electrical treatment of arrhythmias also includes <a href="/facts/Cardiac_pacing/b90Qt8ND">cardiac pacing</a>. Temporary pacing may be necessary for reversible causes of very slow heartbeats, or <a href="/facts/Bradycardia/70msP5HD">bradycardia</a> (for example, from <a href="/facts/Drug_overdose/Jlo2AX3Y">drug overdose</a> or <a href="/facts/Myocardial_infarction/xoGw0qcG">myocardial infarction</a>). A permanent <a href="/facts/Artificial_pacemaker/b90Qt8ND">pacemaker</a> may be placed in situations where the bradycardia is not expected to recover. </p> <h3>Electrical cautery</h3> <p>Some cardiologists further sub-specialize into electrophysiology. In specialized <a href="/facts/Catheter/ehnH1eF5">catheter laboratories</a>, they use fine probes inserted through the blood vessels to map electrical activity from within the heart. This allows abnormal areas of conduction to be located very accurately and subsequently destroyed by heat, cold, electrical, or laser probes in a process called <a href="/facts/Catheter_ablation/WwxY1eeH">catheter ablation</a>. </p><p>This procedure may be completely curative for some forms of arrhythmia, but for others, the success rate remains disappointing. <a href="/facts/AV_nodal_reentrant_tachycardia/FVl8M9b2">AV nodal reentrant tachycardia</a> is often curable by ablating one of the pathways in the <a href="/facts/Atrioventricular_node/rRMrQror">AV node</a> (usually the slow pathway). <a href="/facts/Atrial_fibrillation/Rzkq1tmN">Atrial fibrillation</a> can also be treated, by performing a <a href="/facts/Pulmonary_vein/SBd6pATv">pulmonary vein</a> isolation, but the results are less reliable. </p> <h2 id="research">Research</h2> <p>Arrhythmias due to medications have been reported since the 1920s with the use of <a href="/facts/Quinine/YMB9QgzM">quinine</a>.<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> In the 1960s and 1970s problems with antihistamines and antipsychotics were discovered.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a> It was not until the 1980s that the underlying issue, <a href="/facts/QT_interval/42JWI9Nc">QTc prolongation</a> was determined.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a> <a href="/facts/J_wave/nwQAWaJD">Osborn waves</a> on <a href="/facts/Electrocardiography/YpVswJ0W">electrocardiogram</a> (<a href="/facts/ECG/YpVswJ0W">ECG</a>) are frequent during <a href="/facts/Targeted_temperature_management/8KlMUuaf">targeted temperature management (TTM)</a> after <a href="/facts/Cardiac_arrest/HIAm9AWX">cardiac arrest</a>, particularly in patients treated with 33 °C.<a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> <a href="/facts/J_wave/nwQAWaJD">Osborn waves</a> are not associated with increased risk of <a href="/facts/Ventricular_arrhythmia/ooEpr46Q">ventricular arrhythmia</a>, and may be considered a <a href="/facts/Benign_early_repolarization/aNrT4J3a">benign</a> physiological phenomenon, associated with lower <a href="/facts/Mortality_rate/s4gmxyFV">mortality</a> in univariable analyses.<a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Pre-excitation_syndrome/L27LeXkq">Pre-excitation syndrome</a></li> <li><a href="/facts/Holiday_heart_syndrome/5Ipv5vnu">Holiday heart syndrome</a></li></ul> <h2 id="external-links">External links</h2> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"What Is Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 2 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"What Is Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 2 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"What Are the Signs and Symptoms of an Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 19 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/signs" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/signs</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"What Are the Signs and Symptoms of an Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 19 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/signs" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/signs</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"What Are the Signs and Symptoms of an Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 19 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/signs" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/signs</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"What Is Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 2 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Martin CA, Matthews GD, Huang CL (April 2012). "Sudden cardiac death and inherited channelopathy: the basic electrophysiology of the myocyte and myocardium in ion channel disease". Heart. 98 (7): 536–543. doi:10.1136/heartjnl-2011-300953. PMC 3308472. PMID 22422742. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308472" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308472</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Vogler J, Breithardt G, Eckardt L (July 2012). "Bradyarrhythmias and conduction blocks". Revista Espanola de Cardiologia. 65 (7): 656–667. doi:10.1016/j.rec.2012.01.027. PMID 22627074. S2CID 18983179. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"What Is Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 2 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"How Are Arrhythmias Diagnosed?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 18 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/diagnosis" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/diagnosis</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"What Is Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 2 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>"How Are Arrhythmias Treated?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 17 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>"How Are Arrhythmias Treated?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 17 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>"How Are Arrhythmias Treated?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 17 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>"How Are Arrhythmias Treated?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 17 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>"How Are Arrhythmias Treated?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 17 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>"How Are Arrhythmias Treated?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 17 February 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/treatment</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>"Who Is at Risk for an Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 3 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/atrisk" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/atrisk</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Zoni-Berisso M, Lercari F, Carazza T, Domenicucci S (2014). "Epidemiology of atrial fibrillation: European perspective". Clinical Epidemiology. 6: 213–220. doi:10.2147/CLEP.S47385. PMC 4064952. PMID 24966695. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064952" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064952</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Naghavi M, Wang H, Lozano R, Davis A, Liang X, Zhou M, et al. (GBD 2013 Mortality and Causes of Death Collaborators) (January 2015). "Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013". Lancet. 385 (9963): 117–171. doi:10.1016/S0140-6736(14)61682-2. PMC 4340604. PMID 25530442. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340604" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340604</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>Kuck KH (June 2020). "Arrhythmias and sudden cardiac death in the COVID-19 pandemic". Herz. 45 (4): 325–326. doi:10.1007/s00059-020-04924-0. PMC 7181098. PMID 32333026. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181098" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181098</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>Mehra R (2007). "Global public health problem of sudden cardiac death". Journal of Electrocardiology. 40 (6 Suppl): S118 – S122. doi:10.1016/j.jelectrocard.2007.06.023. PMID 17993308. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>Mehra R (2007). "Global public health problem of sudden cardiac death". Journal of Electrocardiology. 40 (6 Suppl): S118 – S122. doi:10.1016/j.jelectrocard.2007.06.023. PMID 17993308. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>"Who Is at Risk for an Arrhythmia?". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 3 March 2015. Retrieved 7 March 2015. <a href="http://www.nhlbi.nih.gov/health/health-topics/topics/arr/atrisk" target="_blank">http://www.nhlbi.nih.gov/health/health-topics/topics/arr/atrisk</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>"Types of Arrhythmia". National Heart, Lung, and Blood Institute. July 1, 2011. Archived from the original on 7 June 2015. Retrieved 7 March 2015. <a href="https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types" target="_blank">https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>Farzam K, Richards JR (2022-12-27). "Premature ventricular contraction". StatPearls. PMID 30422584. <a href="https://www.ncbi.nlm.nih.gov/books/NBK532991/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK532991/</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>Wagner GS (2001). Marriott's Practical Electrocardiography (10th ed.). Philadelphia, PA: Williams & Wilkins. ISBN 0683307460.[page needed] <a href="0683307460" target="_blank">0683307460</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> <li id="fn:34"><p>Zipes DP, Wellens HJ (November 1998). "Sudden cardiac death". Circulation. 98 (21): 2334–2351. doi:10.1161/01.CIR.98.21.2334. PMID 9826323. <a href="https://doi.org/10.1161%2F01.CIR.98.21.2334" target="_blank">https://doi.org/10.1161%2F01.CIR.98.21.2334</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></p></li> <li id="fn:35"><p>Deo R, Albert CM (January 2012). "Epidemiology and genetics of sudden cardiac death". Circulation. 125 (4): 620–637. doi:10.1161/circulationaha.111.023838. PMC 3399522. PMID 22294707. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3399522" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3399522</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></p></li> <li id="fn:36"><p>Chugh SS, Reinier K, Teodorescu C, Evanado A, Kehr E, Al Samara M, et al. (2008). "Epidemiology of sudden cardiac death: clinical and research implications". Progress in Cardiovascular Diseases. 51 (3): 213–228. doi:10.1016/j.pcad.2008.06.003. PMC 2621010. PMID 19026856. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621010" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621010</a> <a href="#fnref:36" class="footnote-back-ref">↩</a></p></li> <li id="fn:37"><p>Winkel BG, Holst AG, Theilade J, Kristensen IB, Thomsen JL, Ottesen GL, et al. (April 2011). "Nationwide study of sudden cardiac death in persons aged 1-35 years". European Heart Journal. 32 (8): 983–990. doi:10.1093/eurheartj/ehq428. PMID 21131293. <a href="https://doi.org/10.1093%2Feurheartj%2Fehq428" target="_blank">https://doi.org/10.1093%2Feurheartj%2Fehq428</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></p></li> <li id="fn:38"><p>Batra AS, Balaji S (2019). "Fetal arrhythmias: Diagnosis and management". Indian Pacing and Electrophysiology Journal. 19 (3): 104–109. doi:10.1016/j.ipej.2019.02.007. PMC 6531664. PMID 30817991. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531664" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531664</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></p></li> <li id="fn:39"><p>Batra AS, Balaji S (2019). "Fetal arrhythmias: Diagnosis and management". Indian Pacing and Electrophysiology Journal. 19 (3): 104–109. doi:10.1016/j.ipej.2019.02.007. PMC 6531664. PMID 30817991. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531664" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531664</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></p></li> <li id="fn:40"><p>"Passing Out (Syncope) Caused by Arrhythmias". Retrieved 13 April 2020. <a href="https://www.cardiosmart.org/healthwise/te71/52ab/c/te7152abc" target="_blank">https://www.cardiosmart.org/healthwise/te71/52ab/c/te7152abc</a> <a href="#fnref:40" class="footnote-back-ref">↩</a></p></li> <li id="fn:41"><p>Antzelevitch C, Burashnikov A (March 2011). "Overview of Basic Mechanisms of Cardiac Arrhythmia". Cardiac Electrophysiology Clinics. 3 (1): 23–45. doi:10.1016/j.ccep.2010.10.012. PMC 3164530. PMID 21892379. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164530" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164530</a> <a href="#fnref:41" class="footnote-back-ref">↩</a></p></li> <li id="fn:42"><p>Willcox ME, Compton SJ, Bardy GH (2021-12-01). "Continuous ECG monitoring versus mobile telemetry: A comparison of arrhythmia diagnostics in human- versus algorithmic-dependent systems". Heart Rhythm O2. 2 (6, Part A): 543–559. doi:10.1016/j.hroo.2021.09.008. ISSN 2666-5018. PMC 8703156. PMID 34988499. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8703156" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8703156</a> <a href="#fnref:42" class="footnote-back-ref">↩</a></p></li> <li id="fn:43"><p>Kiladze MR, Lyakhova UA, Lyakhov PA, Nagornov NN, Vahabi M (2023). "Multimodal Neural Network for Recognition of Cardiac Arrhythmias Based on 12-Load Electrocardiogram Signals". IEEE Access. 11: 133744–133754. Bibcode:2023IEEEA..11m3744K. doi:10.1109/ACCESS.2023.3335176. ISSN 2169-3536. <a href="https://doi.org/10.1109%2FACCESS.2023.3335176" target="_blank">https://doi.org/10.1109%2FACCESS.2023.3335176</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></p></li> <li id="fn:44"><p>Anier A, Kaik J, Meigas K (2008). "Device and methods for performing transesophageal stimulation at reduced pacing current threshold". Estonian Journal of Engineering. 57 (2): 154. doi:10.3176/eng.2008.2.05. S2CID 42055085. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></p></li> <li id="fn:45"><p>Pehrson SM, Blomström-Lundqvist C, Ljungström E, Blomström P (October 1994). "Clinical value of transesophageal atrial stimulation and recording in patients with arrhythmia-related symptoms or documented supraventricular tachycardia--correlation to clinical history and invasive studies". Clinical Cardiology. 17 (10): 528–534. doi:10.1002/clc.4960171004. PMID 8001299. S2CID 7097362. <a href="https://doi.org/10.1002%2Fclc.4960171004" target="_blank">https://doi.org/10.1002%2Fclc.4960171004</a> <a href="#fnref:45" class="footnote-back-ref">↩</a></p></li> <li id="fn:46"><p>Pehrson SM, Blomström-Lundqvist C, Ljungström E, Blomström P (October 1994). "Clinical value of transesophageal atrial stimulation and recording in patients with arrhythmia-related symptoms or documented supraventricular tachycardia--correlation to clinical history and invasive studies". Clinical Cardiology. 17 (10): 528–534. doi:10.1002/clc.4960171004. PMID 8001299. S2CID 7097362. <a href="https://doi.org/10.1002%2Fclc.4960171004" target="_blank">https://doi.org/10.1002%2Fclc.4960171004</a> <a href="#fnref:46" class="footnote-back-ref">↩</a></p></li> <li id="fn:47"><p>Yasuma F, Hayano J (February 2004). "Respiratory sinus arrhythmia: why does the heartbeat synchronize with respiratory rhythm?". Chest. 125 (2): 683–690. doi:10.1378/chest.125.2.683. PMID 14769752. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:47" class="footnote-back-ref">↩</a></p></li> <li id="fn:48"><p>Peressutti C, Martín-González JM, M García-Manso J, Mesa D (November 2010). "Heart rate dynamics in different levels of Zen meditation". International Journal of Cardiology. 145 (1): 142–146. doi:10.1016/j.ijcard.2009.06.058. PMID 19631997. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></p></li> <li id="fn:49"><p>Wiener N, Rosenblueth A (July 1946). "The mathematical formulation of the problem of conduction of impulses in a network of connected excitable elements, specifically in cardiac muscle". Archivos del Instituto de Cardiologia de Mexico. 16 (3): 205–265. PMID 20245817. <a href="/wiki/PMID_(identifier)" target="_blank">/wiki/PMID_(identifier)</a> <a href="#fnref:49" class="footnote-back-ref">↩</a></p></li> <li id="fn:50"><p>Allessie MA, Bonke FI, Schopman FJ (August 1976). "Circus movement in rabbit atrial muscle as a mechanism of tachycardia. II. The role of nonuniform recovery of excitability in the occurrence of unidirectional block, as studied with multiple microelectrodes". Circulation Research. 39 (2): 168–177. doi:10.1161/01.RES.39.2.168. PMID 939001. <a href="/wiki/Maurits_Allessie" target="_blank">/wiki/Maurits_Allessie</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></p></li> <li id="fn:51"><p>Mandel WJ, ed. (1995). Cardiac Arrhythmias: Their Mechanisms, Diagnosis, and Management (3 ed.). Lippincott Williams & Wilkins. ISBN 978-0-397-51185-3.[page needed] <a href="978-0-397-51185-3" target="_blank">978-0-397-51185-3</a> <a href="#fnref:51" class="footnote-back-ref">↩</a></p></li> <li id="fn:52"><p>Den Ruijter HM, Berecki G, Opthof T, Verkerk AO, Zock PL, Coronel R (January 2007). "Pro- and antiarrhythmic properties of a diet rich in fish oil". Cardiovascular Research. 73 (2): 316–325. doi:10.1016/j.cardiores.2006.06.014. PMID 16859661. <a href="https://doi.org/10.1016%2Fj.cardiores.2006.06.014" target="_blank">https://doi.org/10.1016%2Fj.cardiores.2006.06.014</a> <a href="#fnref:52" class="footnote-back-ref">↩</a></p></li> <li id="fn:53"><p>Barrett ML, Smith MW, Elizhauser A, Honigman LS, Pines JM (December 2014). "Utilization of Intensive Care Services, 2011". HCUP Statistical Brief (185). Rockville, MD: Agency for Healthcare Research and Quality. PMID 25654157. Archived from the original on 2015-04-02. <a href="https://www.hcup-us.ahrq.gov/reports/statbriefs/sb185-Hospital-Intensive-Care-Units-2011.jsp" target="_blank">https://www.hcup-us.ahrq.gov/reports/statbriefs/sb185-Hospital-Intensive-Care-Units-2011.jsp</a> <a href="#fnref:53" class="footnote-back-ref">↩</a></p></li> <li id="fn:54"><p>"AED Buyer's Guide | AED Prices & Comparison". AED Brands. Retrieved 2021-08-13. <a href="https://www.aedbrands.com/aed-buyers-guide/" target="_blank">https://www.aedbrands.com/aed-buyers-guide/</a> <a href="#fnref:54" class="footnote-back-ref">↩</a></p></li> <li id="fn:55"><p>Heist EK, Ruskin JN (October 2010). "Drug-induced arrhythmia". Circulation. 122 (14): 1426–1435. doi:10.1161/circulationaha.109.894725. PMID 20921449. <a href="https://doi.org/10.1161%2Fcirculationaha.109.894725" target="_blank">https://doi.org/10.1161%2Fcirculationaha.109.894725</a> <a href="#fnref:55" class="footnote-back-ref">↩</a></p></li> <li id="fn:56"><p>Heist EK, Ruskin JN (October 2010). "Drug-induced arrhythmia". Circulation. 122 (14): 1426–1435. doi:10.1161/circulationaha.109.894725. PMID 20921449. <a href="https://doi.org/10.1161%2Fcirculationaha.109.894725" target="_blank">https://doi.org/10.1161%2Fcirculationaha.109.894725</a> <a href="#fnref:56" class="footnote-back-ref">↩</a></p></li> <li id="fn:57"><p>Heist EK, Ruskin JN (October 2010). "Drug-induced arrhythmia". Circulation. 122 (14): 1426–1435. doi:10.1161/circulationaha.109.894725. PMID 20921449. <a href="https://doi.org/10.1161%2Fcirculationaha.109.894725" target="_blank">https://doi.org/10.1161%2Fcirculationaha.109.894725</a> <a href="#fnref:57" class="footnote-back-ref">↩</a></p></li> <li id="fn:58"><p>Hadziselimovic E, Thomsen JH, Kjaergaard J, Køber L, Graff C, Pehrson S, et al. (July 2018). "Osborn waves following out-of-hospital cardiac arrest—Effect of level of temperature management and risk of arrhythmia and death". Resuscitation. 128: 119–125. doi:10.1016/j.resuscitation.2018.04.037. ISSN 0300-9572. PMID 29723608. S2CID 19236851. <a href="https://doi.org/10.1016/j.resuscitation.2018.04.037" target="_blank">https://doi.org/10.1016/j.resuscitation.2018.04.037</a> <a href="#fnref:58" class="footnote-back-ref">↩</a></p></li> <li id="fn:59"><p>Hadziselimovic E, Thomsen JH, Kjaergaard J, Køber L, Graff C, Pehrson S, et al. (July 2018). "Osborn waves following out-of-hospital cardiac arrest—Effect of level of temperature management and risk of arrhythmia and death". Resuscitation. 128: 119–125. doi:10.1016/j.resuscitation.2018.04.037. ISSN 0300-9572. PMID 29723608. S2CID 19236851. <a href="https://doi.org/10.1016/j.resuscitation.2018.04.037" target="_blank">https://doi.org/10.1016/j.resuscitation.2018.04.037</a> <a href="#fnref:59" class="footnote-back-ref">↩</a></p></li> </ol>