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Supraventricular tachycardia (SVT) is an umbrella term for fast heart rhythms arising from the upper part of the heart. This is in contrast to the other group of fast heart rhythms –
ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a cardiovascular disorder in which fast heart rate occurs in the ventricles of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple ...
, which start within the lower chambers of the heart. There are four main types of SVT:
atrial fibrillation Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods ...
,
atrial flutter Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia (SVT). ...
,
paroxysmal supraventricular tachycardia Paroxysmal supraventricular tachycardia (PSVT) is a type of supraventricular tachycardia, named for its intermittent episodes of abrupt onset and termination. Often people have no symptoms. Otherwise symptoms may include palpitations, feeling li ...
(PSVT), and Wolff–Parkinson–White syndrome. The symptoms of SVT include
palpitations Palpitations occur when a person becomes aware of their heartbeat. The heartbeat may feel hard, fast, or uneven in their chest. Symptoms include a very fast or irregular heartbeat. Palpitations are a sensory symptom. They are often described as ...
, feeling of faintness, sweating,
shortness of breath Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that con ...
, and/or
chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in the shoulder, arm, upper abdomen, or jaw, along with n ...
. These abnormal rhythms start from either the atria or
atrioventricular node The atrioventricular node (AV node, or Aschoff-Tawara node) electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the ...
. They are generally due to one of two mechanisms:
re-entry Atmospheric entry (sometimes listed as Vimpact or Ventry) is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. Atmospheric entry may be ''uncontrolled entry ...
or increased automaticity. Diagnosis is typically by electrocardiogram (ECG), Holter monitor, or event monitor.
Blood test A blood test is a medical laboratory, laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose ...
s may be done to rule out specific underlying causes such as
hyperthyroidism Hyperthyroidism is a endocrine disease in which the thyroid gland produces excessive amounts of thyroid hormones. Thyrotoxicosis is a condition that occurs due to elevated levels of thyroid hormones of any cause and therefore includes hyperth ...
, pheochromocytomas, or electrolyte abnormalities. A normal resting heart rate is 60 to 100 beats per minute. A resting heart rate of more than 100 beats per minute is defined as a tachycardia. During an episode of SVT, the heart beats about 150 to 220 times per minute. Specific treatment depends on the type of SVT and can include medications, medical procedures, or surgery. Vagal maneuvers, or a procedure known as catheter ablation, may be effective in certain types. For atrial fibrillation, calcium channel blockers or beta blockers may be used for rate control, and selected patients benefit from blood thinners (anticoagulants) such as
warfarin Warfarin, sold under the brand name Coumadin among others. It is used as an anticoagulant, anticoagulant medication. It is commonly used to prevent deep vein thrombosis and pulmonary embolism, and to protect against stroke in people who ha ...
or novel anticoagulants. Atrial fibrillation affects about 25 per 1000 people, paroxysmal supraventricular tachycardia 2.3 per 1000, Wolff-Parkinson-White syndrome 2 per 1000, and atrial flutter 0.8 per 1000.


Signs and symptoms

Signs and symptoms can arise suddenly and may resolve without treatment. Stress, exercise, and emotion can all result in a normal or physiological increase in heart rate, but they can precipitate SVT in rare cases. Episodes can last from a few minutes to one or two days. They sometimes persist until treated. The rapid heart rate, if fast enough, reduces the opportunity for the "pump" to fill between beats decreasing cardiac output and consequently
blood pressure Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term ...
. The following symptoms are typical with a rate of 150–270 or more beats per minute: * Pounding heart * Rapid heart beat *
Shortness of breath Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that con ...
*
Chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in the shoulder, arm, upper abdomen, or jaw, along with n ...
* Rapid breathing *
Dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to Balance disorder, disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a ...
* Sweating * Loss of consciousness Symptoms of heart arrhythmias, such as SVT, are more difficult to assess in infants and toddlers because of their limited ability to communicate. Caregivers should watch for lack of interest in feeding, shallow breathing, and lethargy. These symptoms may be subtle and may be accompanied by vomiting and/or a decrease in responsiveness.


Pathophysiology

The main pumping chamber, the ventricle, is protected (to a certain extent) against excessively high rates arising from the supraventricular areas by a "gating mechanism" at the
atrioventricular node The atrioventricular node (AV node, or Aschoff-Tawara node) electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the ...
, which allows only a proportion of the fast impulses to pass through to the ventricles. An accessory "bypass tract" can avoid the AV node and its protection so that the fast rate may be directly transmitted to the ventricles. This situation has characteristic findings on ECG. A congenital heart lesion, Ebstein's anomaly, is most commonly associated with supraventricular tachycardia.


Diagnosis

Subtypes of SVT can often be distinguished by their electrocardiogram (ECG) characteristics. Most have a narrow QRS complex, although, occasionally, electrical conduction abnormalities may produce a wide QRS complex that may mimic
ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a cardiovascular disorder in which fast heart rate occurs in the ventricles of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple ...
(VT). In the clinical setting, the distinction between narrow and wide complex tachycardia (supraventricular vs. ventricular) is fundamental since they are treated differently. In addition, ventricular tachycardia can quickly degenerate into
ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricula ...
and death and merits different consideration. In the less common situation in which a wide-complex tachycardia may be supraventricular, a number of
algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...
s have been devised to assist in distinguishing between them. In general, a history of structural heart disease markedly increases the likelihood that the tachycardia is ventricular in origin. *
Sinus tachycardia Sinus tachycardia is a sinus rhythm of the heart, with an increased rate of electrical discharge from the sinoatrial node, resulting in a tachycardia, a heart rate that is higher than the upper limit of normal (90–100 beats per minute for adu ...
is physiologic when a reasonable stimulus, such as the catecholamine surge associated with fright, stress, or physical activity, provokes the tachycardia. It is identical to a normal sinus rhythm, except for its faster rate (>100 beats per minute in adults). However, sinus tachycardia is considered part of the diagnoses included in SVT by most sources. * Sinoatrial node reentrant tachycardia (SANRT) is caused by a reentry circuit localised to the SA node, resulting in a P-wave of normal shape and size ( morphology) that falls before a regular, narrow QRS complex. It cannot be distinguished electrocardiographically from sinus tachycardia unless the sudden onset is observed (or recorded on a continuous monitoring device). It may sometimes be distinguished by its prompt response to vagal maneuvers. * Ectopic (unifocal)
atrial tachycardia Atrial tachycardia is a type of heart rhythm problem in which the heart's electrical impulse comes from an ectopic pacemaker (that is, an abnormally located cardiac pacemaker) in the upper chambers ( atria) of the heart, rather than from the sin ...
arises from an independent focus within the atria, distinguished by a consistent P-wave of abnormal shape and/or size that falls before a narrow, regular QRS complex. It can be caused by ''automaticity'', which means that some cardiac muscle cells, which have the primordial (''primitive, inborn, inherent'') ability to generate electrical impulses that are common to all cardiac muscle cells, have established themselves as a 'rhythm center' with a natural rate of electrical discharge that is faster than the normal SA node. Some atrial tachycardias, rather than being a result of increased automaticity may be a result of a micro-reentrant circuit (defined by some as less than 2 cm in longest diameter to distinguish it from macro-reentrant atrial flutter). Still other atrial tachycardias may be due to triggered activity caused by after-depolarizations. * Multifocal atrial tachycardia (MAT) is tachycardia arising from at least three ectopic foci within the atria, distinguished by P-waves of at least three different morphologies that all fall before irregular, narrow QRS complexes. This rhythm is most commonly seen in elderly people with
COPD Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by chronic respiratory symptoms and airflow limitation. GOLD defines COPD as a heterogeneous lung condition characterized by chronic respiratory s ...
. *
Atrial fibrillation Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods ...
meets the definition of SVT when associated with a ventricular response greater than 100 beats per minute. It is characterized as an "irregularly, irregular rhythm" both in its atrial and ventricular depolarizations and is distinguished by its fibrillatory atrial waves that, at some point in their chaos, stimulate a response from the ventricles in the form of irregular, narrow QRS complexes. *
Atrial flutter Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia (SVT). ...
, is caused by a re-entry rhythm in the atria, with a regular atrial rate often of about 300 beats per minute. On the ECG this appears as a line of "sawtooth" waves preceding the QRS complex. The AV node will not usually conduct 300 beats per minute so the P:QRS ratio is usually 2:1 or 4:1 pattern, (though rarely 3:1, and sometimes 1:1 where class IC antiarrhythmic drug are in use). Because the ratio of P to QRS is usually consistent, A-flutter is often regular in comparison to its irregular counterpart, atrial fibrillation. Atrial flutter is also not necessarily a tachycardia by definition unless the AV node permits a ventricular response greater than 100 beats per minute. * AV nodal reentrant tachycardia (AVNRT) involves a reentry circuit forming next to, or within, the AV node. The circuit most often involves two tiny pathways one faster than the other. Because the node is immediately between the atria and ventricle, the re-entry circuit often stimulates both, appearing as a backward (retrograde) conducted P-wave buried within or occurring just ''after'' the regular, narrow QRS complexes. * Atrioventricular reciprocating tachycardia (AVRT), also results from a reentry circuit, although one physically much larger than AVNRT. One portion of the circuit is usually the AV node, and the other, an abnormal accessory pathway (muscular connection) from the atria to the ventricle. Wolff-Parkinson-White syndrome (WPW) is a relatively common abnormality with an accessory pathway, the bundle of Kent crossing the AV valvular ring. ** In orthodromic AVRT, atrial impulses are conducted down through the AV node and retrogradely re-enter the atrium via the accessory pathway. A distinguishing characteristic of orthodromic AVRT can therefore be an inverted P-wave (relative to a sinus P wave) that follows each of its regular, narrow QRS complexes, due to retrograde conduction. ** In antidromic AVRT, atrial impulses are conducted down through the accessory pathway and re-enter the atrium retrogradely via the AV node. Because the accessory pathway initiates conduction in the ventricles outside of the
bundle of His The bundle of His (BH) or His bundle (HB) ( "hiss"Medical Terminology for Health Professions, Spiral bound Version'. Cengage Learning; 2016. . pp. 129–.) is a collection of heart muscle cells specialized for electrical conduction. As part of ...
, the QRS complex in antidromic AVRT is wider than usual. A delta wave is an initial slurred deflection seen in the initial part of an otherwise narrow QRS of a patient at risk for WPW and is an indicator of the presence of an accessory pathway. These beats are a fusion between the conduction down the accessory pathway and the slightly delayed but then-dominant conduction via the AV node. Once an antidromic AVRT tachycardia is initiated, it is no longer delta waves but rather a wide complex (>120 ms) tachycardia that is seen. * Junctional ectopic tachycardia (JET) is a rare tachycardia caused by increased automaticity of the AV node itself initiating frequent heartbeats. On the ECG, junctional tachycardia often presents with abnormal morphology P-waves that may fall anywhere in relation to a regular, narrow QRS complex. It is often due to drug toxicity.Alasti M, Mirzaee S, Machado C, et al. Junctional ectopic tachycardia (JET). J Arrhythm. 2020;36(5):837-844. Published 2020 Jul 27. doi:10.1002/joa3.12410


Classification

The following types of supraventricular tachycardias are more precisely classified by their specific site of origin. While each belongs to the broad classification of SVT, the specific term/diagnosis is preferred when possible: Sinoatrial origin: * Sinoatrial nodal reentrant tachycardia (SNRT)
Atrial The atrium (; : atria) is one of the two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves. ...
origin: * Ectopic (unifocal)
atrial tachycardia Atrial tachycardia is a type of heart rhythm problem in which the heart's electrical impulse comes from an ectopic pacemaker (that is, an abnormally located cardiac pacemaker) in the upper chambers ( atria) of the heart, rather than from the sin ...
(EAT) * Multifocal atrial tachycardia (MAT) *
Atrial fibrillation Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods ...
with rapid ventricular response *
Atrial flutter Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia (SVT). ...
with rapid ventricular response :(Without rapid ventricular response, fibrillation and flutter are usually not classified as SVT) Atrioventricular origin: * AV nodal reentrant tachycardia (AVNRT) or junctional reciprocating tachycardia (JRT) * AV reciprocating tachycardia (AVRT) – visible or concealed (including Wolff-Parkinson-White syndrome) ** Permanent (or persistent) junctional reciprocating tachycardia (PJRT), a form of SVT that involves a slow retrograde conduction over accessory pathway – occurs predominantly in infants and children but can occasionally occur in adults * Junctional ectopic tachycardia (JET)


Prevention

Once an acute arrhythmia has been terminated, ongoing treatment may be indicated to prevent recurrence. However, those that have an isolated episode, or infrequent and minimally symptomatic episodes, usually do not warrant treatment other than observation and explanation. In general, patients with more frequent or disabling symptoms warrant some form of prevention. A variety of drugs including simple AV nodal blocking agents such as
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 ...
s and verapamil, as well as antiarrhythmic drugs may be used, usually with good effect, although the adverse effects of these therapies need to be weighed against potential benefits. Radiofrequency ablation has revolutionized the treatment of tachycardia caused by a re-entrant pathway. This is a low-risk procedure that uses a catheter inside the heart to deliver radiofrequency energy to locate and destroy the abnormal electrical pathways. Ablation has been shown to be highly effective: around 90% in the case of AVNRT. Similar high rates of success are achieved with AVRT and typical atrial flutter.
Cryoablation Cryoablation is a process that uses extreme cold to destroy tissue. Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive fluids are circulated. Cryoprobes are positioned adjacent to the target in ...
is a newer treatment involving the AV node directly. SVT involving the AV node is often a contraindication to using radiofrequency ablation due to the small (1%) incidence of injuring the AV node, then requiring a permanent pacemaker. Cryoablation uses a catheter supercooled by
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...
gas freezing the tissue to −10 °C (+14.0 °F). This provides the same result as radiofrequency ablation but does not carry the same risk. If it is found that the wrong tissue is being frozen, the freezing process can be quickly stopped with the tissue returning to normal temperature and function in a short time. If after freezing the tissue to −10 °C the desired result is obtained, the tissue can be further cooled to a temperature of −73 °C (-99.4 °F) and it will be permanently ablated. This therapy has further improved the treatment options for AVNRT (and other SVTs with pathways close to the AV node), widening the application of curative ablation to young patients with relatively mild but still troublesome symptoms who might not have accepted the risk of requiring a pacemaker.


Treatment

Most SVTs are unpleasant rather than life-threatening, although very fast heart rates can be problematic for those with underlying
ischemic heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the ...
, or the elderly. Episodes can be treated when they occur by
Valsalva maneuver The Valsalva maneuver is performed by a forceful attempt of exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut while expelling air, as if blowing up a balloon. Variations of the maneuver can be ...
,
adenosine Adenosine (symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9- glycosidic bond. Adenosine is one of the four nucleoside build ...
injection or taking a AV node blocking agent as pill-in-pocket, but regular medication may also be used to prevent or reduce recurrence. While some treatment modalities can be applied to all SVTs, there are specific therapies available to treat some sub-types. Effective treatment consequently requires knowledge of how and where the arrhythmia is initiated and its mode of spread. Lifestyle changes, medication and heart procedures may be needed to control or eliminate the rapid heartbeats and related symptoms. SVTs can be categorised by whether the AV node is involved in maintaining the rhythm. If it is, manoeuvres slowing conduction through the AV node will terminate it. If it is not, AV nodal blocking maneuvers will not terminate it, but resulting temporary suppression of the AV node is still useful to unmask the underlying abnormal rhythm. Acute attacks of supraventricular tachycardia are treated with Esmolol (i.v.).


Society and culture

Notable cases of SVT: * Bobby Julich, American professional
road cyclist Road cycling is the most widespread form of cycling in which cyclists ride on paved roadways. It includes Recreational cycling, recreational, Road bicycle racing, racing, Bicycle commuting, commuting, and utility cycling. As users of the road, ...
, third-place finisher in the 1998 Tour de France, bronze medalist in the
2004 Summer Olympics The 2004 Summer Olympics (), officially the Games of the XXVIII Olympiad (), and officially branded as Athens 2004 (), were an international multi-sport event held from 13 to 29 August 2004 in Athens, Greece. The Games saw 10,625 athletes ...
* Tayyiba Haneef-Park, American
volleyball Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to score points by grounding a ball on the other team's court under organized rules. It has been a part of the official program of the Summ ...
competitor in the
2008 Summer Olympics The 2008 Summer Olympics (), officially the Games of the XXIX Olympiad () and officially branded as Beijing 2008 (), were an international multisport event held from 8 to 24 August 2008, in Beijing, China. A total of 10,942 athletes fro ...
*
Tony Blair Sir Anthony Charles Lynton Blair (born 6 May 1953) is a British politician who served as Prime Minister of the United Kingdom from 1997 to 2007 and Leader of the Labour Party (UK), Leader of the Labour Party from 1994 to 2007. He was Leader ...
, former
Prime Minister of the United Kingdom The prime minister of the United Kingdom is the head of government of the United Kingdom. The prime minister Advice (constitutional law), advises the Monarchy of the United Kingdom, sovereign on the exercise of much of the Royal prerogative ...
* Anastacia, American singer-songwriter. * Rebecca Soni, American Gold Medal Olympic swimmer * Dana Vollmer, American Gold Medal Olympic swimmer * Neville Fields, Australian football player * Paul Bearer, wrestling manager * Nathan Cohen, New Zealand's two-time world champion and Olympic champion rower, was diagnosed with SVT in 2013 when he was 27 years old. Scott Brady of punk band Brave The Wild () has this. He had his first attack on April 9, 2012 while golfing and was hospitalized over night. He was diagnosed April 17, 2014 in Hamilton ON after having an attack walking home from dinner on March 16, 2014. *
Miley Cyrus Miley Ray Cyrus ( , born Destiny Hope Cyrus, November 23, 1992) is an American singer, songwriter, actress and director. Regarded as a contemporary pop icon, Cyrus has been recognized for her evolving artistry and image reinventions. She is ...
, American singer and actress * George Plimpton, notable author, sportswriter, and literary personalitySevero, Richard (September 26, 2003). "George Plimpton, Urbane and Witty Writer, Dies at 76". The New York Times. Retrieved May 25, 2010.


References


External links


Cardiac Disorders – Open Directory Project
{{Circulatory system pathology Cardiac arrhythmia Wikipedia medicine articles ready to translate Wikipedia emergency medicine articles ready to translate