Episodes of fast heartbeat can last for few minutes to 1 to 2 days until the condition gets treated. Increased heartbeat of more than 150 – 279 beats/minutes causes poor cardiac output, which in turn gives rise to the following signs and symptoms [7]:

• Shortness of breath
• Dizziness
• Palpitations
• Chest pain with dyspnea
• Nausea
• Diaphoresis
• Syncope

Infants, who have developed SVT, showcase poor feeding habits, lethargy, and loss of interest in feeding and shallow breathing.

• Pain

  Undifferentiated chest pain and dizziness are common causes for flight diversions and, as such, could potentially be prevented in some instances by using telemedicine.Voerman JJ, Hoffe ME, Surka S, Alves PM. [ncbi.nlm.nih.gov]

  For instance, your physician may instruct you to perform the Valsalva maneuver to try to stop the SVT yourself if you do not have lightheadedness, shortness of breath, chest pain, or other severe symptoms. [ahajournals.org]

  It is often associated with other symptoms, such as weakness, light-headedness, shortness of breath, and chest pain. Usually, the heart is otherwise normal. [msdmanuals.com]

• Fatigue

  However, when symptoms of SVT occur, they may include: Heart palpitations - pounding, fluttering or racing sensations in the chest Pounding Pulse Fatigue or Weakness – lack of energy or feeling over-tired Dizziness - feeling dizzy or light-headed Other [hoag.org]

  Cardiac arrhythmias also may cause light-headedness, fainting, chest pain, shortness of breath, fatigue or no symptoms at all. [hopkinsmedicine.org]

  Rapid heartbeats that occur suddenly and randomly Chest pain Dizziness Syncope (fainting or collapsing), which rarely happens with SVT Symptoms of heart failure (fatigue, shortness of breath, poor feeding) may develop if an episode lasts more than 24 [chop.edu]

  The side effect is fatigue.’ Anastacia’s new album Heavy Rotation is out now. [nowmagazine.co.uk]

• Weakness

  However, when symptoms of SVT occur, they may include: Heart palpitations - pounding, fluttering or racing sensations in the chest Pounding Pulse Fatigue or Weakness – lack of energy or feeling over-tired Dizziness - feeling dizzy or light-headed Other [hoag.org]

  […] the most common ones are: Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast) A slow heartbeat An irregular heartbeat Feeling pauses between heartbeats More serious signs and symptoms include: Anxiety Weakness [web.archive.org]

  ‘The doctors say it’s a weakness triggered by stress,’ she tells Hello! ‘I’ll be sitting chatting and suddenly my heart will beat like I’m running a marathon. I’ve fainted backstage because I can’t get rid of the palpitations. [nowmagazine.co.uk]

  It is often associated with other symptoms, such as weakness, light-headedness, shortness of breath, and chest pain. Usually, the heart is otherwise normal. [msdmanuals.com]

  This condition can cause symptoms such as weakness, fatigue, dizziness, fainting, or palpitations if the heart rate becomes too fast. [piedmont.org]

• Swelling

  You have swelling in your ankles or feet. You have questions or concerns about your condition or care. Care Agreement You have the right to help plan your care. Learn about your health condition and how it may be treated. [drugs.com]

  During a physical exam, your doctor may: Listen to the rate and rhythm of your heartbeat Listen to your heart for a heart murmur (an extra or unusual sound heard during your heartbeat) Check your pulse to find out how fast your heart is beating Check for swelling [web.archive.org]

  The condition is most often caused by aging or by the swelling or scarring of the heart that sometimes results from coronary artery disease. [texasheart.org]

  This may progress to swelling of the lower extremities, a manifestation of congestive heart failure. [en.wikipedia.org]

• Unconsciousness

  Common symptoms include: Dizziness Palpitations Shortness of breath Nausea Lightheadedness Falling unconscious Cardiac arrest, in extreme cases Treatment options The cause of your ventricular tachycardia will inform your treatment options. [heart.org]

  In extreme cases, an episode of supraventricular tachycardia may cause unconsciousness or cardiac arrest. [mayoclinic.org]

• Cough

  Cough Method: Have a patient cough forcefully. This is a simple form of vagal maneuver. A cough stimulates an increase in intrathoracic pressure which will stimulate the vagus nerve. [acls-algorithms.com]

  […] tachycardia (AVNRT) Atrioventricular reciprocating tachycardia (AVRT), which includes Wolff-Parkinson-White syndrome Atrial tachycardia SVT can go away on its own, with medication, or with certain actions used to slow heart rate: holding your breath, coughing [bidmc.org]

  For symptoms, treatment includes vagal maneuvers, such as the Valsalva maneuver or coughing, and splashing ice water on the face. Drugs include adenosine and verapamil. [carle.org]

  Vagal maneuvers may include: Holding breath and bearing down (valsalva maneuver) Immersing face in ice-cold water (diving reflex) Coughing The Cardiac team at CHOP will give you more information about vagal maneuvers and let you know which technique or [chop.edu]

• Dyspnea

  Sudden onset of an accelerated heart rate can cause palpitations, light-headedness, chest discomfort, anxiety, dyspnea, or fatigue. [ncbi.nlm.nih.gov]

  Symptoms may include palpitations, diaphoresis, dyspnea, dizziness, and mild chest pain (even in the absence of associated CHD). Syncope is rare. Obtaining a 12-lead ECG when feasible is important to help determine the tachycardia mechanism. [accessmedicine.mhmedical.com]

  The sudden episodes are usually associated with symptoms of hemodynamic compromise such as light headedness, chest discomfort and dyspnea. The attacks may last from few seconds to up to several hours, rarely exceeding 12 hours. [newhealthadvisor.com]

  Associated symptoms may include chest pain, pulsations in the neck, dyspnea, light-headedness, fatigue, sweating, etc. [heartracing.com]

• Nausea

  Increased heartbeat of more than 150 – 279 beats/minutes causes poor cardiac output, which in turn gives rise to the following signs and symptoms: Shortness of breath Dizziness Palpitations Chest pain with dyspnea Nausea Diaphoresis Syncope Infants, who [symptoma.com]

  Common symptoms include: Dizziness Palpitations Shortness of breath Nausea Lightheadedness Falling unconscious Cardiac arrest, in extreme cases Treatment options The cause of your ventricular tachycardia will inform your treatment options. [heart.org]

• Tachycardia

  He reverted to sinus rhythm with a higher dose of adenosine, suggesting that such doses may be required in refractory supraventricular tachycardia. [ncbi.nlm.nih.gov]

  Atrial tachycardias – The least common type of paroxysmal supraventricular tachycardia is an atrial tachycardia. [wexnermedical.osu.edu]

  Supraventricular tachycardia is by far the most common heart arrhythmia seen in infants and children. [chop.edu]

  There are almost double the amount of QRS complexes in all of the SVT when compared to the Sinus Tachycardia. This is the easiest way to tell SVT from Sinus tachycardia. Also, P-waves are only clear in the sinus tachycardia. [acls-algorithms.com]

• Palpitations

  Symptoms of supraventricular tachycardia in children may include: Heart palpitations — an uncomfortable sensation caused by the heart beating hard and fast. [chop.edu]

  […] by using Valsalva maneuvers.[1] The rhythm of the palpitations may indicate the etiology of the palpitations (irregular palpitations indicate atrial fibrillation as a source of the palpitations).[1] An irregular pounding sensation in the neck can be [en.wikipedia.org]

  As well, there are numerous abnormalities in the AV node that cause rapid heartbeats and palpitations. [medicinenet.com]

  It is almost always experienced as an uncomfortable awareness of the heartbeat, such as feeling like the heart is pounding or racing ( palpitations ). [msdmanuals.com]

• Heart Disease

  Supraventricular arrhythmias represent a major source of morbidity in adults with congenital heart disease (ACHD). [ncbi.nlm.nih.gov]

  Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Prevention, Anticoagulation Management and Atrial Fibrillation [acc.org]

  This arrhythmia is associated with the following conditions [12, 23, 11] : Rheumatic heart disease Hypertension Ischemic heart disease Pericarditis Thyrotoxicosis Alcohol intoxication Mitral valve prolapse and other disorders of the mitral valve Digitalis [emedicine.medscape.com]

• Heart Block

  Third-degree heart block is very serious and can lead to heart failure or death. [texasheart.org]

  Read Less Expand All Collapse All Bradycardia and heart block treatment Treatment options for bradycardia and heart block may include: Heart pacemaker surgery Bradycardia and heart block arrhythmias are typically treated with implantation of a device [scripps.org]

  Catheter ablation has a success rate of 95% and recurrence rate of less than 5%, and causes inadvertent heart block in less than 1% of patients. It is the preferred treatment for symptomatic patients with Wolff-Parkinson-White syndrome. [ncbi.nlm.nih.gov]

• Irregular Heart Rhythm

  Published on May 17, 2019 Paroxysmal supraventricular tachycardia (PSVT) is a type of arrhythmia—or irregular heart rhythm—that affects around 1.7 million Americans. This type of arrhythmia causes the heart to beat too quickly. [youtube.com]

  Implantable loop recorder: This small device, implanted just under the skin of the chest, is automatically triggered by an irregular heart rhythm, but can also be triggered manually. [baptisthealth.com]

  Supraventricular tachycardia (pronounced sue-prah-ven-TRIK-yu-lar tack-ih-CAR-dee-ah) is a problem with the heart’s electrical activity that causes an irregular heart rhythm. Tachycardia is a broad term used to describe fast heart rates and rhythms. [seattlechildrens.org]

  The ventricles are usually able to respond to this signal, but the result is an irregular heart rhythm. PACs are common and may occur as the result of stimulants such as coffee, tea, alcohol, cigarettes, or medications. [piedmont.org]

• Quickening

  Your heartbeat quickens, and you feel as if your heart is “skipping beats.” This rhythm may cause severe shortness of breath, dizziness, or fainting (syncope). [texasheart.org]

  Tachycardia occurs when an abnormality in the heart produces rapid electrical signals that quicken the heart rate, which is normally about 60 to 100 beats a minute at rest. In some cases, tachycardia may cause no symptoms or complications. [mayoclinic.org]

• Suggestibility

  He reverted to sinus rhythm with a higher dose of adenosine, suggesting that such doses may be required in refractory supraventricular tachycardia. [ncbi.nlm.nih.gov]

• Dizziness

  Undifferentiated chest pain and dizziness are common causes for flight diversions and, as such, could potentially be prevented in some instances by using telemedicine.Voerman JJ, Hoffe ME, Surka S, Alves PM. [ncbi.nlm.nih.gov]

  However, when symptoms of SVT occur, they may include: Heart palpitations - pounding, fluttering or racing sensations in the chest Pounding Pulse Fatigue or Weakness – lack of energy or feeling over-tired Dizziness - feeling dizzy or light-headed Other [hoag.org]

  These symptoms occur more frequently with a heart rate >150 beats per minute: Shortness of air (S) Palpitation feeling in chest (S) Ongoing chest pain (U) Dizziness (S) Rapid breathing (S) Loss of consciousness (U) Numbness of body parts (S) The pathway [acls-algorithms.com]

  Supraventricular Tachycardia Symptoms and Diagnosis The most common symptoms of SVT include: Palpitations (racing heart sensation) A pounding pulse Feeling dizzy or lightheaded Fainting (syncope) Shortness of breath Chest pain Throat tightness Sweating [bidmc.org]

  […] common ones are: Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast) A slow heartbeat An irregular heartbeat Feeling pauses between heartbeats More serious signs and symptoms include: Anxiety Weakness, dizziness [web.archive.org]

• Stroke

  Strikingly high mortality and stroke rates in follow-up were observed in AFL patients, who apparently need consistent long-term anticoagulation and more medical attention. Published on behalf of the European Society of Cardiology. [ncbi.nlm.nih.gov]

  Keywords: atrial fibrillation, epidemiology, risk factors, mortality, stroke This work is published and licensed by Dove Medical Press Limited. [doi.org]

  Like AFib, atrial flutter typically affects elderly patients and those with other types of heart disease, and it can increase the risk of stroke. [baptisthealth.com]

• Headache

  Medical history included SVT, asthma, anxiety, depression, type 2 diabetes, and migraine headaches. [ncbi.nlm.nih.gov]

  This can lead to fatigue, lightheadedness, headaches, blurry vision, and fainting. [texasheart.org]

  However some patients need to be on such medications for other reasons such as hypertension or migraine headaches. In these patients, such medications should generally be tried before considering other medications or ablation. [heartracing.com]

  Associated symptoms include dizziness, shortness of breath, sweating, headaches and chest pain. [en.wikipedia.org]

• Giddiness

  Some people may develop side effects from the drugs, such as giddiness, a low heart rate or low blood pressure. [arrhythmia.com.sg]

• Polyuria

  Polyuria can occur after termination of the episode (due to the release of atrial natriuretic factor). AVNRT may cause or worsen heart failure in patients with poor left ventricular function. [af-ablation.org]

  The patient may complain of shortness of breath, anxiety and occasionally polyuria due to elevated atrial pressure releasing atrial natriuretic peptide. The tachycardia typically ranges between 140-280 bpm and is regular in nature. [lifeinthefastlane.com]

  This phenomenon is less likely in SVTs in which the AV interval is greater, as occurs in accessory pathway-mediated SVTs, because the pressure gradient is usually lower. 4 Polyuria associated with episodes of tachycardia is due to the increased release [revespcardiol.org]

• A preliminary physical examination will be done to determine the heart rate. Physical examination would also reveal a forceful pulse rate in the neck. Heart rate in individuals with SVT would be above 100 – 250 beats/minute. Children would have a higher heart beat and would also show signs of poor blood circulation. 
• Conducting electrocardiography (ECG) is important for diagnosing SVT. If this test is carried out during an episode of SVT, then appropriate diagnosis can be made and other causes of rapid heartbeat can also be ruled out [8].
• In addition to ECG, more specialized tests such as electrophysiology to diagnose the exact location in the heart that is triggering SVT would also be necessary. Imaging studies such as chest radiography, transthoracic echocardiography and MRI of heart are also indicated in diagnosing other associated conditions such as pulmonary edema, congenital heart disease and cardiomegaly [9].

• First-Degree Atrioventricular Block

  Electrophysiological significance of first degree atrioventricular block with intraventricular conduction disturbance. Circulation 1971;43:491–502. 74. Dhingra RC, Wyndham C, Bauernfeind R et al. [cardiologieladomiciliu.ro]

• Inverted P Wave

  Inverted P waves are sometimes seen after the QRS complex. These are called retrograde p waves. The heart fills during diastole, and diastole is normally 2/3 the cardiac cycle. [acls-algorithms.com]

  (ii) Typical AVNRT (slow-fast pathway): P wave close to QRS complex, if seen at all ( (iii) Atypical AVNRT (fast-slow pathway): negative P waves in III and aVF, with long R-P interval. Retrograde (inverted) P waves may also be seen. 5. [clinicaladvisor.com]

  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. [en.wikipedia.org]

The following methods are involved in the treatment of supraventricular tachycardia:

• Physical maneuvers: This is the method of choice when the atrioventricular node is involved in the causation of SVT. Physical maneuvers work by increasing the intra thoracic pressure which in turn affects the pressure sensor in the arch of the aorta. The valsavar maneuver should be primarily tried in order to end the episode of SVT. In this, the individuals are asked to hold their breath and simultaneously exhale forcibly similar to the process of bowel straining.
• Medications: Medications such as adenosine, is indicated if physical maneuvers does not bring about any positive effect [10]. 
• Cardioversion: Electrocardioversion is used in cases when other treatment methods did not bring about any desired effect. It is one of the most effective modes for restoring sinus rhythm.

In majority of cases, prognosis of the condition mainly depends on the underlying heart disease. Individuals with SVT having a structurally normal heart, have an excellent prognosis. In cases, when SVT occurs due to Wolff-Parkinson-White syndrome, there is a certain percentage of sudden death due to development of atrial fibrillation [6].

Patients with paroxysmal SVT are at an increase risk of developing heart failure, myocardial ischemia and pulmonary edema. Individuals, who do not have any congenital heart defect and are suffering from SVT, are at least risk of sudden death.

SVT has many causes among which the noted cause is Wolff-Parkinson-White syndrome which can be inherited. It can be caused by other underlying diseases like chronic obstructive pulmonary disease (COPD) or heart failure. Prolonged intake of medicines like digoxin or theophylline, and heart surgery can also predispose to the development of the condition.

Anatomically, the heart has a total of 4 chambers, constituting of 2 atria and 2 ventricles. A heartbeat occurs as a result of electrical signal that is produced by the sinoatrial node. These electrical signals spread across the muscles of the heart causing it to contract, thereby producing a “beat”. Any disturbance in this pathway causes abnormal electrical signals to be transmitted to heart, and this gives rise to the condition known as supraventricular tachycardia. Tachycardia means fast heartbeat and supraventricualr means the region above the ventricles. Therefore, fast heartbeat that originates within the ventricles is termed as supraventricualr tachycardia [2]. 

Paroxysmal SVT occurs in about 1 – 3 cases per 1000 individuals. In other words, it has a prevalence rate of 0.2%. Of the several types, atrial fibrillation is the most common type affecting approximately 3 million individuals of US. Statistics have revealed that, by the year 2050, atrial fibrillation will affect more than 7.5 million people.
The incidence of Wolff-Parkinson-White syndrome is estimated to occur in about 3 out of every 1000 individuals [3] [4].

There are two mechanisms that trigger the onset of SVT; re-entry and automaticity. In the re-entry mode, individuals experience a sudden increase in the heartbeats; which is characterized by about 150 – 200 beats per minute. In the automaticity mode, there is a gradual increase in heartbeat. Such a type of condition occurs majorly due to generation of the heart’s own electrical signal.

Supraventricular tachycardia can also occur as a result of abnormal electrical activity in the heart due to congenital defect; a condition known as Wolff-Parkinson-White syndrome. In this syndrome, there is a “bypass tract” that bypasses the atrioventricular node, which in turn results in transmission of the fast heartbeat directly to the ventricles. This creates several loops of overlapping signals which predisposes an individual to develop SVT [5].

There is no way to prevent the onset of SVT. However, to prevent the recurrence of SVT in the future, medications such as verapamil and beta-blockers are used. These drugs along with anti-arrhythmics can also be given for preventing recurrence of SVT episodes.

Supraventricular tachycardia (SVT) is a potentially life threatening condition, demanding immediate medical attention. SVT often refers to paroxysmal supraventricular tachycardia which is an episodic disorder with an abrupt onset and termination. Medications and other therapies help in controlling the occurrence of SVT [1].

• Definition: Supraventricular tachycardia is a condition wherein there is rapid heartbeat of more than 150 – 200 beats/min that originates from above the ventricles. This occurs due to improper electrical activity in the heart which causes development of SVT.
• Cause: Abnormal electrical activity in the heart causes SVT. If infants have congenital defect in the structure of the heart, it is a favorable sign for the development of SVT. In addition, other factors such as excessive consumption of alcohol and caffeine, smoking and use of illicit drugs can also trigger episodes of SVT.
• Symptoms: Symptoms of SVT include shortness of breath, palpitations, anxiety, and development of discomfort in the chest, rapid pulse rate and dizziness. In severe cases, individuals can also faint due to SVT.
• Diagnosis: A preliminary physical examination to determine the heart rate will be done. Following this, electrocardiogram will also be carried out. Imaging studies such as chest radiography, cardiac MRI and transthoracic echocardiography are also indicated in diagnosis of SVT.
• Treatment: Physical maneuvers are the preliminary line of treatment for SVT. If these don’t work then medications and cardioversion techniques may have to be employed.

1. Ganz LI, Friedman PL. Supraventricular tachycardia. N Engl J Med 1995; 332:162.
2. Montoya PT, Brugada P, Smeets J, et al. Ventricular fibrillation in the Wolff-Parkinson-White syndrome. Eur Heart J. Feb 1991;12(2):144-50.
3. Orejarena LA, Vidaillet H Jr, DeStefano F, et al. Paroxysmal supraventricular tachycardia in the general population. J Am Coll Cardiol. Jan 1998;31(1):150-7. 
4. Chugh SS, Havmoeller R, Narayanan K, et al. Worldwide epidemiology of atrial fibrillation: a Global Burden of Disease 2010 Study. Circulation 2014; 129:837.
5. Trohman RG. Supraventricular tachycardia: implications for the intensivist. Crit Care Med. Oct 2000;28(10 Suppl):N129-35.
6. Benjamin EJ, Wolf PA, D'Agostino RB, et al. Impact of atrial fibrillation on the risk of death: the Framingham Heart Study. Circulation 1998; 98:946.
7. Wood KA, Drew BJ, Scheinman MM. Frequency of disabling symptoms in supraventricular tachycardia. Am J Cardiol. Jan 15 1997;79(2):145-9.
8. Farre J, Wellens HJ. The value of the electrocardiogram in diagnosing site of origin and mechanism of supraventricular tachycardia. In: Wellens HJJ, Kulbetus HE, eds. What's New in Electrocardiography. The Hague, Belgium; Martinus Nijhoff; 1981:131-71.
9. Xie B, Thakur RK, Shah CP, Hoon VK. Clinical differentiation of narrow QRS complex tachycardias. Emerg Med Clin North Am. May 1998;16(2):295-330. 
10. Camm AJ, Garratt CJ. Adenosine and supraventricular tachycardia. N Engl J Med 1991; 325:1621.