Paroxysmal supraventricular tachycardia

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Paroxysmal supraventricular tachycardia
Other namesSupraventricular tachycardia, paroxysmal atrial tachycardia (PAT) [1]
SVT Lead II-2.JPG
Lead II electrocardiogram strip showing PSVT with a heart rate of about 180.
Specialty Emergency medicine, cardiology
Symptoms Palpitations, feeling lightheaded, increased heart rate, sweating, shortness of breath, chest pain [2]
Usual onsetStarts and stops suddenly [3]
CausesNot known [3]
Risk factors Alcohol, caffeine, nicotine, psychological stress, Wolff-Parkinson-White syndrome [3]
Diagnostic method Electrocardiogram [3]
Prevention Catheter ablation [3]
Treatment Valsalva maneuver, adenosine, calcium channel blockers, synchronized cardioversion [4]
Prognosis Generally good [3]
Frequency2.3 per 1000 people [5]

Paroxysmal supraventricular tachycardia (PSVT) is a type of supraventricular tachycardia, named for its intermittent episodes of abrupt onset and termination. [3] [6] Often people have no symptoms. [1] Otherwise symptoms may include palpitations, feeling lightheaded, sweating, shortness of breath, and chest pain. [2]

Contents

The cause is not known. [3] Risk factors include alcohol, psychostimulants such as caffeine, nicotine, and amphetamines, psychological stress, and Wolff-Parkinson-White syndrome, which often is inherited. [3] The underlying mechanism typically involves an accessory pathway that results in re-entry. [3] Diagnosis is typically by an electrocardiogram (ECG) which shows narrow QRS complexes and a fast heart rhythm typically between 150 and 240 beats per minute. [3]

Vagal maneuvers, such as the Valsalva maneuver, are often used as the initial treatment. [4] If not effective and the person has a normal blood pressure the medication adenosine may be tried. [4] If adenosine is not effective a calcium channel blocker or beta blocker may be used. [4] Otherwise synchronized cardioversion is the treatment. [4] Future episodes can be prevented by catheter ablation. [3]

About 2.3 per 1000 people have paroxysmal supraventricular tachycardia. [5] Problems typically begin in those 12 to 45 years old. [3] [5] Women are more often affected than men. [3] Outcomes are generally good in those who otherwise have a normal heart. [3] An ultrasound of the heart may be done to rule out underlying heart problems. [1]

Signs and symptoms

Symptoms may include palpitations, feeling faint, sweating, shortness of breath, and chest pain. [2] [7] [8] Episodes start and end suddenly. [3]

Types

Anatomy

Lead II of electrocardiogram shows 3 rapid heartbeats, supraventricualar extrasistoles due to atrioventricular nodal reentry, shown as red, demonstrating unexplained onset and stop of the episode in paroxysmal supraventricular tachycardia among normal heart rhythm shown as blue Supraventricular-extrasystole-leadII.png
Lead II of electrocardiogram shows 3 rapid heartbeats, supraventricualar extrasistoles due to atrioventricular nodal reentry, shown as red, demonstrating unexplained onset and stop of the episode in paroxysmal supraventricular tachycardia among normal heart rhythm shown as blue

Paroxysmal supraventricular tachycardia is a type of arrhythmia that originates in the atrioventricular (AV) junction. The most common underlying anatomical cause of PSVT is atrioventricular nodal reentry, which accounts for more than half of the cases. [9]

The underlying anatomical causes of PSVT, specifically atrioventricular nodal reentry, involve the presence of two functionally distinct conduction pathways within the AV node and the formation of a reentrant circuit that sustains the tachycardia. [8] These pathways within the AV node are known as the fast pathway and the slow pathway. [9]

The AV node is the structure that controls how electrical signals travel between the upper chambers (atria) and lower chambers (ventricles). During normal sinus rhythm, these signals pass through only one pathway, known as the fast pathway. The fast pathway conducts signals quickly but has a longer rest period before it can send another signal. However, in people with PSVT caused by atrioventricular nodal reentry, both the fast and the slow pathways are activated. [9] The slow pathway conducts signals more slowly but has a shorter rest period. [9]

In a healthy heart during normal sinus rhythm, only either the fast pathway or the slow pathway is used at any given moment for conducting electrical signals through the AV node, not both simultaneously. [10]

During PSVT episodes, an irregular heartbeat is triggered by an early electrical signal from one of the atria. This premature signal enters both pathways simultaneously. It encounters no problem traveling along the slow pathway because its conduction speed matches up well with this specific arrhythmia type. However, it faces difficulty passing through effectively down the faster path since it takes slightly longer for that path to be ready following the conduction of a recent signal. At this point, if retrograde or backward flow overcomes the forward movement's pace in the fast pathway, then unwanted feedback further intensifies the rapid heartbeat until something intervenes to stop the episode. There is currently no solid understanding on what stops the episode in PSVT. [9]

Treatment

Treatment depends on the type of heart rhythm shown on an electrocardiogram test, and the stability of the patient's blood circulation.

If a patient has low blood pressure, difficulty breathing, chest pain, shock, or confusion, they are considered unstable and must have an electrocardiogram result checked to determine if the heart is beating normally. If this is not the case, cardioversion, which uses electricity to reset the heartbeat, should be performed urgently. If an electrocardiogram shows that the high heart rate is caused by something other than PSVT itself (such as a reduction in blood flow to the heart), injections of drugs called beta-blockers may help. The same medication can also be used if someone is found to be unstable due to inappropriate sinus tachycardia (a fast but unexplained normal heartbeat). [11]

AV nodal blocking can be achieved in at least three ways:

Physical maneuvers

A number of physical maneuvers increase the resistance of the AV node to transmit impulses (AV nodal block), principally through activation of the parasympathetic nervous system, conducted to the heart by the vagus nerve. These manipulations are collectively referred to as vagal maneuvers. [12]

The Valsalva maneuver should be the first vagal maneuver tried [13] and works by increasing intra-thoracic pressure and affecting baroreceptors (pressure sensors) within the arch of the aorta. It is carried out by asking the patient to hold his/her breath while trying to exhale forcibly as if straining during a bowel movement. Holding the nose and exhaling against the obstruction has a similar effect. [14] Pressing down gently on the top of closed eyes may also bring heartbeat back to normal rhythm for some people with atrial or supraventricular tachycardia (SVT). [15] This is known as the oculocardiac reflex. [15] A 2023 review confirms the success of the Valsalva maneuver as a non-pharmaceutical intervention in PSVT. [16]

Medications

Termination of PSVT following adenosine administration Hr scan.jpg
Termination of PSVT following adenosine administration

Adenosine, an ultra-short-acting AV nodal blocking agent, is indicated if vagal maneuvers are not effective. [17] If unsuccessful or the PSVT recurs, calcium channel blockers, such as diltiazem or verapamil, are recommended. [4] Adenosine may be safely used during pregnancy. [18] Adenosine can be administered together with nondihydropyridine calcium channel blockers. [16]

Calcium channel blockers such as verapamil and diltiazem have a longer half-life compared to adenosine. Although these blockers are safe when administered slowly, adenosine is considered safer and particularly useful in cases where an electrocardiogram does not provide clear information. Calcium channel blockers and verapamil have similar effectiveness. However, despite being safer overall, adenosine was associated with higher costs and an increased likelihood of arrhythmia recurrence compared to calcium channel blockers. [19]

SVT that does not involve the AV node may respond to other anti-arrhythmic drugs such as sotalol or amiodarone. [20]

Cardioversion

If the person is hemodynamically unstable or other treatments have not been effective, synchronized electrical cardioversion may be used. In children this is often done with a dose of 0.5 to 1 J/Kg. [21]

Invasive treatment

Radiofrequency catheter ablation (RFCA) is a safe and effective treatment in both adults and children. [22] RFCA is considered a minimally invasive procedure rather than surgery. It does not involve making large incisions or opening up the chest cavity. Instead, it is performed using thin catheters that are inserted through blood vessels and guided to the heart. The catheter delivers radiofrequency energy to specific areas of the heart to disrupt abnormal electrical pathways causing arrhythmias. While it may require mild sedation or local anesthesia, it doesn't typically involve extensive cutting or suturing of tissue associated with traditional surgical procedures. [23]

Over the decade of 2010s, there have been significant advancements in catheter ablation techniques for ventricular arrhythmias, including improved mapping methods like ultra-high density mapping and innovative energy sources like electroporation. New types of catheters, such as lattice and saline-enhanced radiofrequency catheters, provide more precise and longer-lasting tissue damage. Additionally, cardiac imaging technologies like MRI can help identify abnormal areas causing arrhythmias and evaluate the success of the ablation procedure. [24]

Related Research Articles

<span class="mw-page-title-main">Tachycardia</span> Heart rate exceeding normal resting rate

Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal or abnormal.

<span class="mw-page-title-main">Wolff–Parkinson–White syndrome</span> Abnormal heart rhythm due to faulty electrical connections in the heart

Wolff–Parkinson–White syndrome (WPWS) is a disorder due to a specific type of problem with the electrical system of the heart involving an accessory pathway able to conduct electrical current between the atria and the ventricles, thus bypassing the atrioventricular node. About 60% of people with the electrical problem developed symptoms, which may include an abnormally fast heartbeat, palpitations, shortness of breath, lightheadedness, or syncope. Rarely, cardiac arrest may occur. The most common type of irregular heartbeat that occurs is known as paroxysmal supraventricular tachycardia.

<span class="mw-page-title-main">Palpitations</span> Perceived cardiac abnormality in which ones heartbeat can be felt

Palpitations are perceived abnormalities of the heartbeat characterized by awareness of cardiac muscle contractions in the chest, which is further characterized by the hard, fast and/or irregular beatings of the heart.

<span class="mw-page-title-main">Verapamil</span> Calcium channel blocker medication

Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina, and supraventricular tachycardia. It may also be used for the prevention of migraines and cluster headaches. It is given by mouth or by injection into a vein.

<span class="mw-page-title-main">Antiarrhythmic agent</span> Heart rhythm medication

Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a class of drugs that are used to suppress abnormally fast rhythms (tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia.

<span class="mw-page-title-main">Atrial flutter</span> Abnormal heart rhythm beginning in the atria

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. Atrial flutter is characterized by a sudden-onset (usually) regular abnormal heart rhythm on an electrocardiogram (ECG) in which the heart rate is fast. Symptoms may include a feeling of the heart beating too fast, too hard, or skipping beats, chest discomfort, difficulty breathing, a feeling as if one's stomach has dropped, a feeling of being light-headed, or loss of consciousness.

<span class="mw-page-title-main">Cardiac conduction system</span> Aspect of heart function

The cardiac conduction system transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the body's circulatory system. The pacemaking signal travels through the right atrium to the atrioventricular node, along the bundle of His, and through the bundle branches to Purkinje fibers in the walls of the ventricles. The Purkinje fibers transmit the signals more rapidly to stimulate contraction of the ventricles.

<span class="mw-page-title-main">Supraventricular tachycardia</span> Abnormally fast heart rhythm

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, which start within the lower chambers of the heart. There are four main types of SVT: atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and Wolff–Parkinson–White syndrome. The symptoms of SVT include palpitations, feeling of faintness, sweating, shortness of breath, and/or chest pain.

<span class="mw-page-title-main">AV nodal reentrant tachycardia</span> Medical condition

AV-nodal reentrant tachycardia (AVNRT) is a type of abnormal fast heart rhythm. It is a type of supraventricular tachycardia (SVT), meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia. It is more common in women than men. The main symptom is palpitations. Treatment may be with specific physical maneuvers, medications, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.

<span class="mw-page-title-main">Sinus tachycardia</span> Sinus rhythm with a rate that is higher than normal

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.

Premature atrial contraction (PAC), also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common cardiac dysrhythmia characterized by premature heartbeats originating in the atria. While the sinoatrial node typically regulates the heartbeat during normal sinus rhythm, PACs occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat, in contrast to escape beats, in which the normal sinoatrial node fails, leaving a non-nodal pacemaker to initiate a late beat.

Lown–Ganong–Levine syndrome (LGL) is a pre-excitation syndrome of the heart. Those with LGL syndrome have episodes of abnormal heart racing with a short PR interval and normal QRS complexes seen on their electrocardiogram when in a normal sinus rhythm. LGL syndrome was originally thought to be due to an abnormal electrical connection between the atria and the ventricles, but is now thought to be due to accelerated conduction through the atrioventricular node in the majority of cases. The syndrome is named after Bernard Lown, William Francis Ganong, Jr., and Samuel A. Levine.

In cardiology, an accessory pathway is an additional electrical connection between two parts of the heart. These pathways can lead to abnormal heart rhythms (arrhythmias) associated with symptoms of palpitations. Some pathways may activate a region of ventricular muscle earlier than would normally occur, referred to as pre-excitation, and this may be seen on an electrocardiogram. The combination of an accessory pathway that causes pre-excitation with arrhythmias is known as Wolff–Parkinson–White syndrome.

Re-entry ventricular arrhythmia is a type of paroxysmal tachycardia occurring in the ventricle where the cause of the arrhythmia is due to the electric signal not completing the normal circuit, but rather an alternative circuit looping back upon itself. There develops a self-perpetuating rapid and abnormal activation. Conditions necessary for re-entry include a combination of unidirectional block and slowed conduction. Circus movement may also occur on a smaller scale within the AV node, a large bypass tract is not necessary.

A vagal maneuver is an action used to stimulate the parasympathetic nervous system by activating the vagus nerve. The vagus nerve is the longest nerve of the autonomic nervous system and helps regulate many critical aspects of human physiology, including heart rate, blood pressure, sweating, and digestion through the release of acetylcholine. Common maneuvers that activate the vagus nerve include the Valsalva maneuver and carotid sinus massage, which can serve diagnostic or therapeutic functions.

<span class="mw-page-title-main">Junctional ectopic tachycardia</span> Irregular heartbeat due to abnormal conduction from the atrioventricular nerve

Junctional ectopic tachycardia (JET) is a rare syndrome of the heart that manifests in patients recovering from heart surgery. It is characterized by cardiac arrhythmia, or irregular beating of the heart, caused by abnormal conduction from or through the atrioventricular node. In newborns and infants up to 6 weeks old, the disease may also be referred to as His bundle tachycardia or congenital JET.

<span class="mw-page-title-main">Atrioventricular reentrant tachycardia</span> Abnormally fast heart rhythm due to electrical connection between the ventricles and atria

Atrioventricular reentrant tachycardia (AVRT), or atrioventricular reciprocating tachycardia, is a type of heart arrhythmia with an abnormally fast rhythm (tachychardia); it is classified as a type of supraventricular tachycardia (SVT). AVRT is most commonly associated with Wolff–Parkinson–White syndrome, but is also seen in permanent junctional reciprocating tachycardia (PJRT). In AVRT, an accessory pathway allows electrical signals from the heart's ventricles to enter the atria and cause earlier than normal contraction, which leads to repeated stimulation of the atrioventricular node.

<span class="mw-page-title-main">Arrhythmia</span> Group of medical conditions characterized by irregular heartbeat

Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia. Some types of arrhythmias have no symptoms. Symptoms, when present, may include palpitations or feeling a pause between heartbeats. In more serious cases, there may be lightheadedness, passing out, shortness of breath, chest pain, or decreased level of consciousness. While most cases of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in sudden death.

<span class="mw-page-title-main">Permanent junctional reciprocating tachycardia</span> Medical condition

Permanent junctional reciprocating tachycardia(PJRT) is a rare cardiac arrhythmia. It is a supraventricular tachycardia, and a cause of atrioventricular reentrant tachycardia (AVRT). PJRT can cause chronic tachycardia that, untreated, leads to cardiomyopathy. The cause is an accessory pathway in the heart which conducts from the ventricles back to the atria. Unlike the accessory pathway in a more common cause of AVRT, Wolff–Parkinson–White syndrome, the accessory pathway in PJRT conducts slowly. This means that the associated tachycardia may be subclinical and only diagnosed at a late stage, after significant damage to the heart has been caused from prolonged and recurrent episodes of AVRT. While PJRT generally presents itself in infants, and often immediately after birth, few adults can suffer from a sudden onset of PJRT in which the degrading accessory pathway can more often than not be in a non-posteroseptal site.

<span class="mw-page-title-main">Automatic tachycardia</span> Medical condition

An automatic tachycardia is a cardiac arrhythmia which involves an area of the heart generating an abnormally fast rhythm, sometimes also called enhanced automaticity. These tachycardias, or fast heart rhythms, differ from reentrant tachycardias in which there is an abnormal electrical pathway which gives rise to the pathology. Most automatic tachycardias are supraventricular tachycardias (SVT). It is important to recognize an automatic tachycardia because the treatment will be different to that for a reentrant tachycardia. The most useful clue will be the presence of 'warm up' and 'cool down'. This means that whereas a reentrant tachycardia will both begin and end abruptly as cardiac conduction uses then ceases to use the accessory pathway, an automatic tachycardia will rise and fall gradually in rate as the automatic focus increases and decreases its automatic rate of electrical discharge.

References

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  12. ↑ "UpToDate".
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  17. ↑ "Adenosine vs Verapamil (calcium channel blocker) in the acute treatment of supraventricular tachycardias". Archived from the original on 16 June 2010.
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