Supraventricular tachycardia

Overview

Supraventricular tachycardia (SVT), often referred to as paroxysmal supraventricular tachycardia, is an abnormally fast or irregular heartbeat (arrhythmia) that affects the upper chambers of the heart. The underlying issue lies in the malfunctioning electrical signals and circuitry within the heart. When the heart beats excessively fast, it hinders the proper filling of blood during each beat, thereby impeding the adequate supply of blood to the body.

The average heartbeat is between 60 and 100 beats per minute. A tachycardia is characterized by a heartbeat rate more than 100 per minute. The heart typically beats between 150 and 220 times per minute throughout an episode of SVT, while it can occasionally beat more quickly or slowly.

The three primary types of supraventricular tachycardia (SVT) are as follows: 

• Atrial tachycardia: Heart disease patients are more likely to have this type of SVT diagnosed. The AV node is not involved in atrial tachycardia. 
• Atrioventricular nodal reentrant tachycardia (AVNRT): Supraventricular tachycardia most frequently occurs in this type.
• Atrioventricular reciprocating tachycardia (AVRT): The AVRT is the second most typical variety of supraventricular tachycardia. Younger individuals are most frequently diagnosed with it. 
• Supraventricular tachycardia can also take the following types:
  • Premature atrial contractions (PACs) 
  • Paroxysmal supraventricular tachycardia (PSVTP)
  • Accessory pathway tachycardias such as Wolff–Parkinson–White (WPW) syndrome 
  • Sinus tachycardia
  • Sinus nodal reentrant tachycardia (SNRT)
  • Inappropriate sinus tachycardia (IST)
  • Multifocal atrial tachycardia (MAT)
  • Junctional ectopic tachycardia (JET)
  • Nonparoxysmal junctional tachycardia (NPJT)

Supraventricular tachycardia (SVT) often does not necessitate treatment or restrictions on daily activities for the majority of patients. However, certain individuals may benefit from making lifestyle modifications, taking medications, or undergoing heart surgeries to control or eliminate their rapid heartbeats and accompanying symptoms. 

Symptoms

Supraventricular tachycardia (SVT) is identified by an accelerated heart rate that exceeds 100 beats per minute, surpassing the normal range. This condition can endure for a brief period of a few minutes to several days. It typically occurs sporadically, interspersed with intervals of normal heart rate.

Supraventricular tachycardia signs and symptoms can include:

• Rapid heartbeat
• Chest pain
• Palpitation or pounding in the chest
• Neck pounding sensation
• Weakness or fatigue
• Shortness of breath
• Lightheadedness or dizziness
• Sweating
• Fainting or syncope
• Serious cases can cause cardiac arrest or make a person unconscious. 

Identifying signs and symptoms of SVT in infants and young children can pose a challenge. These symptoms include perspiration, pale skin, poor feeding and a rapid heartbeat. It is advisable to consult a healthcare provider regarding the possibility of SVT screening if an infant or young child displays any of these symptoms. 

In the absence of heart injury or other underlying heart conditions, supraventricular tachycardia (SVT) is generally not considered life–threatening. However, if an individual encounters their first episode of a significantly rapid heartbeat or if an irregular heartbeat persists for more than a few seconds, it is advisable to seek medical attention by contacting a healthcare provider. In severe instances, an episode of SVT has the potential to lead to loss of consciousness or cardiac arrest.

Certain symptoms and signs of SVT may indicate a significant medical concern. It is crucial to promptly seek medical attention if an SVT episode extends beyond a few minutes or if accompanying symptoms such as chest pain, shortness of breath, weakness, or dizziness are experienced. Taking these indicators seriously and seeking immediate medical evaluation is recommended.

Causes

Supraventricular tachycardia (SVT) arises from an issue with the heart’s electrical signals or circuits, although some individuals may be unaware of the specific causes behind their symptoms. In certain cases, the episodes of SVT can be attributed to clear triggers like physical activity, stress, or inadequate sleep. However, for some individuals, identifying an obvious trigger may be challenging or not possible. 

An SVT episode may result from various factors, such as: 

• Too much caffeine
• Excessive alcohol intake
• Cigarette smoking
• Heart disease or heart failure
• Wolff–Parkinson–White syndrome
• Chronic lung disease
• Illegal drugs intake, such as methamphetamine and cocaine
• A few medications, such as those for asthma and antihistamines for allergies and colds
• Pregnancy
• Thyroid disease

Risk factors

Factors that could increase the risk of supraventricular tachycardia include: 

• Age: The most frequent type of arrhythmia in infants and young children is supraventricular tachycardia (SVT). Short–lived paroxysmal supraventricular tachycardia (PSVT) is more common in young people who exercise or train excessively. Both young adults and the elderly are prone to have AV (atrioventricular) nodal reentrant tachycardia (AVNRT). 
• Gender: Though anyone can get it, women tend to have it more frequently, especially during pregnancy. 
• Food consumption: Alcohol intake and too much caffeine increases the risk in developing the condition.
• Illegal drug use: A supraventricular tachycardia episode may be brought on by nicotine and illicit substances like cocaine and amphetamines.
• Other medical condition: SVT risk factors include heart disease, heart failure, cardiomyopathy, damaged heart or heart valves, and narrowed heart arteries. Congenital heart diseases, thyroid disease, diabetes, or obstructive sleep apnea increases the risk of supraventricular tachycardia.