Supraventricular Tachycardia

Supraventricular tachycardia (SVT) is a arrhythmia that causes the heart to beat unusually fast. It starts in the upper chambers of the heart. During an SVT episode, the heart beats much faster than normal. The heart rate typically ranges from 150 to 250 beats per minute. These episodes can start and end suddenly.

SVT affects people of all ages. While it’s not usually life-threatening, it can be very uncomfortable. Stress, excessive caffeine intake, and fatigue are common triggers for SVT episodes.

What is Supraventricular Tachycardia?

SVT refers to a group of tachycardias originating above the heart’s ventricles. It typically presents as sudden episodes of rapid heartbeat, often accompanied by symptoms such as dizziness, chest pain, and shortness of breath. The duration of episodes may vary, lasting from seconds to several hours.

The condition often arises due to the presence of an extra electrical pathway in the heart, overactive regions within the atria, or reentry circuits in the heart’s conduction system. SVT may be triggered by stress, excessive alcohol or caffeine consumption, or certain medications. It can also occur without identifiable triggers. Structural heart diseases (e.g., valvular heart disease) and congenital electrical abnormalities, such as Wolff-Parkinson-White syndrome or Long QT Syndrome, may also lead to SVT.

What are the Types of Supraventricular Tachycardia?

SVT encompasses several subtypes based on their origin and underlying electrical mechanisms:

AV Nodal Reentrant Tachycardia (AVNRT)

AVNRT occurs due to a reentry circuit within the AV node, leading to rapid and regular heartbeats. It is the most common type of SVT, more frequently seen in women.

Atrioventricular Reentrant Tachycardia (AVRT)

AVRT arises from an extra electrical pathway between the atria and ventricles, causing a “short-circuit” effect. Wolff-Parkinson-White (WPW) syndrome is a classic example of this condition.

Atrial Fibrillation (AFib)

Atrial fibrillation is characterized by chaotic electrical activity in the atria, leading to rapid, irregular heartbeats. It reduces the efficiency of the heart’s pumping mechanism and may increase the risk of stroke.

Atrial Flutter

Atrial flutter involves a rapid but regular rhythm caused by a reentrant circuit in the atria. The heart rate may range between 250 and 350 beats per minute.

Wolff-Parkinson-White (WPW) Syndrome

WPW syndrome is a congenital condition characterized by the presence of an accessory electrical pathway (Kent bundle), which bypasses the normal conduction system and predisposes individuals to SVT.

Atrial Tachycardia (AT)

Atrial tachycardia originates from a focal area or reentry circuit in the atria. Symptoms can range from mild palpitations to more severe episodes of rapid heart rate.

Nodal Tachycardia

This type originates from the AV node and may be triggered by medications, surgical interventions, or without an apparent cause.

What are the Symptoms of Supraventricular Tachycardia?

The symptoms of supraventricular tachycardia can vary significantly from person to person. While some individuals experience mild sensations, others may face more severe symptoms.

Symptoms of SVT include:

• A rapid fluttering or pounding sensation in the chest

• Episodes of palpitations that begin and end abruptly

• Shortness of breath

• Dizziness or lightheadedness

• Fainting (syncope)

• Feelings of anxiety or panic

• Chest pain or discomfort (especially if coronary artery disease is present)

In individuals with coexisting conditions such as heart failure, coronary artery disease, or valvular heart disease, these symptoms may be more severe and significantly impact their quality of life.

What Causes Supraventricular Tachycardia?

The primary causes of SVT include congenital heart defects or structural abnormalities in the heart resulting from prior heart attacks. These anomalies disrupt the heart’s normal electrical pathways, leading to rapid palpitations. Additionally, conditions like cardiomyopathy, which affect the heart muscle, can further increase the risk of SVT.

Causes of SVT include:

• Congenital heart defects
• Post-heart attack structural changes
• Cardiomyopathy
• Stress and anxiety
• Stimulants such as caffeine, nicotine, and recreational drugs
• Hormonal changes (e.g., pregnancy or menopause)
• Hyperthyroidism
• Electrolyte imbalances (e.g., abnormal potassium, magnesium, or calcium levels)
• Certain medications (e.g., decongestants or beta-agonists)
• Genetic predisposition

What are the Complications of Supraventricular Tachycardia?

Although SVT is usually not life-threatening, if left untreated or poorly managed, it can lead to dangerous complications. One potential complication is heart failure, particularly in individuals with underlying heart conditions. Continuous rapid heart rates can weaken the heart muscle over time, reducing its ability to pump blood effectively. This can cause symptoms such as fatigue, shortness of breath, and fluid retention.

Another complication associated with SVT is an increased risk of stroke. Rapid heart rates, especially in patients with atrial fibrillation, can lead to the formation of blood clots within the heart. If a clot travels to the brain, it can cause a stroke with potentially severe consequences.

When Should I see my Healthcare Provider?

Patients experiencing any of these symptoms should seek medical advice:

• Frequent or severe episodes of rapid heartbeats
• Chest pain
• Shortness of breath
• Dizziness
• Fainting

Early diagnosis and treatment can prevent complications and improve quality of life.

Lifestyle Changes to Manage or Prevent SVT

In addition to medical treatments, lifestyle modifications can significantly reduce the frequency and severity of SVT episodes. These changes include:

• Stress Management: Practicing relaxation techniques such as yoga, meditation, or deep breathing can help reduce stress, a common trigger for SVT.
• Limiting Stimulants: Reducing or avoiding caffeine, alcohol, and nicotine consumption can lower the risk of triggering SVT episodes.
• Maintaining a Healthy Weight: Obesity is associated with an increased risk of arrhythmias. A balanced diet and regular exercise can support overall heart health.
• Adequate Sleep: Ensuring sufficient rest can prevent fatigue, another potential SVT trigger.
• Monitoring Electrolytes: Maintaining proper hydration and a balanced diet can help regulate electrolytes, which play a critical role in heart rhythm stability.

How is an Supraventricular Tachycardia Diagnosed?

Diagnosing SVT begins with a detailed medical history and physical examination. Key diagnostic tests include:

• Electrocardiogram (ECG): Used to detect abnormal heart rhythms during episodes.
• Holter Monitoring: Continuous monitoring for 24–48 hours to capture intermittent episodes.
• Echocardiography: Evaluates structural abnormalities or underlying heart disease.
• Stress Testing: Identifies SVT triggered by physical exertion.
• Blood Tests: Assesses electrolyte imbalances or thyroid function.