Supraventricular Tachcardia
What is Supraventricular Tachycardia?
Supraventricular tachycardia (SVT), also called paroxysmal supraventricular tachycardia, is a type of abnormal heart rhythm (arrhythmia). It is characterized by an abnormally fast heart rate (tachycardia) originating above the ventricles (the lower chambers of the heart). The term "supraventricular" means "above the ventricles." In SVT, electrical signals in the heart’s upper chambers (atria) or the junction between the atria and ventricles (atrioventricular node) cause the heart to beat too quickly.
Types of Supraventricular Tachycardia
Supraventricular tachycardia is categorized into 3 main types:
- Atrioventricular Nodal Reentrant Tachycardia (AVNRT): This is the most common type of SVT and is caused by an extra electrical pathway within or near the AV node.
- Atrioventricular Reciprocating Tachycardia (AVRT): This is the second most common type of SVT and involves an accessory pathway (extra electrical connection) outside the AV node. It is most commonly seen in younger people.
- Atrial Tachycardia: This type of SVT is more commonly seen in individuals who have heart disease and originates from abnormal electrical activity in the atria.
Symptoms of Supraventricular Tachycardia
Supraventricular tachycardia usually does not cause serious symptoms other than a rapid heartbeat. However, some people may experience symptoms like:
- Palpitations (a fluttering or pounding sensation in the chest)
- Dizziness or lightheadedness
- Shortness of breath
- Chest discomfort or pain
- Fatigue
- In rare cases, fainting (syncope)
Causes and Risk Factors of Supraventricular Tachycardia
Causes and risk factors of supraventricular tachycardia include:
- Excessive caffeine or alcohol intake
- Stress or anxiety
- Certain medications, such as stimulants and decongestants
- Thyroid disorders
- Structural heart abnormalities
- Electrolyte imbalances
Diagnosis of Supraventricular Tachycardia
In general, diagnosis of supraventricular tachycardia may include the following:
- Electrocardiogram (ECG): This is the primary diagnostic tool for identifying SVT episodes and involves attaching the electrodes to the chest and sometimes legs or arms to record the heart’s rhythm over time in a clinic/hospital setting.
- Holter Monitor: A portable device that records heart activity over 24-48 hours during daily activities in a home setting.
- Event Monitor: A device that is worn for about 30 days in a home setting and is used for recording intermittent symptoms during this period.
- Electrophysiological Study (EPS): A specialized test to map the heart’s electrical system in a clinic/hospital setting.
Treatment for Supraventricular Tachycardia
Acute Episode Management
- Vagal Maneuvers: Techniques like bearing down, coughing, or applying ice to the face can help slow the heart rate by stimulating the vagus nerve.
- Medications: Intravenous adenosine is often used to terminate SVT. Other medications include beta-blockers or calcium channel blockers.
- Cardioversion: In severe cases, an electrical shock may be needed to restore normal rhythm.
Long-Term Management
- Lifestyle Changes
- Avoid triggers like caffeine, alcohol, and stress.
- Medications
- Oral beta-blockers or anti-arrhythmic drugs for prevention.
- Catheter Ablation
- A minimally invasive procedure that uses radiofrequency energy or cryotherapy to destroy the abnormal electrical pathway causing SVT.
- Implantable Cardioverter Defibrillator (ICD)
- A small device placed in the chest that monitors your heart rhythm and delivers an electrical shock to correct abnormal heartbeats.
- Surgical Intervention
- Rarely needed unless there is structural heart disease or other complications.
Prognosis
Most cases of supraventricular tachycardia can be effectively managed or cured with treatment. Catheter ablation offers a high success rate for those who experience recurrent or severe episodes. If untreated, frequent or prolonged SVT episodes can weaken the heart over time, although SVT is generally not life-threatening in most cases.
