From the Guidelines
Supraventricular tachycardia (SVT) is primarily caused by abnormal electrical pathways or focal areas in the heart above the ventricles, with the most common causes including accessory pathways, AV nodal reentrant tachycardia (AVNRT), and atrial tachycardia, as supported by the latest guidelines 1. The causes of SVT can be understood by considering the mechanisms of arrhythmia, which include disorders of impulse initiation and abnormalities of impulse conduction, as outlined in the guidelines 1. Some key points to consider when evaluating the causes of SVT include:
- Abnormal automaticity, which can occur in the atria, AV junction, or vessels communicating directly with the atria, such as the vena cava or pulmonary veins 1
- Triggered activity, which is associated with disturbances of recovery or repolarization, and can generate afterdepolarizations that trigger early action potentials 1
- Re-entry, which is the most common arrhythmia mechanism, and can occur in different forms, including orthodromic AV re-entry and antidromic AV re-entry 1
- Accessory pathways, such as those found in Wolff-Parkinson-White syndrome, which can contribute to SVT 1
- AV nodal reentrant tachycardia (AVNRT), which is a common cause of SVT, and can be triggered by vagal maneuvers or other factors 1
- Atrial tachycardia, which can be caused by a variety of factors, including hyperthyroidism, heart failure, and chronic lung disease 1
- Other medical conditions, such as hyperthyroidism, heart failure, chronic lung disease, and electrolyte imbalances, which can contribute to SVT 1
- Physical factors, such as pregnancy, which can trigger SVT due to increased blood volume and hormonal changes 1
- Genetic factors, which may play a role in some cases of SVT, as it can run in families 1 Understanding these causes is crucial for guiding appropriate treatment, which may include vagal maneuvers, medications like adenosine or beta-blockers, or catheter ablation for definitive treatment of the abnormal pathways 1.
From the Research
Causes of Supraventricular Tachycardia (SVT)
The causes of SVT can be attributed to various factors, including:
- Reentry phenomena or automaticity at or above the atrioventricular node 2
- Abnormal rapid cardiac rhythm that involves atrial or atrioventricular node tissue from the His bundle or above 3
- Underlying mechanisms that can be deduced from electrocardiography during tachycardia, comparing it with sinus rhythm, and assessing the onset and offset of tachycardia 4
Types of SVT
The most common types of SVT include:
- Atrioventricular nodal reentrant tachycardia
- Atrioventricular reentrant tachycardia
- Atrial tachycardia 3, 2, 4
Symptoms of SVT
Common symptoms of SVT include:
- Palpitations
- Chest discomfort or pressure
- Dyspnea
- Fatigue
- Lightheadedness 3, 2, 5
- Anxiety 2
- Altered consciousness 3
Diagnosis and Management of SVT
Diagnosis of SVT can be made using:
- Electrocardiogram during an arrhythmic event
- Ambulatory monitoring 5
- Holter monitor or event recorder 3, 2 Management of SVT includes:
- Vagal maneuvers as first-line therapy for hemodynamically stable patients 5, 4
- Adenosine as first-line therapy for hemodynamically stable patients 2, 5
- Calcium channel blockers and beta blockers as alternative therapies 2, 4
- Catheter ablation as a curative treatment for symptomatic patients 3, 2, 5, 4