From the Guidelines
Supraventricular tachycardia (SVT) can be caused by several factors, including disorders of impulse initiation and abnormalities of impulse conduction, such as abnormal automaticity and re-entry mechanisms, as stated in the 2003 guidelines 1. The most common mechanisms of SVT include:
- Abnormal automaticity, where tissues in the atria, AV junction, or vessels exhibit enhanced diastolic phase 4 depolarization, leading to an increased firing rate compared to pacemaker cells 1
- Re-entry, which occurs when there is unidirectional conduction block in one limb of a circuit, allowing for the initiation and maintenance of a circus movement tachycardia 1
- Triggered activity, associated with disturbances of recovery or repolarization, generating afterdepolarizations that can trigger early action potentials during repolarization 1 Other factors that can contribute to SVT include:
- Structural heart abnormalities
- Heart disease
- Stress
- Caffeine
- Alcohol
- Smoking
- Certain medications
- Electrolyte imbalances
- Thyroid problems
- Fatigue
- Dehydration
- Stimulants like energy drinks
- Genetic predisposition
- Hormonal changes during pregnancy According to the 2020 European Heart Journal guidelines, SVT can result in heart failure, pulmonary edema, and/or myocardial ischemia secondary to an increased heart rate, and in adults with congenital heart diseases, SVT can increase the risk of heart failure, stroke, and sudden cardiac death 1. The 2016 Circulation guidelines provide a comprehensive approach to the management of adult patients with SVT, including the use of vagal maneuvers, IV adenosine, and other treatments, and emphasize the importance of distinguishing between different types of SVT, such as AVNRT, atrial tachycardia, and atrial flutter 1. In summary, the causes of SVT are multifactorial, and understanding these mechanisms is crucial for the prevention and management of SVT episodes through lifestyle modifications and appropriate medical treatment, as recommended by the most recent guidelines 1.
From the FDA Drug Label
By interrupting reentry at the AV node, verapamil can restore normal sinus rhythm in patients with paroxysmal supraventricular tachycardias (PSVT), including PSVT associated with Wolff-Parkinson-White syndrome. The cause of Supraventricular Tachycardia (SVT) is not directly stated in the label, but it can be inferred that reentry at the AV node may contribute to its development, as verapamil can restore normal sinus rhythm by interrupting this reentry 2.
From the Research
Causes of Supraventricular Tachycardia (SVT)
- SVT is caused by a reentry phenomenon producing accelerated heart rates 3, 4, 5, 6
- The condition is caused by reentry phenomena or automaticity at or above the atrioventricular node 4
- SVT can be caused by structurally normal hearts, and it is unusual for it to be caused by structurally abnormal hearts 3
- The most common SVTs include atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia, and atrial tachycardia 4, 6
- Wolff-Parkinson-White syndrome is a potentially curative option for SVT, and expedient referral to a cardiologist is warranted if this syndrome is present 3, 4, 5, 6
Types of SVT
- Atrioventricular nodal reentrant tachycardia
- Atrioventricular reciprocating tachycardia
- Atrial tachycardia
- Paroxysmal SVT, a subset of supraventricular dysrhythmias 5