From the Guidelines
Paroxysmal supraventricular tachycardia (PSVT) is primarily caused by abnormal electrical conduction pathways or mechanisms in the heart, with atrioventricular nodal reentrant tachycardia (AVNRT) being the most common cause, as noted in a study published in the European Heart Journal 1. The most common causes of PSVT include:
- Atrioventricular nodal reentrant tachycardia (AVNRT), where dual pathways within the AV node create a circuit for electrical impulses to continuously cycle
- Accessory pathways, as seen in Wolff-Parkinson-White syndrome, which form an alternative route for electrical signals outside the normal conduction system
- Atrial tachycardia from enhanced automaticity in atrial tissue
- Atrioventricular reentrant tachycardia (AVRT) involving accessory pathways Several factors can trigger PSVT episodes, including:
- Caffeine
- Alcohol
- Stress
- Fatigue
- Certain medications Underlying heart conditions like valvular disease, heart failure, or previous heart attacks may predispose individuals to PSVT, as mentioned in a study published in the European Heart Journal 1. Thyroid disorders, particularly hyperthyroidism, can increase heart rate and trigger episodes, and genetic factors play a role in some cases, especially with accessory pathways 1. Electrolyte imbalances, particularly low potassium or magnesium levels, can disrupt normal cardiac electrical activity and precipitate PSVT. Understanding these causes helps guide appropriate treatment strategies, which may include vagal maneuvers, medications like adenosine or beta-blockers, and in some cases, catheter ablation to eliminate the abnormal conduction pathways, as recommended in the latest ESC guidelines for the management of patients with supraventricular tachycardia 1.
From the Research
Causes of Paroxysmal SVT
The causes of paroxysmal supraventricular tachycardia (PSVT) can be attributed to various electrophysiologic mechanisms, including:
- Atrial tachycardia, which may be reentrant or caused by abnormal automaticity or triggered activity 2
- Atrioventricular (AV) nodal reentry, where the reentrant circuit is confined to the AV node or the region around the AV node, and is the most common type of PSVT in adults 2, 3
- Tachycardia involving an accessory AV connection, such as orthodromic supraventricular tachycardia, where antegrade conduction occurs via the AV node and retrograde conduction occurs via an accessory AV connection 2, 4
- Junctional tachycardia, although less common 2
Types of PSVT
The most common types of PSVT include:
- Atrioventricular nodal reentrant tachycardia (AVNRT) 5, 4, 3
- Atrioventricular reentrant tachycardia (AVRT) 5, 4
- Atrial tachycardia 2, 4
- Orthodromic supraventricular tachycardia, which is the most frequently found tachycardia in patients with accessory AV connections 2
Mechanisms of PSVT
PSVT is caused by re-entry due to the presence of inhomogeneous, accessory, or concealed conducting pathways 6. The mechanisms of PSVT can be complex and may involve multiple pathways, including the AV node, atrial tissue, and accessory pathways 2, 3. Understanding the mechanism of PSVT is crucial for diagnosis and treatment, as the response to antiarrhythmic drugs and the efficacy of catheter ablation may differ depending on the type of PSVT 2, 5, 4.