From the Guidelines
Paroxysmal nonsustained supraventricular tachycardia (SVT) is a heart rhythm disorder characterized by sudden episodes of rapid heartbeat that originate above the ventricles and terminate spontaneously within 30 seconds, as defined by the most recent guidelines 1.
Definition and Characteristics
The condition is considered paroxysmal because it occurs in unpredictable episodes rather than continuously, and nonsustained because each episode resolves on its own within a short time frame.
- Heart rates typically range between 150-250 beats per minute.
- Episodes start and stop abruptly.
- Common symptoms include palpitations, lightheadedness, shortness of breath, chest discomfort, and anxiety during episodes.
Management and Treatment
Management depends on frequency and severity of symptoms, ranging from:
- Vagal maneuvers (like bearing down or carotid sinus massage) for acute episodes.
- Medications such as beta-blockers, calcium channel blockers, or antiarrhythmics for prevention. For recurrent symptomatic episodes that significantly impact quality of life, catheter ablation may be recommended as a definitive treatment, as suggested by recent guidelines 1. The condition results from abnormal electrical pathways or focal triggers in the atria that create rapid circular patterns of electrical activity.
- A clinical history describing the pattern in terms of the number of episodes, duration, frequency, mode of onset, and possible triggers is crucial in clinical decision making, as emphasized in earlier guidelines 1.
From the Research
Definition of Paroxysmal Nonsustained SVT
- Paroxysmal supraventricular tachycardia (PSVT) is defined as tachyarrhythmias that originate from or conduct through the atria or atrioventricular node with abrupt onset 2.
- It is characterized by regular tachycardia rhythm with sudden onset and abrupt termination 3.
- PSVT is caused by re-entry due to the presence of inhomogeneous, accessory, or concealed conducting pathways 3.
Types of Supraventricular Tachycardia
- Paroxysmal SVT has three common types: atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and atrial tachycardia 4.
- The most common SVTs include atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia, and atrial tachycardia 5.
Diagnosis and Management
- Diagnosis is made on electrocardiogram during an arrhythmic event or using ambulatory monitoring 2.
- First-line acute therapy for hemodynamically stable patients includes vagal maneuvers and intravenous adenosine 2, 4, 5.
- Emergent cardioversion is recommended for patients who are hemodynamically unstable 2, 4, 5.
- Catheter ablation is safe, highly effective, and recommended as first-line therapy to prevent recurrence of PSVT 2, 4, 6, 5.