From the Guidelines
Supraventricular tachycardia (SVT) on an EKG is characterized by a rapid, regular heart rhythm with a rate typically between 150-250 beats per minute, and the initial management for stable patients includes vagal maneuvers and adenosine as the first-line medication, as recommended by the 2015 ACC/AHA/HRS guideline 1. The key identifying features of SVT on an EKG include:
- Narrow QRS complexes (less than 120 milliseconds)
- Absent P waves or abnormal P wave morphology
- Abrupt onset and termination Initial management for stable patients includes:
- Vagal maneuvers such as the Valsalva maneuver or carotid sinus massage to attempt termination
- Adenosine as the first-line medication, administered as a rapid IV bolus starting at 6 mg, followed by 12 mg if needed, and another 12 mg dose if the arrhythmia persists, as stated in the guideline 1 For longer-term management, calcium channel blockers like verapamil (5-10 mg IV) or diltiazem (0.25 mg/kg IV), or beta-blockers such as metoprolol (5 mg IV) may be used, as mentioned in the guideline 1. SVT occurs due to abnormal electrical conduction pathways or mechanisms in the heart, most commonly involving AV nodal reentry or accessory pathways, and patients with recurrent episodes may require electrophysiology studies and catheter ablation for definitive treatment, as discussed in the guideline 1. Immediate cardioversion is necessary if the patient is hemodynamically unstable with hypotension or signs of shock, emphasizing the importance of prompt and appropriate management to prevent morbidity and mortality 1.
From the Research
SVT on an EKG
- SVT refers to rapid rhythms that originate and are sustained in atrial or atrioventricular node tissue above the bundle of His 2
- The condition is caused by reentry phenomena or automaticity at or above the atrioventricular node, and includes atrioventricular nodal reentrant tachycardia, atrioventricular reciprocating tachycardia, and atrial tachycardia 2
- Symptoms of SVT include palpitations, light-headedness, chest discomfort, anxiety, dyspnea, or fatigue 2, 3
Diagnosis of SVT
- Diagnosis is made on electrocardiogram during an arrhythmic event or using ambulatory monitoring 3
- A Holter monitor or event recorder may be needed to confirm the diagnosis 2
- ECG interpretation is crucial in diagnosing SVT, and vagal maneuvers or intravenous adenosine administration during 12-lead ECG recording should be performed in hemodynamically stable patients for diagnosis and treatment 4
Treatment of SVT
- First-line acute therapy for hemodynamically stable patients includes vagal maneuvers such as the modified Valsalva maneuver and intravenous adenosine 3
- Emergent cardioversion is recommended for patients who are hemodynamically unstable 3, 4
- Catheter ablation is safe, highly effective, and recommended as first-line therapy to prevent recurrence of PSVT, with single catheter ablation procedure success rates of 94.3% to 98.5% 3, 4
- Pharmacotherapy, including calcium channel blockers, β-blockers, and antiarrhythmic agents, is an important component of acute and long-term management of PSVT 3