Medical Management of Supraventricular Tachycardia (SVT)
The optimal management of SVT includes vagal maneuvers as first-line treatment for hemodynamically stable patients, followed by adenosine if vagal maneuvers fail, with oral beta blockers or calcium channel blockers for long-term management, and catheter ablation as a definitive treatment option for recurrent symptomatic SVT. 1, 2
Acute Management
Hemodynamically Unstable Patients
- Synchronized cardioversion is the first-line treatment for hemodynamically unstable patients with SVT 1, 2
Hemodynamically Stable Patients
First-line: Vagal Maneuvers
- Modified Valsalva maneuver is the most effective vagal maneuver, performed by having the patient bear down against a closed glottis for 10-30 seconds in a supine position, then immediately lying flat with legs raised 1, 2, 3
- Other vagal maneuvers include applying an ice-cold wet towel to the face (diving reflex) 4, 1
- Carotid sinus massage should only be performed after confirming absence of carotid bruits 1
- AVOID applying pressure to the eyeball as this practice is dangerous 1
Second-line: Pharmacological Therapy
- Adenosine is the first-line medication if vagal maneuvers fail, with 90-95% effectiveness rate 1, 2
- Initial dose: 6 mg rapid IV bolus followed by saline flush
- Can be repeated at 12 mg if ineffective
- If adenosine fails, IV calcium channel blockers (diltiazem or verapamil) or beta blockers can be used 1, 2
- CAUTION: Avoid AV nodal blocking agents (verapamil, diltiazem, beta blockers) in patients with suspected pre-excitation as they may accelerate ventricular rate and lead to ventricular fibrillation 1, 2
- Adenosine is the first-line medication if vagal maneuvers fail, with 90-95% effectiveness rate 1, 2
Long-term Management
Pharmacological Options
First-line: Oral AV Nodal Blocking Agents
Second-line: Class IC Antiarrhythmics
- Flecainide or propafenone can be used in patients without structural heart disease or ischemic heart disease who are not candidates for ablation 4, 5
- CAUTION: Flecainide has a risk of proarrhythmia in patients with structural heart disease or ischemic heart disease and should not be used in these patients 5
- Flecainide is indicated for prevention of paroxysmal SVT including AVNRT, AVRT, and other SVTs associated with disabling symptoms 5
Definitive Treatment
- Catheter Ablation
- Electrophysiology study with the option of ablation is useful as first-line therapy for definitive treatment of symptomatic SVT 4, 1, 6
- Provides potential for cure without need for chronic pharmacological therapy 4
- High success rates with low frequency of serious complications 4
- Particularly recommended for patients with:
Patient Education
- Patients should be educated on proper vagal maneuver techniques for self-management of SVT episodes 4, 1
- Teach patients to perform Valsalva maneuver by forcefully exhaling against a closed airway for 10-30 seconds while in a supine position 4, 1
Special Considerations
Pre-excited SVT/Atrial Fibrillation
- For hemodynamically stable patients with pre-excited AF, ibutilide or IV procainamide are recommended 1, 2
- AVOID AV nodal blocking agents in patients with suspected pre-excitation 1, 2
Pregnancy
- Vagal maneuvers are safe and recommended as first-line treatment during pregnancy 2
- Adenosine is considered safe during pregnancy due to its short half-life 2
- Synchronized cardioversion can be performed safely at all stages of pregnancy if necessary 2
Common Pitfalls and Caveats
- Always obtain a 12-lead ECG to differentiate tachycardia mechanisms before treatment 2
- Distinguish SVT with aberrancy from ventricular tachycardia before initiating treatment 2
- Avoid AV nodal blocking agents in patients with suspected pre-excitation, ventricular tachycardia, or systolic heart failure 1, 2
- Flecainide should not be used in patients with recent myocardial infarction or structural heart disease due to increased risk of proarrhythmia 5