Management Criteria for SVT with Aberrancy
The management of SVT with aberrancy should follow a structured approach that first differentiates it from ventricular tachycardia using specific ECG criteria, then proceeds with treatment based on hemodynamic stability. 1
Differentiating SVT with Aberrancy from Ventricular Tachycardia
When faced with a wide-complex tachycardia, the first critical step is determining whether it's SVT with aberrancy or ventricular tachycardia (VT). The 2015 ACC/AHA/HRS guidelines provide specific ECG criteria:
Key ECG Criteria to Differentiate VT from SVT with Aberrancy:
QRS complex in leads V1-V6 (Brugada criteria):
- Lack of any R-S complexes suggests VT
- R-S interval >100 ms in any precordial lead suggests VT
QRS complex in aVR (Vereckei algorithm):
- Initial R wave suggests VT
- Initial R or Q wave >40 ms suggests VT
- Notch on descending limb at onset of predominantly negative QRS suggests VT
AV dissociation:
- Presence of AV dissociation (ventricular rate faster than atrial rate) or fusion complexes suggests VT
QRS pattern:
- QRS complexes all positive or all negative in precordial leads (concordant) suggests VT
- QRS in tachycardia identical to sinus rhythm suggests SVT
- R-wave peak time ≥50 ms in lead II suggests VT 1
Management Algorithm for SVT with Aberrancy
1. Assess Hemodynamic Stability
Hemodynamically unstable: Proceed immediately to synchronized cardioversion (Class I, Level B-NR) 2
Hemodynamically stable: Proceed with pharmacological management
2. Acute Management for Hemodynamically Stable Patients
First-line: Vagal maneuvers
- Modified Valsalva maneuver
- Carotid sinus massage
- Cold stimulus to face
- Success rate: approximately 27.7% 2
Second-line: Intravenous adenosine (Class I, Level B-R)
Third-line: If adenosine fails or is contraindicated:
- IV beta-blockers (e.g., metoprolol) OR
- IV non-dihydropyridine calcium channel blockers (e.g., diltiazem, verapamil) (Class I, Level B-R) 2
Fourth-line: If pharmacological therapy fails, proceed to synchronized cardioversion 2
3. Long-term Management
First-line: Oral beta-blockers, diltiazem, or verapamil (Class I, Level B-R) 2
Second-line: Flecainide or propafenone (Class IIa, Level B-R)
- Important: Contraindicated in structural heart disease or coronary artery disease 2
Definitive treatment: Catheter ablation (Class I, Level B-NR)
Special Considerations
Pre-existing Bundle Branch Block
- SVT with pre-existing bundle branch block will consistently show the same aberrancy pattern 1
Tetralogy of Fallot
- Most patients have RBBB on baseline ECG
- SVTs will conduct with RBBB aberrancy
- VT may have LBBB or RBBB configuration (in 25% of cases)
- RBBB configuration does not reliably distinguish SVT from VT 1
Ebstein's Anomaly
- Right bundle-branch block often present
- Right-sided accessory pathways more common (up to 25% of patients)
- Pre-excitation may mask RBBB
- LBBB-configuration tachycardias may be antidromic AVRT or conduction over bystander pathway 1
Common Pitfalls to Avoid
Misdiagnosing VT as SVT with aberrancy: This is dangerous as VT requires different management. Always apply ECG criteria systematically.
Using dihydropyridine calcium channel blockers: These should be avoided for SVT treatment due to potential harm (Class III: Harm, Level B) 2
Using Class Ic antiarrhythmics in structural heart disease: Flecainide and propafenone are contraindicated in patients with structural heart disease or coronary artery disease 2
Overlooking the need for specialist referral: Refer patients to cardiology or electrophysiology within 1-2 weeks after initial presentation 2
Failing to recognize SVT with aberrancy in congenital heart disease: These patients often have baseline conduction abnormalities that complicate diagnosis 1