Supraventricular Tachycardia Management

Diagnosis and Clinical Characteristics

The American College of Cardiology states that supraventricular tachycardia encompasses three main types: atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), and atrial tachycardia (AT), each requiring specific diagnostic and therapeutic approaches 1
AVNRT is the most common form of SVT, accounting for the majority of cases, typically occurring in young adults without structural heart disease, with over 60% of cases in women 1
Heart rate in AVNRT typically ranges from 180-200 bpm but can vary from 110 to >250 bpm 1
Patients with AVNRT present with sudden onset palpitations, shortness of breath, dizziness, and characteristic neck pulsations 1
The arrhythmia is usually well tolerated and rarely life-threatening, with syncope being uncommon 1
Triggers for AVNRT include exertion, coffee, tea, or alcohol 1
Multifocal atrial tachycardia (MAT) represents a specific subtype often associated with pulmonary disease 1

Typical AVNRT shows a pseudo R' wave in lead V1 and pseudo S waves in inferior leads due to P waves hidden within or immediately after the QRS complex 2
The reentrant circuit in AVNRT involves anterograde conduction over a slow AV nodal pathway and retrograde conduction over a fast pathway, creating a short RP tachycardia 3
Atypical AVNRT demonstrates a long RP interval with retrograde P waves (negative in inferior leads) 3
Orthodromic AVRT conducts anterograde through the AV node and retrograde through the accessory pathway, producing narrow QRS complexes 2
Antidromic AVRT conducts anterograde through the accessory pathway and retrograde through the AV node, producing wide QRS complexes 2
P waves appear in the ST segment, separated from the QRS by >70 ms in orthodromic AVRT 2
Wide QRS with left bundle branch block morphology suggests anterograde conduction over the accessory pathway 2

The American College of Cardiology recommends performing vagal maneuvers immediately as first-line intervention, with the patient in supine position 1
Modified Valsalva maneuver, carotid sinus massage, and ice-cold towel to face or facial immersion in 10°C water are effective vagal maneuvers 1
Overall success rate of vagal maneuvers is approximately 27.7%, with Valsalva being more effective than carotid massage 1
Adenosine is the second-line treatment, with 90-95% success rate for terminating AVNRT and orthodromic AVRT 1
IV calcium channel blockers or beta blockers are third-line treatments, with 80-98% success rates, particularly effective for AVNRT conversion 1
Synchronized cardioversion is performed if pharmacological therapy fails or is contraindicated 1
Immediate synchronized cardioversion is first-line management for patients with hypotension, altered mental status, signs of shock, chest pain, or acute heart failure 1

Catheter ablation is the most effective first-line therapy for preventing recurrent symptomatic SVT, with success rates of 94.3-98.5% and recurrence rates <5% 4
Oral beta blockers, diltiazem, or verapamil serve as first-line pharmacological options for patients declining ablation or unsuitable candidates 4
Flecainide or propafenone are effective in patients without structural heart disease for preventing paroxysmal SVT 4

Never administer verapamil or diltiazem for wide-complex tachycardia unless SVT with aberrancy is definitively proven, as these agents may cause hemodynamic collapse in ventricular tachycardia 2
Never use AV nodal blocking agents in patients with pre-excited atrial fibrillation, as this may accelerate ventricular rate and precipitate ventricular fibrillation 1, 4