orthodromic AV reciprocating tachycardia

Introduction

Consists of a macro-re-entrant circuit involving the atria, AV node, the ventricles & an accessory bypass tract. Depolarization occurs normally (orthodromically) through the AV node to the ventricles & at the same time retrogradely through the accessory path to re-excite the atria. The accessory bypass tract is generally congenital in origin. Episodes of orthodromic AV reciprocating tachycardia are generally initiated by atrial or ventricular premature complexes.

Epidemiology

• accounts for 30% of clinically significant supraventricular tachycardias (SVT).
• most common sustained arrhythmia in patients with Wolff-Parkinson-White (WPW) syndrome.

Clinical manifestations

• Symptoms:
• palpitations
• nervousness
• light-headedness
• angina
• syncope & near syncope
• onset is usually abrupt

Diagnostic procedures

• electrocardiogram:
  • heart rate typically 150-250/min
  • p-wave generally seen at the end of a normal or aberrant QRS complex or within the early ST segment

Management

• acute episodes are managed similar to AVNRT
  • vagal maneuvers
    • carotid massage
    • Valsalva maneuver
  • AV nodal blocking agents (short-acting)
    • adenosine 6-12 mg IV
    • verapamil 5 mg IV every 5 min for a maximum of 3 doses
    • diltiazem 15-20 mg IV over 2 min for a maximum of 2 doses
• chronic therapy
  • Ca+2-channel antagonists
  • beta-adrenergic receptor antagonists
  • class Ia, Ic & III anti-arrhythmic agents
  • radio frequency catheter ablation of accessory tract

More general terms

• narrow complex tachycardia
• paroxysmal supraventricular tachycardia (PSVT)

Additional terms

• Wolff-Parkinson-White (WPW) syndrome