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orthodromic AV reciprocating tachycardia
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:
1) accounts for 30% of clinically significant supraventricular tachycardias (SVT).
2) most common sustained arrhythmia in patients with Wolff-Parkinson-White (WPW) syndrome.
Clinical manifestations:
- Symptoms:
1) palpitations
2) nervousness
3) light-headedness
4) angina
5) syncope & near syncope
6) onset is usually abrupt
Special laboratory:
- electrocardiogram:
a) heart rate typically 150-250/min
b) p-wave generally seen at the end of a normal or aberrant QRS complex or within the early ST segment
Management:
1) acute episodes are managed similar to AVNRT
a) vagal maneuvers
- carotid massage
- Valsalva maneuver
b) 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
2) chronic therapy
- Ca+2-channel antagonists
- beta-adrenergic receptor antagonists
- class Ia, Ic & III anti-arrhythmic agents
- radio frequency catheter ablation of accessory tract
Related
Wolff-Parkinson-White (WPW) syndrome
General
narrow complex tachycardia
paroxysmal supraventricular tachycardia (PSVT)
References
- Manual of Medical Therapeutics, 28th ed, Ewald &
McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 144
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998