Atrioventricular reciprocating tachycardia, orthodromic

**Definition:** An atrioventricular reciprocating tachycardia that uses an accessory pathway for retrograde conduction and the atrioventricular node for anterograde conduction resulting in a narrow or usual complex tachycardia.

**Long definition:** Tachycardia secondary to accessory connection(s) (pathway[s]). Typical accessory pathways are extra nodal pathways that connect the myocardium of the atrium and the ventricle across the atrioventricular groove and are classified by location, type of conduction (decremental versus nondecremental), and whether they are capable of anterograde (manifest, demonstrating pre-excitation on standard ECG) or retrograde (concealed) conduction, or both. During orthodromic tachycardia, the re-entrant impulse conducts over the atrioventricular node and the specialized conduction system from the atrium to the ventricle and utilizes the accessory connection (pathway) for conduction from the ventricle to the atrium.