A 10-year-old child presents with episodic palpitations and an ECG showing a regular narrow-complex tachycardia at 220 bpm with a retrograde P wave visible just after the QRS complex. The MOST likely diagnosis is:
- A Atrioventricular nodal reentrant tachycardia (AVNRT) ✓
- B Atrial flutter with 2:1 block
- C Atrioventricular reentrant tachycardia (AVRT)
- D Junctional ectopic tachycardia
Correct answer: A. Atrioventricular nodal reentrant tachycardia (AVNRT)
Explanation
AVNRT is the most common mechanism of supraventricular tachycardia (SVT) in older children and adolescents. It produces a regular narrow-complex tachycardia (typically 180–250 bpm) with a retrograde P wave inscribed immediately after the QRS (RP interval <70 ms, giving pseudo-S waves in inferior leads or pseudo-R' in V1). In AVRT (via an accessory pathway), the retrograde P wave is usually visible with a longer RP interval because the atrium is activated via the accessory pathway.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.