Overview
Definition
An abnormally fast heart rhythm originating above the ventricles (often involving the AV node). The most common type is AVNRT.
Epidemiology
Most common paroxysmal tachycardia in healthy young adults without structural heart disease.
Etiology & Risk Factors
- Reentry circuits (AVNRT - AV Nodal Reentrant Tachycardia; AVRT - involves an accessory pathway like WPW)
- Increased automaticity (Atrial Tachycardia)
Clinical Symptoms
- Sudden onset of rapid palpitations
- Lightheadedness / Dizziness
- Shortness of breath
- Chest discomfort
- Anxiety
Clinical Approach
Diagnosis
- ECG during episode: Narrow QRS complex tachycardia, regular rhythm, rate typically 150-250 bpm, P waves often hidden in the QRS or inverted after the QRS
Management
- Stable: Vagal maneuvers (Valsalva, carotid massage), IV Adenosine (first-line drug), IV Non-DHP CCB (Diltiazem) or Beta-blocker
- Unstable (hypotension, altered mental status): Immediate synchronized cardioversion
- Long-term: Catheter ablation (curative for AVNRT/AVRT)
Complications
- Syncope
- Tachycardia-induced cardiomyopathy (if prolonged/unrecognized)