Which description best fits the electrocardiogram finding in typical supraventricular tachycardia?

Which description best fits the electrocardiogram finding in typical supraventricular tachycardia?

• A. Narrow QRS tachycardia with regular rhythm
• B. Wide QRS tachycardia with irregular rhythm
• C. Atrial fibrillation with rapid ventricular response
• D. Ventricular tachycardia with wide complexes

Answer: (A)

Supraventricular tachycardia is a rapid heart rhythm that originates above the ventricles, so the impulse travels through the normal His-Purkinje system. This keeps the QRS complexes narrow because ventricular depolarization occurs through the usual pathway. The ventricular response is typically regular, reflecting a stable reentrant circuit or atrial triggering driving the ventricles at a constant rate. On the ECG you’d expect a fast rate with narrow QRS complexes and a regular rhythm, though P waves may be hidden within or just after the QRS complexes. The other patterns don’t fit typical SVT: a wide QRS tachycardia points to ventricular origin or aberrant conduction; an irregular rhythm suggests atrial fibrillation or another irregular tachyarrhythmia; and ventricular tachycardia classically shows wide QRS complexes.

Supraventricular tachycardia is a rapid heart rhythm that originates above the ventricles, so the impulse travels through the normal His-Purkinje system. This keeps the QRS complexes narrow because ventricular depolarization occurs through the usual pathway. The ventricular response is typically regular, reflecting a stable reentrant circuit or atrial triggering driving the ventricles at a constant rate. On the ECG you’d expect a fast rate with narrow QRS complexes and a regular rhythm, though P waves may be hidden within or just after the QRS complexes. The other patterns don’t fit typical SVT: a wide QRS tachycardia points to ventricular origin or aberrant conduction; an irregular rhythm suggests atrial fibrillation or another irregular tachyarrhythmia; and ventricular tachycardia classically shows wide QRS complexes.