Which of the following is TRUE of supraventricular tachycardia?

Which of the following is TRUE of supraventricular tachycardia?

• A. It originates in the ventricles
• B. There may be periods of normal rate and rhythm between episodes
• C. The QRS complex appears abnormal
• D. The P wave is absent

Answer: (B)

Supraventricular tachycardia is a rapid rhythm that originates above the ventricles, usually in the atria or at the AV node, so the ventricular activation remains through the normal conduction pathways. Because of this, the QRS complexes are typically narrow and of normal appearance. A key feature is that these episodes can be paroxysmal—fast bursts that start and stop suddenly—with patients returning to normal sinus rhythm between episodes. That return to normal rate and rhythm between spells is what makes this statement true. P waves may be difficult to see during tachycardia because they can be hidden in the preceding or following waves, but they’re not universally absent. The other points—origin in the ventricles, consistently abnormal QRS during SVT, or a definite absence of P waves—don’t fit the usual pattern of SVT.

Supraventricular tachycardia is a rapid rhythm that originates above the ventricles, usually in the atria or at the AV node, so the ventricular activation remains through the normal conduction pathways. Because of this, the QRS complexes are typically narrow and of normal appearance. A key feature is that these episodes can be paroxysmal—fast bursts that start and stop suddenly—with patients returning to normal sinus rhythm between episodes. That return to normal rate and rhythm between spells is what makes this statement true. P waves may be difficult to see during tachycardia because they can be hidden in the preceding or following waves, but they’re not universally absent. The other points—origin in the ventricles, consistently abnormal QRS during SVT, or a definite absence of P waves—don’t fit the usual pattern of SVT.