Most common sustained tachycardia in healthy young women is?
First, sustained tachycardia means it's a rhythm that lasts more than 30 seconds and isn't going to terminate on its own. The key here is "healthy young women." So, I should think about conditions that are more common in this demographic.
The options aren't listed, but common tachycardias include sinus tach, SVT (specifically AVNRT or AVRT), atrial fibrillation, and others like WPW or atrial flutter. Since the patient is healthy, structural heart disease is less likely, so SVT makes sense. Among SVT types, AVNRT is the most common in young women. AVNRT occurs due to reentry within the AV node, which has dual pathways. The accessory pathway in AVRT (like WPW) is possible but less common. Atrial fibrillation is typically in older individuals or those with underlying conditions. Sinus tach is a response to something like stress or exercise, not a sustained arrhythmia. So the correct answer should be AVNRT. Let me make sure. Yes, AVNRT is indeed the most common sustained tachycardia in this group. The other options are either less common or not typically sustained. Need to explain why each wrong option is incorrect. For example, AVRT (WPW) is another form of SVT but less common in young women. Atrial flutter is less likely in healthy individuals. So the correct answer is AVNRT.
**Core Concept**
The question assesses knowledge of supraventricular tachycardias (SVT) in young, healthy individuals. **Atrioventricular nodal reentrant tachycardia (AVNRT)** is the most common sustained tachycardia in this demographic due to anatomical and hormonal factors influencing AV node conduction.
**Why the Correct Answer is Right**
AVNRT occurs via a reentrant circuit within the AV node, which has dual pathways (fast and slow). In young women, hormonal influences (e.g., estrogen) may increase AV node automaticity. The arrhythmia is sustained due to a stable reentry loop, often triggered by premature atrial contractions. It typically presents with sudden onset, regular rhythm, and normal QRS complexes on ECG.
**Why Each Wrong Option is Incorrect**
**Option A:** *Atrial fibrillation* is rare in healthy young women and typically occurs in older individuals or those with structural heart disease.
**Option B:** *Wolff-Parkinson-White (WPW) syndrome* involves an accessory pathway but is less common than AVNRT in this population.
**Option D:** *Sinus tachycardia* is not a true arrhythmia; it’s a physiological response to stress or exercise, not a reentrant mechanism.
**Clinical Pearl / High-Yield Fact**
AVNRT accounts for **~60% of SVT cases in young women**. A key differentiator from AVRT is the absence of delta waves on ECG. Use vagal maneuvers (e.g., carotid sinus massage) for acute management;