An 8 month old female child presented to emergency with a hea rate of 220/minute and features of cogestive hea failure. Her hea rate comes down to normal after administering intravenous adenosine. What is the most likely diagnosis ?
**Core Concept**
The child's presentation of tachyarrhythmia with congestive heart failure and subsequent response to adenosine administration suggests a supraventricular tachycardia (SVT) with Wolff-Parkinson-White (WPW) syndrome. This condition is characterized by an accessory electrical pathway between the atria and ventricles, leading to abnormal heart rhythms.
**Why the Correct Answer is Right**
Adenosine works by transiently blocking the AV node, thereby interrupting the re-entrant circuit in WPW syndrome. This results in a brief pause in heart rhythm, allowing the child's heart rate to return to normal. The absence of an AV block suggests that the accessory pathway is bypassing the AV node, which is a hallmark of WPW syndrome.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not account for the child's response to adenosine. While atrial fibrillation can present with tachycardia, it does not typically respond to adenosine.
* **Option B:** This option is incorrect because it does not explain the child's symptoms of congestive heart failure. SVT with WPW syndrome can lead to heart failure due to the abnormal heart rhythm and increased cardiac workload.
* **Option C:** This option is incorrect because it does not account for the child's response to adenosine. While SVT can present with tachyarrhythmia, it does not typically respond to adenosine without an accessory pathway.
**Clinical Pearl / High-Yield Fact**
WPW syndrome is a congenital condition that can be diagnosed on ECG by the presence of a delta wave (slurred upstroke) in the QRS complex. It is essential to recognize this condition and differentiate it from other supraventricular tachycardias, as treatment and management differ.
**Correct Answer:** C. Supraventricular tachycardia with Wolff-Parkinson-White syndrome.