All of the following features given below suggest broad complex ventricular tachycardia except :
**Core Concept**
Broad complex ventricular tachycardia (VT) is a life-threatening arrhythmia characterized by a wide QRS complex (>120 ms) and a ventricular origin. It is a medical emergency requiring prompt recognition and treatment.
**Why the Correct Answer is Right**
The correct answer is a feature that is more typical of narrow complex tachycardia (NCT), which is usually a supraventricular tachycardia (SVT) originating from the atria or AV node. In VT, the QRS complex is wide and often bizarre, whereas in NCT, the QRS complex is narrow. The presence of a wide QRS complex is a key feature of VT.
**Why Each Wrong Option is Incorrect**
* **Option A:** A ventricular rate of 150 beats per minute is consistent with VT, which often presents with a rapid ventricular rate.
* **Option B:** A QRS complex duration of 150 ms is considered wide and is a characteristic feature of VT.
* **Option D:** The presence of a monophasic R wave in lead V1 is a classic feature of VT, which often shows a "rabbit ear" or "M" shaped QRS complex.
**Clinical Pearl / High-Yield Fact**
Remember the "Sgarbossa criteria" for diagnosing VT: (1) a QRS complex with a monophasic R wave in lead V1, (2) a QRS complex with an M-shaped QRS complex, and (3) a QRS complex with a R/S ratio >1 in lead V5 or V6.
**Correct Answer:** D.