If a child's ECG shows monomorphic wide QRS complexes and absent P waves, what condition does this most likely indicate?

The presence of monomorphic wide QRS complexes combined with absent P waves on an ECG is highly indicative of ventricular tachycardia (VT). In this scenario, the QRS complexes are wide because they originate from the ventricles rather than the atria. This means the electrical impulse is not traveling through the normal conduction pathways, leading to a wide QRS appearance, which is characteristic of ventricular activity.

The absence of P waves suggests that there is no atrial depolarization occurring in a coordinated manner, which aligns with the ventricular tachycardia condition where the ventricles are beating rapidly and independently from the atria. This combination of findings—monomorphic (indicating a consistent shape due to a single circuit in the ventricle) wide QRS complexes and absent P waves—supports the diagnosis of ventricular tachycardia over other potential arrhythmias.

In contrast, conditions like atrial fibrillation would display an irregularly irregular rhythm with no discernible P waves but usually present with narrow QRS complexes. Supraventricular tachycardia typically results in narrow QRS complexes because the origin is above the ventricles, and bradycardia is characterized by a slow heart rate, which would not correlate with wide Q