When analyzing an ECG for torsades de pointes, what is typically indicated?

When analyzing an ECG for torsades de pointes, the presence of wide QRS complexes with changing polarity is characteristic of this arrhythmia. Torsades de pointes, often shortened to TdP, is a specific type of polymorphic ventricular tachycardia that arises in the setting of a prolonged QT interval.

The wide QRS complexes indicate that the electrical activity of the ventricles is not proceeding normally, which is central to the manifestation of torsades de pointes. The changing polarity refers to the rapid shifts in the direction of the QRS complexes, which creates a twisting or "twisting of the points" appearance on the ECG trace. This visual depiction is crucial in diagnosing the condition, as it is distinct from other arrhythmias that may present with more regular or uniform QRS complexes.

The other choices reflect factors that are not typically associated with torsades de pointes. The presence of distinct P waves is more indicative of a normal sinus rhythm, a prolonged PR interval would suggest issues like atrioventricular block rather than torsades, and a consistent heart rate is generally not a feature of cycles of torsades, which is characterized by variability and can change rapidly. Therefore, the nature of the QRS complexes is