Which of the following best describes a Paroxysmal Supraventricular Tachycardia (PSVT)?

Which of the following best describes a Paroxysmal Supraventricular Tachycardia (PSVT)?

• A. Heart rate greater than 100 bpm; rhythm usually regular with narrow QRS; P waves often hard to discern due to rapid rate
• B. Irregular rhythm with no P waves
• C. Wide QRS tachycardia
• D. P waves are difficult to discern due to rapid rate, with a regular narrow-QRS tachycardia

Answer: (D)

Paroxysmal supraventricular tachycardia is a sudden-onset, rapid heart rhythm that originates above the ventricles and typically presents as a regular, fast rhythm with a narrow QRS complex. The rapid rate often makes the atrial activity (P waves) hard to see on the ECG, either being buried in the QRS or occurring in a way that makes them difficult to discern. So the best description is a regular narrow-QRS tachycardia with P waves difficult to discern due to the rapid rate, because it captures both the regularity and the narrow conduction pathway characteristic of PSVT and the common masking of P waves at high speeds. This differs from irregular rhythms with no clear P waves, which point to atrial fibrillation, and from wide-QRS tachycardias, which suggest ventricular tachycardia or SVT with aberrant conduction.

Paroxysmal supraventricular tachycardia is a sudden-onset, rapid heart rhythm that originates above the ventricles and typically presents as a regular, fast rhythm with a narrow QRS complex. The rapid rate often makes the atrial activity (P waves) hard to see on the ECG, either being buried in the QRS or occurring in a way that makes them difficult to discern.

So the best description is a regular narrow-QRS tachycardia with P waves difficult to discern due to the rapid rate, because it captures both the regularity and the narrow conduction pathway characteristic of PSVT and the common masking of P waves at high speeds.

This differs from irregular rhythms with no clear P waves, which point to atrial fibrillation, and from wide-QRS tachycardias, which suggest ventricular tachycardia or SVT with aberrant conduction.