Which of the following are classified as irregular narrow complex tachydysrhythmias?

Irregular narrow complex tachydysrhythmias refer to a class of arrhythmias characterized by a rapid heart rate and narrow QRS complexes on the ECG, alongside an irregular rhythm. Atrial fibrillation, atrial flutter, and multifocal atrial tachycardia all fit this description.

Atrial fibrillation is characterized by an absence of identifiable P waves and a rapid, chaotic atrial electrical activity leading to an irregularly irregular ventricular response. Atrial flutter involves a rapid re-entrant circuit typically in the right atrium, presenting with a regular or irregular atrial rate but can also lead to an irregular ventricular response depending on the conduction through the AV node. Multifocal atrial tachycardia features multiple ectopic foci in the atria, resulting in a distinct pattern of P waves that can vary in morphology, and this condition usually presents with an irregular rhythm when conducted to the ventricles.

The option highlights these conditions, emphasizing their irregular rhythms along with narrow QRS complexes, which are hallmark characteristics of this category of tachydysrhythmias. Therefore, this choice correctly identifies the group classified as irregular narrow complex tachydysrhythmias.