Which rhythm is defined by a rate of 60-100 BPM and irregular rhythm with P wave morphology changing from beat to beat?

The rhythm characterized by a rate of 60-100 BPM and an irregular rhythm, with P wave morphology changing from beat to beat, is known as Wandering Atrial Pacemaker. This arrhythmia occurs due to the impulse being generated from multiple ectopic foci within the atria, leading to variability in the P wave shape as the site of origin shifts. This results in the irregular presentation of the P waves, distinguishing it from other rhythms where the P wave morphology is consistent.

In contrast, Sinus Arrhythmia also presents an irregular rhythm but does not feature changing P wave morphology; instead, it is often related to respiratory patterns. Ventricular Tachycardia is characterized by a much higher heart rate and is typically life-threatening, while Normal Sinus Rhythm has a steady rate with consistent P wave morphology, thus neither describes the variability found in Wandering Atrial Pacemaker. These distinctions clarify why Wandering Atrial Pacemaker is the correct identification of the rhythm in question.