Which rhythm is defined as having a heart rate greater than 100 bpm?

The definition of a rhythm having a heart rate greater than 100 bpm is aligned with junctional tachycardia. This arrhythmia specifically occurs when the heart's impulses originate from the junctional area, typically between the atria and ventricles, and the rate exceeds 100 beats per minute. Junctional tachycardia is characterized by a distinct appearance on an electrocardiogram (ECG), where the P waves may be absent or inverted due to the proximity to the junction, and it maintains a regular rhythm.

In contrast, while other rhythms like sinus tachycardia can also have a heart rate greater than 100 bpm, junctional tachycardia is strictly defined by its origin from the junctional tissue, making it the most accurate choice for this question. Sinus tachycardia, for example, arises from the sinoatrial (SA) node and may not reflect the same underlying mechanism as junctional tachycardia. Junctional escape and accelerated junctional rhythms typically present at rates less than 100 bpm, further distinguishing them from junctional tachycardia. Thus, junctional tachycardia fits the specific criteria set by the question and accurately identifies the heart rate context provided.