What is the primary characteristic of tachycardia?

Tachycardia is defined as an abnormally fast heart rate, typically over 100 beats per minute in adults, as the normal resting heart rate is usually between 60 to 100 beats per minute. This increased heart rate can result from various factors, such as stress, physical activity, fever, or underlying medical conditions, and may lead the heart to pump blood less efficiently, affecting oxygen delivery throughout the body.

In contrast, stating that the heart is too slow refers to bradycardia, which is a different condition characterized by a heart rate below 60 beats per minute. A heart in normal rhythm doesn't apply to tachycardia, as the essence of the term involves a deviation from normal heart rate. An enlarged heart could be related to numerous cardiac conditions but doesn't specifically characterize the heart rate itself. Thus, recognizing that tachycardia is associated unequivocally with an elevated heart rate is essential in understanding its medical significance.