Certified Rhythm Analysis Technician (CRAT) Practice Exam 2026 – All-in-One Study Guide for Exam Success!

The correct answer is sinus dysrhythmia because it is characterized by a variation in heart rate that is directly influenced by the patient's breathing patterns. This phenomenon is known as respiratory sinus arrhythmia, where the heart rate increases during inhalation and decreases during exhalation. This response is a natural physiological adaptation, particularly common in young, healthy individuals.

In contrast, sinus tachycardia typically refers to a consistently elevated heart rate that is not directly linked to breathing patterns, but rather to factors such as physical activity, stress, or fever. Sinus bradycardia indicates a slower than normal heart rate, which also does not inherently depend on the respiratory cycle. Normal sinus rhythm reflects a steady heart rate without the variability seen in sinus dysrhythmia.

Thus, the defining feature of sinus dysrhythmia — its responsiveness to the respiratory cycle — makes it the appropriate choice for the question.