Patient Care Technician (PCT) AAH Practice Exam

What is sinus arrhythmia usually associated with, in terms of heart rate changes?

1. Inspiration

2. Expiration

3. Postural changes

4. Physical exertion

The correct answer is: Expiration

Sinus arrhythmia is a natural variation in heart rate that commonly occurs with the respiratory cycle. This physiological phenomenon is primarily associated with inspiration, where the heart rate increases, and during expiration, the heart rate decreases. This response is driven by the autonomic nervous system's regulation of heart rate, particularly the influence of the vagus nerve. When a person inhales, the increased venous return to the heart stimulates the heart to beat faster to accommodate the increase in blood flow. Conversely, during exhalation, the heart rate slows down as the vagal tone increases. Although expiration can lead to variations in heart rate, the primary and most noticeable change occurs during inhalation. Given that sinus arrhythmia is most pronounced with the act of breathing, particularly during the inhalation phase, the correct answer aligns with this physiological response. Understanding this relationship is crucial for recognizing normal cardiovascular responses, especially in clinical settings where monitoring of heart rate and rhythm is essential.