What common cause is associated with sinus arrhythmia?

Sinus arrhythmia is often linked to respiratory changes, particularly those influenced by vagal tone. During normal breathing, the heart rate can increase during inhalation and decrease during exhalation, a phenomenon known as respiratory sinus arrhythmia. This variation is a normal part of physiological function and is primarily mediated by the vagus nerve, which regulates heart rate in response to changes in intrathoracic pressure during respiration.

The relationship between breathing and heart rate is important because it demonstrates the body's ability to adapt and maintain homeostasis. Enhanced vagal tone during deep inhalation can lead to a temporary increase in heart rate, while exhalation can produce a slowing of heart rate. This is a common and benign occurrence, particularly in healthy individuals and is often more pronounced in younger people.

While other factors such as thyroid dysfunction, exercise, and electrolyte imbalances can affect heart rhythm and lead to other types of arrhythmias, they are not the typical causes associated with sinus arrhythmia. Understanding the role of respiratory patterns and vagal tone is essential in recognizing sinus arrhythmia as a normal and often benign phenomenon.