Sinus arrhythmia is a commonly encountered variation of ''normal''

sinus rhythm A sinus rhythm is any cardiac rhythm in which depolarisation of the cardiac muscle begins at the sinus node. It is necessary, but not sufficient, for normal electrical activity within the heart. On the electrocardiogram (ECG), a sinus rhythm ...

. Sinus arrhythmia characteristically presents with an irregular rate in which the variation in the R-R interval is more than 0.12 seconds (120 milliseconds). Additionally, P waves are typically mono-form and in a pattern consistent with atrial activation originating from the sinus node.

Respiratory sinus arrhythmia

During respiration, the intermittent

vagus nerve The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibe ...

activation occurs, which results in beat to beat variations in the resting heart rate. During inspiration vagal tone is slowed down and the heart rate goes up (being maximal at the peak of inspiration), while during expiration vagal tone is increased and heart rate decreases, being slowest at end-expiration. When present, respiratory sinus arrhythmia typically indicates good cardiovascular health and is more commonly seen in young healthy people, especially those with enhanced vagal tone or slower heart rates. Text was copied from this source, which is available under
Creative Commons Attribution 4.0 International License

References

{{reflist Vagus nerve Cardiac electrophysiology Cardiac arrhythmia

Respiratory sinus arrhythmia

See also

References