what is sinus arrhythmias

Dear student,

Arrhythmia means an irregular heartbeat.
Sinus arrhythmia is an irregular heartbeat that is either too fast or too slow. One type of sinus arrhythmia, is called respiratory sinus arrhythmia.
In this, the heartbeat changes pace when we inhale and exhale. When we breathe in, our heart rate increases. When we exhale, it falls.

Regards