Why do abnormal heart rhythms cause nausea?

Vagal Response: In general, most cardiac rhythm disturbances will not cause nausea. However, there is a condition that can cause both nausea and arrhythmia (particularly slow heart rate), and that is called a vagal response. This is an abnormal reflex response which causes the heart rate to abnormally slow, and also has concurrent symptoms of nausea and/or "cold sweats" and/or lightheadedness.