Overactive Thyroid
The thyroid is a gland with the shape of a butterfly in the neck. It produces hormones that can help regulate your metabolism rate and other conditions. When you suffer from hyperthyroidism or an overactive thyroid, it would lead to an excess amount of thyroid hormone. As a result, it will speed up the heartbeat so much that you can feel it in the chest. Using too much hormone to deal with hypothyroidism or an underactive thyroid would also cause similar effects. [7]
