Why can heart pain be felt in the chest and arm during angina pectoris?

The sensation of heart pain in the chest and arm during angina pectoris is a classic example of referred pain. This phenomenon occurs because of the specific anatomical organization of the human nervous system.12

In the spinal cord, the dorsal horns receive sensory input from both visceral organs (like the heart) and somatic tissues (such as the skin and muscles of the chest wall and upper limbs). Because afferent nerve fibers from the heart travel to the same spinal regions as those from the chest and arms, there is an intermingling of these signals.12

The brain, which is more accustomed to receiving sensory input from the skin and body wall than from internal organs, often misinterprets these visceral pain signals as originating from the more familiar somatic tissues. Consequently, the pain is "referred" to the chest and arm rather than being localized to the heart itself.12