New research helps explain how the body's "flight-or-fight" response is mediated. The study may provide new answers to the question of how the heart pacemaker -- the sinoatrial node -- is regulated.

Having an accelerated junctional rhythm occurs when the atrioventricular node in your heart beats too quickly. It happens as a result of damage to your heart’s primary natural pacemaker. There’s no ...

The term bradycardia refers to an abnormally slow heart rate, of under 60 beats per minute (bpm). The heart has a complex system of nerves that conduct the electrical impulses fired by the sino-atrial ...