Heart rate is the number of times the heart beats per minute. This is normally determined by the electrical activity of the Sino-Atrial node. The autonomic nervous system controls the rate of discharge of the S-A node.
Heart rate is determined by four factors:
- Intrinsic rate: The natural rate of discharge of cardiac tissue in the absence of other factors.
- Sympathetic activity: Increases heart rate.
- Parasympathetic activity: Decreases heart rate.
- Pharmacologic: Increases or decreases heart rate depending on the drug.