These bundle branches in turn ramify and divide, much like the roots of a plant, into the Purkinje system. The Purkinje fibers branch out and deliver the electrical impulse in uniform fashion to the right and left ventricular myocardium. Bradycardia is a term used to describe a pulse, or heart rate, that is less than 60 beats per minute. The number of 60, however, is a somewhat arbitrary choice, so a pulse of less than 60 beats per minute may be due to normal physiologic variation and not because of disease or illness. A slow heart beat can take its origin in one of several parts of the heart's normal electrical system and can be the result of physiologic adaptation, medication effect or the result of congenital or acquired illness.
Symptoms related to bradycardia vary widely, as do the medical implications and prognosis.
Treatment of bradycardia, when necessary, might include medications or an implanted pacemaker. Classification is useful to your doctor in guiding evaluation and therapy, directing investigation to other possible cardiac and medical conditions, as well as in outlining prognosis. Bradycardias can also be categorized by their mechanism, as in their relationship to intrinsic disease, altered autonomic neural tone, acquired illness or effect of medication. The heart rate, governed by the sinus node, is subject to a number of external influences, in particular autonomic nervous system tone. The heart rate is designed to fluctuate, both up and down, in response to the physiologic demands of the body.