Bradycardia

Bradycardia, as applied in adult medicine, is defined as a heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min http://www.emedicine.com/emerg/topic534.htm.

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It is also less commonly known as brachycardia. Trained athletes tend to have slow resting heart rates, and resting bradycardia in athletes should not be considered abnormal if the individual has no symptoms associated with it.

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The term relative bradycardia is used to explain a heart rate that, while not technically below 60 beats per minute, is considered too slow for the individual's current medical condition.

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This cardiac arrhythmia can be underlied by several causes, which are best divided into cardiac and non-cardiac causes.

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Non-cardiac causes are usually secondary, and can involve drug use or abuse; metabolic or endocrine issues, especially in the thyroid; an electrolyte imbalance; neurologic factors; autonomic reflexes; situational factors such as prolonged bed rest; and autoimmunity.

Related Topics:
Drug - Abuse - Metabolic - Endocrine - Thyroid - Electrolyte - Neurologic - Autoimmunity

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Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease, or degenerative primary electrical disease.

Related Topics:
Ischemic heart disease - Heart disease

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Ultimately, the causes act by three mechanisms: depressed automaticity of the heart, conduction block, or escape pacemakers and rhythms.

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