Tachycardia

Tachycardia is an abnormally rapid beating of the heart, defined as a resting heart rate of over 100 beats per minute.

Related Topics:
Heart - Heart rate

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It can have harmful effects in two ways. First, when the heart beats too rapidly, it performs inefficiently (since there is not enough time for the ventricles to fill completely), causing blood flow and blood pressure to diminish. Second, it increases the work of the heart, causing it to require more oxygen while also reducing the blood flow to the cardiac muscle tissue, increasing the risk of ischemia and resultantly infarction.

Related Topics:
Ventricle - Blood flow - Blood pressure - Oxygen - Ischemia - Infarction

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Tachycardia is a general symptomatic term that does not describe the cause of the rapid rate. Common causes are autonomic nervous system or endocrine system activity, hemodynamic responses, and various forms of cardiac arrhythmia.

Related Topics:
Autonomic nervous system - Endocrine system - Cardiac arrhythmia

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