tachycardia

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tachycardia A rapid heart beat. This happens as a normal response to physical work and exercise, up to a maximum of about 200 beats per minute in a young adult, decreasing with age to about 150 at age 70. This is sinus tachycardia and it is brought about by the increased discharge rate of the heart's built-in pacemaker, the sino–atrial node, under the influence of the sympathetic nervous system. Likewise heart rate increases in response to excitement or anxiety or to blood loss. Paroxysmal tachycardia — disturbing attacks of palpitation — can occur for no apparent reason and often with no evidence of cardiac abnormality. Ventricular tachycardia is more ominous: driven from an abnormal focus of electrical activity in the ventricles themselves.

Stuart Judge


See heart.

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