Harvard Heart Letter

A pacemaker to prevent fainting

If your heart rate slows, a device can stop you from dropping.

If you have ever fainted, you know it can be a frightening experience. There are many conditions that can cause fainting, but a nervous system reflex is often responsible. Certain triggers—for example, standing in a hot, crowded area—can cause blood pressure to fall, and with it, blood flow to the brain. The person may or may not feel faint or nauseated before blacking out.

Three forms of syncope

There are three forms of this condition, called "vasovagal syncope." (Syncope is the medical term for loss of consciousness.) In people with vasodepressor syncope, blood pools in their legs, blood pressure falls, and the person passes out. If it happens often, medications and salt can be used to keep blood pressure up.

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