Leg Maneuver May Prevent Fainting

Vasovagal syncope, or fainting, results from a neurological reflex that originates in the brain. In response to a physical or emotional trigger, the brain emits signals that cause blood vessels to dilate and causes blood to pool in the legs. The heart rate also slows. Subsequently, the brain does not receive enough oxygen-carrying blood, leading to fainting.

Standard treatment includes educating patients about the causes of the condition, instructing them how to avoid situations that trigger fainting, and maintaining adequate salt and fluid intake. Several drugs have been studied as treatment, but results have been inconsistent.

"Leg muscle crossing and tensing should be part of an intense nonpharmacological regimen for patients with vasovagal faints," says Wieling.

Physical counter-maneuvers such as leg crossing and muscle tensing have been developed in patients with low blood pressure when rising from a reclining position (orthostatic hypotension) – a condition caused by rare diseases of the autonomic nervous system. Wieling and colleagues in Amsterdam and the United States theorized that the same maneuvers might help people who have vasovagal syncope.

The researchers evaluated the maneuver in 20 patients (ages 17 to 74) who had a history of vasovagal syncope, but were otherwise healthy. The number of lifetime syncope episodes ranged between one and 200.

Patients learned to cross their legs while in a standing position and tense the muscles of the legs, abdomen, and buttocks. Each patient underwent a head-up tilt table test, which involved lying down on a table that can be rotated to an upright position. The table was manually tilted to a 60-degree angle and held in that position for 20 minutes. If the patient did not faint or develop symptoms, nitroglycerine was administered under the tongue to promote blood vessel dilation, followed by a 15-minute tilt test.

The patient's head remained in an upright position during tilting, while researchers monitored their heart's electrical activity with an electrocardiogram and blood pressure with a device that follows changes beat to beat. The table could be returned to a horizontal position almost immediately if syncope appeared imminent.

During the test, researchers told patients to begin the maneuver when blood pressure began to fall and syncope symptoms such as lightheadness and nausea appeared. All the patients had a substantial decrease in blood pressure. Ten patients also had a heart rate decrease of more than 10 beats per minute in the 30 seconds before performing the counter-maneuver.

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