This is the first study of its kind to document the effectiveness of a simple maneuver to prevent or delay loss of consciousness. The counter-maneuver could prove a simple, inexpensive alternative to medication or pacemaker implantation, says study senior author Wouter Wieling, M.D., Ph.D. associate professor of internal medicine and head of the syncope unit at the Academic Medical Center of the University of Amsterdam, the Netherlands.
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.
The counter-maneuver stabilized blood pressure and heart rate in all patients. Symptoms disappeared shortly after blood pressure became stable, and none of the patients lost consciousness while performing the counter-maneuver. In five patients syncope was prevented. The remaining 15 patients either could not prevent fainting or asked to be tilted back to a horizontal position, but the counter-maneuvers delayed the faint by an average of 2.5 minutes.
During the counter-maneuver, systolic blood pressure increased by an average of about 40 points and heart rate by an average of nine beats per minute. Patients had an almost "instantaneous increase" in blood pressure when they performed the counter-maneuver.
Each patient received a follow-up phone call seven to 14 months after testing to determine whether any new syncope episodes had occurred and whether they had tried the counter-maneuver. The follow-up interviews found that one patient had been diagnosed with a condition that could have contributed to syncope; three others had no recurrence of syncope since the test, two patients had faints but did not use the counter-maneuver, and one could not be located. The remaining 13 patients reported regular use of the counter-maneuver to prevent or control syncope. Only two of the 13 had fainted since the test.
The researchers conclude that the counter-maneuvers "can abort or delay impending faints in subjects prone to vasovagal reactions." "You often see people standing with their legs crossed at cocktail parties, and we call this the cocktail party posture," says Wieling. "In our experience patients will do this automatically after awhile. A great advantage of leg crossing is that it can be done almost unnoticed."
"In case crossing the legs alone does not provide sufficient relief during prolonged standing, we advise patients to perform leg muscle tensing as an additional measure, and then if the symptoms are mild, to uncross their legs and walk with tensed muscles to a safe place to sit down. If the symptoms are overwhelming, subjects are advised to crouch down immediately."
Co-authors include medical student C.T. Paul Krediet; Nynke van Dijk; Mark Linzer, M.D.; and Johannes J. van Lieshout, M.D.
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