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Vasovagal syncope

Vasovagal syncope (also vasodepressor syncope, neurally mediated syncope or neurocardiogenic syncope), a form of dysautonomia, is the most common cause of fainting ("syncope" in medical terminology). Although it is particularly common (both historically and stereotypically) among young women, it is seen across all ages and genders and in otherwise completely healthy people. It is triggered by a number of factors, including prolonged standing, alcohol, fatigue, hunger, and anxiety. more...

VACTERL association
Van der Woude syndrome
Van Goethem syndrome
Varicella Zoster
Variegate porphyria
Vasovagal syncope
VATER association
Velocardiofacial syndrome
Ventricular septal defect
Viral hemorrhagic fever
Vitamin B12 Deficiency
VLCAD deficiency
Von Gierke disease
Von Hippel-Lindau disease
Von Recklinghausen disease
Von Willebrand disease

Vasovagal syncope is caused by low heart rate and blood pressure, leading to inadequate circulation. The reduced oxygen supply to the brain results in syncope, or temporary loss of consciousness. Individuals usually regain consciousness within a few minutes and their prognosis is good, although the syncope has a tendency to recur.


Prior to losing consciousness, the individual usually experiences symptoms such as nausea, inability to hear properly, difficulty speaking, exhaustion, tightness in the throat and blurry vision. Sweatiness and dizziness are also very common. These symptoms may last anywhere from seconds to minutes. This is followed by an episode of fainting; the individual regains consciousness within seconds to minutes. It is uncommon for vasovagal syncope to occur while the individual is lying down (supine); it normally occurs while standing or sitting.

During the episode, the individual will be unresponsive, and the pulse and blood pressure will be low. In some cases the individual may react violently while unconscious, this may be due to a fear response and increased adrenaline. The reaction may have the appearance of a seizure. Upon regaining consciousness, the individual may appear flushed and feel generally lethargic. The heart rate may still be slow, although it soon returns to normal.


In addition to vasovagal syncope, a number of other medical conditions may cause fainting. It is essential to perform a thorough history (interview of the patient) and physical examination. If there is no sign of other medical problems or causes of fainting, and the patient's description is consistent with or suggestive of vasovagal syncope, no diagnostic testing may be necessary. However, if the fainting is recurrent, a tilt table test is usually performed. In this test, the patient lies flat on a table and is then tilted upright so that blood pressure and heart rate may be observed and measured to identify any severe changes. This test is particularly effective in identifying patients suffering from sensitive nervous systems. Depending on the physician's level of suspicion, other tests, including an electrocardiogram, may be performed.


Vasovagal syncope is due to a disorder of autonomic control of the cardiovascular system. It commonly occurs in normal people of all ages. Precipitating factors include alcohol consumption, fatigue, pain, hunger, and prolonged standing. It can also be triggered by situations causing anxiety, such as having blood drawn, as well as by hot or crowded situations.

The initial responses appear to be venous pooling and increased activity of the sympathetic nervous system. This causes the heart to contract forcefully while relatively empty, triggering ventricular mechanoreceptors and vagal nerve fibers. This has the effect of reducing sympathetic activity while stimulating parasympathetic activity, resulting in bradycardia and vasodilation, followed by syncope.


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Applied Tension Treatment of Vasovagal Syncope during Pregnancy
From Military Medicine, 9/1/04 by Peterson, Alan L

Vasovagal syncope is a common clinical problem that is often difficult and expensive to diagnose and treat. Applied tension is a behavioral treatment approach that has been demonstrated to be efficacious for the treatment of vasovagal syncope associated with injection phobia. The present case study evaluated the treatment of vasovagal syncope in a 41-year-old pregnant patient with injection phobia. The treatment included the use of applied muscle tension to increase blood pressure and prevent syncope during graduated exposure to increasingly greater anxiety-provoking stimuli. After completion of the treatment, the patient was able to undergo a blood draw and other medical procedures involving exposure to needles, with significantly reduced anxiety and no episodes of syncope. Applied tension is an effective and relatively inexpensive treatment for patients with vasovagal syncope related to injection phobia and may hold promise as a treatment for other types of syncope.


Vasovagal syncope is a common clinical problem that is often difficult to evaluate and treat.12 The pathophysiological features of vasovagal syncope (know alternatively as neurocardiogenic, vasodepressor, or neurally mediated syncope) are complicated and not fully understood.3 Vasovagal syncope has been described as a biphasic response consisting of an initial increase in blood pressure followed by a sudden decrease in blood pressure, often resulting in fainting.4 Treatment approaches for syncope often include the use of medications and cardiac pacemakers.5-8

Vasovagal syncope is also associated with injection, blood, or injury phobia.9 Injection phobia is the specific fear and avoidance of needles, receiving injections, or having blood drawn via venipuncture.10 A hallmark of injection phobia is the high probability of fainting or vasovagal syncope during an injection or blood drawing or with the anxious anticipation of such medical procedures.11

The prevalence of injection phobia in the general population has not been established. Studies of blood/injury phobia have reported prevalences of 3.1%12 to 4.5%.13 The lifetime prevalence of simple phobia was reported to be 11.3% in the National Comorbidity Survey.14 However, simple phobia includes a number of specific phobias, such as those involving snakes, spiders, and dogs.15

A common suggestion by health care providers to a patient with a history of injection phobia and syncope is for the patient to "just relax." However, relaxation in this situation often has the antithetical effect of further decreasing blood pressure and increasing the likelihood of vasovagal syncope. Applied tension is a behavioral treatment that has been demonstrated to be effective for the treatment of injection and blood phobia.10,16-18 The goal of this treatment is to apply muscle tension to temporarily increase blood pressure, to prevent vasovagal syncope, during graduated exposure to increasingly greater anxiety-provoking stimuli. This approach uses applied isometric tensing of muscles, similar to the "anti-G maneuver" used by fighter pilots to avoid syncope when flying high-performance aircraft. The combination of applied tension and repeated graduated exposure usually results in the eventual extinction of the vasovagal syncope reaction, often with only one extended treatment session. In most cases, patients no longer need to use the applied tension technique, because future exposure to the stressful stimuli (e.g., needles or injections) no longer triggers the vasovagal syncope response. However, once patients have learned the applied tension technique, they are usually confident that they can avoid any future syncopal episodes by using the applied tension technique if necessary. A randomized trial of applied tension for injection phobia, with stringent criteria for clinically significant improvement (finger prick, subcutaneous injection, and venipuncture), demonstrated that 80% of patients exhibited clinical improvement after just one treatment session and 90% continued to exhibit improvement at the 1-year follow-up evaluation.10

This case study outlines the use of applied tension for the treatment of a pregnant patient with needle phobia and vasovagal syncope. The use of behavioral treatment was requested by the patient's referring provider, because the patient required medical assessment and treatment procedures involving the use of needles. There was also concern regarding potential injury to the patient and/or fetus related to falling during a syncopal episode. In addition, there was concern regarding the potential negative consequences of medications or other more invasive medical interventions with a pregnant patient. Written informed consent was obtained from the patient before submission of the case study for publication.

Case Report

The patient was a 41-year-old female subject who was 17 weeks pregnant. She had a 16-year history of fainting and had previously been diagnosed with vasovagal syncope and convulsive syncope related to injections and blood draws. She was referred to the clinical health psychology service at Wilford Hall Medical Center for behavioral treatment after she experienced a syncopal episode while undergoing amniocentesis. A 1-hour clinical interview was conducted, for completion of a full assessment and discussion of treatment planning. Voluntary informed consent was obtained from the patient before initiation of the behavioral treatment.

Because the patient was pregnant, her obstetrician was consulted regarding possible complications of using the applied tension technique. It was recommended that the patient not tense any of her abdominal muscles during the applied tension treatment, to limit any possibility of inducing premature labor. The behavioral treatment was seen as posing minimal risk to the patient and being greatly preferable to medical or surgical interventions for the syncope.

The treatment included the use of applied muscle tension combined with graduated exposure to increasingly stressful stimuli.10 Before the initiation of the applied tension treatment, a 1-hour clinic appointment was spent in preparation for the behavioral treatment session. A hierarchy of stimuli likely to induce a syncopal episode, including verbal descriptions of needles, injections, and blood draws, watching others undergo subcutaneous injection or venipuncture, and actually experiencing an injection or blood drawing, was developed. The patient was asked to use a rating scale of O to 10 (O = no fainting symptoms and 10 = being passed out) subjective units of distress (SUDs) and decided that she would initiate the applied tension at a level of 5 or greater.

A detailed description of the applied tension treatment was also provided during this session, and the patient practiced the applied tension technique without exposure to any stressful stimuli. The applied muscle tension consisted of tensing the muscles in the arms, torso, and legs until a feeling of warmth was noticed in her face (10-20 seconds). The patient was encouraged to practice the applied tension exercise at home, in a similar manner, five times per day in the upcoming week.

The treatment was initiated during the third clinic appointment. This session was scheduled for an extended 3-hour period and included exposure to the hierarchy of stressful stimuli and use of the applied tension technique. The session began with a discussion of needles and a verbal description of the procedures involved in giving an injection. The patient was instructed to use the applied tension technique at the earliest signs of a possible syncopal episode (e.g., feelings of intense warmth in her face and sweating). During the initial exposure to the verbal description of needles and injections, the patient's presyncopal symptoms increased to a SUDs level of 6 and she initiated the applied tension. The patient was instructed to gradually reduce the muscle tension as the sensory symptoms related to fainting subsided but not to fully relax, because this might lead to syncope. Repeated cycles of tensing and gradually reducing the muscle tension, until the patient was able to decrease the muscle tension without fainting, were sometimes required. Subsequently, continued verbal discussions and descriptions of needies, injections, and blood draws failed to elevate the patient's SUDs levels above a 4 rating. Exposure to each of the stressful stimuli in the hierarchy was not initiated until the patient was ready to proceed voluntarily.

The next phase of the treatment session was conducted in the immunization clinic of the hospital. Initially, the patient was asked to remain seated while watching others receive injections. While the patient was observing the first injection, her SUDs level quickly increased to a 9. With vigorous encouragement, she used the applied tension and successfully avoided a syncopal episode. During subsequent observations, her SUDs level never increased above 3. After watching five patients receive injections, the patient moved to the hospital laboratory to observe patients having their blood drawn. She observed 12 blooddrawing trials without experiencing a syncopal episode, using the applied tension technique as needed. The patient then reported that she was confident she could have her own blood drawn. She successfully underwent a blood draw and reported that her SUDs level had reached only a 3. The patient reported that she was confident she could undergo more such tests in the future.

A follow-up visit with the patient 6 months later indicated that she had successfully delivered her child and had undergone numerous injections, blood draws, and other medical procedures without experiencing a single syncopal episode. In most cases, she no longer needed to use the applied tension technique because exposure to the needles did not trigger the syncopal symptoms. She did note that the first set of four immunizations received by her new infant led her to feel as if she were going to faint. However, she was again able to use the applied tension technique to avoid syncope. The patient reported that subsequent immunizations of her child were somewhat anxiety provoking but did not require her to use the applied tension technique to prevent syncope.


This case study reports the successful use of behavioral treatment for blood phobia with vasovagal syncope. The case is noteworthy because it is the first published report of the use of applied tension for treatment of vasovagal syncope during pregnancy. After completion of the treatment, the patient was able to undergo numerous medical procedures involving exposure to needles, with significantly reduced anxiety and no episodes of syncope.

Applied tension is an effective and relatively inexpensive treatment for patients with vasovagal syncope related to injection phobia. The use of applied tension for other types of syncope, not related to injection, blood, or injury phobia, has not been evaluated. Previous research suggested that the pathophysiological features of vasovagal syncope related to blood/ injury phobia might be similar to those of syncope related to a variety of other medical conditions. One study found that 82% of patients with vasovagal syncope related to blood/injury phobia demonstrated positive head-up tilt table test results.9 It is not known whether the applied tension treatment approach may be useful as an adjunct or alternative to medications or cardiac pacing for other types of syncope. Additional research is needed to assess the potential application of applied tension treatment to other cases of syncope.


We thank Yvette Cortez, Lesley Webb, and Diane Isler, PhD, for their assistance in the preparation of this article.


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Guarantor: Lt Col Alan L. Peterson, USAF BSC

Contributors: Lt Col Alan L. Peterson, USAF BSC; Capt William C. Isler III, USAF BSC

Clinical Health Psychology Service, 59 MDOS/MMCPH, Wilford Hall Medical Center, 2200 Bergquist Drive, Suite 1, lackland AFB, TX 78236-5300.

The views expressed in this article are the authors' and do not reflect the official position of the U.S. Air Force, the Department of Defense, or the U.S. government.

This manuscript was received for review in February 2002 and was accepted for publication in August 2003.

Copyright Association of Military Surgeons of the United States Sep 2004
Provided by ProQuest Information and Learning Company. All rights Reserved

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