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Vasovagal syncope, also termed neurocardiogenic syncope, manifests as fainting triggered by the body’s exaggerated response to certain stimuli, like seeing blood or experiencing intense emotional distress. This response prompts a sudden decline in heart rate and blood pressure, resulting in decreased blood flow to the brain and a brief loss of consciousness. Although generally benign and often not necessitating treatment, there exists a potential for injury during an episode. To rule out more serious underlying conditions, such as heart disorders, your physician might suggest diagnostic tests.
Symptoms
Some of the following symptoms may manifest prior to vasovagal syncope-related fainting:
- Tunnel vision, a condition in which your field of vision narrows, allowing you to see only what is directly in front of you.
- Vision becomes blurred
- Lightheadedness
- Nausea
- Pale skin
- Warm sensation
- A cold, clammy sweat
- Yawning
When someone witnesses a vasovagal syncope event, they could observe:
- Dilated pupils
- Jerky, irregular movements
- A slow, faint pulse
Recovery after a vasovagal episode usually starts within a minute. However, standing up too soon after fainting—typically within 15 to 30 minutes—can increase the risk of fainting again.
Fainting can sometimes indicate a more serious condition, such as a heart or brain disorder. It’s advisable to consult your doctor after a fainting episode, especially if it’s your first time experiencing one.
Causes
Vasovagal syncope occurs when the section of your nervous system responsible for regulating heart rate and blood pressure responds abnormally to a stimulus, like the sight of blood. This triggers a slowdown in heart rate and the widening of blood vessels in your legs, causing blood to accumulate in the legs and a decrease in blood pressure. This dual effect, comprising lowered blood pressure and a slower heart rate, diminishes blood flow to the brain, leading to fainting.
While sometimes there may be no obvious trigger, common triggers for vasovagal syncope include:
- Prolonged standing
- Exposure to heat
- Observing blood
- Having blood drawn
- Fear of physical harm
- Exerting oneself, as in getting a bowel movement
Risk factors
Approximately one in three individuals will experience vasovagal syncope at least once in their lifetime, and it can affect people of any age. In those under 40, vasovagal syncope accounts for about 85% of all fainting episodes. Among older adults, it constitutes around half of such cases.
Individuals with autonomic nervous system disorders, like Parkinson’s disease, are highly unlikely to experience vasovagal syncope. This is because their condition interferes with the normal functioning of their nervous system.
Diagnosis
Diagnosing vasovagal syncope typically starts with a physical examination. During this exam, your doctor will listen to your heart and measure your blood pressure. They may also gently massage the main arteries in your neck to check if this induces a fainting sensation.
To rule out other potential causes of your fainting, especially heart-related issues, your doctor may suggest several tests, including:
- Electrocardiogram. The electrical impulses your heart generates are recorded throughout this test. It can identify various cardiac issues as well as abnormal heart rhythms. It could be necessary for you to wear a portable monitor for a month or at least for one day.
- Echocardiogram. This test looks for disorders including valve issues, which can lead to fainting, by using ultrasonography to view the heart.
- Exercise stress test. This test examines heart rhythms during exercise and is typically conducted while you walk or jog on a treadmill.
- Blood tests. Your physician may check for diseases like anemia that can either cause or exacerbate episodes of fainting.
- Tilt table test. Your doctor can recommend a tilt table test if there is no indication that your fainting is due to a cardiac condition. You lie flat on your back on a table that tilts you upward at different angles during the test. Throughout the test, a technician keeps an eye on your blood pressure and heart rhythms to see if shifting your posture has an impact on either.
Treatment
In most instances of vasovagal syncope, treatment is unnecessary. Your doctor can help pinpoint your fainting triggers and work with you to develop strategies to mitigate them.
However, if vasovagal syncope occurs frequently enough to disrupt your daily life, your doctor may recommend trying one or more of the following remedies:
- Medications: Fludrocortisone acetate, typically prescribed for low blood pressure, might be beneficial in preventing vasovagal syncope. Selective serotonin reuptake inhibitors could also be considered.
- Therapies: Your doctor might recommend techniques to diminish blood pooling in your legs, like performing foot exercises, donning compression stockings, or tensing your leg muscles while standing. If high blood pressure is not a concern for you, increasing your salt intake may be advised. It’s important to steer clear of prolonged standing, especially in hot, congested spaces, and maintain sufficient fluid intake.
- Surgery: In rare cases, implanting an electrical pacemaker to regulate the heartbeat may be an option for individuals with vasovagal syncope who have not responded to other treatments.
