From the Guidelines
Vasovagal syncope, which is often preceded by presyncope, can be prevented with physical counterpressure maneuvers (PCMs) such as muscle contractions in the legs, arms, abdomen, or neck, as recommended by the 2024 American Heart Association and American Red Cross guidelines for first aid 1. The vagal nerve plays a significant role in presyncope, which is the feeling of lightheadedness or dizziness that often precedes fainting (syncope). Presyncope occurs when there is a temporary reduction in blood flow to the brain, often triggered by vagal nerve stimulation.
Key Points to Consider
- The vagus nerve, when overstimulated, can cause a sudden drop in heart rate (bradycardia) and blood pressure (vasodilation), leading to decreased cerebral perfusion.
- Common triggers include prolonged standing, dehydration, emotional stress, pain, or straining during urination or bowel movements.
- To manage vagal-induced presyncope, patients should sit or lie down immediately when symptoms begin, increase fluid and salt intake, avoid triggers, and consider counterpressure maneuvers like leg crossing or hand gripping.
- According to the 2024 American Heart Association and American Red Cross guidelines for first aid, PCMs can help prevent syncope by causing a rise in blood pressure and alleviating symptoms of near syncope originating from vasovagal or orthostatic causes 1.
Prevention and Treatment
- Understanding the connection between vagal stimulation and presyncope helps patients recognize early warning signs and take appropriate preventive actions.
- For recurrent episodes, medications such as fludrocortisone, midodrine, or beta-blockers may be prescribed, but the first line of treatment should always be non-pharmacological interventions like PCMs and lifestyle modifications.
- The 2024 guidelines emphasize the importance of prompt intervention during the prodromal phase of syncope, which can last for a few seconds and may include symptoms such as lightheadedness, dizziness, blurry vision, nausea, and diaphoresis 1.
From the Research
Vasovagal Nerve and Presyncope
- The vasovagal nerve is involved in the regulation of heart rate and blood pressure, and its dysfunction can lead to presyncope and syncope 2, 3, 4.
- Presyncope is a state of near-fainting, characterized by symptoms such as dizziness, lightheadedness, and nausea 2, 5.
- The treatment of presyncope and syncope involves a combination of non-pharmacological and pharmacological interventions, including physical counterpressure maneuvers, fluid and salt intake, and medications such as midodrine and fludrocortisone 2, 3, 4, 6.
Non-Pharmacological Interventions
- Physical counterpressure maneuvers (PCM) have been shown to be effective in preventing syncope and improving symptoms in patients with presyncope of vasovagal or orthostatic origin 2.
- PCM involves applying pressure to certain areas of the body, such as the legs and abdomen, to increase blood flow to the brain 2.
- Other non-pharmacological interventions, such as orthostatic training and yoga, may also be helpful in managing presyncope and syncope, although their efficacy is limited 6.
Pharmacological Interventions
- Midodrine is a medication that has been shown to be effective in reducing the frequency of syncope in patients with vasovagal syncope 3, 4, 6.
- Fludrocortisone is another medication that has been shown to be effective in reducing syncope recurrences, although its use is limited by potential side effects 3, 4, 6.
- Other medications, such as beta-blockers, have been studied as potential treatments for vasovagal syncope, but their efficacy is limited and they are not recommended as first-line therapy 3, 6.