From the Guidelines
Vasovagal syncope is a common type of fainting that occurs when your body overreacts to certain triggers, causing a sudden drop in heart rate and blood pressure that reduces blood flow to the brain, and is typically characterized by diaphoresis, warmth, nausea, and pallor, often preceded by identifiable triggers and/or a characteristic prodrome, as defined by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Key Characteristics of Vasovagal Syncope
- It is the most common form of reflex syncope mediated by the vasovagal reflex
- May occur with upright posture or exposure to emotional stress, pain, or medical settings
- Typically characterized by:
- Diaphoresis
- Warmth
- Nausea
- Pallor
- Often associated with vasodepressor hypotension and/or inappropriate bradycardia
- Frequently followed by fatigue
- Diagnosis is made primarily on the basis of a thorough history, physical examination, and eyewitness observation, if available, as outlined in the 2017 ACC/AHA/HRS guideline 1 and supported by the European Heart Journal guidelines from 2001 1 and 2004 1
Management and Prevention
- Most cases are benign and do not require specific medication
- Management typically involves:
- Avoiding known triggers
- Staying hydrated
- Increasing salt intake if appropriate
- Learning to recognize warning signs to sit or lie down to prevent falling
- For recurrent or severe cases, medications like fludrocortisone, midodrine, or beta-blockers might be prescribed by a doctor, although the evidence for beta-blockers is not strong, as noted in the 2001 European Heart Journal guidelines 1
- Physical counterpressure maneuvers such as crossing legs and tensing muscles can help prevent episodes by maintaining blood pressure, as suggested by the 2017 ACC/AHA/HRS guideline 1 and the European Heart Journal guidelines from 2001 1 and 2004 1
From the Research
Definition of Vasovagal Syncope
- Vasovagal syncope is a condition characterized by an abrupt loss of consciousness in response to reduced perfusion to the brain, resulting from a complex neurologic reflex 2.
- It is also known as neurocardiogenic syncope, and its treatments aim to modulate aspects of this reflex to prevent recurrence.
Causes and Mechanisms
- The exact causes of vasovagal syncope are not fully understood, but it is thought to involve a complex interplay between the nervous system, heart, and blood vessels 2.
- The condition can be triggered by various factors, including stress, pain, and certain medications.
Treatment Options
- Conservative measures, such as lifestyle modifications, are often recommended as the first line of treatment for vasovagal syncope 3.
- Pharmacologic treatments, including midodrine, fludrocortisone, and beta blockers, may be prescribed to prevent recurrence in patients who do not respond to conservative measures 2, 3, 4, 5, 6.
- Midodrine has been shown to be effective in reducing the likelihood of syncope in patients with vasovagal syncope, particularly in those with a high syncope burden 5, 6.
- Fludrocortisone has also been studied as a potential treatment for vasovagal syncope, but its effectiveness is still being researched and debated 4.
Research and Studies
- Several studies have investigated the efficacy of midodrine and fludrocortisone in preventing vasovagal syncope, including randomized controlled trials and systematic reviews 3, 4, 5, 6.
- The COMFORTS trial, a multi-center randomized controlled trial, is currently underway to compare the effectiveness of midodrine and fludrocortisone in preventing recurrence of vasovagal syncope 3.
- A systematic review and meta-analysis of published studies found that midodrine can reduce the likelihood of syncope in patients with vasovagal syncope, particularly in those with a high syncope burden 5.