From the Guidelines
Vasovagal hypotension is triggered by an emotional or physical stimulus that activates the vagus nerve, leading to a sudden drop in heart rate and blood vessel dilation, which can result in decreased blood flow to the brain and potentially cause dizziness, lightheadedness, or fainting (syncope) 1.
Key Points to Consider
- The process of vasovagal hypotension typically starts with an initial trigger such as the sight of blood, prolonged standing, fear, or pain, which stimulates the vagus nerve 1.
- Once activated, the vagus nerve sends signals that slow the heart rate (bradycardia) while simultaneously causing blood vessels to dilate (vasodilation), rapidly reducing blood pressure 1.
- Management of vasovagal hypotension includes lying down with legs elevated, avoiding triggers, staying hydrated, and increasing salt intake if appropriate 1.
- In recurrent cases, medications like fludrocortisone, midodrine, or beta-blockers might be prescribed, and physical counterpressure maneuvers such as leg crossing and muscle tensing can help prevent episodes by maintaining blood pressure when early symptoms appear 1.
Recommendations for Management
- Patient education on the diagnosis and prognosis of vasovagal syncope is recommended 1.
- Physical counter-pressure maneuvers can be useful in patients with vasovagal syncope who have a sufficiently long prodromal period 1.
- Midodrine is reasonable in patients with recurrent vasovagal syncope with no history of hypertension, heart failure, or urinary retention 1.
- Encouraging increased salt and fluid intake may be reasonable in selected patients with vasovagal syncope, unless contraindicated 1.
From the Research
Vasovagal Hypotension Treatment
- Vasovagal hypotension is a condition that can be managed conservatively in most patients, with only a minority requiring treatment 2.
- Patients with vasovagal syncope can be encouraged to liberalize their fluid and salt intake, unless they have contraindications such as hypertension 2.
- Physical counterpressure maneuvers can be taught to all patients to help manage the condition 2.
Medications for Vasovagal Hypotension
- Midodrine is considered the first-line therapy for patients with frequent presyncope or syncope, or for those with brief or no prodromes 2, 3.
- Midodrine has been shown to prevent hypotension and syncope during tilt tests in patients with vasovagal syncope 3.
- Fludrocortisone has also been found to be effective in increasing 24-h systolic blood pressure and reducing systolic blood pressure drops in patients with symptoms due to hypotension 4.
- Beta-blockers, serotonin-specific reuptake inhibitors, and ACE inhibitors have also been proposed as potential treatments for vasovagal syncope, although the evidence is not as strong 5.
Efficacy of Midodrine
- A systematic review and meta-analysis found that midodrine substantially reduced the likelihood of positive head-up-tilt test outcomes and had a modest benefit for the prevention of clinical syncope 6.
- The study also found that midodrine was effective in preventing syncope induced by head-up-tilt testing and had a significant risk reduction in randomized, double-blinded clinical trials 6.
- Another study found that midodrine can reduce the recurrence of syncope in healthy, younger patients with a high syncope burden 3.