Can vasovagal syncope cause vomiting?

Vasovagal Syncope and Vomiting

Yes, vasovagal syncope can cause vomiting as part of its clinical presentation, particularly during the prodromal phase before loss of consciousness. 1

Pathophysiology and Mechanism

• Vasovagal syncope occurs when a triggered reflex causes inappropriate vasodilation and bradycardia, resulting in systemic hypotension and cerebral hypoperfusion 2
• The vasovagal response includes activation of the autonomic nervous system, which can trigger gastrointestinal symptoms including nausea and vomiting 1, 2
• The contribution of vasodilation and bradycardia varies between individuals and episodes, but both contribute to the overall clinical presentation 2

Clinical Presentation of Vasovagal Syncope

Prodromal Symptoms

• Nausea is a common prodromal symptom of vasovagal syncope 1
• Vomiting is specifically listed as a typical sign of presyncope in the 2019 American Heart Association guidelines 1
• Other autonomic activation symptoms include:
  • Sweating (diaphoresis) 1, 2
  • Pallor/paleness 1
  • Feeling warm/hot or cold 1
  • Abdominal discomfort 1

During the Episode

• The European Society of Cardiology guidelines identify that gastrointestinal stimulation can be both a trigger for situational syncope and a symptom during the episode 1
• Vomiting may occur during the presyncope phase or during the recovery phase 1

Types of Vasovagal Syncope Associated with Vomiting

• Classical vasovagal syncope: Mediated by emotional distress (fear, pain, blood phobia) or orthostatic stress, commonly presents with autonomic symptoms including nausea and potentially vomiting 1, 2
• Situational syncope: Specific circumstances can trigger the vasovagal reflex, including gastrointestinal stimulation 1, 3

Diagnostic Considerations

• When evaluating a patient with syncope and vomiting, it's important to differentiate between:
  • Vomiting as a prodromal symptom of vasovagal syncope 1
  • Vomiting as a trigger for situational syncope 1
  • Other causes of syncope with vomiting (e.g., cardiac, neurological) 1

Clinical Implications and Management

• Recognition of vomiting as a potential sign of presyncope allows for early intervention 1
• If presyncope symptoms (including vomiting) occur, the patient should:
  • Assume a safe position (sitting or lying down) 1
  • Consider physical counterpressure maneuvers (PCMs) to prevent progression to syncope 1
• Lower-body PCMs are preferable to upper-body maneuvers when possible 1

Pitfalls and Caveats

• Vomiting alone is not diagnostic of vasovagal syncope and must be considered in the context of other symptoms and triggers 1
• Vomiting can also be a symptom of more serious conditions causing syncope, such as cardiac arrhythmias or structural heart disease 1
• In older adults, atypical presentations of vasovagal syncope are more common, and the prodromal symptoms (including vomiting) may be abbreviated or absent 4
• Volume depletion from persistent vomiting can exacerbate orthostatic hypotension and increase syncope risk 1

In conclusion, vomiting is a recognized sign of vasovagal syncope that can occur during the prodromal phase as part of autonomic nervous system activation. Recognizing this association is important for proper diagnosis and management of patients with syncope.