Neurocardiogenic syncope

Disease Description (Causes and Symptoms)

• Definition: Neurogenic (cardioneurogenic/vasovagal, neurocardiogenic) syncope is a condition in which a temporary imbalance in the autonomic nervous system causes a rapid drop in blood pressure due to decreased heart rate (bradycardia) and/or vasodilation, resulting in temporary loss of consciousness.
• Pathophysiology: Specific stimuli such as standing, stress, pain, urination, or defecation overactivate the vagus nerve (parasympathetic nervous system) or suppress the sympathetic response, causing a decrease in heart rate and peripheral vasodilation → reduced cerebral perfusion → syncope after prodromal symptoms. Structural abnormalities of the heart are generally not present.
• Main triggers and risk situations: Standing for a long time (especially in hot or stuffy environments), dehydration, fatigue, violent or horrific scenes, severe pain, urination, defecation, coughing, sudden standing, acute excitement or fear, etc.
• Symptoms: Prodromal symptoms (dizziness, chest discomfort, nausea, cold sweats, yawning, blurred vision, etc.) → loss of consciousness (spontaneous recovery within several tens of seconds) — typically occurring while sitting or standing. Unlike syncope associated with heart disease, the risk of sudden death is low.
• Key points in diagnosis (brief summary): Detailed medical history (circumstances of onset, prodromal symptoms, family history), physical examination (orthostatic blood pressure), standard 12-lead electrocardiogram, and, when necessary, a tilt-table test (provocation and reproduction), long-term electrocardiography (Holter/ILR), and cardiac examinations to rule out cardiac causes.

Treatment Methods and Precautions

• Basic principles: Avoid triggers (dehydration, excessive heat, prolonged standing, etc.); when symptoms are recognized, immediately sit or lie down (lowering the head) to preserve cerebral perfusion and prevent injury.
• Non-pharmacological treatment
  • Lifestyle management: Adequate fluid and salt intake (as directed by a physician), limit alcohol and excessive caffeine, do not stand up suddenly, and avoid hot environments.
  • Physical response: When prodromal symptoms occur before syncope, sit or lie down and raise the legs. Physical counterpressure maneuvers, such as crossing the legs, contracting the thigh and abdominal muscles, pressing the palms together, or clenching the fists, can help prevent worsening of symptoms.
  • Assistive measures: Compression stockings (especially when venous pooling in the legs is a cause), and tilt training.
• Pharmacological treatment
  • Midodrine: May be used to improve symptoms in orthostatic hypotensive syncope as a vasoconstrictor (prescribed at the physician’s discretion).
  • Fludrocortisone: Effective in some patients by increasing fluid volume. The risks of hypertension, heart failure, and hypokalemia should be considered.
  • Beta-blockers: Consistent effectiveness has not been demonstrated in young patients with vasovagal syncope. Limited use may be considered depending on patient selection.
  • The choice of medication varies according to the patient’s age, comorbidities, syncope pattern, and test results.
• Procedural/mechanical treatment
  • In cases where prolonged and severe suppression of the heartbeat (cardiac arrest or prolonged asystole) is objectively confirmed repeatedly (e.g., prolonged pauses on an implantable electrocardiographic monitor or Holter monitor), implantation of an artificial pacemaker (pacer) may be considered on a limited basis — however, indications are strict and are determined according to age, symptom pattern, and other factors.
• Precautions and risk of complications
  • Syncope itself is generally not life-threatening, but there is a significant risk of trauma from falling (head trauma, fractures, etc.).
  • If syncope occurs during exercise, is accompanied by chest pain or shortness of breath, occurs suddenly without prodromal symptoms, or there is a family history of sudden death, a cardiac cause should be suspected → immediate specialist evaluation is necessary.
  • Pay attention to medication side effects (hypertension, hypokalemia, gastrointestinal symptoms, etc.) and interactions.

Checkpoints Before an Outpatient Visit (Including Items to Bring, Records, and Example Questions)

• Items and materials to bring
  • A list of all medications and supplements currently being taken (including doses and times of administration)
  • If available, recent electrocardiogram (ECG), chest X-ray, and echocardiography results
  • Results of previous tests related to syncope (Holter monitoring, tilt-table test, etc.)
  • Notes describing the circumstances when syncope occurred (when, where, what you were doing, whether prodromal symptoms were present, duration, and recovery pattern)
  • Video of the event (if possible)
  • Photos of injuries caused by syncope (if any)
• Items that are helpful to record before the visit
  • Number of syncopal episodes · date of the most recent episode · detailed circumstances of each event
  • Food, medications, and alcohol consumed before syncope
  • Family history (sudden death or heart disease)
  • Whether dizziness or a faint feeling usually occurs when standing
• Tests that may be expected during the outpatient visit
  • 12-lead electrocardiogram, orthostatic blood pressure measurement, and, if necessary, tilt-table test, Holter monitoring, ILR, echocardiography, etc.

Example questions (for self-checking before the outpatient visit)

• Did you have prodromal symptoms such as dizziness, nausea, or cold sweats before syncope?
• Did you have palpitations, chest pain, or shortness of breath during or immediately before syncope?
• Did you sustain a wound from hitting your head (or another part of your body) when you fell?

Examples of General Questions to Ask the Doctor

• What do you think is the cause of my syncope? How likely is it to be a heart problem?
• What additional tests should I undergo (tilt-table test, Holter monitoring, ILR, etc.)? What information will those tests provide?
• What is the recommended first treatment (lifestyle changes or medication)? What effects and side effects can be expected?
• What symptoms should prompt me to go to the emergency room if syncope recurs?
• Are there any restrictions related to driving or my occupation (working at heights, operating machinery, etc.)? When can I safely resume these activities?

Examples of Disease-Specific Questions

• When I feel prodromal symptoms, what specific actions can I take to prevent syncope (sitting down, lying down, physical counterpressure maneuvers, etc.)?
• If recurrent syncope cannot be controlled with medication, what additional treatments (such as pacemaker implantation) might be considered? What are the criteria?

(Brief epidemiological summary) Syncope is common, with approximately 3% of men and 3.5% of women experiencing it during their lifetime, and approximately one-third of people who have experienced syncope once may experience a recurrence. Typical neurocardiogenic syncope generally has a relatively favorable prognosis, but preventing trauma and ruling out cardiac syncope are important.