Vasovagal syncope, also known as neurocardiogenic syncope or reflex syncope, is a common reason why some people faint. This condition is usually harmless and does not indicate a serious underlying problem.
Various nerves work together to regulate the speed and force of the heartbeat, as well as blood pressure. Sometimes, these nerves can send incorrect signals, causing blood vessels to widen, the heart rate to slow down, and reduced blood flow to the brain, resulting in loss of consciousness. Nevertheless, blood flow to the brain typically returns to normal when the individual lies down.
Vasovagal syncope is widespread and can impact individuals of any age and gender. Unlike other causes of fainting, it is not a sign of heart or brain issues.
Triggers of Vasovagal Syncope
Fainting due to vasovagal syncope can be triggered by a variety of factors. In addition to standing for extended periods, high temperatures, strong emotions, pain, and specific activities such as urinating or coughing, other triggers may include dehydration, hunger, alcohol consumption, and certain medications. It is important for individuals who experience vasovagal syncope to identify their specific triggers in order to better manage and prevent episodes. Additionally, practicing stress-reducing techniques, maintaining a healthy diet, and staying physically active can help reduce the likelihood of fainting episodes.
Symptoms and Treatment
Prior to fainting, individuals may feel nauseous, warm, pale, or dizzy. Lying down can prevent fainting, with most episodes occurring while sitting or standing. Fainting from vasovagal syncope generally resolves quickly once blood flow to the brain is restored.
Healthcare providers may perform tests like ECGs or tilt table tests to diagnose vasovagal syncope. Lifestyle changes or medications may be suggested to manage repeated episodes.
Prevention and Management Strategies
To avoid fainting, individuals with vasovagal syncope should lie down, elevate their legs, and steer clear of triggers. Lifestyle modifications such as increasing salt intake or wearing compression stockings may be beneficial. In severe cases, medications or heart pacemakers could be considered.
It is also important for individuals with vasovagal syncope to stay hydrated and to avoid prolonged standing or sudden changes in body position. Regular exercise and stress management techniques can help improve overall cardiovascular health and may reduce the frequency of fainting episodes.
In addition to lifestyle changes, it is recommended that individuals with vasovagal syncope work closely with their healthcare provider to develop a personalized treatment plan. This may include regular monitoring of blood pressure and heart rate, as well as keeping a diary of fainting episodes to identify potential triggers.
Considerations
Vasovagal syncope itself is usually not dangerous, but fainting in unsafe circumstances could lead to injuries. It is advisable to consult healthcare providers for recurring episodes or persistent symptoms.
Some common triggers for vasovagal syncope include prolonged standing, dehydration, emotional stress, and sudden changes in posture. It is important to stay hydrated, avoid triggers when possible, and learn how to recognize warning signs of an impending episode.
In addition to consulting healthcare providers, individuals with vasovagal syncope may benefit from making lifestyle changes such as increasing salt intake, wearing compression stockings, and practicing stress-reducing techniques like meditation or deep breathing exercises.
It is crucial for individuals with vasovagal syncope to be aware of their condition and take necessary precautions to prevent accidents or injuries. By working closely with healthcare providers and adopting appropriate coping strategies, individuals can effectively manage vasovagal syncope and improve their quality of life.
Summary of Vasovagal Syncope
- Vasovagal syncope can cause a temporary reduction in blood flow to the brain due to widened blood vessels or a slower heart rate.
- Fainting from vasovagal syncope is typically harmless.
- Prevent fainting by avoiding triggers and lying down at the first sign of symptoms.
- Lifestyle changes and medications may help manage vasovagal syncope.
Tips for Healthcare Provider Visits
- Come prepared with questions and bring a companion.
- Take notes about diagnoses, treatments, and instructions.
- Understand prescribed medications and potential side effects.
- Ask about alternative treatments and expected outcomes.
- Follow up on appointments and contact information.
The American College of Cardiology, American Heart Association, and Heart Rhythm Society recommend hospital evaluation for individuals experiencing syncope and serious medical conditions. Targeted blood tests may be necessary, while routine comprehensive tests are often unnecessary.
The frequency and characteristics of syncope events should determine the type of cardiac monitoring selected (class I). In inpatient settings, telemetry is helpful for individuals admitted due to suspected cardiac causes of syncope (class I).
In specific patients with syncope suspected to be caused by arrhythmias, electrophysiology studies (EPS) can be useful (class IIa). However, EPS is not beneficial and is not recommended for syncope evaluation in cases of normal ECG and cardiac structure and function—unless an arrhythmic cause is suspected (class III).
In patients with syncope and known or suspected neurodegenerative diseases, referral for autonomic evaluation may enhance diagnostic and prognostic accuracy (class IIa).
2021 ACR appropriateness criteria
The American College of Radiology (ACR) does not consider any imaging studies essential in cases where the probability of cardiac or neurological pathology is low, but chest radiography may be appropriate in specific clinical scenarios.
Suspected cardiovascular origin of syncope or presyncope
In cases of suspected cardiovascular origin of syncope or presyncope (based on history, physical examination, and ECG findings), the recommended initial imaging evaluation is resting transthoracic echocardiography (TTE). Other initial imaging studies that may be suitable are:
– Computed tomography (CT) angiography (CTA) of the chest or coronary arteries with intravenous (IV) contrast
– Magnetic resonance imaging (MRI) of heart function with or without IV contrast
The following initial imaging studies are typically not suitable in this scenario:
– Resting and stress 99m Tc single-photon emission CT (SPECT) or SPECT/CT myocardial perfusion imaging (MPI)
Low probability of cardiovascular origin of syncope or presyncope
Chest radiography may be an appropriate initial imaging in cases where syncope or presyncope is unlikely to have a cardiovascular origin based on history, physical examination, and ECG results.
The following initial imaging studies are typically not suitable in this scenario:
– Resting and stress SPECT or SPECT/CT MPI
Laboratory Studies
At present, there is no specific test that is absolutely necessary for the evaluation of syncope. Tests can be tailored to any signs or symptoms that suggest a specific underlying condition. Recommendations based on research and consensus guidelines are provided below.
Serum glucose level
In a study, two out of 170 syncope patients tested for serum glucose were found to have hypoglycemia. Despite the low yield, rapid blood glucose assessment is simple, quick, and can be diagnostic, leading to prompt intervention.
Complete blood cell (CBC) count
A complete blood count (CBC) has very low utility in syncope if performed empirically. Some risk stratification protocols consider a low hematocrit level as a poor prognostic indicator.
In a study assessing syncope, four out of 170 patients had signs and symptoms of gastrointestinal hemorrhage confirmed by CBC. However, no occult bleeding was identified based on an empirical CBC in this study.
Anemia has been associated with poor short-term outcomes in several studies.
Serum electrolyte levels with renal function tests
If conducted empirically, these tests show very low yield in syncope. Some risk stratification protocols use electrolyte abnormalities and renal insufficiency as indicators of poor prognosis.
In a study, electrolyte tests were performed on 134 syncope patients as part of routine workup. One patient was unexpectedly found to have hyponatremia due to diuretic use.
Cardiac enzymes
These tests are recommended in patients with a history of chest pain, dyspnea, or exertional syncope; those with multiple cardiac risk factors; and those strongly suspected of a cardiac origin.
Total creatine kinase
An increase in creatine kinase (CK) levels may be linked to prolonged seizure activity or muscle damage due to extended loss of consciousness.
B-type natriuretic peptide (BNP) levels over 300 pg/mL can predict serious outcomes at 30 days.
Urinalysis/dipstick
In elderly and debilitated patients, urinary tract infections (UTIs) are common, easily diagnosed, and treatable conditions that may precipitate syncope, even without typical symptoms.
Imaging Studies
The American College of Cardiology (ACC), American Heart Association (AHA), and the Heart Rhythm Society (HRS) do not recommend routine cardiac imaging in the evaluation of syncope unless there are signs of a cardiac origin based on initial assessment, including history, physical examination, or electrocardiogram findings (class III). Also, in the absence of focal neurologic findings warranting further investigation in patients with syncope (class III):
– Routine cranial computed tomography (CT) scanning and magnetic resonance imaging (MRI) are not suggested.
– Routine electroencephalography (EEG) recording is not recommended unless specific neurologic features suggestive of a seizure are present.
Radiography
Pneumonia is common in elderly and debilitated patients, easy to diagnose, treatable, and may lead to syncope. Chest radiography may aid in evaluating specific causes of syncope like pneumonia, congestive heart failure, lung mass, effusion, or widened mediastinum, guiding appropriate therapy.
CT scanning
Noncontrast CT scanning of the head is not indicated for nonfocal patients after a syncopal event, as it has limited diagnostic value in syncope.
Out of the 134 patients examined for syncope using CT scans, 39 of them had abnormal results on the scans. Only one head CT scan provided a diagnosis for a patient not suspected to have intracranial issues. Among the remaining scans, five revealed subdural hematomas believed to be caused by syncope.
If patients exhibit new neurological symptoms or have experienced head trauma due to syncope, a head CT may be necessary.
Chest and Abdomen
CT scans of these areas may be beneficial for certain patients with syncope related to potential cardiac issues. Only select cases, such as suspected aortic dissection, ruptured abdominal aortic aneurysm (AAA), or pulmonary embolism (PE), necessitate CT of the chest and abdomen.
In specific cases, MRI of the brain and magnetic resonance arteriography (MRA) may be needed to assess the vertebrobasilar vasculature and should be done in consultation with a neurologist or neurosurgeon while the patient is in the hospital. MRI can be helpful for some patients with suspected cardiac-related syncope.
Ventilation-perfusion scanning
Ventilation-perfusion (V/Q) scanning is appropriate for patients suspected of having PE.
Echocardiography
In patients with known heart disease, left ventricular function and ejection fraction are closely linked to mortality. For investigating suspected mechanical cardiac causes of syncope, echocardiography is the preferred test.
If there are concerns about structural heart disease, transthoracic echocardiography can be useful in selected syncope patients.
Other Tests
Electrocardiography
It is recommended to perform a standard 12-lead electrocardiogram (ECG) for syncope patients. This recommendation is supported by the 2007 American College of Emergency Physicians (ACEP) consensus guidelines and the 2017 American College of Cardiology (ACC), American Heart Association (AHA), and Heart Rhythm Society (HRS) syncope guidelines. ECG is a key component in most risk stratification protocols.
A normal ECG result is a positive sign. An ECG can diagnose acute myocardial infarction, myocardial ischemia, or preexisting cardiac issues or dysrhythmias. Certain conditions, like Wolff-Parkinson-White syndrome, Brugada syndrome, atrial flutter, or atrioventricular (AV) blocks, can be detected through ECG.
Bradycardia, sinus pauses, ventricular tachycardia, atrioventricular conduction defects, and other rhythm issues become more common with age and are diagnostic when correlated with symptoms.
Holter monitor/loop event recorder
This is an outpatient procedure. Previously, all syncope patients were monitored in the hospital for 24 hours. With advancements like loop recorders, longer monitoring periods improve the likelihood of detecting arrhythmias.
Studies have shown that asymptomatic individuals and symptomatic arrhythmic events can be captured with ambulatory monitoring. Loop recorders are more effective and cost-efficient than Holter monitors.
Research by Sulke et al. demonstrated positive results in diagnosing and reducing recurrent episodes of unexplained syncope using an implantable loop recorder (ILR).
A study by Gibson and Heitzman on 1512 patients revealed low rates of symptomatic arrhythmias among those referred for syncope, potentially indicating a higher diagnostic yield with ambulatory monitoring for negative results.
Head-up tilt-table test
Tilt-table testing can confirm autonomic dysfunction and assist in distinguishing reflex syncope, orthostatic hypotension, and other conditions. Results are based on changes in blood pressure and NE levels.
In pediatric cases, head-up tilt-table testing can help differentiate between presyncopal and syncopal events in children with seizure-like symptoms.
Tilt-table testing is recommended for patients with vasovagal syncope or delayed orthostatic hypotension, although it should not be used to predict responses to VVS medical treatment.
Electroencephalography
Neurologists may conduct EEG to rule out seizures as a cause of syncope.
Stress testing
Stress testing and electrophysiologic studies have higher diagnostic rates than Holter monitoring and are recommended for patients with suspected arrhythmia-related syncope.
Carotid sinus massage is employed to diagnose carotid sinus syncope but should be done cautiously to prevent complications like embolic stroke.
References
For more information, please refer to the mentioned research articles and publications.
Syncope, a temporary loss of consciousness, is a common medical condition. Numerous studies have explored the risk factors, prognosis, and outcomes associated with syncope. Risk assessment is vital for determining appropriate management strategies.
Various risk stratification tools, such as the San Francisco Syncope Rule, the OESIL risk score, and the ROSE study, have been developed to predict adverse events in syncope patients. These tools have significantly enhanced the evaluation and management of syncope in emergency settings.
Different diagnostic strategies have been proposed to differentiate between different types of syncope causes. Clinical decision rules, tilt table testing, implantable loop recorders, and non-pharmacological therapies have been investigated to improve the diagnosis and management of syncope.
Guidelines from organizations like the European Society of Cardiology (ESC) offer recommendations for diagnosing and managing syncope. These guidelines provide a standardized approach to evaluating syncope, assessing risks, and selecting treatment options. Adhering to these guidelines is crucial for improving outcomes in syncope patients.