Authors:
Dr. Felipe Cañas Orduz, Cardiologist – Electrophysiologist
It can happen to anyone: you're standing in line, in the bathroom, after a strong emotion, or getting up quickly… and suddenly a strange sensation hits you: dizziness, cold sweats, blurred vision, anxiety. Your vision goes dark, and although you can hear everything, you can't understand anything. A few seconds later, everything goes dark. When you wake up, the typical phrase comes up: “It was just a drop in blood pressure” or “they probably didn't eat breakfast.”
Most of the time, syncope (transient fainting) is benign. In small groups of people, it can be the first sign of a heart or autonomic nervous system problem. Knowing when it's "just a scare" and when it requires further investigation can prevent falls, injuries, and, in specific cases, serious complications that require guidance from a healthcare professional.
What exactly is syncope?
Syncope is the medical term for a sudden, transient loss of consciousness accompanied by loss of muscle tone (weakness), caused by a temporary decrease in blood flow to the brain. During syncope, blood pressure drops to very low levels, sometimes accompanied by a profound bradycardia. Once the person is lying down, blood pressure and pulse recover, along with blood flow to the brain and the return of consciousness, so awakening is usually quick and complete. Fatigue, confusion, and tiredness may persist, but these resolve within a few minutes.
Is syncope the same as "fainting", seizure or "low blood sugar"?
It's not the same thing. Syncope is also called "fainting," "a blackout," "a fit," "a sudden faint," "a stroke," "a blackout," among other names. For doctors, it's a priority, and sometimes a challenge, to distinguish it from other similar situations.
- Seizures/epilepsy: A seizure is very rare in a patient without brain injury, infection, metabolic disorders, or a history of childhood seizures; therefore, evaluating this history is vitally important. Seizures usually begin with a focal manifestation, also known as an aura, which may include visual disturbances, limb movements, muscle spasms, repeated words, or behavioral changes, followed by prolonged rhythmic movements that do not improve when lying down. Recovery after a seizure is usually not rapid and tends to be longer. Normal or elevated blood pressure during the seizure rules out syncope, as it demonstrates normal blood flow to the brain.
- Hypoglycemia: It can cause sweating, tremors, and progressive confusion; loss of consciousness is not usually present. It is almost always associated with insulin use, although some diseases alter insulin secretion, causing hypoglycemia. It is diagnosed when blood pressure and heart rate are normal during the attack, and blood glucose levels are documented as lower than 55 mg/dL during the onset of symptoms.
- Falls due to tripping or loss of balance: A stumble or fall with head trauma can cause amnesia of the event (what in boxing is known as a knockout), so reviewing the circumstances and having witnesses is key to differentiating a fall with a brain contusion from syncope.
Therefore, describing the event well - what they felt before, how long it lasted, how they woke up - is key.
What are the most frequent causes?
The most common cause is reflex or vasovagal syncope, typical in young or middle-aged people. This is a reflex called the "fight or flight reflex" of the autonomic nervous system: the system responsible for many automatic functions, such as heart rate and blood pressure. It is triggered by a stimulus that alerts the body to danger: pain, emotions, the sight of blood, prolonged standing, heat, dehydration, or a combination of factors. It is perceived as a feeling of distress, usually with cold sweats, stomach discomfort, a feeling of emptiness in the stomach, and the sensation that "something bad is going to happen or is happening." The most frequent trigger is standing for a long time without moving: in line, standing in school, at church, or at the kitchen counter, especially when fasting or dehydrated. If the person does not lie down during the episode, the hormones of the autonomic nervous system that try to maintain normal blood pressure collapse, resulting in the sudden drop in blood pressure and heart rate that culminates in syncope.
There is also orthostatic hypotension, which refers to a drop in blood pressure immediately upon standing up. It usually occurs when standing up too quickly after prolonged rest, especially in people taking medication for high blood pressure, those who are dehydrated, have anemia, or are using certain medications.
A smaller but more important group, due to its risk, is syncope of cardiac origin, for example:
- arrhythmias: The heart beats too slowly or too quickly. These irregularities can be benign, causing only fainting, or malignant, associated with sudden death. They are especially relevant in patients with a history of heart attacks that have resulted in scarring of the heart or other heart disease, and in families with a high incidence of heart attacks, pacemakers, or sudden death.
- Structural heart disease: patients with a history of heart valve disease, cardiomyopathies, obstructions, pulmonary hypertension, or pericardial diseases.
- Ischemia such as that present in an acute myocardial infarction, or other less frequent causes.
“Most syncope episodes are benign, but some are a warning sign from the heart.” What warning signs indicate that I should seek urgent medical attention?
It is advisable to seek medical attention on the same day or as a priority if the syncope is accompanied by:
- Chest pain, intense palpitations, or significant shortness of breath.
- Appearance during exercise, especially cardiovascular.
- Occurrence without warning (without dizziness or sensations prior to syncope) or with sudden fall and injuries.
- History of heart disease, heart failure, heart attacks, heart surgery or devices.
- Use of anticoagulants, anticonvulsants, or recent adjustment of blood pressure medications.
- Family history of sudden death, childhood deafness, epilepsy, or unexplained deaths.
- Persistent neurological alterations including weakness or difficulty speaking, or moving any part of the body.
- Repeated episodes in a short period of time.
If the event occurred in an older adult, if there was significant trauma, or if symptoms persist, priority assessment is also worthwhile.
What information is most useful to the doctor?
If you can, write down (or ask someone to write down) these details:
- What were you doing? (standing, sitting, getting up, exercising, heat).
- Were there any "warnings"? (nausea, cold sweats, blurred vision, ringing in the ears).
- How long did the loss of consciousness last?
- How was the awakening? (quick, confusing, drowsy).
- Were there palpitations, chest pain, or shortness of breath?
- Recent medications, diuretics, antihypertensives, alcohol, fasting, diarrhea/vomiting, bleeding.
- If anyone saw the episode, their description is invaluable. Even better would be if we could get hold of a video (security camera footage).
What tests do they usually ask for and why?
Investigating the clinical characteristics of the episode, a focused physical examination (including blood pressure measurement while lying down and standing), and an electrocardiogram (ECG) are usually sufficient to determine whether it was vasovagal syncope or to detect signs of arrhythmias or heart disease. Echocardiography, stress testing, 24-hour Holter monitoring, or blood tests are required in less than 5% of cases. Neurological examinations (imaging, electroencephalogram, neck Doppler) almost never contribute to the diagnosis. The tilt table test is useful for evaluating syncope.
What does it offer? Fundación Valle del Lili in the evaluation of syncope?
In Fundación Valle del LiliSyncope is assessed using a comprehensive and stepwise approach, including education and support based on the cause of the syncope, and education to prevent recurrent vasovagal syncope. The multidisciplinary evaluation combines cardiology and electrophysiology studies when an arrhythmic origin is suspected, and functional tests when the presentation suggests reflex or orthostatic mechanisms. This allows for more precise classification of the type of syncope, avoidance of unnecessary tests, patient education and reassurance, and the definition of preventive measures that usually do not require medication. If necessary, medication adjustments or specific treatments may be made (including therapies for arrhythmias, if identified).
Can it be prevented?
Often yes, especially vasovagal or orthostatic syncope with:
- Proper hydration and avoiding prolonged fasting. Ensuring adequate salt intake.
- Get up gradually (sit for a few seconds before standing up).
- Recognize the “warning” and perform physical maneuvers (cross legs, tense legs and buttocks, lower head below heart level) or sit/lie down.
- Review with your doctor the medications that lower blood pressure.
- In selected cases, there are specific treatments depending on the cause.
If you or someone close to you has experienced a fainting episode, especially if it recurs or occurs with warning signs, don't normalize it. Syncope is a symptom, not a diagnosis: understanding its cause is the best way to prevent further falls and detect problems that do require treatment early on. Fundación Valle del Lili You have access to a comprehensive evaluation service and, if needed, additional studies can be carried out, with the aim of making informed and safe decisions about your health.
