Syncope (Passing out)

What is Syncope?

Syncope or passing out, occurs due to a temporary decrease in blood flow to the brain. Presyncope is when you feel that you are about to faint. It describes the phase when a person feels unwell but is still conscious. Syncope can be a simple condition that most people experience at some point in their lives, or it can be the first and only warning before sudden death. The underlying cause should be thoroughly investigated.

what is Syncope (fainting)
Syncope (fainting) is a loss of consciousness or unconsciousness due to temporary impairment of brain blood supply and oxygenation.

Why does syncope happen?

Syncope or passing out, occurs when there is not enough blood supply to your brain. Serious underlying life-threatening illnesses or milder causes can also cause syncope. The most common are the following;

  • Cardiac Syncope (heart-related causes)
  • Vasovagal syncope (Reflex syncope)
  • Orthostatic syncope (positional, that is, low blood pressure when standing up)

What is Cardiac Syncope?

If fainting occurs frequently, usually without symptoms and suddenly, it may be caused by problems with the heart.

Fainting due to heart arrhythmia occurs when the heart speeds up (tachyarrhythmia) or slows down (bradyarrhythmia). The heart cannot pump enough blood, blood pressure drops and fainting occurs. AV blocks, cardiac pauses, ventricular tachycardia and rarely SVTs can cause fainting. Patients may not feel any symptoms before fainting and may suddenly lose consciousness. Some patients feel palpitations just before fainting.

Apart from arrhythmias, some heart diseases that cause syncope include

  • Serious valve stenosis
  • Some heart diseases characterized by thickening of the heart wall
  • Clot in the vessel carrying blood to the lungs
  • Severe fluid accumulation around the heart
  • Tears in the aortic artery can cause fainting.

If the cause of fainting is directly related to cardiac arrhythmia or other structural heart diseases, it can be life-threatening and requires cardiological evaluation.

What is Vasovagal Syncope?

In reflex syncope, also known as vasovagal syncope, certain triggers cause a drop in heart rate, blood pressure or both, resulting in a brief loss of consciousness and fainting. Vasovagal syncope is the most common cause of syncope.

What are the Triggers of Vasovagal Syncope?

The triggers for fainting in vasovagal syncope can be pain, a bad image, giving blood, standing for a long time, extreme heat or crowded environment, or basic functions such as coughing. Sometimes it can also occur without any cause.

What are the Symptoms of Vasovagal Syncope?

In vasovagal syncope, just before the person faints;

  • Darkening of the eyes
  • Cold sweats or hot flashes
  • Feeling faint
  • Nausea, vomiting, abdominal discomfort
  • Symptoms such as palpitations (due to a condition called sinus tachycardia, in which the rhythm is normal but only the rate is increased) may occur.

In vasovagal syncope, the patient appears pale and cold. A short period of fainting occurs and then the person regains consciousness. This condition is usually not life-threatening in people without structural heart disease. However, with fainting comes the risk of accidents and serious problems can occur as a result of a fall.

How is Vasovagal Syncope Treated?

The most important treatment for vasovagal syncope is to avoid the cause of fainting. If fainting is always caused by standing for a long time, this can be avoided. Apart from that, it is important to increase fluid intake. It is useful to do leg strengthening exercises. If doing these exercises while standing causes complaints, you may prefer seated exercises. Rowing is an effective seated exercise. Your doctor may use appropriate medication according to the characteristics of your disease.

If the main cause of fainting is low pulse rate or both low pulse rate and low blood pressure, it is possible to increase the pulse rate and prevent fainting attacks with ablation treatments (cardioneuroablation).

What is Orthostatic Syncope?

Syncope due to low blood pressure when standing up is called orthostatic syncope. It is usually diagnosed after other causes are excluded. It is caused by fluid losses or disorders in the system that regulates our heart rate / blood pressure balance, which we call the autonomic system.

How is Syncope Diagnosed?

Syncope can usually be diagnosed by ECG, Echocardiography, Effort test, Tilt test or Electrophysiological study (EPS).

Some of the frequently asked questions about syncope and fainting are as follows.

How many minutes is a syncope?

Syncope is a short-term loss of consciousness. It lasts 1-2 minutes. If it lasts longer, it is life-threatening.

Why did I passing out while on the toilet?

Syncope or passing out sometimes occurs in the toilet. We can explain the reason for this as follows. When going to bed at night, everyone’s pulse and blood pressure drops a little. Because the need is low. However, when we wake up and stand up, our blood pressure and pulse rate must rise so that adequate circulation can be provided. Some people’s blood pressure and pulse rate do not rise immediately when they get out of bed at night. In this case, if we try to stand up or even push and lower our blood pressure a little more, the blood flow to the brain is not sufficient and blackouts and fainting may occur. In some people, the reflex mechanism (parasympathetic system) also kicks in, further lowering the blood pressure and pulse rate. If we continue to try to stand, fainting occurs.

After fainting, unless there is a serious structural heart disease, blood pressure and pulse rate increase because the person is in a horizontal position and the sympathetic system, which acts as the body’s countermeasure system, is activated, blood flow to the brain increases and the person usually comes to within a short time. In this situation, we should not force ourselves to stand up and, if possible, remain in a horizontal or at least sitting position until full recovery is achieved.

This condition, called reflex or vasovagal syncope, is usually not life-threatening, but falling on a hard surface such as a toilet creates a risk of trauma. It is a condition that needs to be prevented and treated.

What to do in a syncope episode?

What to do in case of fainting depends on the cause of the syncope. The first thing to check is the presence of breathing during fainting. It is checked whether the person is breathing or not. The pulse is checked. Check whether there is a pulse, and if so, whether it is low. If the cause is reflex syncope (vasovagal), the person is expected to regain consciousness within 1-2 minutes. After regaining consciousness, the person should stay in a lying position for 10-15 minutes if possible. If it is not possible to stay in a lying position, the person should stay in a sitting position for a while. If the person does not regain consciousness within a few minutes, emergency help should be called immediately.

Can medicines cause fainting?

The use of medicines that lower the heart rate, lower blood pressure or diuretics can sometimes cause fainting. Other causes of fainting are low blood sugar, low oxygen in the blood, alcohol intake, illegal drugs can also cause fainting.

Reference: Syncope

Update: February 13, 2024

Share this post
Picture of Prof. Dr. Taylan Akgün
Prof. Dr. Taylan Akgün

He is a cardiologist specialised in the diagnosis and treatment of heart rhythm problems (ablation), pacemaker procedures.
He works in Istanbul province.

Related Articles