What Is Presyncope and Why Does It Happen

What Is Presyncope and Why Does it Happen?

The term “presyncope” refers to a condition in which someone experiences sudden difficulty in maintaining consciousness during or immediately after physical exertion. The most common cause of this phenomenon is cardiac arrest (the cessation of blood flow to the brain). Other causes include hypoxia (lack of oxygen) and other physiological changes.

Presyncope may occur suddenly or gradually over time. People with the condition may experience dizziness, fainting spells, confusion, fatigue, anxiety, nausea, sweating and even chest pain. They may have trouble breathing or gasp for air when they do breathe normally. Some people feel like their heart is going to stop beating altogether; others have no symptoms at all!

People with presyncope often suffer from shortness of breath, weakness, numbness, tingling or paralysis in one or both legs. They may also experience a loss of balance and fall down. Others may lose consciousness completely without having any symptoms whatsoever.

Some people who have had cardiac arrests but survived have developed conditions called postcardiac arrest syndrome (PACEs), which are characterized by recurrent episodes of syncope lasting minutes to hours after physical exertion.

While most people with presyncope have no underlying heart conditions, some develop a type of condition called post-heart attack syndrome (PHAS). This is when someone has experienced cardiac arrest due to a heart attack and then begins to experience syncopal episodes after or between attacks.

Phases of Presyncope

Presyncope may be divided into three different phases: prodrome, orthostatic, and true syncope.

The prodromal phase is a warning that someone may be about to experience presyncope or an actual heart attack. The symptoms in this phase are non-specific and may include “adrenaline-like” palpitations, fatigue, a sensation of the heart pounding in the throat ( called globus), upper abdominal pain, diarrhea, and nausea.

During the orthostatic phase there is decreased blood flow to the brain. Some people experience this before presyncope or a heart attack even occurs, while others experience it during the actual event.

During the syncopal event itself, the autonomic nervous system takes over and causes rapid shifting of blood from the limbs to the vital organs. This is quite often unknown or unexpected by the person experiencing it and can last from a few seconds to minutes.

Treatment depends on the cause of presyncope.

If high blood pressure, clogged arteries or an overworked heart are the cause, then these conditions need to be treated. Presyncope may be a precursor to a heart attack.

Sometimes there is no known cause of presyncope and more testing is required. A tilt table test may be ordered to check for possible issues with the autonomic nervous system. If this test is normal, then the person may be prescribed a medication to take during times of physical or emotional stress to help prevent any possible loss of consciousness. Sometimes, when people suffer from presyncope and there is no known cause, doctors will use medical treatments to try to prevent any future fainting events. These treatments can include propranolol or midodrine.

It is important to remember that many people experience presyncope and do not know why. In these cases, it can be helpful to learn how to prevent fainting and to remain calm if it does occur. Sometimes a person can faint after standing for a long time or after they are under emotional stress. Knowing the warning signs of presyncope can help in preventing these events from occurring.

It is also important to talk with your doctor about any potential risk factors you may have.


Sources & references used in this article:

A young man with palpitations and pre-syncope by D Chatterjee – Bmj, 2017 – bmj.com

What Happens before Syncope? Study of the Time Frame Preceding Vasovagal Syncope by A Lagi, S Cencetti, A Cartei – International Scholarly Research Notices, 2011 – hindawi.com

Workshop 3C: Dizziness in Older Adults by V Johnston – laterlifetraining.co.uk

Arterial baroreflexes and cardiovascular modeling by DL Eckberg – Cardiovascular Engineering, 2008 – Springer

The choice of surgical specialization by medical students and their syncopal history by J Rudnicki, D Zyśko, D Kozłowski, W Kuliczkowski… – PloS one, 2013 – journals.plos.org

Postexercise hypotension and sustained postexercise vasodilatation: what happens after we exercise? by JR Halliwill, TM Buck, AN Lacewell… – Experimental …, 2013 – Wiley Online Library