Skip to content

Passing Out (Syncope) Caused by Arrhythmias

Font Size

Topic Overview

Syncope (say "SING-kuh-pee") refers to a sudden loss of consciousness that soon passes. Syncope may be the first sign that you have an arrhythmia. And it is a very worrisome symptom for several reasons:

  • Passing out can cause a serious injury. For example, passing out while climbing the stairs or while driving can cause serious harm.
  • If you pass out because your brain did not get enough oxygen to function, this may be a warning sign that you have a serious medical condition.

An arrhythmia can cause syncope in the same way that it causes lightheadedness (presyncope). Your heart cannot pump blood effectively during excessively fast (tachycardia) or slow (bradycardia) heart rates, reducing the amount of blood that reaches your brain.

Recommended Related to Heart Disease

His Guide to a Heart Attack: Symptoms in Men

In the movies, you never doubt when a man's having a heart attack. He clutches his chest, screams, or moans, and falls to the ground. If he's lucky, help is on its way. In real life, the signs aren't always so clear. Some people do experience Hollywood-type symptoms, says Mohamud Daya, MD, an associate professor of emergency medicine at Oregon Health and Science University in Portland. But others don’t. “Some people say they just feel uneasy discomfort or vague discomfort, not pain that really hurts...

Read the His Guide to a Heart Attack: Symptoms in Men article > >

With syncope, though, the arrhythmia causes such a dramatic drop in the blood pressure that the brain does not receive enough blood to keep you conscious, and you lose consciousness as a result. For an arrhythmia to cause syncope, your heart rate must be extremely fast or extremely slow, or you must have some other heart condition in addition to the arrhythmia.

How long does syncope last?

It is important to recognize that syncope is transient, meaning that you wake up soon after passing out. You may wake up because the arrhythmia stops on its own and a normal rhythm and blood pressure return. Even if the arrhythmia persists, you may still regain consciousness. When you have an episode of syncope due to an arrhythmia, it typically happens while you are standing or sitting, and the loss of consciousness causes you to fall to the floor. As soon as you are lying down, blood flows back into your brain, even though your blood pressure may remain low. When enough blood flows back into your brain, you will likely wake up.

What are the risks associated with passing out from an arrhythmia?

Fast or slow arrhythmias may cause you to pass out. Depending on your position and activity at the time of the episode, you may seriously injure yourself. If you are standing up at the time of the arrhythmia, you may pass out and fall. The fall may cause you to injure your head, break an arm or leg, or receive other injuries. If you are driving, you may crash, causing severe injury to yourself and anyone else involved.

Passing out may be a sign that you are at risk for a life-threatening arrhythmia. If you have symptoms of an arrhythmia that may cause you to pass out, do not drive any vehicle until your condition has been evaluated and treated.

1|2

WebMD Medical Reference from Healthwise

Last Updated: June 02, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
Next Article:

Passing Out (Syncope) Caused by Arrhythmias Topics

Hot Topics

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

MS Overview
Recognizing symptoms.
feet
Solutions for 19 types.
pregnancy test and calendar
Helping you get pregnant.
build a better butt
How to build a better butt.
lone star tick
How to identify that bite.
woman standing behind curtains
How it affects you.
brain scan with soda
Tips to avoid complications.
row of colored highlighter pens
Tips for living better.
stressed working woman
And how to fix them?
woman dreaming
What Do Your Dreams Say About You?
spinal compression fracture
Treatment options.

Women's Health Newsletter

Find out what women really need.