What is Syncope?

Your brain and body need a steady supply of oxygen-rich blood. If your blood pressure drops too low, your brain may not get enough blood, and your body responds by briefly losing consciousness. You may slump or fall down. This problem is called syncope, fainting, or a blackout.

Your heart rate and blood pressure adjust to maintain a steady blood supply throughout all your activities. The heart creates electrical signals that travel through it on pathways. These signals set the heart rate, and tell the heart when to pump blood. In response to your body’s needs, your brain may also trigger changes in your heart rate and blood pressure. This keeps your blood flow strong.

What causes syncope?

Syncope is a common problem with many possible causes. Often these causes are not serious. For instance, syncope can be caused by standing for too long or sitting up too fast. In some cases, you may never faint again.

When syncope is not serious

Your doctor may call your problem vasovagal syncope or orthostatic hypotension. These two types of syncope are not serious. They can be caused by:

  • Strong feelings, such as anxiety or fear. A nerve signal may briefly change your heart rate and lower your blood pressure too much.
  • Standing for too long. Standing may cause blood to pool in your legs. When this happens, your brain may not receive all the blood it needs.
  • Standing up too quickly. Your blood pressure may not adjust fast enough to changes in posture and may drop too low. Certain medications can also cause this problem.

When heart trouble causes syncope

If heart trouble causes syncope, this can be serious. A heart problem can decrease the amount of oxygen-rich blood that reaches the brain. Symptoms that may indicate heart trouble include:

A slow heart rate. Electrical signals tell the chambers of the heart when to pump. But the signals may be slowed or blocked (heart block) as they travel on the heart’s pathways. This can be caused by aging, scarred heart tissue or damage from heart disease. When the heart rate slows, not enough blood is pumped. 

A fast heart rate. Certain problems can make the heart race. For instance, after a heart attack, abnormal electrical signals may be created. These signals can make the heart suddenly beat very fast. The heart pumps before the chambers can fill with blood. So less blood reaches the brain and other parts of the body. Illegal drugs, certain medications, heart disease, or an inherited condition can also cause this.

Syncope may also indicate a heart valve problem. Blood travels through the chambers of the heart as it is pumped. Heart valves open and close to help move blood in the right direction. But if it’s hardened or scarred, a valve may not open or close fully. As a result, less blood is pumped through the heart to the brain and body and you experience syncope.

How is syncope treated?

Treatment depends on the cause of syncope, which your doctor can determine. To provide the most appropriate treatment, your doctor will want to learn why you fainted. If you have more than one instance of syncope, try to take note of the circumstances so you can tell your doctor.