Syncope

What causes syncope?

Most often referred to as fainting or passing out, syncope is a temporary loss of consciousness related to insufficient blood flow to the brain. It’s most often due to what’s called neurally mediated syncope (NMS). Your doctor may also call it reflex syncope or vasovagal syncope.

NMS typically starts in childhood but can occur in adults as well. It’s caused by a glitch in the portion of your nervous system that regulates blood pressure and heart rate. The malfunction may cause you to faint in response to emotional stress, such as a sudden fright in a haunted house or the sight of blood.

This type of syncope typically occurs when you’re standing and a sensation of warmth, nausea, lightheadedness, or tunnel vision may warn you an episode is about to occur. Patients often report that their vision grays out right before experiencing a fainting spell.

These fainting episodes end when you’re placed in a supine position (lying down with your face upward). NMS can also be caused by certain physical functions, such as violent coughing or excessive laughing.

When should I be concerned about syncope?

If you’ve suddenly developed fainting episodes, it’s always best to check with your doctor to rule out serious conditions. It’s especially important that you seek medical care if you have a family history of recurrent syncope or sudden death, or if your fainting episodes are related to:

• Exercise
• A medication you’re taking, such as a drug to lower your blood pressure
• Palpitations or an irregular heart rhythm

What causes cardiac syncope?

While the loss of consciousness experienced with cardiac syncope is also due to insufficient blood flow to the brain, its underlying cause can be related to various heart issues. An excessively slow heart rate (bradycardia) and an excessively fast heart rate (tachycardia) can lead to spells of cardiac syncope and may also cause sudden cardiac death.

Other conditions that may cause cardiac syncope include:

• Coronary artery disease
• Aortic valve stenosis (narrowing of the aortic heart valve)
• Heart failure

What is the treatment for cardiac syncope?

The first step in treatment is a thorough evaluation that may include diagnostic studies to rule out serious cardiac issues. Treatment is then based what’s causing decreased blood flow to your brain that’s leading to syncope.