A left atrial appendage closure is a procedure that's sometimes done when you have atrial fibrillation.

The heart has its own electrical system that helps keep the heart in rhythm and helps control how fast it beats.

With atrial fibrillation, tiny areas of heart tissue send extra electrical signals.

Those extra signals cause the upper chambers of your heart—called the atria— to quiver, or "fibrillate."

That quivering motion can lead to blood clots in the left atrium.

Most of these clots form in the left atrial appendage, a small sac in the left atrium.

And when the blood pools there, it can form blood clots.

If a clot moves out of the heart and travels to the brain, it may cause a stroke.

So a left atrial appendage closure is done to close off the appendage and help prevent a blood clot from moving out of the appendage.

The closure can block off the sac completely so clots can't form there.

The idea of having this procedure may seem scary.

But it can help to learn as much as you can about what it is, how it can help you, and how to prepare.

This is how a left atrial appendage closure is done.

You may be asleep for the procedure.

Or you may get a sedative to help you relax.

To begin, the doctor makes a small cut, an incision—or it might just be a small poke—in a blood vessel.

This is typically done in your groin.

A thin tube called a catheter is then carefully guided through the blood vessel to the heart and to the left atrium.

To guide the catheter, your doctor looks at pictures of your heart using an X-ray.

Now, there are different devices that can be used for this procedure.

No matter which device is used, your doctor will move the tip of the catheter to the appendage and then place the device inside it.

The device is collapsed to fit inside the catheter.

Once it's in place, the device expands and closes off the opening.

It stays inside your heart.

At the end of the procedure, the doctor will remove the catheter.

You'll stay in a recovery room for a while.

If the catheter was put in your groin, you will need to lie still and keep your leg straight for several hours.

This is to make sure the catheter site has healed enough to stop any bleeding.

After the procedure, you may stay at least one night in the hospital.

Before the procedure, tell your doctor about all the medicines and natural health products you take, especially blood thinners.

Some can raise the risk of bleeding or cause problems with anesthesia.

Your doctor will tell you which medicines to take or stop before the procedure.

And follow your doctor's directions for preparing for your procedure, including when you should stop eating and drinking.

Be sure to bring your photo ID, health insurance card, and any paperwork your hospital may have asked for.

Having a heart procedure can be stressful.

But knowing what to expect and how to prepare can help.

And remember, you can always call your doctor if you have any questions or concerns.