More than 2.6 million Americans have atrial fibrillation (sometimes called A-fib), a fast, irregular heartbeat rhythm caused by chaotic electrical activity in the heart's two upper chambers (atria). Because the heart isn't pumping in a steady, coordinated way, the blood flow out to the body is reduced.

A-fib can cause uncomfortable symptoms, such as fatigue, palpitations and shortness of breath. More serious, it can cause blood clots that may lead to a stroke. Up to 90 percent of these stroke-causing clots originate in the left atrial appendage, a small, hollow sac attached to the left atrium where blood can collect. To prevent clots from forming, patients with A-fib are usually prescribed blood-thinning medications. But some patients can't tolerate these drugs. For A-fib patients who aren't on blood thinners, the risk of stroke increases with age: A-fib causes 15 percent of all strokes, but in patients 70 years and older, it accounts for up to 25 percent of strokes.

An effective way to reduce stroke risk from A-fib is to close off the left atrial appendage. For decades, this was done through open-heart surgery. But recently developed devices have made it possible to close off the appendage through minimally invasive procedures, in which thin, flexible tubes (catheters) are guided through blood vessels to access the heart. If you are considering these procedures, understand that closing the appendage lowers stroke risk but doesn't cure A-fib.

The Watchman is an implantable device that acts as a plug to seal off the left atrial appendage. This parachute-shaped device is about the size of a quarter and made of light, compact materials used in many other medical implants.

UCSF was among the first medical centers to perform a procedure that uses a lasso-like device called the Lariat to close the appendage. The Lariat is a pre-tied loop of suture (stitching material) that the doctor places around the outside of the appendage to tie it off from the heart. UCSF cardiologist Dr. Randall Lee helped develop the Lariat and has since trained cardiologists from more than 100 medical centers to perform the procedure.

UCSF is one of the few hospitals in the country to offer both treatments.


Potential candidates for either procedure are evaluated in our electrophysiology clinic. To be eligible for the Watchman device, you must be able to take anticoagulation and antiplatelet medications for a period of time after the procedure. Having the Lariat procedure doesn't require this. Some patients can't undergo either procedure because of prior heart surgery or the particular anatomy of their left atrial appendage.

To determine the size and shape of your atrial appendage, your doctor will order one or more imaging tests. Options include:

  • A cardiac MRI uses powerful magnets and radio waves to create pictures of the heart. A harmless dye that highlights blood vessels and heart structures may be injected into the circulatory system.
  • A cardiac CT scan takes detailed X-ray images of the heart and blood vessels. When patients may be having the Lariat procedure, this test is used to evaluate the size and shape of the left atrial appendage.
  • The transesophageal echocardiogram (TEE) is an ultrasound test in which a thin tube conveys a transducer (a device emitting sound waves) down the throat to obtain clear heart images from inside the body. TEE is the preferred imaging test for the Watchman procedure.


For both the Watchman and Lariat procedures, patients stay in the hospital for at least one night.

These minimally invasive procedures are performed in a similar manner. A catheter carrying the device is inserted into the femoral artery (in the groin) and threaded through blood vessels to the heart. A combination of X-rays and TEE imaging is used to guide implantation. Once the device is in place, the catheter is withdrawn. Each procedure takes two to three hours, and patients are under general anesthesia (completely asleep).

In the Watchman procedure, the left atrial appendage is accessed from inside the heart. The device is placed across the opening of the appendage, sealing off the space so that blood can't collect in it. Over time, scar tissue grows around the device, securing it in place. Watch this video to learn more about the Watchman procedure.

In the Lariat procedure, the loop is placed around the outside of the left atrial appendage and pulled tight, sealing it off from the rest of the heart. This requires accessing the heart through both the groin and chest wall. The chest access is obtained by passing a long needle under the rib cage, rather than cutting through the chest wall as in open-heart surgery.


Following either procedure, you have to stay in bed for at least four hours to prevent bleeding. During that time, we closely monitor your heart rate, blood pressure, oxygen levels and breathing.

Most patients can go home the day after their procedure. Your doctor may advise you to avoid driving for several days to a few weeks and to avoid strenuous exercise for a week. You may be instructed to take aspirin for about a month to reduce the risk of clots forming in your heart and blood vessels.

Remember, closing the left atrial appendage doesn't cure atrial fibrillation. These procedures reduce stroke risk in people with A-fib. Patients who undergo one of these procedures still have A-fib and may experience palpitations or other symptoms related to the condition.