Illustration: The Watchman device placed in opening to the Left Atrial Appendage

The Watchman™ Device: An Alternative to Blood Thinners

By Steve S. Ryan, PhD, Last updated: August 26, 2020

Available internationally since 2009, the U.S. Food and Drug Administration (FDA) approved Boston Scientific’s WATCHMAN™ occlusion device for use in the U.S. in 2015. The WATCHMAN has been implanted in more than 75,000 patients worldwide.

Do you hate having to take Coumadin or other blood thinners? Hate the side effects? Or are you allergic to them? A replacement for taking blood thinners is the Watchman, an occlusion device.

The theory behind the WATCHMAN™ LAA closure technology is that most A-Fib clots originate in the Left Atrial Appendage (LAA). The Watchman closes off the LAA where 90%-95% of A-Fib strokes come from. It’s a very low risk procedure that takes as little as 20 minutes to install. Afterwards, you would usually not need to be on blood thinners.

Anticoagulants increase the risk of intracerebral hemorrhages (ICH), a less common but more deadly and disabling type of stroke. Over 50% of patients who have a warfarin-related ICH die within the first three months. The Watchman, however, considerably decreases ICH risk by over 50%, even when compared to NOACs.

The Watchman device comes in multiple sizes from 21mm to 33mm to accommodate the different sizes of LAAs. Once a patient’s Left Atrial Appendage is measured, a wide-sheathed catheter with a spline is used to insert the Watchman device which has a self-expanding Nitinol (a special metal) open-ended circular frame.

The atrial surface of this frame is covered with a thin, permeable 160 μm (micron) pore filter made of polyester material (Polyethylene Terephthalate known as Dacron or PET). This filter allows blood to pass through while stopping clots. Little hooks or anchors called fixation barbs at the middle of the device make sure it is attached firmly to the LAA wall.

Before the catheter is removed (which fixes the Watchman in place), contrast agents are used to make sure the Watchman is stable and closes off the LAA opening. Over time heart tissue grows over the polyester (PET) material so that it completely closes off the LAA with smooth heart tissue similar to other heart surfaces.

Photo at right: In this anatomical view of the WATCHMAN device, the heart tissue has completely covered the Watchman device after only nine months. (FYI: This image is an autopsy image; the patient died from non-heart related causes.)

Anatomical View of the WATCHMAN Device in the LAA 9 months after implantation.

Patients on Coumadin continue to take it for six weeks after the Watchman device is inserted. They are then examined using a TEE (Transesophageal Echocardiogram) to make sure there is complete closure of the LAA. At that time they are taken off of Coumadin and put on a different type of blood thinner called clopidogrel (Plavix) until six months after the implant procedure. 

Think of the Watchman as a replacement for blood thinners; both reduce but do not totally eliminate the risk of stroke. The stroke risk is reduced to that of a person with a normal heart.

Even while you are waiting for or trying to decide on having a Pulmonary Vein Ablation, you can have the Watchman inserted and reduce your stroke risk to that of a person without A-Fib.

The Future

Just as closing off the LAA is standard practice in the Cox Maze/Mini-Maze operations, in the future, the Watchman device could become part of most catheter ablation procedures. If included with the ablation procedure, the Watchman would protect the patient from blood clots even if the catheter ablation procedure was unsuccessful. 

And the Watchman device may become standard therapy for anyone at risk of a stroke, not just for people with A-Fib.

For a list of US doctors installing the Watchman device, go to Steve’s Lists/Doctors Installing the Watchman Device.

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