Atritech (Booth 2857) is highlighting its Watchman left atrial appendage (LAA) system, designed to keep blood clots that form in the LAA from entering the blood stream, potentially causing stroke or other complications. The Watchman system is made of nitinol with the atrial facing surface covered with a thin permeable polyester material. The device is constrained within a catheter until delivery in the LAA and is available in varying sizes. The Watchman currently has FDA approval as an investigational device.