What shape is described for the disc in the CLOSE criteria?

The correct choice describes the disc used in the CLOSE criteria as elliptical and concave. This design is significant because the shape contributes to the effectiveness of the Left Atrial Appendage Occlusion device in sealing the left atrial appendage (LAA). The elliptical and concave geometry allows for a better fit within the anatomical variations of the LAA, enhancing the device's ability to conform to the surrounding tissue. This conformance is crucial for preventing blood flow into the appendage, thereby reducing the risk of thrombus formation and subsequent embolic events such as strokes.

Understanding the design attributes of the LAAO device helps clinicians appreciate its function and the rationale behind certain functional features in relation to patient anatomy and the pathophysiology of atrial fibrillation.