Changfu Wu1, Bernard Vasseur1, William Maisel2. 1. Division of Circulatory Support, Structural and Vascular Devices, Office of Cardiovascular Devices, Office of Product Evaluation and Quality, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland. 2. Office of Product Evaluation and Quality, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland.