1. Department of Anatomy and Cell Biology, Faculty of Medicine, University of Extremadura, 06071 Badajoz, Spain
2. Servicio de Cardiología, Hospital Infanta Cristina, 06006 Badajoz, Spain
3. Hospital Universitario Quirón-Madrid, European University of Madrid, 28223 Madrid, Spain
4. Department of Radiology, University of Southern California, Los Angeles, CA 90089-4019, USA