1. University of California San Francisco, San Francisco, CA, USA
2. Baylor College of Medicine, Houston, TX, USA
3. The Methodist Hospital-Michael E Debakey Heart and Vascular Institute, Houston, TX, USA
4. Duke University Medical Center, Durham, NC, USA
5. Harris County Hospital District – Ben Taub General Hospital, Houston, TX, USA
6. Michael E Debakey Veterans Affairs Hospital, Houston, TX, USA