1. Section of Valvular Heart Disease; Institute Dante Pazzanese of Cardiology; São Paulo Brazil
2. Oral Anticoagulation Unit; Institute Dante Pazzanese of Cardiology; São Paulo Brazil
3. Laboratory at the Orthopedics and Traumatology Institute - HCFMUSP; São Paulo Brazil
4. Laboratory at the Institute Dante Pazzanese of Cardiology; São Paulo Brazil