Poor Sympathetic Compensation During Active Standing Increases the Risk or Morbidity-Mortality in the Post-Surgery of Patients with Severe Calcific Aortic StenosisBy Nydia Ávila-Vanzzini, Anayanci Santana-Ortiz, Daniela Sánchez-Estrada, Rashidi Springall, Abel Lerma, Héctor Herrera-Bello, Martín Calderón-Juárez and Claudia Lerma