Interview with Thenappan Thenappan, MD, author of Trends and Outcomes of Pulmonary Arterial Hypertension–Related Hospitalizations in the United States: Analysis of the Nationwide Inpatient Sample Database From 2001 Through 2012, Bradley A. Maron, MD, author of Pulmonary Arterial Hypertension in the Contemporary Era, and Vallerie V. McLaughlin, MD, author of Burden of Pulmonary Arterial Hypertension