 Common procedures between protocols: After screening to determine eligibility, subjects visit the lab for either EDD or Rapid Onset Vasodilator ROV study visit. All pre-screening and pre-visit procedures will be identical. A physician will place a brachial arterial catheter in the non-dominant arm for local drug infusion. Changes in blood flow will be quantified by Doppler ultrasound at the brachial artery. Monitoring of subject hemodynamics Heart Rate, Blood Pressure, blood oxygen is identical. 