Orthostatic hypotension (OH) and orthostatic intolerance (OI) are common conditions where blood pressure drops when standing up, causing dizziness, fainting, or fatigue. These affect up to 30% of adults over 65 and raise risks for heart disease, stroke, kidney problems, and more. Current medications often don't fully help and can cause side effects like high blood pressure when lying down. The STANDUP study tests a new approach: using a minimally invasive procedure to open narrowed veins above the heart (supracardiac veins) that may block blood flow back to the heart. We believe fixing these blockages could improve blood pressure control and reduce symptoms. This is a 2-year study enrolling 100 adults (age 18+) with OH or OI that hasn't improved with standard treatments or is worsened by lying-down high blood pressure. What happens in the study? Participants get imaging (like X-rays and ultrasound) to check for vein narrowing. If needed, doctors use a thin tube (catheter) through a small skin puncture to inflate a tiny balloon (angioplasty) or place a small mesh tube (stent) to widen the veins. The procedure takes a few hours under local anesthesia, with monitoring for safety. Follow-up visits check symptoms, blood pressure, and quality of life at 2-4 weeks, 3 months, 6 months, 1 year, and 2 years. Who can join? Adults 18+ with diagnosed OH/OI not helped by meds. Must give informed consent. Not eligible if: Pregnant, breastfeeding, actively infected, or unable to take blood thinners. Possible benefits: Better standing tolerance, fewer symptoms, improved daily life, less need for meds, and new knowledge on vein issues in OH/OI. Risks: Rare but include bleeding, infection, stroke, vein clots, stent issues, radiation from imaging, or temporary symptom worsening. We'll monitor closely and report any problems. This single-arm trial (no placebo group) will compare before-and-after results to see if the procedure helps. No study drug costs; covered by insurance or clinic. Led by Dr. Karthikeyan Arcot at St. Francis Hospital, Roslyn, NY. Contact for details.