Trumps not getting enough blood to the brain...you'd think the anti christ minion could fix that: Chronic venous insufficiency (CVI) occurs when leg veins have difficulty returning blood to the heart, leading to blood pooling and increased pressure. The primary underlying cause is usually malfunctioning or damaged valves in the veins, which normally prevent backflow of blood. This can be caused by various factors, including blood clots (deep vein thrombosis), inflammation, injury, or even age-related wear and tear.