Sam had a condition called Paget-Schroetter syndrome, which is effort-induced thrombosis (blood clot) of the subclavian vein (the major vein of the arm and shoulder). The condition is named for two physicians that independently described this condition in the late 1800s. It occurs most often in young healthy men. The only details I know of Sam's medical conditions are from reading the press, but it is clear that in 2016 he had a major infection in his neck, which required surgery. An infection like that can cause scarring, which can make the tight space where Paget-Schroetter occurs, the thoracic outlet, even tighter, which increases the risk of blood clot at that site.