Pulmonary valvulotomy for the relief of congenital pulmonary stenosis. Report of three cases.

"Brock performed the first successful valvotomies for isolated pulmonary stenosis in 1948. He gained access to the blood-filled beating heart through a small incision in the right ventricle through which he passed a valvulotome that was used to enlarge the opening of the stenotic value" (W. Bruce Fye). See Brock's book, The anatomy of congenital pulmonary stenosis, London, 1957.