The clinical features of pulmonary arteriovenous fistulae have been well documented (Goldman, 1948; Baer, Behrend, and Goldburgh, 1950; Giampalmo, 1950; Muri, 1953; Steinberg and McClenahan, 1955; Le Roux, 1959; Hodgson et al., 1959; Steinberg, 1961; Moyer, Glantz, and Brest, 1962; Jeresaty, Knight, and Hart, 1966), and are largely due to the right-to-left shunt which leads to arterial desatura...