Ballooning deformity (mucoid degeneration) of atrioventricular valves.

In the past three years several reports have drawn attention to a type of mitral incompetence associ- ated with a peculiar deformity of the mitral valve. This is characterized by an increase in area of the affected leaflets which become voluminous and prolapse into the atrium in systole. Various names or descriptions have been applied to the condition, based either on pathological findings (described as myxomatous transformation or floppy valve syndrome by Read, Thal, and Wendt, 1965, and Read and Thal, 1966; and as billowing sail deformity by Oka and Angrist, 1961) or on cine-angiographic appearances (described as ballooning of posterior leaflet by Linhart and Taylor, 1966, and Behar, Whalen, and McIntosh, 1967; as prolapse of posterior leaflet by Criley et al., 1966, and Stannard et al., 1967; as aneurysmal protrusion and billowing of posterior leaflet by Barlow et al., 1968, and Barlow and Bosman, 1966). It appears identical to the two cases described in 1958 by Fernex and Fernex as mucoid degeneration. Most of these reports have been from centres in the U.S.A. and South Africa, but necropsy observations suggest that similar cases are not uncommon in this country.