The Billowing Mitral Valve Leaflet

Fourteen patients with billowing mitral valves have been studied. In 11 the abnormality was not accompanied by significant cardiac disability. In three, severe mitral insufficiency required mitral valve replacement. Pathological examination of the excised mitral valves showed myxomatous degeneration of mitral valve substance and chordae tendineae. Inhalation of amyl nitrite by the nine patients with late systolic murmurs resulted in a change from late systolic to pansystolic murmur in seven and to mid-systolic murmur in two. On the basis of the known effects of amyl nitrate, this response gives support to the concept that the critical pathogenetic factor is the degree of elongation of chordae tendineae.