Prolapsed mitral cusps in atrial septal defect. An erroneous radiological interpretation.

Forty patients with simple atrial septal defect had left ventriculograms using cineangiography and/or Elema or Sircam still films. All had open heart surgery and careful scrutiny of the mitral valve by experienced surgeons. Prolapse of the posterior cusp was diagnosed from angiography in 28 patients but was confirmed at operation in only 5. Another 5 had a different mitral valve abnormality and the remaining 18 had no clinical signs to suggest mitral valve dysfunction after operation. It is concluded that though true ballooning or prolapse of the mitral cusps may coexist with simple atrial septal defect, its presence is overdiagnosed from the appearances of left ventriculography on anteroposterior, lateral, and right anterior oblique views. Left ventriculography was equally unreliable in the exact recognition of other anatomical abnormalities of the mitral valve in secundum defect, but accurate when the mitral valve was pronounced to be structurally normal.