Roberts W C, Waller B F
Am Heart J. 1981 May;101(5):619-21. doi: 10.1016/0002-8703(81)90229-5.
Attention is called to the occurrence of a complete circle or "O"-shaped ring of calcium at the mitral anular region in each of two women, aged 67 and 82 years. Extension of mitral anular calcium from behind the posterior mitral leaflet across the ventricular aspect of the anterior mitral leaflet to form a complete circle has not been reported previously.
值得注意的是，在两名分别为67岁和82岁的女性中，二尖瓣环区域均出现了完整的圆形或“O”形钙环。二尖瓣环钙化从二尖瓣后叶后方延伸至二尖瓣前叶心室面并形成完整的环，此前尚未见报道。
