Machii K
Third Department of Internal Medicine, Toho University School of Medicine, Tokyo.
J Cardiogr Suppl. 1986(11):35-56.
Several unsolved problems in the echocardiographic diagnosis of mitral valve prolapse were reviewed. At present, two-dimensional echocardiography is the most reliable method for assessing mitral valve prolapse. However, basic knowledge on the anatomical orientation of the mitral annulus, hitherto not sufficiently studied, is indispensable before making adequate echocardiographic diagnosis. The annulus is not like a geometrical plane and occupies certain millimeters' width between the left atrium and the ventricle. Therefore, assuming the left atrial margin of the annulus as the reference, many unmistakable prolapse with mitral regurgitation are overlooked, while assuming the left ventricular margins as the reference, some false positive diagnoses will be inevitable. Consulting several autopsy specimens, the author noticed that the central fibrous body, the site of the anterior mitral valve insertion to the interventricular septum, forms the most inferior part of the mitral annulus. This fact could explain a higher sensitivity of the apical four-chamber view for detecting anterior mitral valve prolapse reported by several investigators, and also more frequent over-diagnosis according to our experience. Although the author prefers the left ventricular margin of the mitral annulus defined by the long-axis view as the reference for echocardiographic diagnosis of mitral prolapse, further investigation should be made in relation to the clinical significance of this abnormality diagnosed by echocardiography.
回顾了二尖瓣脱垂超声心动图诊断中几个尚未解决的问题。目前，二维超声心动图是评估二尖瓣脱垂最可靠的方法。然而，在进行充分的超声心动图诊断之前，二尖瓣环解剖方位的基础知识是必不可少的，而这方面迄今尚未得到充分研究。二尖瓣环并非一个几何平面，在左心房和心室之间占据一定的毫米宽度。因此，以二尖瓣环的左心房边缘为参照，许多伴有二尖瓣反流的明确脱垂会被漏诊，而以左心室边缘为参照，则不可避免地会出现一些假阳性诊断。通过查阅多个尸检标本，作者注意到二尖瓣前叶附着于室间隔的部位即中心纤维体，构成了二尖瓣环的最下部。这一事实可以解释一些研究者报道的在心尖四腔心切面检测二尖瓣前叶脱垂时具有较高的敏感性，以及根据我们的经验出现更频繁的过度诊断。虽然作者倾向于将由长轴切面定义的二尖瓣环的左心室边缘作为二尖瓣脱垂超声心动图诊断的参照，但对于通过超声心动图诊断的这种异常的临床意义仍需进一步研究。
