Size and motion of the mitral valve annulus in man. II. Abnormalities in mitral valve prolapse.

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Abstract
Changes in mitral annular areas and cyclic area changes were measured in 17 patients with mitral valve prolapse (MVP) and compared with those in 12 normal subjects. Using wide-angle, phased-array, 2-dimensional echocardiography, mitral valve annular attachments were recorded in a view close to the apical 4-chamber view, then at 30.degree. rotational intervals around the circumference of the annulus. Diameters and chords from planes at 30.degree. rotational intervals were used to reconstruct the annulus at selected times during the cardiac cycle. Annular areas were measured by planimetry, corrected for body surface area and expressed as area index. In normal subjects, the maximal mitral annular area index was 3.9 .+-. 0.7 cm2/m2 (mean .+-. SD). Of 11 MVP patients with minimal mitral regurgitation (MR), 5 had a dilated annulus (5.8 .+-. 0.3 cm2/m2, P < 0.001) and 6 had a normal-sized annulus (4.2 .+-. 0.5 cm2/m2). In 6 MVP patients with at least moderate MR, annular dilatation was marked (area index 8.5 .+-. 1.4 cm2/m2, P < 0.001) and systolic annular area reduction (16 .+-. 5%) was less than in normal subjects (27 .+-. 3%, P < 0.001). Cyclic annular area changes in MVP patients with minimal MR were similar to those in normal subjects. Mitral annular size in patients with MVP ranges from normal to markedly dilated. The occurrence of mitral annular dilatation in MVP patients with minimal MR indicates primary or intrinsic annular dilatation rather than annular dilatation secondary to left atrial or left ventricular enlargement. Patients with MVP and significant MR had marked annular dilatation and less-than-normal systolic annular area reduction.