Schwammenthal E, Nakatani S, He S, Hopmeyer J, Sagie A, Weyman A E, Lever H M, Yoganathan A P, Thomas J D, Levine R A
Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Boston 02114, USA.
Circulation. 1998 Sep 1;98(9):856-65. doi: 10.1161/01.cir.98.9.856.
In hypertrophic cardiomyopathy, a spectrum of mitral leaflet abnormalities has been related to the mechanism of mitral systolic anterior motion (SAM), which causes both subaortic obstruction and mitral regurgitation. In the individual patient, SAM and regurgitation vary in parallel; clinically, however, great interindividual differences in mitral regurgitation can occur for comparable degrees of SAM. We hypothesized that these differences relate to variations in posterior leaflet length and mobility, restricting its ability to follow the anterior leaflet (participate in SAM) and coapt effectively.
Different mitral geometries produced surgically in porcine valves were studied in vitro. Comparable degrees of SAM resulted in more severe mitral regurgitation for geometries characterized by limited posterior leaflet excursion. Mitral geometry was also analyzed in 23 patients with hypertrophic cardiomyopathy by intraoperative transesophageal echocardiography. All had typical anterior leaflet SAM with significant outflow tract gradients but considerably more variable mitral regurgitation; therefore, regurgitation did not correlate with obstruction. In contrast, mitral regurgitation correlated inversely with the length over which the leaflets coapted (r= -0.89), the most severe regurgitation occurring with a visible gap. Regurgitation increased with increasing mismatch of anterior to posterior leaflet length (r=0.77) and decreasing posterior leaflet mobility (r= -0.79).
SAM produces greater mitral regurgitation if the posterior leaflet is limited in its ability to move anteriorly, participate in SAM, and coapt effectively. This can explain interindividual differences in regurgitation for comparable degrees of SAM. Thus, the spectrum of leaflet length and mobility that affects subaortic obstruction also influences mitral regurgitation in patients with SAM.
在肥厚型心肌病中，一系列二尖瓣叶异常与二尖瓣收缩期前向运动（SAM）的机制有关，SAM会导致主动脉瓣下梗阻和二尖瓣反流。在个体患者中，SAM和反流呈平行变化；然而在临床上，对于程度相当的SAM，二尖瓣反流在个体之间可能存在很大差异。我们推测这些差异与后叶长度和活动度的变化有关，这限制了后叶跟随前叶（参与SAM）并有效对合的能力。
对猪瓣膜手术制造的不同二尖瓣几何形状进行体外研究。对于以有限的后叶活动为特征的几何形状，程度相当的SAM会导致更严重的二尖瓣反流。还通过术中经食管超声心动图分析了23例肥厚型心肌病患者的二尖瓣几何形状。所有患者均有典型的前叶SAM，伴有明显的流出道梯度，但二尖瓣反流的变化要大得多；因此，反流与梗阻无关。相反，二尖瓣反流与瓣叶对合长度呈负相关（r = -0.89），最严重的反流发生在可见间隙时。反流随着前后叶长度不匹配的增加（r = 0.77）和后叶活动度的降低（r = -0.79）而增加。
如果后叶向前移动、参与SAM并有效对合的能力受限，SAM会导致更严重的二尖瓣反流。这可以解释在程度相当的SAM情况下反流的个体差异。因此，影响主动脉瓣下梗阻的瓣叶长度和活动度范围也会影响SAM患者的二尖瓣反流。
