Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-dong Songpa-gu, Seoul 138-736, South Korea.
Circulation. 2010 Sep 28;122(13):1298-307. doi: 10.1161/CIRCULATIONAHA.109.935551. Epub 2010 Sep 13.
Analyzing the determinants of systolic anterior motion of the mitral valve and consequent left ventricular outflow tract (LVOT) obstruction in patients with asymmetrical septal hypertrophy requires a comprehensive 3-dimensional analysis of mitral leaflet (ML) area, papillary muscle (PM) geometry, and the distribution of left ventricular hypertrophy.
Real-time 3-dimensional echocardiography was performed in 47 patients with asymmetrical septal hypertrophy and 32 normal controls. Patients included 20 with resting LVOT obstruction (group I) and 27 without (group II). Customized software (Omni 4D) provided a validated measure of ML surface area, LVOT area, mitral annular area and nonplanarity, LVOT hypertrophy index by topography (percent area with wall thickness >16 mm), and 3-dimensional PM positions relative to annulus. ML area was more than twice as large in group I than normal and 1.4 times normal in group II (P<0.001). Group I patients were also characterized by higher LVOT hypertrophy index and medial and anterior displacements of both PMs, resulting in a shorter inter-PM distance. Independent determinants of LVOT obstruction were indexed total ML area (adjusted odds ratio, 5.651; 95% confidence interval, 1.573 to 20.304; P=0.008) and inter-PM distance (adjusted odds ratio, 0.416; 95% confidence interval, 0.203 to 0.854; P=0.0169). Minimal LVOT area during systole correlated well with peak LVOT pressure gradient (R(2)=0.83, P<0.001); its independent determinants were left ventricular end-systolic volume (P=0.0183), indexed total ML area (P=0.0108), inter-PM distance (P=0.0378), annular height (P=0.0047), and LVOT hypertrophy index (P=0.0098).
Myocardium is not the only tissue affected in patients with asymmetrical septal hypertrophy, and primary changes of the mitral apparatus, including ML area increase and PM displacement, are independent determinants of LVOT obstruction and provide a comprehensive mechanism that determines leaflet slack and anteriorly directed motion. Abnormal PM-mitral valve geometry assessed by real-time 3-dimensional echocardiography can provide reasonable new targets for individualized intervention.
分析二尖瓣前叶运动和左心室流出道（LVOT）梗阻的决定因素在不对称性室间隔肥厚患者中需要全面的二尖瓣叶（ML）面积，乳头肌（PM）几何形状和左心室肥厚分布的三维分析。
对 47 例不对称性室间隔肥厚患者和 32 例正常对照进行实时三维超声心动图检查。患者包括 20 例静息性 LVOT 梗阻（I 组）和 27 例无梗阻（II 组）。定制软件（Omni 4D）提供了 ML 表面积，LVOT 面积，二尖瓣环面积和非平面性，LVOT 肥厚指数（通过拓扑学测量的壁厚度> 16mm 的百分比面积）以及相对于瓣环的 3D PM 位置的验证性测量。I 组的 ML 面积比正常组大两倍，比 II 组大 1.4 倍（P<0.001）。I 组患者还具有较高的 LVOT 肥厚指数和两个 PM 的内侧和前移位，导致 PM 之间的距离缩短。LVOT 梗阻的独立决定因素是指数化总 ML 面积（调整后的优势比，5.651；95％置信区间，1.573 至 20.304；P=0.008）和 PM 之间的距离（调整后的优势比，0.416；95％置信区间，0.203 至 0.854；P=0.0169）。收缩期最小 LVOT 面积与 LVOT 压力梯度峰值相关性良好（R（2）=0.83，P<0.001）；其独立决定因素是左心室收缩末期容积（P=0.0183），指数化总 ML 面积（P=0.0108），PM 之间的距离（P=0.0378），瓣环高度（P=0.0047）和 LVOT 肥厚指数（P=0.0098）。
不对称性室间隔肥厚患者的心肌不是唯一受影响的组织，二尖瓣装置的主要变化，包括 ML 面积增加和 PM 移位，是 LVOT 梗阻的独立决定因素，并提供了决定瓣叶松弛和向前运动的综合机制。实时三维超声心动图评估的异常 PM-二尖瓣几何形状可为个体化干预提供合理的新目标。
