Cardiovascular Imaging Institute, Houston Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA.
Department of Mathematics, University of Houston, Houston, Texas, USA.
JACC Cardiovasc Imaging. 2021 Jun;14(6):1099-1109. doi: 10.1016/j.jcmg.2021.01.006. Epub 2021 Mar 17.
The aim of this study was to quantitate patient-specific mitral valve (MV) strain in normal valves and in patients with mitral valve prolapse with and without significant mitral regurgitation (MR) and assess the determinants of MV strain.
Few data exist on MV deformation during systole in humans. Three-dimensional echocardiography allows for dynamic MV imaging, enabling digital modeling of MV function in health and disease.
Three-dimensional transesophageal echocardiography was performed in 82 patients, 32 with normal MV and 50 with mitral valve prolapse (MVP): 12 with mild mitral regurgitation or less (MVP - MR) and 38 with moderate MR or greater (MVP + MR). Three-dimensional MV models were generated, and the peak systolic strain of MV leaflets was computed on proprietary software.
Left ventricular ejection fraction was normal in all groups. MV annular dimensions were largest in MVP + MR (annular area: 13.8 ± 0.7 cm) and comparable in MVP - MR (10.6 ± 1 cm) and normal valves (10.5 ± 0.3 cm; analysis of variance: p < 0.001). Similarly, MV leaflet areas were largest in MVP + MR, particularly the posterior leaflet (8.7 ± 0.5 cm); intermediate in MVP - MR (6.5 ± 0.7 cm); and smallest in normal valves (5.5 ± 0.2 cm; p < 0.0001). Strain was overall highest in MVP + MR and lowest in normal valves. Patients with MVP - MR had intermediate strain values that were higher than normal valves in the posterior leaflet (p = 0.001). On multivariable analysis, after adjustment for clinical and MV geometric parameters, leaflet thickness was the only parameter that was retained as being significantly correlated with mean MV strain (r = 0.34; p = 0.008).
MVs that exhibit prolapse have higher strain compared to normal valves, particularly in the posterior leaflet. Although higher strain is observed with worsening MR and larger valves and annuli, mitral valve leaflet thickness-and, thus, underlying MV pathology-is the most significant independent determinant of valve deformation. Future studies are needed to assess the impact of MV strain determination on clinical outcome.
本研究旨在定量分析正常瓣和伴有或不伴有显著二尖瓣反流（MR）的二尖瓣脱垂（MVP）患者的特定二尖瓣（MV）应变，并评估 MV 应变的决定因素。
关于人类收缩期 MV 变形的数据很少。三维经食管超声心动图可进行 MV 动态成像，从而实现健康和疾病状态下 MV 功能的数字建模。
对 82 例患者进行了三维经食管超声心动图检查，其中 32 例为正常 MV，50 例为 MVP：12 例为轻度 MR 或以下（MVP-MR），38 例为中度 MR 或以上（MVP+MR）。生成 MV 三维模型，并在专有的软件上计算 MV 瓣叶的峰值收缩期应变。
所有组的左心室射血分数均正常。MVP+MR 的 MV 环形尺寸最大（瓣环面积：13.8±0.7cm），与 MVP-MR（10.6±1cm）和正常瓣（10.5±0.3cm）相似（方差分析：p<0.001）。同样，MV 瓣叶面积在 MVP+MR 中最大，尤其是后瓣（8.7±0.5cm）；MVP-MR 居中（6.5±0.7cm）；正常瓣最小（5.5±0.2cm；p<0.0001）。总体而言，MVP+MR 的应变最高，正常瓣的应变最低。MVP-MR 患者的后瓣应变值高于正常瓣（p=0.001）。多变量分析显示，在调整临床和 MV 几何参数后，瓣叶厚度是唯一与 MV 平均应变显著相关的参数（r=0.34；p=0.008）。
与正常瓣相比，表现为脱垂的 MV 应变更高，尤其是后瓣。尽管随着 MR 恶化、瓣环和瓣面积增大，应变值升高，但 MV 瓣叶厚度——即潜在的 MV 病理——是 MV 变形的最重要独立决定因素。需要进一步的研究来评估 MV 应变测定对临床结局的影响。
