Department of Cardiothoracic Sciences, Second University of Naples c/o Monaldi Hospital, Naples, Italy.
J Thorac Cardiovasc Surg. 2012 Aug;144(2):360-9, 369.e1. doi: 10.1016/j.jtcvs.2011.10.014. Epub 2011 Nov 3.
Bicuspid aortic valve disease is heterogeneous with respect to valve morphology and aortopathy risk. This study searched for early imaging predictors of aortopathy in patients with a bicuspid aortic valve with right-left coronary cusp fusion, the most common morphotype.
Time-resolved magnetic resonance imaging was performed in 36 subjects with nonstenotic, nonregurgitant bicuspid aortic valves and nondilated aortas and in 10 healthy controls with tricuspid aortic valves. Sinus dimensions (diameter, width, and height), ascending tract diameters, and wall strain were measured for each sinus/leaflet unit and corresponding ascending tract area to account for asymmetries. A novel parameter, "cusp opening angle," measured the degree of valve leaflet alignment to outflow axis in systole, quantifying cusp motility. Phase-contrast magnetic resonance imaging and computational fluid dynamic models assessed flow patterns. Aortic growth rate was estimated over a follow-up period ranging from 9 to 84 months.
The expected restriction of bicuspid aortic valve opening (conjoint cusp opening angle, 62°±5° vs 76°±3° for nonfused leaflet and 75°±3° for tricuspid aortic valve cusps; P<.001) was confirmed, and the introduced parameter reproducibly quantified this phenomenon. Phase-contrast magnetic resonance imaging demonstrated systolic flow deflection toward the right, affecting the right anterolateral ascending wall. Computational models confirmed that restricted cusp motion alone is sufficient to cause the observed flow pattern. Ascending tract wall strain was not circumferentially homogeneous in bicuspid aortic valves. In multivariable analyses, the conjoint cusp opening angle independently predicted ascending aorta diameters and growth rate (P<.001).
In the bicuspid aortic valve commonly defined as normofunctional by echocardiographic criteria, restricted systolic conjoint cusp motion causes flow deflection. The novel measurement introduced can quantify restricted cusp opening, possibly assuming prognostic importance.
二叶式主动脉瓣病变在瓣叶形态和主动脉病变风险方面具有异质性。本研究旨在寻找一种二叶式主动脉瓣右冠-左冠瓣融合最常见形态的患者发生主动脉病变的早期影像学预测因子。
对 36 例非狭窄性、非反流性二叶式主动脉瓣和非扩张性主动脉患者以及 10 例三叶式主动脉瓣健康对照者进行时间分辨磁共振成像。测量每个窦/瓣叶单位和相应升主动脉区域的窦尺寸（直径、宽度和高度）、升主动脉直径和壁应变，以计算不对称性。一种新的参数“瓣叶开口角”测量了瓣叶在收缩期相对于流出道轴的对齐程度，量化了瓣叶活动度。相位对比磁共振成像和计算流体动力学模型评估了血流模式。在 9 至 84 个月的随访期间估计主动脉生长速度。
二叶式主动脉瓣开口的预期限制（联合瓣叶开口角为 62°±5°，而非融合瓣叶为 76°±3°，三叶式主动脉瓣瓣叶为 75°±3°；P<.001）得到证实，所提出的参数可重复性地量化了这一现象。相位对比磁共振成像显示收缩期血流向右侧偏转而影响右侧前外侧升主动脉壁。计算模型证实，瓣叶活动受限本身足以引起观察到的血流模式。二叶式主动脉瓣升主动脉壁应变并非呈圆周均匀分布。在多变量分析中，联合瓣叶开口角独立预测升主动脉直径和生长速度（P<.001）。
在通常根据超声心动图标准定义为正常功能的二叶式主动脉瓣中，收缩期联合瓣叶运动受限导致血流偏转。所提出的新测量方法可定量瓣叶开口受限，可能具有预后意义。
