Maes Frédéric, Pierard Sophie, de Meester Christophe, Boulif Jamila, Amzulescu Mihaela, Vancraeynest David, Pouleur Anne-Catherine, Pasquet Agnès, Gerber Bernhard, Vanoverschelde Jean-Louis
Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium.
Division of Cardiology, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
J Cardiovasc Magn Reson. 2017 Mar 15;19(1):37. doi: 10.1186/s12968-017-0344-8.
The pathophysiology of paradoxical low-gradient (LG) severe aortic stenosis (SAS) remains controversial. As low transvalvular flow has been implicated, we sought to investigate the impact of left ventricular outflow tract (LVOT) ellipticity on the estimation of the LV stroke volume, the calculation of the aortic valve area (AVA) by use of the continuity equation and on AS severity grading.
We studied 190 consecutive patients (mean age: 72 ± 13 years; male: 57%) with SAS (indexed AVA < 0.6 cm/m) and preserved LV ejection fraction, including 120 patients with severe high gradient (HG) AS and 70 with severe paradoxical LG-AS. AS severity, LV volumes and LVOT ellipticity were assessed by 2D-Doppler echocardiography and cardiac magnetic resonance (CMR).
The LVOT exhibited an elliptical shape on CMR images, with a shorter anterior-posterior than median-lateral diameter (2.2 ± 0.2 vs 2.8 ± 0.3 cm, p < 0.01). Accordingly, the LVOT area measured by planimetry was larger than by 2D-echocardiography, assuming a circular orifice (4.9 ± 0.9 cm vs 3.7 ± 0.8 cm, p < 0.01). Inputting the elliptical LVOT area into the continuity equation resulted in a 29% increase in the indexed AVA (from 0.41 ± 0.09 cm to 0.54 ± 0.10 cm). Accordingly, 30 (43%) patients with severe paradoxical LG-SAS were reclassified as having moderate AS. Similar results were obtained when considering 3D-echo for direct planimetry of the LVOT in a subset of 75 patients.
Our results confirm that the LVOT is elliptical in shape and that taking this parameter into account in the calculation of the AVA results in reclassification of 43% of patients with severe paradoxical LG-AS into moderate AS.
矛盾性低梯度（LG）重度主动脉瓣狭窄（SAS）的病理生理学仍存在争议。由于低跨瓣血流被认为与之相关，我们试图研究左心室流出道（LVOT）椭圆度对左心室搏出量估计、使用连续方程计算主动脉瓣面积（AVA）以及对AS严重程度分级的影响。
我们研究了190例连续的SAS患者（平均年龄：72±13岁；男性：57%），其左心室射血分数保留，包括120例重度高梯度（HG）AS患者和70例重度矛盾性LG-AS患者。通过二维多普勒超声心动图和心脏磁共振（CMR）评估AS严重程度、左心室容积和LVOT椭圆度。
CMR图像上LVOT呈椭圆形，前后径比中侧径短（2.2±0.2对2.8±0.3cm，p<0.01）。因此，假设为圆形孔口，通过面积测量法测得的LVOT面积大于二维超声心动图测得的面积（4.9±0.9cm对3.7±0.8cm，p<0.01）。将椭圆形LVOT面积代入连续方程导致指数化AVA增加29%（从0.41±0.09cm增至0.54±0.10cm）。相应地，30例（43%）重度矛盾性LG-SAS患者被重新分类为中度AS。在75例患者的子集中考虑使用三维超声心动图直接测量LVOT面积时，也得到了类似结果。
我们的结果证实LVOT呈椭圆形，在AVA计算中考虑该参数会导致43%的重度矛盾性LG-AS患者被重新分类为中度AS。
