Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Oxford, United Kingdom.
Circ Cardiovasc Imaging. 2013 Jul;6(4):499-507. doi: 10.1161/CIRCIMAGING.113.000528. Epub 2013 Jun 14.
Ascending aortic dilation is important in bicuspid aortic valve (BAV) disease, with increased risk of aortic dissection. We used cardiovascular MR to understand the pathophysiology better by examining the links between 3-dimensional flow abnormalities, aortic function, and aortic dilation.
A total of 142 subjects underwent cardiovascular MR (mean age, 40 years; 95 with BAV, 47 healthy volunteers). Patients with BAV had predominantly abnormal right-handed helical flow in the ascending aorta, larger ascending aortas (18.3±3.3 versus 15.2±2.2 mm/m²; P<0.001), and higher rotational (helical) flow (31.7±15.8 versus 2.9±3.9 mm²/s; P<0.001), systolic flow angle (23.1°±12.5° versus 7.0°±4.6°; P<0.001), and systolic wall shear stress (0.85±0.28 versus 0.59±0.17 N/m²; P<0.001) compared with healthy volunteers. BAV with right-handed flow and right-non coronary cusp fusion (n=31) showed more severe flow abnormalities (rotational flow, 38.5±16.5 versus 27.8±12.4 mm²/s; P<0.001; systolic flow angle, 29.4°±10.9° versus 19.4°±11.4°; P<0.001; in-plane wall shear stress, 0.64±0.23 versus 0.47±0.22 N/m²; P<0.001) and larger aortas (19.5±3.4 versus 17.5±3.1 mm/m²; P<0.05) than right-left cusp fusion (n=55). Patients with BAV with normal flow patterns had similar aortic dimensions and wall shear stress to healthy volunteers and younger patients with BAV showed abnormal flow patterns but no aortic dilation, both further supporting the importance of flow pattern in the pathogenesis of aortic dilation. Aortic function measures (distensibility, aortic strain, and pulse wave velocity) were similar across all groups.
Flow abnormalities may be a major contributor to aortic dilation in BAV. Fusion type affects the severity of flow abnormalities and may allow better risk prediction and selection of patients for earlier surgical intervention.
升主动脉扩张在二叶式主动脉瓣（BAV）疾病中很重要，与主动脉夹层的风险增加有关。我们使用心血管磁共振（cardiovascular MR）通过检查三维血流异常、主动脉功能和主动脉扩张之间的联系，更好地了解病理生理学。
共有 142 名受试者接受了心血管磁共振（平均年龄 40 岁；95 名 BAV，47 名健康志愿者）。BAV 患者升主动脉主要存在异常的右旋螺旋血流，升主动脉更大（18.3±3.3 与 15.2±2.2 mm/m²；P<0.001），旋转（螺旋）血流更高（31.7±15.8 与 2.9±3.9 mm²/s；P<0.001），收缩期血流角度更大（23.1°±12.5°与 7.0°±4.6°；P<0.001），收缩期壁面剪切应力更大（0.85±0.28 与 0.59±0.17 N/m²；P<0.001）。与健康志愿者相比，BAV 伴右旋血流和右无冠窦融合（n=31）表现出更严重的血流异常（旋转血流，38.5±16.5 与 27.8±12.4 mm²/s；P<0.001；收缩期血流角度，29.4°±10.9°与 19.4°±11.4°；P<0.001；平面壁面剪切应力，0.64±0.23 与 0.47±0.22 N/m²；P<0.001），升主动脉更大（19.5±3.4 与 17.5±3.1 mm/m²；P<0.05），而右-左窦融合（n=55）。血流模式正常的 BAV 患者的主动脉尺寸和壁面剪切应力与健康志愿者相似，而年轻的 BAV 患者表现出异常的血流模式，但没有主动脉扩张，这进一步支持血流模式在主动脉扩张发病机制中的重要性。主动脉功能测量（可扩张性、主动脉应变和脉搏波速度）在所有组中均相似。
血流异常可能是 BAV 中主动脉扩张的主要原因。融合类型影响血流异常的严重程度，并可能允许更好地进行风险预测和选择患者进行早期手术干预。
