Department of Cardiology, Hospital Universitari Vall d'Hebron, Vall d'Hebron Barcelona CIBER-CV, Vall d'Hebron Institut de Recerca (VHIR), Barcelona, Spain.
Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
Prog Cardiovasc Dis. 2020 Jul-Aug;63(4):442-451. doi: 10.1016/j.pcad.2020.06.003. Epub 2020 Jun 9.
Bicuspid aortic valve (BAV) patients are at increased risk of valve dysfunction and ascending aorta aneurysm. Imaging techniques are essential to establish diagnosis, identify complications and indicate surgical treatment. Transthoracic echocardiography (TTE) is the imaging technique of choice to diagnose BAV, valve morphotype and valvular dysfunction in clinical practice. However, it can be less precise in assessing the aortic root and proximal ascending aorta, and visualization of the mid-distal ascending aorta and the arch may be difficult in some adults where cardiac magnetic resonance (CMR) and computed tomography, using multiplanar reconstructions, are better at assessing aortic diameters. Although valvular dysfunction is very variable, almost half of the patients have more than mild aortic valve disease. TTE is the most effective and accurate test for evaluating the severity of valvular dysfunction and guiding appropriate management decisions. Aorta dilation is a common finding in patients with BAV. The pattern of aortic dimensions has been categorized in three aortic phenotypes: no-dilation phenotype, ascending aorta phenotype and root phenotype. Controversial data exist regarding the relationship between BAV morphology and aorta dilation phenotype. The assessment of aortic stiffness (measuring distensibility or the velocity of propagation of flow) has raised special interest in order to predict progressive aorta dilation. However, current data indicates that BAV aortas do not show altered stiffness compared to those associated with a tricuspid valve with a similar aorta size. Moreover, novel 4D-flow CMR sequences have been crucial in the evaluation of abnormal ascending aorta flow, showing that flow in the aorta of BAV patients is asymmetric and includes the formation of large vortices. Such flow abnormalities are thought to produce changes in wall shear stress which has been associated with extracellular matrix dysregulation. The key points to understand familial screening and the recommendations for establishing the follow-up and therapeutic management of BAV patients are exposed in the review. The main objective of this article is to review the advantages and limitations of the imaging techniques in the diagnosis and management of BAV and the best strategies in the use of multimodality imaging.
二叶式主动脉瓣（BAV）患者发生瓣叶功能障碍和升主动脉瘤的风险增加。影像学技术对于确立诊断、识别并发症和指导手术治疗至关重要。经胸超声心动图（TTE）是临床诊断 BAV、瓣叶形态和瓣叶功能障碍的首选影像学技术。然而，它在评估主动脉根部和近端升主动脉方面可能不够精确，并且在一些成年人中，心脏磁共振（CMR）和计算机断层扫描（使用多平面重建）可能更有助于评估主动脉直径，因此，中远端升主动脉和弓部的可视化可能较为困难。尽管瓣叶功能障碍的变化很大，但几乎一半的患者有超过轻度的主动脉瓣疾病。TTE 是评估瓣叶功能障碍严重程度和指导适当管理决策的最有效和准确的检查。BAV 患者常见主动脉扩张。主动脉尺寸模式已分为三种主动脉表型：无扩张表型、升主动脉表型和根部表型。BAV 形态与主动脉扩张表型之间的关系存在争议数据。评估主动脉僵硬度（测量顺应性或血流传播速度）引起了人们的特别关注，以便预测主动脉进行性扩张。然而，目前的数据表明，与具有相似主动脉大小的三尖瓣相比，BAV 主动脉的僵硬度没有改变。此外，新型 4D 流 CMR 序列对于评估异常升主动脉血流至关重要，表明 BAV 患者的主动脉血流不对称，并包括大涡流的形成。这些异常的血流被认为会改变壁面切应力，而壁面切应力与细胞外基质失调有关。本文回顾了理解家族筛查以及建立 BAV 患者随访和治疗管理建议的要点。本文的主要目的是综述影像学技术在 BAV 的诊断和管理中的优缺点，以及多模态影像学的最佳应用策略。
