Shah Dipan J
Methodist DeBakey Heart & Vascular Center, Houston, Texas, USA.
Methodist Debakey Cardiovasc J. 2010 Jan-Mar;6(1):15-9. doi: 10.14797/mdcj-6-1-15.
The prevalence of valvular heart disease is increasing along with the life span of the population. In assessing individuals with valve disease, echocardiography is the primary imaging modality used by clinicians both for initial assessment and for longitudinal evaluation. Information regarding valve morphology and function, cardiac chamber size, wall thickness, ventricular function, and estimates of pulmonary artery pressures can be readily obtained and integrated to formulate an assessment of valve disease severity. In some instances, body habitus or the presence of coexisting lung disease may result in suboptimal acoustic windows on echocardiography, which may lead to technically difficult studies. Additionally, in some patients, information from clinical history and physical examination or other diagnostic tests may be discordant with echocardiographic findings. In these instances, there is a significant clinical role for cardiovascular magnetic resonance (CMR). The diagnostic capabilities of CMR have increased substantially over the past 20 years due to hardware and software advances. Today, CMR has a number of unique advantages over other imaging modalities - primarily, it provides a view of the entire heart without limitations from inadequate imaging windows or body habitus. Furthermore, CMR can obtain imaging data in any imaging plane prescribed by the scan operator, which makes it ideal for accurate investigation of all cardiac valves - aortic, mitral, pulmonic, and tricuspid. In addition, CMR for valve assessment is noninvasive, free of ionizing radiation, and in most instances does not require contrast administration. Since a comprehensive review of the role of CMR in all valve lesions is beyond the scope of this article, we will focus on the most common valvular indication for performance of clinical CMR techniques and an overview of selected validation and reproducibility studies. The objectives of a comprehensive CMR study for evaluating mitral insufficiency are threefold: 1) to provide insight into the mechanism of mitral insufficiency, and 3) to discern the consequences of the lesions including the effects on left ventricular (LV) volume, LV systolic function, and left atrial volumes. In most instances this information can be obtained without the need for intravenous contrast agents (gadolinium). Therefore, CMR can be performed even in patients with severe renal failure.
随着人群寿命的延长，心脏瓣膜病的患病率正在上升。在评估患有瓣膜疾病的个体时，超声心动图是临床医生用于初始评估和纵向评估的主要成像方式。关于瓣膜形态和功能、心腔大小、壁厚、心室功能以及肺动脉压力估计值的信息可以很容易地获得并整合起来，以形成对瓣膜疾病严重程度的评估。在某些情况下，身体体型或并存的肺部疾病可能导致超声心动图的声学窗口不理想，这可能导致技术上困难的检查。此外，在一些患者中，临床病史、体格检查或其他诊断测试的信息可能与超声心动图结果不一致。在这些情况下，心血管磁共振（CMR）具有重要的临床作用。由于硬件和软件的进步，CMR的诊断能力在过去20年中有了显著提高。如今，CMR相对于其他成像方式具有许多独特的优势——主要是，它可以观察整个心脏，不受成像窗口不足或身体体型的限制。此外，CMR可以在扫描操作员规定的任何成像平面上获取成像数据，这使其成为准确检查所有心脏瓣膜（主动脉瓣、二尖瓣、肺动脉瓣和三尖瓣）的理想选择。此外，用于瓣膜评估的CMR是无创的，无电离辐射，并且在大多数情况下不需要使用造影剂。由于全面综述CMR在所有瓣膜病变中的作用超出了本文的范围，我们将重点关注临床CMR技术应用最常见的瓣膜适应证以及选定的验证和可重复性研究的概述。评估二尖瓣反流的全面CMR研究的目标有三个：1）深入了解二尖瓣反流的机制，以及3）识别病变的后果，包括对左心室（LV）容积、LV收缩功能和左心房容积的影响。在大多数情况下，无需静脉注射造影剂（钆）即可获得这些信息。因此，即使在严重肾衰竭的患者中也可以进行CMR检查。
