随着人口老龄化，主动脉瓣关闭不全（AR）发病率明显升高，是导致心衰的重要原因。AR患者可在较长时间内无明显症状，一旦进入失代偿心衰迅速进展，给手术和术后恢复带来巨大风险。手术时机选择是困扰AR治疗决策的重要问题。随着AR发展，心肌发生弥漫纤维化。纤维化心肌晚期不能逆转，其程度决定了患者的手术风险和预后。无创性评价心肌纤维化（MF）对患者危险分层具有重要意义。最近，CT心肌细胞外容积（ECV）量化对于评价弥漫MF显示出潜在价值。本课题假设CT心肌ECV量化可以对AR患者MF程度进行有效评价，作为MF的标志，可以对AR患者进行危险分层，为手术时机选择和预后评价提供依据。本项目主动脉瓣患者的研究，确定CT心肌ECV量化对AR弥漫MF评价的有效性。确定CT心肌ECV量化与MRI心肌ECV量化的一致性，揭示MF程度与心衰发生、发展之间的定量关系。为AR患者危险分层、手术时机选择及预后评价提供一种新的无创性评价方法。

With the aging of population, the incidence of aortic regurgitation (AR) has been increasing. AR is an important etiology leading to heart failure. The patients can be asymptomatic for a long period of time. The deterioration of heart failure will rapidly progress when de-compensation once occurs, thus leading to great risks for surgery and post-surgical recovery. The timing of surgical replacement of aortic valve is important issue for AR patients. With the development of AR, the diffuse myocardial fibrosis will progress. Myocardial fibrosis is irreversible and will influence the risk of surgery and prognosis in AR patients. Therefore, non-invasive evaluation of myocardial fibrosis is significant for risks stratification in AR patients. Recently, cardiac CT-based extracellular volume (ECV) quantification demonstrates potential value for evaluation of diffuse myocardial fibrosis. The hypothesis of this study is that CT-baed ECV quantification can be effective for the assessment of myocaridal fibrosis in patients with AR. As a mark of diffuse myocardial fibrosis, CT-baed ECV quantification can be used for risks stratification in AR patients, thus providing evidence for timing selection of surgery and prognostic evaluation. To verify the hypothesis proposed, study will be carried out to validate the effctiveness of CT-based ECV measurement for the evaluation of diffuse myocardial fibrosis, to evaluate the consistency between CT-based ECV measurement and MR-based ECV measurement, and to reveal the relationship between the extent of myocardal fibrosis and the progression of the heart failure. Thus offering a new non-invasive evaluation technique for risks stratification, therapeutic strategy, timing selection of surgery, and prognostic evaluation in AR patients.

心肌纤维化（myocardial fibrosis）以正常心肌组织中出现成纤维细胞增殖和细胞外基质内胶原过度沉积为主要特点，可由冠状动脉粥样硬化性疾病、系统性疾病、心脏瓣膜病或损害心血管系统的药物等引起。心肌纤维化可改变心肌结构，加速心功能的恶化，可诱导恶性心律失常的发生。研究表明心肌纤维化的程度与患者的预后密切相关，定量和定性评价心肌纤维化对于患者的危险分层具有十分重要的临床意义。为了探讨心脏CT定量评价心肌细胞外容积（extracellular volume ECV）以评价心肌纤维化的可行性和准确性，本研究采用了两种心肌纤维化的CT评估模式：单能CT和双能ＣＴ。其中，单能ＣＴ前瞻性纳入２８例临床诊断心力衰竭患者（包含主动脉瓣关闭不全），双能ＣＴ前瞻性纳入３５例临床诊断心力衰竭患者（包含主动脉瓣关闭不全），所有患者签署知情同意书。增强前后2次心脏CT扫描用于计算单能CT ECV，增强后双能CT单次采集用于计算双能CT ECV；心脏MR计算MR ECV及测量功能参数。研究结果表明CT ECV与 MR ECV具有很好的相关性（r=0854，p<0.001），但CT ECV的结果比MR ECV稍高；CT ECV和MR ECV均与射血分数呈负相关。同时，对弥漫性心肌纤维化的比格犬模型的初步研究也揭示了CT心肌ECV量化及MR心肌ECV量化结果的一致性。本研究证实了CT心肌ECV量化对心肌纤维化评价的有效性及可靠性，弥补了心脏MR评价的局限性，揭示了心肌纤维化程度与心衰发生、发展之间的密切关系，有助于心衰患者危险分层、治疗方式及预后评价。