White R D, Obuchowski N A, Gunawardena S, Lipchik E O, Lever H M, Van Dyke C W, Lytle B W
Department of Radiology, Cleveland Clinic Foundation, OH 44195, USA.
Am J Card Imaging. 1996 Jan;10(1):1-13.
Along with hypertrophy of the left ventricle (LV), hypertrophic cardiomyopathy (HC) is characterized by LV outflow tract (LVOT) obstruction, partly from systolic anterior motion (SAM) of the anterior mitral leaflet; if obstruction is significant, excision of excess subaortic septal myocardium may be indicated. In this study, the ability of computed tomography magnetic resonance imaging (Cine MRI) to provide information about LVOT obstruction was assessed in a series of 37 HC cases undergoing evaluation, including echocardiography (0 to 14 days before), for possible septal myectomy; in 4 cases, Cine MRI was used postsurgically (5 to 25 months after). Blinded to echocardiography results, 3 reviewers analyzed by consensus the Cine-MRI LVOT-long-axis image-loops for SAM grade (none, mild, severe) and "aorta:LVOT signal ratio" (intensity in descending aorta/intensity in LVOT at maximum systolic-flow disturbance). Resting LVOT flow velocities were separately determined using Doppler analysis, permitting differentiation between insignificant (< 30 mm Hg) and significant (< or = 30 mm Hg) gradients. With echocardiography, significant resting obstruction was found in 62% of cases, including 92% treated surgically. A significant association between SAM grade and obstruction was found; all cases with a SAM grade of none had insignificant ([-] predictive value: 100%) and most with a severe grade had significant ([+] predictive value: 78%) obstruction. Signal ratio in the absence of a significant gradient was significantly lower than in its presence; a significant linear relationship between aorta:LVOT signal ratio and resting gradient was found: LVOT gradient = ([2.9] x [signal ratio]) + 22.8. SAM grade did not contribute significantly in obstruction categorization when signal ratio was known. In all cases studied after surgery, SAM grade had decreased from severe to insignificant levels and aorta:LVOT signal ratio had been significantly reduced. Insights into the dynamic nature of the LVOT in HC patients can be provided by Cine MRI, either during their evaluation for surgery or after their septal myectomy.
肥厚型心肌病（HC）除了左心室（LV）肥厚外，其特征还包括左心室流出道（LVOT）梗阻，部分原因是二尖瓣前叶的收缩期向前运动（SAM）；如果梗阻严重，可能需要切除多余的主动脉下间隔心肌。在本研究中，对37例接受评估的HC患者进行了计算机断层扫描磁共振成像（电影磁共振成像，Cine MRI），以评估其提供LVOT梗阻信息的能力，这些患者包括接受超声心动图检查（术前0至14天）以评估是否可能进行间隔心肌切除术；4例患者在术后（术后5至25个月）使用了Cine MRI。在不知道超声心动图结果的情况下，3名评估人员通过共识分析了Cine MRI的LVOT长轴图像环，以确定SAM分级（无、轻度、重度）和“主动脉：LVOT信号比值”（最大收缩期血流紊乱时降主动脉强度/LVOT强度）。使用多普勒分析分别测定静息LVOT流速，从而区分不显著（<30 mmHg）和显著（≤30 mmHg）的压力阶差。超声心动图检查发现，62%的病例存在显著的静息梗阻，其中92%接受了手术治疗。发现SAM分级与梗阻之间存在显著关联；所有SAM分级为无的病例均无显著梗阻（[-]预测值：100%），而大多数重度分级的病例存在显著梗阻（[+]预测值：78%）。无显著压力阶差时的信号比值显著低于有显著压力阶差时；发现主动脉：LVOT信号比值与静息压力阶差之间存在显著的线性关系：LVOT压力阶差 = （[2.9] × [信号比值]） + 22.8。当已知信号比值时，SAM分级对梗阻分类的贡献不显著。在所有术后研究的病例中，SAM分级已从重度降至不显著水平，且主动脉：LVOT信号比值已显著降低。Cine MRI可以在HC患者手术评估期间或间隔心肌切除术后，提供对LVOT动态特性的深入了解。
