目的:阻塞性肥厚型心肌病(oHCM)的特征是左心室(LV)流出道(LVOT)的动态阻塞。尽管这可能是由肥大的间隔壁之间的相互作用介导的,二尖瓣的收缩期前移,和乳头状肌肉异常,LV形状的机制作用仍未完全了解。本研究旨在确定支持oHCM的LV舒张末期形态。
结果:作为NHLBIHCM注册的一部分,获得了2398例HCM个体的心血管磁共振图像。三维LV模型的构建和使用,结合主成分分析,来构建捕获形状变化的统计形状模型。建立一组线性判别轴,以定义和量化(Z评分)在不同生理条件下与LVOT阻塞(LVOTO)相关的特征LV形态以及LV表型和基因型之间的关系。oHCM的LV重塑模式不仅包括基底间隔肥大,还包括LV延长的组合。顶端扩张,和LVOT向内重塑。在休息和压力下的阻塞性病例之间观察到显着差异。基因型阴性病例在休息和压力下都显示出更多阻塞性表型的趋势。
结论:支撑oHCM的LV解剖结构包括基底间隔肥大,顶端扩张,LV加长,和LVOT向内重塑。休息和压力下的oHCM病例之间的差异,以及LV表型和基因型之间的关系,建议不同的LVOTO机制。提出的Z分数为根据LV解剖结构与LVOTO之间的关系重新定义管理策略提供了机会。
Obstructive hypertrophic cardiomyopathy (oHCM) is characterized by dynamic obstruction of the left ventricular (LV) outflow tract (LVOT). Although this may be mediated by interplay between the hypertrophied septal wall, systolic anterior motion of the mitral valve, and papillary muscle abnormalities, the mechanistic role of LV shape is still not fully understood. This study sought to identify the LV end-diastolic morphology underpinning oHCM.
Cardiovascular magnetic resonance images from 2398 HCM individuals were obtained as part of the NHLBI HCM Registry. Three-dimensional LV models were constructed and used, together with a principal component analysis, to build a statistical shape model capturing shape variations. A set of linear discriminant axes were built to define and quantify (Z-scores) the characteristic LV morphology associated with LVOT obstruction (LVOTO) under different physiological conditions and the relationship between LV phenotype and genotype. The LV remodelling pattern in oHCM consisted not only of basal septal hypertrophy but a combination with LV lengthening, apical dilatation, and LVOT inward remodelling. Salient differences were observed between obstructive cases at rest and stress. Genotype negative cases showed a tendency towards more obstructive phenotypes both at rest and stress.
LV anatomy underpinning oHCM consists of basal septal hypertrophy, apical dilatation, LV lengthening, and LVOT inward remodelling. Differences between oHCM cases at rest and stress, as well as the relationship between LV phenotype and genotype, suggest different mechanisms for LVOTO. Proposed Z-scores render an opportunity of redefining management strategies based on the relationship between LV anatomy and LVOTO.