Department of Cardiology, Taunton & Somerset Hospital, Musgrove Park, UK.
Biological Physics Group, Department of Astronomy and Physics, University of Manchester, Manchester, UK.
Sci Rep. 2022 Jul 26;12(1):12717. doi: 10.1038/s41598-022-15509-8.
The left ventricular ejection fraction does not accurately predict exercise capacity or symptom severity and has a limited role in predicting prognosis in heart failure. A better method of assessing ventricular performance is needed to aid understanding of the pathophysiological mechanisms and guide management in conditions such as heart failure. In this study, we propose two novel measures to quantify myocardial performance, the global longitudinal active strain energy (GLASE) and its density (GLASED) and compare them to existing measures in normal and diseased left ventricles. GLASED calculates the work done per unit volume of muscle (energy density) by combining information from myocardial strain and wall stress (contractile force per unit cross sectional area). Magnetic resonance images were obtained from 183 individuals forming four cohorts (normal, hypertension, dilated cardiomyopathy, and cardiac amyloidosis). GLASE and GLASED were compared with the standard ejection fraction, the corrected ejection fraction, myocardial strains, stroke work and myocardial forces. Myocardial shortening was decreased in all disease cohorts. Longitudinal stress was normal in hypertension, increased in dilated cardiomyopathy and severely decreased in amyloid heart disease. GLASE was increased in hypertension. GLASED was mildly reduced in hypertension (1.39 ± 0.65 kJ/m), moderately reduced in dilated cardiomyopathy (0.86 ± 0.45 kJ/m) and severely reduced in amyloid heart disease (0.42 ± 0.28 kJ/m) compared to the control cohort (1.94 ± 0.49 kJ/m). GLASED progressively decreased in the hypertension, dilated cardiomyopathy and cardiac amyloid cohorts indicating that mechanical work done and systolic performance is severely reduced in cardiac amyloid despite the relatively preserved ejection fraction. GLASED provides a new technique for assessing left ventricular myocardial health and contractile function.
左心室射血分数不能准确预测运动能力或症状严重程度，对心力衰竭预后的预测作用有限。需要一种更好的心室功能评估方法，以帮助了解病理生理机制，并指导心力衰竭等疾病的管理。在这项研究中，我们提出了两种新的量化心肌性能的指标，即整体纵向主动应变能（GLASE）及其密度（GLASED），并将其与正常和病变左心室中的现有指标进行了比较。GLASED 通过结合心肌应变和壁应力（单位横截面积的收缩力）的信息来计算单位肌肉体积所做的功（能量密度）。从 183 名个体中获得了磁共振图像，这些个体分为四个队列（正常、高血压、扩张型心肌病和心脏淀粉样变性）。将 GLASE 和 GLASED 与标准射血分数、校正射血分数、心肌应变、每搏功和心肌力进行比较。在所有疾病队列中，心肌缩短均减少。高血压时纵向应变正常，扩张型心肌病时增加，淀粉样心脏病时严重减少。高血压时 GLASE 增加。与对照组（1.94±0.49 kJ/m）相比，高血压组 GLASED 轻度降低（1.39±0.65 kJ/m），扩张型心肌病组中度降低（0.86±0.45 kJ/m），淀粉样心脏病组严重降低（0.42±0.28 kJ/m）。GLASED 在高血压、扩张型心肌病和心脏淀粉样变性组中逐渐降低，表明尽管射血分数相对保留，但心脏淀粉样变性中的机械功和收缩性能严重降低。GLASED 为评估左心室心肌健康和收缩功能提供了一种新的技术。
