Objective Heart failure(HF)is divided into two types:Heart failure with reduced ejection fraction(HFrEF)and heart failure with preserved ejection fraction(HFpEF).The latter always results in diastolic dysfunction,char...Objective Heart failure(HF)is divided into two types:Heart failure with reduced ejection fraction(HFrEF)and heart failure with preserved ejection fraction(HFpEF).The latter always results in diastolic dysfunction,characterized by changes in mechanical properties.The objective of this study is to build a finite element(FE)model of HFpEF and analyze diastolic and systolic function in rats.Methods Ten Dahl salt-sensitive rats were fed either a low-salt(LS)(n=5)or highsalt(HS)(n=5)diet beginning at 7 weeks of age and scanned by ultrasonic machine at 14 weeks of age.A non-linear FE model of the left ventricle(LV)was built from cardiac echo images at end-diastole and passive material properties of the LV were prescribed using Fung’s transversely isotropic constitutive law.Fiber angles of the endocardium and epicardium were prescribed as 53°°and-52°,respectively,with respect to the circumferential direction and varied linearly through the LV wall.The method developed by Krishnamurthywas used to determine the unloaded geometry to estimate the Fung passive material parameters.LV end-diastolic pressure(EDP)was determined from the measured pressure waves and applied to the endocardium at the unloaded geometry to simulate passive filling.Active material properties of the LV were prescribed using Guccione’s time-varying elastance model and maximum isometric tension was scaled to match the measured peak systolic pressure.The finite element model was then coupled to the Windkessel model,whose parameters were adjusted to the measured hemodynamics.Results Measured LVEDPs of LS and HS rats were 4.9±3.4 mmHg and 13.2±5.4 mmHg(P-0.030 8),respectively.End-diastolic Cauchy stress along the fiber direction for LS rats was significantly lower than for HS rats(0.91±0.60 kPa vs 3.00±0.63 kPa,P=0.001 4)and there was a similar trend in end-diastolic Green Strain along the fiber direction(0.058±0.003 vs 0.072±0.010,P=0.012 8,Figure 1b),as well.There was no distinctive difference between end-systolic Cauchy stress along the fiber direction for LS rats and HS rats(17.2±4.3 kPa vs 17.2±5.5 kPa,P=0.991 9)but end-systolic Green Strain along the fiber direction for LS rats was significantly higher than for HS rats(-0. 108±0.017 vs-0.065±0.024,negative sign represents direction).Conclusions For rats with HFpEF,it is the elevated LVEDP that induces the increase in end-diastolic stress and strain,thereby leading to diastolic dysfunction.Because of the preserved ejection fraction,HFpEF has less effect on systolic function.展开更多
在射血分数降低型心力衰竭(heart failure with reduced ejection fraction,HFrEF)患者中,部分患者的左室射血分数(left ventricular ejection fraction,LVEF)经治疗后在后续评估中出现明显改善。2022年美国心脏学会/美国心脏病协会/美...在射血分数降低型心力衰竭(heart failure with reduced ejection fraction,HFrEF)患者中,部分患者的左室射血分数(left ventricular ejection fraction,LVEF)经治疗后在后续评估中出现明显改善。2022年美国心脏学会/美国心脏病协会/美国心衰学会(American Heart Association/American College of Cardiology/Heart Failure Society of America,AHA/ACC/HFSA)颁布的心力衰竭管理指南将既往LVEF≤40%且在随访过程中提升至40%以上的心力衰竭类型命名为射血分数改善型心力衰竭(heart failure with improved ejection fraction,HFimpEF)。研究表明,HFimpEF患者的全因死亡率、心力衰竭再住院率较低,预后明显优于HFrEF,可作为HFrEF患者的阶段性治疗目标。关于HFimpEF患者的热点讨论主要围绕2个方面,即HFimpEF的目标人群特征及LVEF提升的有效手段、HFimpEF患者心功能维持治疗方案;尤其是后者,尚无明确的临床指南推荐。因此,回顾现有研究,系统总结促使HFrEF向HFimpEF转归的治疗方案,以及有效针对HFimpEF的维持手段至关重要。该文对现有药物、器械、手术治疗的LVEF改善效果及HFimpEF患者的监测与治疗方法进行综述。对于HFrEF患者,现有临床研究提示β受体阻滞剂及心脏再同步治疗等能够显著改善LVEF并提升至40%以上;对于HFimpEF患者,钠-葡萄糖转运体2抑制剂及肾素-血管紧张素系统抑制剂能够有效维持患者LVEF及其心脏功能。此外,该文也提出HFimpEF现有研究的不足与未来的研究方向。展开更多
基金supported by the National Natural Science Foundation of China ( 11732001)
文摘Objective Heart failure(HF)is divided into two types:Heart failure with reduced ejection fraction(HFrEF)and heart failure with preserved ejection fraction(HFpEF).The latter always results in diastolic dysfunction,characterized by changes in mechanical properties.The objective of this study is to build a finite element(FE)model of HFpEF and analyze diastolic and systolic function in rats.Methods Ten Dahl salt-sensitive rats were fed either a low-salt(LS)(n=5)or highsalt(HS)(n=5)diet beginning at 7 weeks of age and scanned by ultrasonic machine at 14 weeks of age.A non-linear FE model of the left ventricle(LV)was built from cardiac echo images at end-diastole and passive material properties of the LV were prescribed using Fung’s transversely isotropic constitutive law.Fiber angles of the endocardium and epicardium were prescribed as 53°°and-52°,respectively,with respect to the circumferential direction and varied linearly through the LV wall.The method developed by Krishnamurthywas used to determine the unloaded geometry to estimate the Fung passive material parameters.LV end-diastolic pressure(EDP)was determined from the measured pressure waves and applied to the endocardium at the unloaded geometry to simulate passive filling.Active material properties of the LV were prescribed using Guccione’s time-varying elastance model and maximum isometric tension was scaled to match the measured peak systolic pressure.The finite element model was then coupled to the Windkessel model,whose parameters were adjusted to the measured hemodynamics.Results Measured LVEDPs of LS and HS rats were 4.9±3.4 mmHg and 13.2±5.4 mmHg(P-0.030 8),respectively.End-diastolic Cauchy stress along the fiber direction for LS rats was significantly lower than for HS rats(0.91±0.60 kPa vs 3.00±0.63 kPa,P=0.001 4)and there was a similar trend in end-diastolic Green Strain along the fiber direction(0.058±0.003 vs 0.072±0.010,P=0.012 8,Figure 1b),as well.There was no distinctive difference between end-systolic Cauchy stress along the fiber direction for LS rats and HS rats(17.2±4.3 kPa vs 17.2±5.5 kPa,P=0.991 9)but end-systolic Green Strain along the fiber direction for LS rats was significantly higher than for HS rats(-0. 108±0.017 vs-0.065±0.024,negative sign represents direction).Conclusions For rats with HFpEF,it is the elevated LVEDP that induces the increase in end-diastolic stress and strain,thereby leading to diastolic dysfunction.Because of the preserved ejection fraction,HFpEF has less effect on systolic function.
文摘在射血分数降低型心力衰竭(heart failure with reduced ejection fraction,HFrEF)患者中,部分患者的左室射血分数(left ventricular ejection fraction,LVEF)经治疗后在后续评估中出现明显改善。2022年美国心脏学会/美国心脏病协会/美国心衰学会(American Heart Association/American College of Cardiology/Heart Failure Society of America,AHA/ACC/HFSA)颁布的心力衰竭管理指南将既往LVEF≤40%且在随访过程中提升至40%以上的心力衰竭类型命名为射血分数改善型心力衰竭(heart failure with improved ejection fraction,HFimpEF)。研究表明,HFimpEF患者的全因死亡率、心力衰竭再住院率较低,预后明显优于HFrEF,可作为HFrEF患者的阶段性治疗目标。关于HFimpEF患者的热点讨论主要围绕2个方面,即HFimpEF的目标人群特征及LVEF提升的有效手段、HFimpEF患者心功能维持治疗方案;尤其是后者,尚无明确的临床指南推荐。因此,回顾现有研究,系统总结促使HFrEF向HFimpEF转归的治疗方案,以及有效针对HFimpEF的维持手段至关重要。该文对现有药物、器械、手术治疗的LVEF改善效果及HFimpEF患者的监测与治疗方法进行综述。对于HFrEF患者,现有临床研究提示β受体阻滞剂及心脏再同步治疗等能够显著改善LVEF并提升至40%以上;对于HFimpEF患者,钠-葡萄糖转运体2抑制剂及肾素-血管紧张素系统抑制剂能够有效维持患者LVEF及其心脏功能。此外,该文也提出HFimpEF现有研究的不足与未来的研究方向。
