Kovács Sándor J
Department of Internal Medicine, Washington University, St. Louis, MO 63110, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:2354-7. doi: 10.1109/IEMBS.2009.5335021.
Because 50% of heart failure hospital admissions have diastolic heart failure (DHF) quantifying diastolic function (DF) has reached new prominence. Conventionally DF indices have been computed from shape-based features (height, duration, area) of Doppler waveforms such as the E-wave, (transmitral flow velocity), or E'-wave (mitral annular velocity) without regard to causal mechanisms. Solution of the 'inverse problem' has been achieved via the parametrized diastolic filling (PDF) formalism, a linear, kinematic model which treats the elastic, recoil-driven suction-pump attribute of the left ventricle as a damped simple harmonic oscillator (SHO). PDF uses the E-wave as input and generates stiffness (k), relaxation/ damping (c) and load (x(o)) as output. Scientific successes include the prediction that filling must be driven by a linear, bi-directional spring, later validated as a property of the giant cardiac protein titin, which generates a recoiling force at the cellular level in early diastole. Selected recent kinematic modeling achievements include: explanation why E-wave deceleration time must be determined jointly by stiffness (k) and relaxation (c), rather than by stiffness alone; LV equilibrium volume is the volume at diastasis; solution of the load-independent index of diastolic function (LIIDF) problem; solution of the isovolumic pressure decay (IVPD) problem. Clinical application reveals that contrary to dogma, chamber relaxation/viscoelasticity (PDF parameter c) rather than chamber stiffness (PDF parameter k) most often differentiates between controls vs. diastolic dysfunction subjects, thereby providing mechanistic insights into DHF.
由于50%的心力衰竭住院病例为舒张性心力衰竭（DHF），对舒张功能（DF）进行量化已变得格外重要。传统上，DF指标是根据多普勒波形（如E波，即跨二尖瓣血流速度，或E'波，即二尖瓣环速度）基于形状的特征（高度、持续时间、面积）计算得出的，而未考虑其因果机制。“逆问题”已通过参数化舒张期充盈（PDF）形式得以解决，这是一种线性运动学模型，将左心室的弹性、反冲驱动的抽吸泵属性视为一个阻尼简谐振荡器（SHO）。PDF以E波作为输入，并生成刚度（k）、松弛/阻尼（c）和负荷（xₒ）作为输出。该理论在科学上的成功之处包括预测充盈必须由线性双向弹簧驱动，后来这一特性在巨大的心脏蛋白肌联蛋白中得到验证，肌联蛋白在舒张早期在细胞水平产生反冲力。近期在运动学建模方面取得的成就包括：解释了为何E波减速时间必须由刚度（k）和松弛（c）共同决定，而非仅由刚度决定；左心室平衡容积是舒张末期容积；解决了舒张功能负荷无关指数（LIIDF）问题；解决了等容压力衰减（IVPD）问题。临床应用表明，与传统观念相反，心室舒张/粘弹性（PDF参数c）而非心室刚度（PDF参数k）最常区分对照组与舒张功能障碍患者，从而为DHF提供了机制上的见解。
