Zhong L, Ghista D N, Ng E Y K, Lim S T, Chua T S J, Lee C N
School of Mechanical and Production Engineering, College of Engineering, Nanyang Technological University, Nanyang Avenue, Republic of Singapore.
J Med Eng Technol. 2007 Jul-Aug;31(4):253-62. doi: 10.1080/03091900500412692.
We have investigated the effect of left ventricular (LV) shape on contractility and ejection function. In this study, a new contractility index is developed in terms of the wall stress (sigma*, normalized with respect to LV pressure) by means of an LV ellipsoidal model. Using cine-ventriculography data, the LV ellipsoidal model (LVEM) major (B) and minor axes (A) are derived for the entire cardiac cycle. Thereafter, a new contractility index (CONT1) is derived as dsigma*/dt, incorporating the LV ellipsoidal shape factor. Also, another contractility index (CONT2) was developed in terms of the generated sigma* at the start of ejection phase, and maximized with respect to B/Ashape parameter, to obtain the optimal value of B/Aover the physiological ranges of the ratio of myocardial volume and LV volume. The in vivovalue of B/Aat the start of ejection is compared with this optimal value, and the LV contractility is evaluated in terms of the proximity of the in vivo B/Ato the optimal B/A. The results indicate that a non-optimal less-ellipsoidal shape (or more spherical) is associated with decreased contractility (and poor systolic function) of the LV, associated with a failing heart.
我们研究了左心室（LV）形状对收缩性和射血功能的影响。在本研究中，通过左心室椭圆模型，根据壁应力（σ*，相对于左心室压力进行归一化）开发了一种新的收缩性指数。利用电影心室造影数据，在整个心动周期中推导左心室椭圆模型（LVEM）的长轴（B）和短轴（A）。此后，将左心室椭圆形状因子纳入，推导出一个新的收缩性指数（CONT1），即dsigma*/dt。此外，还根据射血期开始时产生的σ*开发了另一个收缩性指数（CONT2），并相对于B/A形状参数进行最大化，以在心肌体积与左心室体积之比的生理范围内获得B/A的最佳值。将射血开始时B/A的体内值与该最佳值进行比较，并根据体内B/A与最佳B/A的接近程度评估左心室收缩性。结果表明，非最佳的较不椭圆形状（或更球形）与左心室收缩性降低（和收缩功能不良）相关，这与心力衰竭有关。
