Department of Biomechanics, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Biomed Eng Online. 2013 Nov 22;12:122. doi: 10.1186/1475-925X-12-122.
The aim of this study was to propose a method to estimate the maximum pressure in the left ventricle (MPLV) for a healthy subject, based on cardiac outputs measured by echo-Doppler (non-invasive) and catheterization (invasive) techniques at rest and during exercise.
Blood flow through aortic valve was measured by Doppler flow echocardiography. Aortic valve geometry was calculated by echocardiographic imaging. A Fluid-structure Interaction (FSI) simulation was performed, using an Arbitrary Lagrangian-Eulerian (ALE) mesh. Boundary conditions were defined as pressure loads on ventricular and aortic sides during ejection phase. The FSI simulation was used to determine a numerical relationship between the cardiac output to aortic diastolic and left ventricular pressures. This relationship enabled the prediction of pressure loads from cardiac outputs measured by invasive and non-invasive clinical methods.
Ventricular systolic pressure peak was calculated from cardiac output of Doppler, Fick oximetric and Thermodilution methods leading to a 22%, 18% and 24% increment throughout exercise, respectively. The mean gradients obtained from curves of ventricular systolic pressure based on Doppler, Fick oximetric and Thermodilution methods were 0.48, 0.41 and 0.56 mmHg/heart rate, respectively. Predicted Fick-MPLV differed by 4.7%, Thermodilution-MPLV by 30% and Doppler-MPLV by 12%, when compared to clinical reports.
Preliminary results from one subject show results that are in the range of literature values. The method needs to be validated by further testing, including independent measurements of intraventricular pressure. Since flow depends on the pressure loads, measuring more accurate intraventricular pressures helps to understand the cardiac flow dynamics for better clinical diagnosis. Furthermore, the method is non-invasive, safe, cheap and more practical. As clinical Fick-measured values have been known to be more accurate, our Fick-based prediction could be the most applicable.
本研究旨在提出一种基于超声心动图（非侵入性）和导管测量的健康受试者左心室最大压力（MPLV）的方法，在休息和运动期间测量心输出量。
通过多普勒血流超声心动图测量主动脉瓣血流。通过超声心动图成像计算主动脉瓣几何形状。使用任意拉格朗日-欧拉（ALE）网格进行流固耦合（FSI）模拟。在射血期，心室和主动脉侧定义为压力负荷。FSI 模拟用于确定心输出量与主动脉舒张和左心室压力之间的数值关系。该关系使我们能够从侵入性和非侵入性临床方法测量的心输出量预测压力负荷。
从多普勒、Fick 血氧定量法和热稀释法测量的心脏输出中计算出心室收缩压峰值，在整个运动过程中分别增加了 22%、18%和 24%。基于多普勒、Fick 血氧定量法和热稀释法的心室收缩压曲线获得的平均梯度分别为 0.48、0.41 和 0.56 mmHg/心率。与临床报告相比，Fick-MPLV 预测值相差 4.7%，热稀释-MPLV 相差 30%，多普勒-MPLV 相差 12%。
来自一个受试者的初步结果表明，结果在文献值范围内。该方法需要通过进一步的测试进行验证，包括对室内压力的独立测量。由于流量取决于压力负荷，测量更准确的室内压力有助于了解心脏流量动力学，从而进行更好的临床诊断。此外，该方法是非侵入性的、安全的、廉价的、更实用的。由于临床 Fick 测量值已被证明更准确，因此我们基于 Fick 的预测可能是最适用的。
