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Estimation of maximum intraventricular pressure: a three-dimensional fluid-structure interaction model.

Bahraseman HG, Hassani K, Khosravi A, Navidbakhsh M, Espino DM, Kazemi-Saleh D, Fatourayee N - Biomed Eng Online (2013)

Bottom Line: 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.Furthermore, the method is non-invasive, safe, cheap and more practical.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomechanics, Science and Research Branch, Islamic Azad University, Tehran, Iran. k.hasani@srbiau.ac.ir.

ABSTRACT

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

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The simulated aortic valve geometry. An axisymmetric model was used with one-sixth of the valve represented. The top view was acquired using the assumed symmetry of the model.
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Figure 2: The simulated aortic valve geometry. An axisymmetric model was used with one-sixth of the valve represented. The top view was acquired using the assumed symmetry of the model.

Mentions: A three-dimensional axisymetric model has been used with one-sixth of the valve geometry modelled (Figure 2; Table 1). Briefly, aortic valve geometry was obtained with respect to T-wave of ECG (maximum opening area). Diameters of the aortic valve annulus and the sinus valsalva were measured at the peak T-wave time using a resting para-sternal long-axis view. This data was used to generate the three-dimensional geometry (Figure 2) in Solidworks (Solidworks v2011, Dassault Systèmes SolidWorks Corp, France). In our model, leaflets were assumed to have a uniform thickness (0.6 mm).


Estimation of maximum intraventricular pressure: a three-dimensional fluid-structure interaction model.

Bahraseman HG, Hassani K, Khosravi A, Navidbakhsh M, Espino DM, Kazemi-Saleh D, Fatourayee N - Biomed Eng Online (2013)

The simulated aortic valve geometry. An axisymmetric model was used with one-sixth of the valve represented. The top view was acquired using the assumed symmetry of the model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222736&req=5

Figure 2: The simulated aortic valve geometry. An axisymmetric model was used with one-sixth of the valve represented. The top view was acquired using the assumed symmetry of the model.
Mentions: A three-dimensional axisymetric model has been used with one-sixth of the valve geometry modelled (Figure 2; Table 1). Briefly, aortic valve geometry was obtained with respect to T-wave of ECG (maximum opening area). Diameters of the aortic valve annulus and the sinus valsalva were measured at the peak T-wave time using a resting para-sternal long-axis view. This data was used to generate the three-dimensional geometry (Figure 2) in Solidworks (Solidworks v2011, Dassault Systèmes SolidWorks Corp, France). In our model, leaflets were assumed to have a uniform thickness (0.6 mm).

Bottom Line: 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.Furthermore, the method is non-invasive, safe, cheap and more practical.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomechanics, Science and Research Branch, Islamic Azad University, Tehran, Iran. k.hasani@srbiau.ac.ir.

ABSTRACT

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Show MeSH
Related in: MedlinePlus