Biomedical subjects

M K Pasque

Publications and source records attributed to M K Pasque.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Hybrid DANTE and phase-contrast imaging technique for measurement of three-dimensional myocardial wall motion.

Characterization of myocardial stress and strain is necessary for a complete understanding of myocardial function. The precise quantification of regional myocardial strain is complicated by its time-varying pattern and regional variation resulting from the anisotropy of the myocardium and by complex torsional and shortening motions of the heart during the cardiac cycle. The authors have developed a technique for point-specific tracking of myocardial motion along all three axes in a constant selected section of myocardium by combining prospective section selection with in-plane DANTE (delays alternating with nutations for tailored excitation) tissue tagging and phase-contrast detection of motion perpendicular to the image plane. With this technique, it is possible to determine point-specific myocardial strain values in vivo.

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PubMedDate not supplied

Mathematical three-dimensional solid modeling of biventricular geometry.

The characterization of regional myocardial stress distribution has been limited by the use of idealized mathematical representations of biventricular geometry. State-of-the-art computer-aided design and engineering (CAD/CAE) techniques can be used to create complete, unambiguous mathematical representations (solid models) of complex object geometry that are suitable for a variety of applications, including stress-strain analyses. We have used advanced CAD/CAE software to create a 3-D solid model of the biventricular unit using planar geometric data extracted from an ex vivo canine heart. Volumetric analysis revealed global volume errors of 4.7%, -1.3%, -1.6%, and -1.1% for the left ventricular cavity, right ventricular cavity, myocardial wall, and total enclosed volumes, respectively. Model errors for 34 in-plane area and circumference determinations (mean +/- SD) were 5.3 +/- 6.7% and 3.8 +/- 2.7%. Error analysis suggested that model volume errors may be due to operator variability. These results demonstrate that solid modeling of the ex vivo biventricular unit yields an accurate mathematical representation of myocardial geometry which is suitable for meshing and subsequent finite element analysis. The use of CAD/CAE solid modeling in the representation of biventricular geometry may thereby facilitate the characterization of regional myocardial stress distribution.

Animals↗

PubMedDate not supplied

Ventricular interaction in the pathologic heart. A model based study.

The effects of direct ventricular interaction and interaction mediated by the pericardium on the diastolic left ventricle (LV) were quantified using idealized models of five pathologic conditions. Two-dimensional (2D) mathematical models were constructed in long and short axis views of four pathologic LV conditions and the normal heart (NL): dilated cardiomyopathy (DCM), concentric LV hypertrophy (HYP), chronic anterior-apical infarction in a normal shaped LV (CAINL), and CAI in a dilated LV (CAID). To assess the effects of RV pressure increase on the LV mechanical state, RV pressure was systematically increased for several LV pressures and changes in the LV diastolic pressure-area relationships, and LV free wall and septal principal stresses and strains were quantified. At higher RV pressures, with pericardial effects included in the models, the pressure-area relationship was similar for all models, indicating that, at these higher pressures, the effects of RV and pericardial pressures are more important than global LV shape, wall thickness, or material properties in determining the pressure-area relationship. There were significant differences among models in the changes in LV free wall and septal stress and strain after an increase in RV pressure. These models may be of use in predicting interaction in the corresponding clinical state.

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