Small apex-to-base heterogeneity in radius-to-thickness ratio by three-dimensional magnetic resonance imaging

1993 ◽  
Vol 264 (1) ◽  
pp. H133-H140 ◽  
Author(s):  
R. Beyar ◽  
J. L. Weiss ◽  
E. P. Shapiro ◽  
W. L. Graves ◽  
W. J. Rogers ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Ejection Fraction ◽  
Myocardial Function ◽  
Three Dimensional ◽  
Stress Index ◽  
Radius Of Curvature ◽  
Cross Sectional ◽  
Large Variability ◽  
Small Base ◽  
Image Planes

Reported large base-to-apex differences in endocardial area ejection fraction may suggest large variability in myocardial function and load. To test ventricular load heterogeneities, we measured the ratio of radius of curvature to wall thickness (R/T), as a stress index reflecting myocardial load. End-diastolic (ED) and end-systolic (ES) magnetic resonance cross-sectional images were obtained in 15 open-chest dogs at 5 levels from base to apex, from which 4 three-dimensional thick disks were generated from adjacent image planes. The average R/T for each disk was calculated by planar and three-dimensional methods, using both midwall and endocardial radii of curvature. R/T was normalized to the apical value to quantify the relative changes in myocardial load. Normalized R/T using the midwall three-dimensional approach was 1.08, 1.11, 1.06, and 1.0 for ED (P = NS) and 1.25, 1.013, 1.08, and 1.0 for ES (P < 0.02), base to apex, respectively, while the other methods yielded higher values. Therefore, R/T calculated by the three-dimensional midwall approach shows only small apex-to base variations at ED (< 11%) and ES (< 25%), which is substantially less than the variability in area ejection fraction (102%). This suggests only small base-to-apex load heterogeneities, in spite of large changes in the area ejection fraction, an index reflecting specific ventricular geometry rather than local myocardial function.

Stiffness Constants for Composite Beams Including Large Initial Twist and Curvature Effects

1995 ◽  
Vol 48 (11S) ◽  
pp. S61-S67 ◽  
Author(s):  
Carlos E. S. Cesnik ◽  
Dewey H. Hodges
Keyword(s):  
Wave Length ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Cross Sectional ◽  
Curvature Effects ◽  
Three Dimensional Representation ◽  
Stiffness Model ◽  
Sectional Analysis ◽  
Three Dimensional Elasticity ◽  
Coupling Phenomena

An asymptotically exact methodology, based on geometrically nonlinear, three-dimensional elasticity, is presented for cross-sectional analysis of initially curved and twisted, nonhomogeneous, anisotropic beams. Through accounting for all possible deformation in the three-dimensional representation, the analysis correctly accounts for the complex elastic coupling phenomena in anisotropic beams associated with shear deformation. The analysis is subject only to the restrictions that the strain is small relative to unity and that the maximum dimension of the cross section is small relative to the wave length of the deformation and to the minimum radius of curvature and/or twist. The resulting cross-sectional elastic constants exhibit second-order dependence on the initial curvature and twist. As is well known, the associated geometrically-exact, one-dimensional equilibrium and kinematical equations also depend on initial twist and curvature. The corrections to the stiffness model derived herein are also necessary in general for proper representation of initially curved and twisted beams.

P5266Renal denervation improves diastolic dysfunction in patients with HFpEF - initial results of a multicenter CMR study

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
S Zamani ◽  
F Mahfoud ◽  
L Stoiber ◽  
M Boehm ◽  
B Pieske ◽  
...  
Keyword(s):  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ejection Fraction ◽  
Resistant Hypertension ◽  
Renal Denervation ◽  
Myocardial Function ◽  
Left Ventricular ◽  
Cine Mri ◽  
Preserved Ejection Fraction

Abstract Introduction Renal denervation (RDN) significantly reduces blood pressure (BP) and improves myocardial function in patients with resistant hypertension. Purpose This multicenter study aimed to investigate the intermediate term effect of RDN on left ventricular global longitudinal strain (GLS), a surrogate for diastolic myocardial function in RDN patients with proven heart failure with preserved ejection fraction (HFpEF), assessed by cardiac magnetic resonance imaging (CMR). Methods We analyzed data from 22 patients with resistant hypertension (mean age 68±6 years). 16 patients underwent renal denervation (RDN) and 6 matched control patients received optimal medical therapy (OMT). Both groups had diastolic dysfunction defined by preserved ejection fraction (EF ≥50%) and pathologically elevated GLS at baseline (GLS >−18%) quantified by cardiac magnetic resonance (CMR). A standardized CMR protocol was performed at baseline (BL) and 6 months follow-up (FU). Left ventricular mass index (LVMI) was quantified in end-diastolic and end-systolic endo- and epicardial contouring in short axis cine-MRI images. GLS was measured by end-diastolic and end-systolic endocardial contouring in 2-, 3- and 4-chamber view cine-MRI images. MRI-Images have been analyzed with Medis, Netherlands. Results GLS following RDN patients significantly improved after 6 months by 21% (−14.21% ±3.19 vs. −17.17%± 3.1; p=0.007). In control patients with OMT, no significant change in GLS was detected (−14.77% ±3.05 vs. −17.39% ± 4.49; p=0.327). LVMI was numerically reduced in the RDN group at follow-up but did not reach statistical significance (58.55 g/m2±11.37 vs. 55.46 g/m2±12.76; p=0.085). There was no such effect in control patients with OMT (49.25 g/m2±8.2 vs. 50.18 g/m2±7.27; p=0.665). (See also: Figure A and B). Conclusions We found significantly improved diastolic function (GLS) in patients with HFpEF and resistant hypertension undergoing RDN. Future studies are needed to determine whether RDN represents a treatment option in patients with HFpEF.

scholarly journals Assessment of right ventricular volumes and ejection fraction by echocardiography: from geometric approximations to realistic shapes

2015 ◽  
Vol 2 (1) ◽  
pp. R1-R11 ◽  
Author(s):  
Ellen Ostenfeld ◽  
Frank A Flachskampf
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Ejection Fraction ◽  
Right Ventricular ◽  
Three Dimensional ◽  
3D Echocardiography ◽  
Large Majority ◽  
Prognostic Parameters ◽  
Resonance Imaging ◽  
Ventricular Volumes

Right ventricular volumes and ejection fraction are challenging to assess by echocardiography, but are well established as functional and prognostic parameters. Three-dimensional (3D) echocardiography has become widespread and relatively easy to use, making calculation of these parameters feasible in the large majority of patients. We review past attempts to estimate right ventricular volumes, current strengths and weaknesses of 3D echocardiography for this task, and compare with corresponding data from magnetic resonance imaging.

Three-dimensional magnetic resonance images of the brain: application to neurosurgical planning

1990 ◽  
Vol 72 (3) ◽  
pp. 433-440 ◽  
Author(s):  
Xiaoping Hu ◽  
Kim K. Tan ◽  
David N. Levin ◽  
Simranjit Galhotra ◽  
John F. Mullan ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Three Dimensional ◽  
Preoperative Assessment ◽  
Magnetic Resonance Images ◽  
Interactive Software ◽  
Cross Sectional ◽  
Content Type ◽  
Brain Surface ◽  
Neurosurgical Planning ◽  
The Brain

✓ Data from single 10-minute magnetic resonance scans were used to create three-dimensional (3-D) views of the surfaces of the brain and skin of 12 patients. In each case, these views were used to make a preoperative assessment of the relationship of lesions to brain surface structures associated with movement, sensation, hearing, and speech. Interactive software was written so that the user could “slice” through the 3-D computer model and inspect cross-sectional images at any level. A surgery simulation program was written so that surgeons were able to “rehearse” craniotomies on 3-D computer models before performing the actual operations. In each case, the qualitative accuracy of the 3-D views was confirmed by intraoperative inspection of the brain surface and by intraoperative electrophysiological mapping, when available.

Increased Stiffness of Bioresorbable Plates Following Heating and Three-Dimensional Contouring

2004 ◽  
Author(s):  
Terence E. McIff ◽  
Richard Lark ◽  
Andrea Hilty ◽  
Andrew Cooper ◽  
E. Bruce Toby
Keyword(s):  
Three Dimensional ◽  
Torsional Stiffness ◽  
Radius Of Curvature ◽  
Structural Stiffness ◽  
Metacarpal Fracture ◽  
Cross Sectional ◽  
Fixation Methods ◽  
Metacarpal Bones ◽  
Standard Fixation ◽  
Bioresorbable Plate

A wide copolymer bioresorable plate offers increased structural stiffness following heated contouring of the plate to various diameters which increases its resisting moment of inertia. The increase in bending and torsional stiffness of this design is measured as a function of cross-sectional radius of curvature achieved. Its structural stiffness is compared to three other standard fixation methods used for metacarpal fracture. Substantial increases in stiffness are found after contouring of the wide bioresorbable plate to fit diameters similar to those found in metacarpal bones.

Influence of site of regional ischemia on nonischemic thickening in anesthetized dogs

1989 ◽  
Vol 256 (5) ◽  
pp. H1417-H1425
Author(s):  
P. N. Marino ◽  
D. A. Kass ◽  
L. C. Becker ◽  
J. A. Lima ◽  
J. L. Weiss
Keyword(s):  
Myocardial Function ◽  
Three Dimensional ◽  
Cross Sectional ◽  
Regional Ischemia ◽  
Systolic Thickening ◽  
Lv Mass ◽  
Dimensional Distribution ◽  
Anesthetized Dogs ◽  
Acute Regional Ischemia ◽  
Wall Geometry

The effect of varying the site of acute regional ischemia on nonischemic myocardial function was examined by comparing regional thickening during 2-3 min circumflex (Circ) vs. left anterior descending (LAD) coronary artery occlusions in eight open-chest dogs. Cross-sectional midwall two-dimensional echocardiograms were obtained, and systolic thickening was measured at 16 equal-spaced points around the circumference. The distribution and extent of hypoperfusion was assessed by radiolabeled microspheres. The echo slice was subdivided into a hypoperfused region (Hypo), four adjacent nonischemic regions (ADJ1-4), and the remaining remote segments (Remote). The extent of hypoperfusion (%LV mass) was similar with both sets of occlusions (LAD, 29.4 +/- 2.8%; Circ, 26.0 +/- 4.4%; P = NS), as was endo- and epicardial flow in the nonischemic regions. Yet, even with like-sized Hypo regions, thickening of nonischemic myocardium was significantly greater during Circ than during LAD occlusions (P less than 0.001). These results are consistent with recently reported disparities of global functional impairment during LAD vs. Circ ischemia. The responses likely reflect differences in regional wall geometry, loading, and the three-dimensional distribution of coronary hypoperfusion between the two vascular territories.

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