Piezoelectric polymer curvature sensor for measurement of regional curvature radius of LV wall

1988 ◽  
Vol 254 (5) ◽  
pp. H1010-H1016 ◽  
Author(s):  
K. Tsujioka ◽  
Y. Ogasawara ◽  
K. Mito ◽  
O. Hiramatsu ◽  
Y. Wada ◽  
...  
Keyword(s):  
Myocardial Function ◽  
Accurate Information ◽  
Curvature Radius ◽  
Short Axis ◽  
Regional Myocardial Function ◽  
Regional Ischemia ◽  
Piezoelectric Polymer ◽  
Anesthetized Dogs ◽  
And Function ◽  
Curvature Sensor

To evaluate regional myocardial function, we developed a curvature sensor for direct and instantaneous measurement of the regional curvature radius of the LV wall. The sensor is a bimorph of two sheets of thin piezoelectric polymer film. The relation between output voltage of the sensor and the reciprocal of the known curvature radius has been shown to be linear. In anesthetized dogs, we inserted the curvature sensor into the subepimyocardium with a specially designed introducer. Special care was taken to insert it parallel to the epicardial surface. Circumferential regional curvature radius, which is defined as the reciprocal of regional curvature, showed the same phasic changes as the short-axis diameter under control conditions. Under regional ischemia caused by transient occlusion of the coronary artery, amplitude of the phasic change in regional curvature radius decreased, whereas that of the short-axis diameter did not change or slightly increased. Phasic changes in regional curvature radius cannot be estimated from short-axis diameter during regional ischemia. We calculated regional wall tension from the directly measured regional curvature radius and LV pressure and found that tension-length loop clearly differentiates between regional myocardial function under control and ischemic conditions. We have concluded that our newly developed curvature sensor is accurate, that its practical use is feasible, and that measurement of the regional curvature radius of the LV wall provides detailed and accurate information on regional shape and function of the left ventricle.

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.

Effects of ventricular pacing on regional left ventricular performance in the dog

1980 ◽  
Vol 238 (6) ◽  
pp. H858-H867 ◽  
Author(s):  
F. R. Badke ◽  
P. Boinay ◽  
J. W. Covell
Keyword(s):  
Myocardial Function ◽  
Systolic Pressure ◽  
Lateral Wall ◽  
Left Ventricular ◽  
Atrial Pacing ◽  
Ventricular Pacing ◽  
Regional Myocardial Function ◽  
Ventricular Performance ◽  
Reciprocal Interaction ◽  
Anesthetized Dogs

Changes in regional left ventricular (LV) performance induced by ventricular pacing were studied in two groups of open-chest anesthetized dogs. In the first group of five dogs, local function at the LV anterior base, anterior apex, and posterior apex was assessed by ultrasonic crystal pairs with atrial, right ventricular, LV apical, and LV base pacing. Ventricular pacing produced asynchrony of contraction and marked changes in the shortening pattern at each site, as well as an average 27% reduction in peak systolic pressure and peak dP/dt compared to atrial pacing. Moreover, the extent of shortening during LV ejection was reduced or unchanged at all sites measured during ventricular pacing. In the second group of five dogs, function of the septum and opposing LV lateral wall was studied with atrial and LV lateral wall pacing. Lateral function was assessed with a crystal pair and septal function by cineradiography of a lead bead implanted in the septum. Ventricular pacing produced reciprocal interaction between the two walls, with early lateral shortening inducing septal bulging and late septal shortening inducing lateral wall systolic lengthening. We conclude that ventricular pacing produces significant changes in regional myocardial function, likely induced by reciprocal interaction of opposing myocardial regions. Furthermore, such interaction appears deleterious to global ventricular function, presumably because volume is sequestered and pressure is dissipated into relatively inactive segments that are out of phase with the bulk of contracting myocardium.

scholarly journals Development of a semi-automated segmentation tool for high frequency ultrasound image analysis of mouse echocardiograms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kristi Powers ◽  
Raymond Chang ◽  
Justin Torello ◽  
Rhonda Silva ◽  
Yannick Cadoret ◽  
...  
Keyword(s):  
Image Analysis ◽  
Automated Analysis ◽  
Structure And Function ◽  
Ultrasound Images ◽  
Cardiac Structure ◽  
Short Axis ◽  
Pixel Intensity ◽  
Cardiac Structure And Function ◽  
And Function

AbstractEchocardiography is a widely used and clinically translatable imaging modality for the evaluation of cardiac structure and function in preclinical drug discovery and development. Echocardiograms are among the first in vivo diagnostic tools utilized to evaluate the heart due to its relatively low cost, high throughput acquisition, and non-invasive nature; however lengthy manual image analysis, intra- and inter-operator variability, and subjective image analysis presents a challenge for reproducible data generation in preclinical research. To combat the image-processing bottleneck and address both variability and reproducibly challenges, we developed a semi-automated analysis algorithm workflow to analyze long- and short-axis murine left ventricle (LV) ultrasound images. The long-axis B-mode algorithm executes a script protocol that is trained using a reference library of 322 manually segmented LV ultrasound images. The short-axis script was engineered to analyze M-mode ultrasound images in a semi-automated fashion using a pixel intensity evaluation approach, allowing analysts to place two seed-points to triangulate the local maxima of LV wall boundary annotations. Blinded operator evaluation of the semi-automated analysis tool was performed and compared to the current manual segmentation methodology for testing inter- and intra-operator reproducibility at baseline and after a pharmacologic challenge. Comparisons between manual and semi-automatic derivation of LV ejection fraction resulted in a relative difference of 1% for long-axis (B-mode) images and 2.7% for short-axis (M-mode) images. Our semi-automatic workflow approach reduces image analysis time and subjective bias, as well as decreases inter- and intra-operator variability, thereby enhancing throughput and improving data quality for pre-clinical in vivo studies that incorporate cardiac structure and function endpoints.

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