Cardiovascular Changes in Renal Failure
ABSTRACT In patients with renal failure cardiovascular complications are an important clinical problem and cardiac death is the main cause of death in these patients. It is well documented that cardiac risk is increased by a factor of 20 in uremic patients compared with age- and sex-matched segments of the general population. This finding in patients with renal failure can be at least partially explained by the well-described structural and metabolic abnormalities of the myocardium. The present article focuses on the structural changes in the heart and the vasculature and their potential repercussions for cardiovascular function, in particular their contribution to the high cardiovascular morbidity and mortality in patients with renal failure.
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ABSTRACT: BACKGROUND: Left ventricle (LV) structural change in chronic kidney disease (CKD) patients is due principally to a chronic increase in volume and pressure overload. LV torsion has been shown to be a key factor of evaluating LV function, but has rarely been assessed in CKD by three-dimensional speckle tracking imaging (3D STI). The purpose of this study is to evaluate LV torsion in CKD patients receiving hemodialysis compared with normal healthy subjects. METHODS: Twenty-seven CKD patients on hemodialysis and 27 healthy volunteers were recruited. 3D STI was performed immediately before hemodialysis in the dialysis room. The rotation, twist, and torsion of the LV were automatically calculated by commercialized software for each segment of the LV. RESULTS: Body weight (P < 0.01), both systolic and diastolic blood pressure (P < 0.01), end diastolic and end systolic volume (P < 0.05), and ejection fractions (P < 0.01) showed statistically significant differences between the two groups. There were also significant differences in global value of rotation (3.0 ± 2.0 vs. 2.5 ± 1.9 deg P < 0.05), twist (4.6 ± 3.3 vs. 2.7 ± 1.9 deg P < 0.05), basal torsion (1.6 ± 1.1 vs. 0.9 ± 0.6 deg/cm P < 0.05) and regional torsion (1.6 ± 1.2 vs. 0.9 ± 0.8 deg/cm P < 0.05) between healthy volunteers and CKD patients. CONCLUSION: Assessment of LV torsion by newly developed 3D STI is less laborious and time-consuming. Decrease of LV torsion in CKD patients might be due to the marked disarray of myocardial fibers in a uremic heart that affects LV structure, resulting in non-uniform LV torsion.
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ABSTRACT: Background: The effect of acute volume change by hemodialysis on contractile characteristics of the left ventricle (LV) is not well known and has never been evaluated by 3-dimensional speckle tracking echocardiography (3D-STE). Methods: Twenty-three patients on chronic hemodialysis were recruited. 3D-STE was performed immediately before and after hemodialysis in the dialysis room. The strain, displacement, rotation, torsion, and twist of LV were calculated by commercial software for different segments of LV. Results: Hemodialysis produced significant decreases in body weight, systolic and diastolic blood pressure, end-diastolic and end-systolic volumes, but ejection fraction did not change. The regional torsion increased from 2.1 ± 1.2 to 2.7 ± 1.3 degree/cm (p = 0.012) after dialysis, though the crude global torsion, longitudinal, radial, circumferential, 3D strain, rotation and twist of LV did not change significantly. The regional torsion correlated with the crude global torsion (r = 0.763, p < 0.001). The change of ejection fraction after hemodialysis was significantly correlated with changes of circumferential strain (r = -0.858, p < 0.001), longitudinal strain (r = -0.516, p = 0.012) and LV area (r = -0.883, p < 0.001). Conclusion: Assessment of LV contractile characteristics by 3D-STE is easy and efficient. The regional torsion, which could only be evaluated by 3D-STE, is more sensitive to reduction in preload possibly due to deformation non-uniformity of myocardium in uremic patients.
Conference Paper: Pole assignment and a theorem from exterior algebra[Show abstract] [Hide abstract]
ABSTRACT: This paper presents an extension of a basic decomposition result from the exterior algebra of F-vector spaces to that of free F[s]-modules and explains its relevance to certain pole assignment problems associated with minimal design.Decision and Control including the 16th Symposium on Adaptive Processes and A Special Symposium on Fuzzy Set Theory and Applications, 1977 IEEE Conference on; 01/1978