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Myosplint decreases wall stress without depressing function in the failing heart: a finite element model study Julius M Guccione, PhD, Ali Salahieh, BS, Scott M Moonly, BS, Jeroen Kortsmit, BS, Arthur W Wallace, MD, PhD, Mark B Ratcliffe, MD The Annals of Thoracic Surgery Volume 76, Issue 4, Pages (October 2003) DOI: /S (03)
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Fig 1 The globally dilated left ventricular model (A) in unpressurized state and the same finite element model (B) after the diameters at the points of application of three Myosplints have been reduced so that they are 75% of those at end-diastole (25% reduction). The red rendered surface is the endocardium; blue lines outline the finite elements; arrows indicate the points of Myosplint attachment. The Annals of Thoracic Surgery , DOI: ( /S (03) )
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Fig 2 (A) Effect of a 25% reduction in end-diastolic diameter (Myosplint) on end-systolic elastance (□ = preoperative; ■ = Myosplint) and diastolic compliance (○ = preoperative; • = Myosplint). (B) Nonlinearity of end-systolic elastance before and after Myosplint. In A and B, values are average (nine end-systolic models and three diastolic models). *p < 0.05 by multivariate regression. (LV = left ventricle.) The Annals of Thoracic Surgery , DOI: ( /S (03) )
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Fig 4 The effect of a 25% reduction in end-diastolic diameter (Myosplint) on the transmural distribution of (B) end-diastolic and (C) end-systolic fiber stress. Note the significant reduction in fiber stress in areas “far” from the Myoslint. (A) Areas that are “near” and “far” from the Myosplints are indicated. (kPa = Pascal ×103; * = comparison between preoperative and “near;” † = comparison between preoperative and “far;” p less than 0.05 by two-way ANOVA with Bonferroni correction.) The Annals of Thoracic Surgery , DOI: ( /S (03) )
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Fig 5 (A) Diastolic and (B) end-systolic finite element meshes after a 25% reduction in end-diastolic diameter at the points of application of three Myosplints. The diastolic model has “failing” material properties (see text) and is loaded with 20 mm Hg of intracavitary left ventricular pressure. The end-systolic model also has failing material properties and is loaded with 100 mm Hg of intracavitary left ventricular pressure. The red rendered surface is the endocardium; blue lines outline the finite elements; arrows indicate the points of Myosplint attachment. The Annals of Thoracic Surgery , DOI: ( /S (03) )
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Fig 6 Baseline (preoperative) diastolic (A) and end-systolic (B and C) pressure-volume relationships. (A) Diastolic compliance associated with C of 0.88, 1.10, and 1.40 kPa, respectively (Equation 1 and Table 1). (B) End-systolic elastance curves associated with Ca0 = 2.66, 2.30, and 2.00 μmol/L, respectively, and C = 0.88 kPa. (C) Similar to B but with C = 1.4 kPa. Note that the elastance is dependent on both the diastolic stiffness variable and peak intracellular calcium concentration. (LV = left ventricle.) The Annals of Thoracic Surgery , DOI: ( /S (03) )
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Fig 3 The effect of a 25% reduction in end-diastolic diameter (Myosplint) on the stroke volume/end-diastolic pressure (Starling) relationship. (A) Preoperative EA is calculated by fixing LV pressure at 100 mm Hg. (B) Preoperative EA is fixed at 2, 2.5, or 3. In all cases preoperative EA = Myosplint EA. Although changes were not significantly different (all cases) there is a trend toward an improvement in the Starling relationship at high EA. Note the change in scale in panel B. (ED = end-diastolic; LV = left ventricle.) The Annals of Thoracic Surgery , DOI: ( /S (03) )
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