Surgical ventricular restoration (SVR) or ventriculoplasty of the dilated left ventricle (LV) after antero-apical myocardial infarction (MI) has been proposed as surgical treatment for congestive heart failure (CHF). Unsatisfactory results with standard linear aneurysm repair have stimulated modifications of that operation. Currently, patch aneurymorraphy (Dor procedure), infarct exclusion (no patch) and the Surgical Anterior Ventricular Restoration (SAVER; performed on akinetic infarcts) procedures are being performed. The long-term goal of this research is to use experimental and theoretical models to arrive at an optimal design for SVR of the dilated LV after antero-apical Mi. First, using conductance and micromanometer-tipped catheters, the effect of infarct exclusion, SAVER, and Acorn CorCap(TM) Cardiac Support Device (CSD) operations on LV pressure-volume and global function (Starling) relations will be measured in sheep hearts. Infarct exclusion and the Acorn CSD will be tested in the standard dyskinetic infarct model. The SAVER operation will be tested in the reperfused (akinetic) sheep infarct model. Next, using magnetic resonance imaging (MRI) with tissue tags, the effect of infarct exclusion, SAVER, and Acorn CSD on regional 3D myocardial strain will be measured in vivo. Then, using MR diffusion tensor imaging (MR-DTI), the effect of infarct exclusion, SAVER, and Acorn CSD operations on regional 3D myocyte orientation will be measured ex vivo. Next, realistic mathematical (finite element) models of each of the proposed SVR operations will be developed. These models will be used in conjunction with the regional 3D myocardial strain measurements to: (1) determine in vivo diastolic and systolic myocardial material properties in the beating sheep LV with either a complete transmural (dyskinetic) or reperfused (akinetic) infarct; and (2) calculate regional 3D myocardial stress and global LV function. Finally, the design of infarct exclusion, SAVER, and Acorn CSD operations will be optimized using these models. Specifically, the effect of residual contracting myocytes (dyskinetic vs akinetic infarct; infarct exclusion and SAVER), the amount of excluded or resected myocardium (infarct exclusion and SAVER), patch stiffness and location (endocardium vs. epicardium; SAVER) and the compliance of the Acorn CSD will be simulated. This study will determine the acute and sub-acute effects of infarct exclusion, SAVER and Acorn CSD procedures on the dilated LV after antero-apical MI. These findings should have a major impact on current surgical practice.
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