Acronyms ....................................................................................................................................... 94 4.1 Introduction .......................................................................................................................... 95 4.2 Ischemic Dilated Cardiomyopathy Effect on Left Ventricle: Shape

(Regional Wall Curvedness), Regional Wall Stress, Global Contractility.................... 97 4.2.1 Introduction .............................................................................................................. 97 4.2.2 Methodology ............................................................................................................ 98

4.2.2.1 Subjects Involved in the Study ................................................................ 98 4.2.2.2MRI Scanning for Acquisition of LV Geometry ................................... 98 4.2.2.3 Delayed Gadolinium Enhancement Imaging ....................................... 98

4.2.3 Data Processing and LV Geometry Reconstruction ......................................... 100 4.2.3.1 Contractility and Shape Indices ............................................................ 101 4.2.3.2 Computation of 3D Surface Shape Descriptors .................................. 101 4.2.3.3 Regional Wall Thickening ..................................................................... 103 4.2.3.4 Regional Peak Systolic Wall Stress ....................................................... 104

4.2.4 Results ..................................................................................................................... 106 4.2.4.1 Global Left Ventricular Function .......................................................... 106 4.2.4.2 Variation of Curvedness, Peak Systolic Wall Stress, and Wall

Thickening from Base to Apex in Normal Subjects ........................... 107 4.2.4.3 Comparison of Curvedness, Radius-to-Thickness Ratio, Peak

Systolic Wall Stress, and Wall Thickening in IDCM Patients and Normal Subjects .............................................................................. 108

4.2.4.4 Analysis of Segment Scar Extent in IDCM Patients ........................... 109 4.2.5 Discussion ............................................................................................................... 109

4.2.5.1 In Normal Hearts .................................................................................... 110 4.2.5.2 In IDCM Hearts ....................................................................................... 110 4.2.5.3 End-Systolic Curvedness and Wall Stress ........................................... 111

4.3 Effect of Surgical Ventricular Restoration on Ventricular Shape, Wall Stress, and Function in IDCM Patients ....................................................................................... 111 4.3.1 Introduction ............................................................................................................ 111 4.3.2 Methodology .......................................................................................................... 112

4.3.2.1 Study Population ..................................................................................... 112 4.3.2.2 MRI Image Acquisition .......................................................................... 112

C Curvedness CED Curvedness at end-diastole CES Curvedness at end-systole CI Indexed cardiac output CMR Cardiac magnetic resonance Ea Effective arterial elastance EDVI Indexed end-diastolic volume EF Ejection fraction ESVI Indexed end-systolic volume HR Heart rate IDCM Ischemic dilated cardiomyopathy LV Left ventricle MRI Magnetic resonance imaging R Wall radius RED Wall radius at end-diastole RES Wall radius at end-systole S Surface area SED Surface area at end-diastole

4.3.2.3 Determination of LV Geometry ............................................................ 113 4.3.2.4 Determination of LV Regional Shape and Geometric

Parameters: Curvedness, LV Radius and Wall Thickness, Endocardial Surface Area ...................................................................... 114

4.3.2.5 Determination of Left Ventricular Systolic Function and Vascular Function ........................................................................... 114

4.3.2.6 Determination of Wall Stress Indices at End-Diastole and End-Systole ....................................................................................... 114

4.3.2.7 Denition of Border Zone and Remote Zones .................................... 115 4.3.3 Results ..................................................................................................................... 115

4.3.3.1 Subject Characteristics ........................................................................... 115 4.3.3.2 LV Geometry ............................................................................................ 115 4.3.3.3 Regional Geometric Parameters ........................................................... 116 4.3.3.4 Left Ventricular Function and Vascular Function ............................. 118 4.3.3.5 Regional Wall Stress Indices at End-Diastole and End-Systole ........ 118

4.3.4 Discussion ............................................................................................................... 118 4.3.4.1 Effect of Surgical Ventricular Restoration on LV Shape .................... 118 4.3.4.2 Effect of Surgical Ventricular Restoration on LV Wall Stress ........... 120 4.3.4.3 Effect of Surgical Ventricular Restoration on Ventricular

Systolic Function ..................................................................................... 120 4.3.4.4 Implications and Signicance ............................................................... 120

4A Appendix: Derivation of the Cardiac Contractility Index, Equation 4.1 ................... 121 4B Appendix: Computation of 3D Shape Descriptors ....................................................... 122 4C Appendix: Computation of Wall Radius of Curvature and Wall Thickness

using Short-Axis and Long-Axis Approach and 3D Approach .................................. 124 References ..................................................................................................................................... 127

SES Surface area at end-systole SI Sphericity index SLv Normalized shape index SW Stroke work T Wall thickness TED Wall thickness at end-diastole TES Wall thickness at end-systole WS Wall stress WT Wall thickening σ/P Pressure-normalized stress (σ/P)ED Pressure-normalized stress at end-diastole (σ/P)ES Pressure-normalized stress at end-systole ∆C Percentage curvedness change (dσ*/dt)max Left ventricular contractility index (=1.5(dV/dtmax)/Vm) ∆S Percentage change in surface area 2DLR Two-dimensional radius in the long-axis plane 2DLT Two-dimensional wall thickness in the long-axis plane 2DLWS Wall stress in the long-axis plane 2DLWT Wall thickening in the long-axis plane 2DSR Two-dimensional radius in the short-axis plane 2DST Two-dimensional wall thickness in the short-axis plane 2DSWS Wall stress in the short-axis plane 2DSWT Wall thickening in the short-axis plane 3DR Three-dimensional radius accounting for 3D curvature 3DT Three-dimensional wall thickness accounting for 3D curvature 3DWS Three-dimensional wall stress 3DWT Three-dimensional wall thickening

Cardiomyopathy refers to diseases of the heart muscle. These diseases enlarge the heart m uscle or make it thicker and more rigid than normal. In some cases, scar tissue replaces the muscle tissue. Myocardial ischemia and infarction can cause cardiomyopathy. Cardiomyopathy causes measurable deterioration of myocardial function and can lead to heart failure (HF).