EVALUATION OF REGIONAL LOAD IN ACUTE-ISCHEMIA BY 3-DIMENSIONAL CURVATURES ANALYSIS OF THE LEFT-VENTRICLE

Geometric remodeling of the left ventricle (LV) following myocardial i nfarction and ischemic insult is associated with myocardial load redis tribution. Regional curvatures based on 3-D reconstructions of the LV are used to calculate the regional loads. The technique uses surface n ormals to derive local circumferential and meridional curvatures. Foll owing the validation of the procedure on simple geometric shapes, the effect of acute ischemia on the regional load redistribution was studi ed in six open chest dogs. Short axis magnetic resonance imaging (MRI) scans were used to reconstruct end-diastolic (ED) and end-systolic (E S) LV images by applying our helical shape descriptor, before and afte r acute coronary occlusion. Regional curvatures as well as local wall thickness by the volume element method were calculated before and afte r acute ischemia, and were used to approximate regional loads, by a re gional stress index (sigma/P). Postmortem evaluation using monastral b lue staining was used to divide each LV to normal (NZ), ischemic (IZ), and border (BZ) zones in the ischemic case, and to the anatomically m atched regions in the preischemic LVs. Ischemia affects the local curv atures and loads both at ED and ES. At ED, sigma/P rose significantly only in the IZ. Similarly, at ES, the highest increase in load was det ected in the IZ, but increases in circumferential and meridional load were seen in all regions. Identifying the load redistribution followin g acute ischemia helps delineate the mechanisms affecting geometric LV remodeling following myocardial infarction.