Transient ischemia induced by dobutamine-stress results in distortion of regional and global left ventricular geometry

Using quantitative echocardiographic shape analysis algorithms, we have previously shown in a canine model that acute ischemia affects regional and global geometry of the LV, thereby influencing regional wall stress distribution and global function. While shape abnormalities have been described in infarcted human myocardium, how distinctly they evolve during transient ischemia is not known. We assessed this in this study during transient ischemia induced by dobutamine stress echo (DSE) in 15 pts and compared the data with 20 subjects with normal DSE (N). The pts with positive DSE had predominantly single territory wail motion abnormalities but normal LV in baseline. In short-axis (SAX) and apical long-axis (LAX) and parasternal short-axis (SAX) echo views, digitized endocardial outlines were analyzed to derive an index of global LV shape (Fourier Power index, PI, unitless) and regional shape (curvature, C, unitless) Results: SAX: Ischemia produced distortion of global LV shape ie. a less circular cavity in systole (PI in N:1±0.7 Isch: 2±0.5). Diastolic shape showed no difference. In systole LV was rounder at peak stress (N PI: 49±5 [sch: 32±5). and the curvature at the ischemic apical region was blunter (N C: 43±4 Isch: 32±3). The C abnormalities corresponded well to the ischemic region. Thus, in transient ischemia, the predominant shape abnormality is during systole; systolic deformation attenuates chamber elongation, contributing to the disruption of normal LV shape. The quantitative regional and global shape analysis yields a new approach to study LV remodeling in different forms of ischemia.