Role of infarct expansion in rupture of the ventricular septum after acute myocardial infarction: A two‐dimensional echocardiographic study

To verify the role of infarct expansion (IE) in ventricular septal rupture (VSR) after transmural acute myocardial infarction (TAMI), topographic parameters were measured using tomographic imaging with two-dimensional echocardiography (2-D echo) and computer-aided analysis in four groups of patients: 8 patients with VSR (Group 1); 24 patients with TAMI but no mechanical complications (Group 2); 11 normal athletes (Group 3); 5 adults with congenital ventricular septal defect (Group 4). Measurements made on end-diastolic outlines of mid-left ventricular (LV) short-axis images included: LV asynergy (akinesis and/or dyskinesis), expansion index (asynergy/nonasynergy-containing endocardial segment length), thinning ratio (asynergic/nonasynergic wall thickness), and new indexes of regional shape distortion (RSD) by quantifying the deviation of the actual asynergic segment from the ideal asynergic arc constructed using the nearly circular nonasynergic contour. In Group 1, clinical IE (hypotension, congestive heart failure, no signs of new infarction) preceded detection of the VSR and portable 2-D echo showed the VSR associated with LV asynergy, marked IE, and RSD. Although Groups 1 and 2 had similar LV asynergy (28.7 vs. 26.9% LV) and ejection fraction (38.9 vs. 41.8%), Group 1 had higher expansion index (1.50 vs. 1.17, p less than 0.05), lower thinning ratio (0.54 vs. 0.67, p less than 0.005), and higher RSD parameters (e.g., peak distortion, Pk or maximum radial distance from the ideal arc, 19.3 vs. 3.9 mm, p less than 0.01; area of distortion, Ad, 7.4 vs. 1.1 cm2, p less than 0.05) than Group 2. Groups 3 and 4 had normal regional and global function and no evidence of expansion, thinning, or RSD. Thus, IE with marked diastolic RSD on an early 2-D echo after TAMI might identify patients at risk for VSR.