Early and late effects of passive epicardial constraint on left ventricular geometry: Ellipsoidal re-shaping confirmed by electron-beam computed tomography

Background: Previous studies have shown that passive epicardial constraint using a cardiac support device (CSD) reduces left ventricular (LV) size. However, specific data describing IV shape and the time course of changes in IV geometry are still incomplete. Thus, the aim of this study was- using 3-dimensional data sets obtained by computed tomography (CT)-to test the hypothesis that the CSD not only alters IV size but also IV shape, and that short-term post-operative changes in IV geometry are maintained during long-term follow-up. Methods: Ten patients with non-ischemic dilated cardiomyopathy underwent electron-beam CT examination before and again at 2.6 +/- 0.5 and 32.4 +/- 8.7 months after CSD implantation. At end-diastole and end-systole LV volumes, the length-to-width diameter ratio and a sphericity index were determined and ejection fraction and end-systolic meridional and circumferential wall stress were calculated. Results: Implantation of the CSD led to a significant reduction in IV size, a more ellipsoidal LV shape and a subsequent decrease of IV wall stress post-operatively (p < 0.05 for each), but no substantial changes were found between short- and long-term follow-up (P > 0.05 each). Mean preoperative and early and late post-operative, end-diastolic values were 310.4 +/- 87.8, 235.5 +/- 102.0 and 229.4 +/- 103.1 ml for volume; 1.27 +/- 0.20, 1.37 +/- 0.20 and 1.38 +/- 0.20 for diameter ratio; and 0.78 +/- 0.22, 0.67 +/- 0.26 and 0.65 +/- 0.23 for sphericity index. A similar pattern was observed for end-systolic values. Ejection fraction was 23.4 +/- 6.2%, 32.9 +/- 11.6% and 34.4 +/- 14.9%. End-systolic meridional and circumferential wall stress was 182.2 +/- 45.6, 128.2 +/- 52.6, 130.6 +/- 56.7 kdyn/cm(2) and 411.5 +/- 94.0, 297.4 +/- 108.4 and 302.8 +/- 117.5 kdyn/cM2, respectively. Conclusions: Three-dimensional data obtained by CT demonstrate that passive cardiac constraint leads not only to a size reduction but also to an ellipsoidal re-shaping. Our data indicate that these effects are primarily a short-term consequence of the CSD implantation but are maintained during long-term follow-up. J Heart Lung Transplant 2006;25:90 - 8. Copyright (c) 2006 by the International Society for Heart and Lung Transplantation.