Left ventricular torsional mechanics after left ventricular reconstruction surgery for ischemic cardiomyopathy.

Abstract

Surgical left ventricular reconstruction improves symptoms and potentially prognosis in patients with ischemic cardiomyopathy; however, the effects of reconstruction on myocardial mechanics are not well defined. Therefore, we have computed left ventricular rotation and torsion in patients undergoing left ventricular reconstruction to determine its effects on these quantitative measures of myocardial mechanics. Magnetic resonance imaging with tissue grid-tagging was performed in 26 patients (19 male/7 female, 62 +/- 11 years) (mean +/- standard deviation) before (23 +/- 29 days) and after (231 +/- 106 days) left ventricular reconstruction, as well as in 7 healthy volunteers (5 male/2 female, 34 +/- 7 years). Left ventricular rotation was computed at basal and apical short-axis levels; torsion was defined as the difference between apical and basal rotation. Before left ventricular reconstruction, maximal apical rotation was significantly impaired relative to that of healthy volunteers (P = .001), although maximal basal rotation was preserved (P = .84). After reconstruction, maximal torsion did not change significantly: torsion was 6 degrees +/- 3 degrees both before and after reconstruction (P = .84). However, the rate of early diastolic untwist improved significantly after reconstruction (-18 degrees/s +/- 13 degrees/s vs -23 degrees/s +/- 14 degrees/s; P = .04). Furthermore, patients with relatively worse torsion before reconstruction demonstrated more improved function after reconstruction; patients with torsion of less than 6 degrees (n = 12) showed greater improvement in ejection fraction (15% vs 6%; P = .005), torsion (1 degrees vs -1 degrees; P = .01), and diastolic untwist (-9 degrees/s vs -25 degrees/s; P < .001) than did patients with torsion of 6 degrees or more (n = 14). Torsional mechanics were severely impaired by ischemic cardiomyopathy. On average, left ventricular reconstruction did not affect systolic torsion generation significantly; however, patients with relatively worse torsion did show improvement. Furthermore, the rate of untwist improved after surgery, suggesting that diastolic function was improved.