Right ventricular regional wall curvedness and area strain in patients with repaired tetralogy of Fallot

Zhong L, Gobeawan L, Su Y, Tan JL, Ghista D, Chua T, Tan RS, Kassab G. Right ventricular regional wall curvedness and area strain in patients with repaired tetralogy of Fallot. Am J Physiol Heart Circ Physiol 302: H1306-H1316, 2012. First published December 30, 2011; doi:10.1152/ajpheart.00679.2011.-A quantitative understanding of right ventricular (RV) remodeling in repaired tetralogy of Fallot (rTOF) is crucial for patient management. The objective of this study is to quantify the regional curvatures and area strain based on three-dimensional (3-D) reconstructions of the RV using cardiac magnetic resonance imaging (MRI). Fourteen (14) rTOF patients and nine (9) normal subjects underwent cardiac MRI scan. 3-D RV endocardial surface models were reconstructed from manually delineated contours and correspondence between end-diastole (ED) and end systole (ES) was determined. Regional curvedness (C) and surface area at ED and ES were calculated as well as the area strain. The RV shape and deformation in rTOF patients differed from normal subjects in several respects. Firstly, the curvedness at ED (mean for 13 segments, 0.030 +/- 0.0076 vs. 0.029 +/- 0.0065 mm(-1); P < 0.05) and ES (mean for 13 segments, 0.040 +/- 0.012 vs. 0.034 +/- 0.0072 mm(-1); P < 0.001) was decreased by chronic pulmonary regurgitation. Secondly, the surface area increased significantly at ED (mean for 13 segments, 982 +/- 192 vs. 1,397 +/- 387 mm(2); P < 0.001) and ES (mean for 13 segments, 576 +/- 130 vs. 1,012 +/- 302 mm(2); P < 0.001). In particular, rTOF patients had significantly larger surface area than that in normal subjects in the free wall but not for the septal wall. Thirdly, area strain was significantly decreased (mean for 13 segments, 56 +/- 6 vs. 34 +/- 7%; P < 0.0001) in rTOF patients. Fourthly, there were increases in surface area at ED (5,726 +/- 969 vs. 6,605 +/- 1,122 mm(2); P < 0.05) and ES (4,280 +/- 758 vs. 5,569 +/- 1,112 mm(2); P < 0.01) and decrease in area strain (29 +/- 8 vs. 18 +/- 8%; P < 0.001) for RV outflow tract. These findings suggest significant geometric and strain differences between rTOF and normal subjects that may help guide therapeutic treatment.