Background: Newly developed two-dimensional ultrasound speckle tracking imaging allows measurements of left ventricular rotation and torsion (LVtor). Although midterm results in patients operated with arterial switch for complete transposition of the great arteries (TGA) are promising, there are reported minor alterations in left ventricular (LV) function possibly indicating myocardial dysfunction. The purpose of this study was to assess LVtor and untwisting in complete TGA patients after arterial switch operation. Methods: We acquired basal and apical LV short-axis images in asymptomatic 16 TGA patients (age = 12.7±6.7 yr, follow-up duration after arterial switch operation = 12.5±6.3 yr) and 15 age-matched healthy controls (age = 13.6±5.4 yr). Using two-dimensional strain software, a time-domain speckle tracking was performed, and mean value of LVtor was obtained at each plane. Result: LV ejection fraction in TGA patients was not decreased in comparisons with controls (64±5% vs. 65±5%; P=0.695). LV length was similar (70±13 vs. 73±11; P=0.492), but LV sphericity was increased in TGA patients (0.62±0.08 vs. 0.54±0.03; P <0.001). LV longitudinal strain and basal circumferential strain in TGA patients were significantly reduced (-19.1±2.4% vs. -21.9±2.2%.; P=0.002, -14.8±2.5% vs. -18.2±3.3%.; P= 0.004). Peak LVtor (10.5±6.4 vs. 19.1±4.4 degrees; P <0.001), Peak LVtor / LV length (1.50±0.89 vs. 2.68±0.83 degrees; P <0.001), peak basal rotation (0.96±3.9 vs. -4.56±2.1; P<0.001), peak systolic twisting velocity (88±44 vs. 130±37 degrees/sec; P = 0.008), twisting rate (60±28 vs. 87±22 degrees/sec; P=0.007) and untwisting rate (43±32 vs. 72±44 degrees/sec; P=0.042) were significantly decreased in TGA patients. LVtor and LVtor/length were not significantly correlated with LV ejection fraction (P=0.608, P=0.932). LVtor/length in TGA patients was significantly inversely correlated with the internal diameter of aortic sinotubular junction (R2=0.265, P=0.041) and LV sphericity (R2=0.136, P=0.041). Conclusion: Although LV ejection fraction in TGA patients was normal, LV longitudinal strain and torsion were decreased.
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