Left ventricular torsion abnormalities in patients after the arterial switch operation for transposition of the great arteries with intact ventricular septum.

BACKGROUND: The arterial switch operation (ASO) is currently the treatment of choice for infants with transposition of the great arteries (TGA). Little is known, however, about the alteration of anatomic left ventricular (LV) torsional mechanics after the operation. This study sought to evaluate LV torsion in patients of transposition of the great arteries with intact ventricular septum (TGA/IVS) using speckle tracking echocardiography.

METHODS: Echocardiographic images were prospectively acquired in 32 infants (age range, 0.5-60 months) who successfully underwent ASO repair at about 1 month of age and in 48 normal controls. They were divided into early and late categories according to the age at the time of the study. The LV peak systolic torsion and systolic twisting and diastolic untwisting velocities were determined by speckle tracking. Mitral inflow velocity obtained by Pulsed-wave Doppler and mitral annular velocities drawn by septal tissue Doppler were also analyzed.

RESULTS: Compared with controls, the early postoperative group (TGA1) had significantly higher septal E/e' (P=0.000). In contrast, septal e' velocity (P=0.000), LV peak apical rotation (P=0.01), twist (P=0.02) and peak untwisting velocity (PUV) (P=0.001) were lower in patients than in controls. For the normal younger group (Control1), PUV correlated positively with e' (r=0.68, P<0.001). No significant difference in LV twisting and untwisting was noted between the TGA2 and Control2.

CONCLUSIONS: Two dimensional speckle tracking echocardiography may sensitively detect impaired LV torsional mechanics in patients with TGA/IVS early after ASO, and the impairment of LV relaxation leads to increased LV filling pressure which is consistent with higher E/e'. However, all patients recovered well thereafter and the overall midterm outcome of ASO is satisfactory.