Patients with congenitally corrected transposition are at risk of right ventricular dysfunction and failure. With this in mind, we examined 13 patients with congenitally corrected transposition, 7 not having undergone surgery, and 6 after physiological repair, comparing them with 6 healthy subjects matched for age and sex, using cardiac magnetic resonance imaging, at rest and during dobutamine stress, in order to determine regional and global right ventricular response to stress.
At rest, the patients had significantly decreased overall wall motion compared to their healthy peers (7.2 ± 0.5, versus 9.8 ± 0.4 mm). During infusion of dobutamine, overall wall motion increased to 12.8 ± 0.4 mm in the healthy subjects, versus 8.8 ± 1.0 mm in patients. At the regional level, significant differences in mural motion were found between patients and controls in the anterior (9.5 ± 1.1, versus 13.2 ± 0.6 mm), posterior (10.2 ± 1.6, versus 13.2 ± 0.8 mm), and septal segments (5.0 ± 0.8, versus 11.2 ± 0.6 mm).
At rest, overall mural thickening in patients was similar to that of controls, but significantly less in patients during stress. During dobutamine stress, patients showed significantly less regional wall thickening than controls, particularly in the septal (2.7 ± 0.6, versus 6.0 ± 0.4 mm, respectively) and in the anterior segments (4.2 ± 0.6, versus 7.8 ± 0.6 mm, respectively). Right ventricular ejection fraction strongly correlated with mural motion and thickening, both at rest and during stress.
Abnormal regional function in the systemic morphologically right ventricle may occur in patients with congenitally corrected transposition, which strongly correlates with right ventricular ejection fraction. Our findings support the hypothesis that, in patients with congenitally corrected transposition, ischemia of the right ventricular myocardium contributes to the development of right ventricular dysfunction.