[Alteration of myocardial viability and systemic ventricular dysfunction after Senning procedure].

After a Senning procedure for transposition of the great arteries (TGA), systolic dysfunction of the right ventricle (RV) is common. Pre and peroperative chronicale hypoxia may be the cause of this ventricular myocardial alteration. In order to detect abnormalities of myocardial viability and to study their relationship to RV function, the authors studied 41 patients (pts), 11.3 +/- 3 years after a Senning procedure. All patients underwent myocardial scintigraphy of the RV under basal conditions. 1 hour after injection of 1.5 mCi of Thallium 201. The RV ejection fraction (n = 41) and at peak effort (n = 25). Exercise ability and aerobic capacity were assessed by exercise testing (Bruce) with gas exchange measurement and compared with 41 normal matched subjects. The cardiorespiratory response to exercise was altered in the Senning group : duration of effort (10.5 +/- 2 vs 13.2 +/- 2 min; p < 0.0001), peak VO2 (33 +/- 5 vs 44.4 +/- 6 ml/min/kg; p < 0.0001), anaerobic threshold (6 +/- 1 vs 8.4 +/- 1.9 min; p < 0.05) were lower compared to controls. Abnormalities of RV viability were observed in 18/41 pts (44%), moderate in 12 cases and severe in 6 cases. Resting and exercise RVEF were significantly lower in patients with myocardial defects (45 +/- 5 vs 51 +/- 7%; p < 0.0005, and 49 +/- 9 vs 58 +/- 9%; p < 0.05 respectively). In conclusion, after the Senning procedure for TGA, scintigraphic abnormalities of the systemic ventricule are common and associated with an alteration of systolic function at rest and on exercise.