Arterial switch procedure for D-transposition of the great arteries: Quantitative midterm evaluation of hemodynamic changes with cine MR imaging and phase-shift velocity mapping - Initial experience

PURPOSE: To evaluate cine magnetic resonance (MR) imaging and phase-shift v elocity mapping for assessment of the hemodynamic relevance of stenotic seg ments or specific hemodynamic changes in the great vessels after an arteria l switch procedure for correction of D-transposition of the great arteries. MATERIALS AND METHODS: Twenty consecutive patients (age range, 2-17 years) with an acoustic window that was insufficient for Doppler transthoracic ech ocardiography were included in the study. Flow and diameter measurements of the pulmonary arterial trunk and its primary branches were performed with phase-shift velocity mapping and cine MB, imaging. RESULTS: There were good correlations between pressure gradients in the pul monary arteries estimated with MR imaging and those measured with Doppler e chocardiography (r = 0.83, n = 15) and cardiac catheterization (r = 0.90, n = 13). Cine MR imaging revealed that the diameters of the right and left p ulmonary arteries decreased with the expansion of the aorta during systole, which increased the peak velocity. This temporary stenosis was more severe in the right than in the left pulmonary artery and was accompanied by a si gnificantly (P < .05) lower volume flow in the right artery. CONCLUSION: The anatomic situation after arterial switch repair tended to p roduce temporary stenoses in the primary pulmonary arterial branches, with significant changes in hemodynamics. These changes may affect the long-term outcome and go undetected with other imaging modalities.