Left-sided pulmonary venous pathway obstruction after mustard operation

Objective: Pulmonary venous pathway obstruction (PVPO) is a serious complication of the atrial switch procedure for transposition of the great arteries (TGA). Redistribution of pulmonary arterial blood flow may make conventional echocardiographic measures of unilateral PVPO difficult to interpret. Previous studies have demonstrated altered arterial flow patterns using phase-contrast magnetic resonance imaging (PC-MRI). The purpose of this study was to investigate arterial flow patterns in the setting of unilateral PVPO following the Mustard operation. Methods: We retrospectively reviewed the arterial flow patterns of 12 patients undergoing magnetic resonance imaging between 2006 and 2011 who had had the Mustard operation. Results: Three patients had left PVPO and all showed >65% flow distributed to the right pulmonary artery (RPA). One had severe obstruction and was the only one to show significant continuous diastolic forward flow in the RPA or diastolic flow reversal in the left pulmonary artery. Conclusion: RPA/left pulmonary artery flow ratio appears to be a sensitive marker for PVPO. In the absence of pulmonary regurgitation, reversed diastolic flow in the ipsilateral and continuous in the contralateral pulmonary artery appears specific for severe obstruction. Branch pulmonary artery phase-contrast magnetic resonance imaging (PC-MRI) should be performed routinely for patients who have had an atrial switch for transposition of the great arteries.