OBJECTIVE: We assessed the contribution of acute aortic arch angulation and enhanced systolic pulse wave reflection to dilatation of the ascending aorta and aortic regurgitation late after the arterial switch operation for transposition of the great arteries. METHODS: We performed aortography, radial artery applanation tonometry, and transthoracic echocardiography in 47 children (aged 5-6 years) who underwent the arterial switch operation and in 20 matched healthy controls. The aortic arch angle, ratio of ascending/descending aortic diameter, degree of aortic regurgitation, central pulse pressure, aortic augmentation pressure, and augmentation index were measured. RESULTS: The aortic arch angle was more acute (55 +/- 6.5 degrees vs 68 +/- 5 degrees, respectively, P < .001) and the ratio of the ascending/descending aorta diameter was significantly greater (1.98 +/- 0.4 vs 1.55 +/- 0.06, respectively, P < .001) in the patients who underwent the arterial switch operation compared with controls. Augmentation pressure and augmentation index were higher in the patients who underwent the arterial switch operation than in controls (7.5 +/- 4.6 vs 3.4 +/- 5.8, respectively P = .04; 21 +/- 10 vs 8 +/- 13, respectively, P = .005). A more acute aortic angle was associated with a higher aortic augmentation index (r = 0.41, P < .01), a greater ratio of the ascending to descending aorta (r = -0.6, P < .001), and the degree of aortic regurgitation (r = 0.39, P < .01). CONCLUSION: Sharper angulation of the aortic arch is associated with early pulse wave reflection, dilatation of the ascending aorta, and aortic regurgitation late after the arterial switch operation for transposition of the great arteries.