Discrepancies in aortic growth explain aortic arch gradients during exercise

Objectives. This study was conducted to evaluate the incidence and etiology of hypertension and aortic arch gradients during exercise in patients who have apparent good coarctation repair assessed at rest. Background. The reported incidence of recurrent aortic arch obstruction (rest gradient >20 mm Hg) after previous successful surgical repair varies from 0% to 60% and usually is associated with recurrent stenosis at the site of surgical repair. Methods. Maximal treadmill exercise with Doppler echocardiographic gradient estimation was performed in 28 patients with a good coarctation repair at rest (normal blood pressure and arch gradient <20 mm Hg) who had isolated coarctation repair a mean of 7.8 years previously. Results. Eight (29%) developed systolic hypertension for age and a mean Doppler gradient of 45 ± 13 mm Hg. At cardiac catheterization, the rest peak to peak systolic gradient (6 ± 6 to 28 ± 7 mm Hg, p < 0.001), peak systolic instantaneous gradient (16 ± 11 to 48 ± 9 mm Hg, p < 0.01) and cardiac index (3.5 ± 0.7 to 5.9 ± 1.1 liters/m per m², p < 0.001) all increased during isoproterenol infusion. Angiographic systolic aortic arch measurements proximal to the innominate artery, left common carotid artery, left subclavian artery and the narrowest dimension at the coarctation repair site demonstrated hypoplasia at the left common carotid artery (11.8 ± 1.7 vs. 16.7 ± 2.9 mm/m², p < 0.01) and left subclavian artery (11.6 ± 1.7 vs. 15.4 ± 3.1 mn/m², p < 0.05) compared with findings in 10 patients with normal aortograms. Transverse aortic arch ratios were also smaller in the eight patients with abnormal findings. Preoperative angiographic ratios were not predictive of late postoperative findings. Conclusions. Exercise testing detects hypertension and arch gradients in patients with a good coarctation repair as assessed at rest. The hypertension and arch "obstruction" appear to be related to discrepancies in the growth of the transverse aortic arch proximal to the repair site, rather than a "recoarctation" of the aorta.