Altered baroreceptor function in children with systolic hypertension after coarctation repair.

To determine whether altered baroreceptor function may contribute to systemic hypertension after coarctation of the aorta (C of A) repair, baroreceptor function was evaluated in 6 children with repaired C of A mild arm systolic hypertension. Data were compared with those from 7 normotensive control children with hemodynamically mild heart disease. Age at C of A repair averaged 9.9 +/- 3.1 years (mean +/- standard deviation [SD]). Arm systolic pressure was 143.8 +/- 2.9 mm Hg in the C of A repair group, compared with 118.3 +/- 9.9 for control subjects (p less than 0.001). At catheterization, steady-state sigmoidal baroreceptor function curves relating mean arterial pressure to R-R interval were derived by increasing and decreasing mean arterial pressure with small injections of phenylephrine and nitroprusside. Compared with control subjects, the baroreceptor function curves of children with repaired C of A (1) are reset about a higher baseline mean arterial pressure (108.8 +/- 6.6 versus 90.3 +/- 8.6 mm Hg, p less than 0.01), (2) have a decreased slope (7.9 +/- 3.7 versus 17.4 +/- 3.6 ms/mm Hg, p less than 0.001), and (3) have a diminished R-R interval range (246.7 +/- 81.5 versus 535.7 +/- 97.2 ms, p less than 0.001). Thus, in children with hypertension after C of A repair, the baroreflex is reset to an elevated mean arterial pressure level and has a diminished sensitivity to changes in arterial pressure.