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Altered baroreceptor function in children with systolic hypertension after coarctation repair
Insights
Children with hypertension after coarctation of the aorta repair show altered baroreceptor function. Their baroreflex is reset to higher blood pressure and has reduced sensitivity.
Area of Science:
- Cardiovascular Physiology
- Pediatric Cardiology
- Hypertension Research
Background:
- Coarctation of the aorta (C of A) repair can lead to persistent systemic hypertension.
- Baroreceptor dysfunction is a potential, yet understudied, contributor to post-repair hypertension.
Purpose of the Study:
- To investigate baroreceptor function in children with hypertension following C of A repair.
- To compare baroreceptor function in repaired C of A patients with normotensive controls.
Main Methods:
- Evaluated baroreceptor function using steady-state sigmoidal curves in 6 children post-C of A repair and 7 controls.
- Derived curves by altering mean arterial pressure with phenylephrine and nitroprusside during catheterization.
Main Results:
- Children with repaired C of A exhibited hypertension (143.8 mmHg vs. 118.3 mmHg in controls).
- Baroreceptor curves were reset to a higher mean arterial pressure (108.8 mmHg vs. 90.3 mmHg).
- Decreased slope (7.9 ms/mmHg vs. 17.4 ms/mmHg) and diminished R-R interval range (246.7 ms vs. 535.7 ms) were observed.
Conclusions:
- Hypertension post-C of A repair is associated with baroreflex resetting to elevated pressures.
- Reduced baroreceptor sensitivity contributes to impaired blood pressure regulation in these children.
Abstract:
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.