Exercise blood pressure response, cardiac output and 24-hour ambulatory blood pressure monitoring in children after aortic coarctation repair.

BACKGROUND: The aim of this study was to assess blood pressure at rest, the response to exercise and the 24-hour ambulatory blood pressure monitoring (ABPM) profile in children operated for aortic coarctation.

METHODS: Twenty children were operated upon for aortic coarctation. The patients' data were compared with those obtained from 19 healthy controls of the same age. Treadmill exercise testing was performed and cardiac output was determined using the acetylene-rebreathing method and indexed for the body surface area; ABPM was performed only in the patients group. The main outcome measures were the time of exercise, systolic (SBP) and diastolic (DBP) blood pressure both at rest and at peak exercise, maximal heart rate, total peripheral vascular resistance at rest and at peak exercise, and the pulse pressure (PP = SBP-DBP) at rest, at peak exercise and at ABPM. The Mann-Whitney test (non-parametric) and linear regression analysis were used when appropriate.

RESULTS: Patients compared with healthy controls showed significant differences in SBP and PP at rest, and in DBP, cardiac index, total peripheral vascular resistance and PP at peak exercise. In the patients group only, linear regression analysis showed a significant correlation between PP and cardiac output, both at rest and at peak exercise, and between the arm-leg gradient at rest and PP at ABPM.

CONCLUSIONS: These findings suggest that blood pressure abnormalities could be due both to the altered baroceptor reflex control mechanism, resulting in cardiac output and total peripheral vascular resistance abnormalities, and to the progressive increase in resistance during exercise at the site of the repair, resulting in the higher PP, that may be related to a local loss of the natural aortic elasticity.