Hyperventilation-induced cerebrovascular reactivity among hypertensive and healthy adolescents.

Background: It is known that cerebral vasoreactivity is altered in adult arterial hypertension but no information is available about cerebral arteriolar function in hypertensive adolescents. Therefore, the aim of the present work was to assess cerebral vasoreactivity responses in adolescent hypertension.
Methods: 113 hypertensive and 58 normotensive adolescents were assessed with transcranial Doppler sonography by using voluntary hyperventilation (HV) as vasoconstrictory stimulus. Absolute blood flow velocities (systolic, mean and diastolic) and pulsatility indices (PIs) at rest and after HV, as well as percentage change of the blood flow velocities after HV were compared among the groups.
Results: Blood flow velocities at rest were significantly higher in hypertensive individuals, while PIs were similar in the two groups. After HV, all blood flow velocity parameters were higher among hypertensive teenagers than in healthy controls, while PIs did not differ between the two groups. Taking the relative changes after HV into account, it was found that HV induced a more pronounced change of the systolic and mean blood flow velocities of the control subjects than in hypertensive adolescents.
Conclusions: Cerebrovascular reactivity to hypocapnia is decreased in hypertensive adolescents as compared to healthy teenagers. Further studies are needed to clarify the clinical significance of altered cerebral microvascular function in adolescent hypertension.