Blood pressure and hypertension in childhood and adolescence

Nitric oxide activity in childhood hypertension

OBJECTIVES

To investigate nitric oxide (NO) activity in childhood hypertension using nitrite and nitrate (NOx) concentrations in plasma as an index of nitric oxide generation.

DESIGN

Cross sectional study.

SETTING

Tertiary care paediatric centre and district general hospitals in the UK.

PATIENTS

Children attending the above centre for treatment of hypertension. The control subjects were normotensive healthy children attending district general hospitals for minor medical and surgical disorders.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Plasma (P) and urinary (U) NOx concentrations, blood pressure, and glomerular filtration rate.

RESULTS

Sixteen normal children (mean age 6.9 years), 13 children with renovascular hypertension (mean age 7.8 years), and 25 children with hypertension associated with renal parenchymal disease (mean age 10.7 years) were studied. Mean (SD) PNOx values of children with hypertension with renovascular disease (15.3 (11.4) mumol/l) and renal parenchymal disease (18.3 (11.4) mumol/l) were significantly above that of normal children (11.9 (5.9) mumol/l) after accounting for age and glomerular filtration rate influences. Higher concentrations of PNOx in normal children were associated with younger age, but not in the children with hypertension. Higher PNOx concentrations were also associated with a lower glomerular filtration rate in normal children and children with hypertension with renal parenchymal disease, but not in the children with hypertension with renovascular disease. UNOx excretion expressed as a ratio against urine creatinine (Ucreat) excretion was not statistically different among the study groups.

CONCLUSIONS

PNOx is increased in children with hypertension even after statistical elimination of the glomerular filtration rate and age influences. This suggests a normal or increased NO synthase activity in childhood hypertension in contrast with adults with hypertension in whom it is described as reduced.

The captopril test: an aid to investigation of hypertension

Twenty three children aged from 5 to 16 with mild to moderate hypertension were investigated using the orally active angiotensin converting enzyme inhibitor captopril. Falls in both systolic and diastolic blood pressure after a single dose of captopril were significantly correlated with initial plasma renin activity. In addition, some information about the aetiology of hypertension was deduced from the renin response to captopril. The blood pressure response to captopril is a useful screening test for renin dependent hypertension in childhood.

Brain revascularisation in hypertension

Neurological symptoms in hypertensive subjects may be a reflection of intracranial vascular disease and not just a consequence of hypertension. Two hypertensive children with renovascular disease, neurological symptoms, and severe cerebral arterial disease were treated by extracranial-intracranial arterial bypass surgery with improvement of symptoms and easier control of blood pressure. Where revascularisation surgery is appropriate, this should be undertaken before neurological complications arise.