title: Hemodynamics in childhood hypertension.
abstract: Children with elevated systolic blood pressure have a wide range of cardiac output. We investigated the mechanisms regulating resting and exercise blood pressure in 264 children who were selected from the low, middle, and upper quintile of the distribution of blood pressure of an entire school population. We identified patterns of response to exercise that correlated both with resting cardiac output and resting blood pressure. During isometric exercise, systolic blood pressure adjusted for age and body size increased in all groups. The low group mean pressure remained significantly lower than the high group's pressures throughout the entire exercise period. Body size adjusted group systolic and diastolic blood pressure level differences existed during dynamic exercise. The product of the systolic blood pressure times the heart rate in the high blood pressure group was significantly higher throughout dynamic exercise than in the other two groups. Elevated resting resistance was correlated with elevated resistance during isometric exercise and elevated diastolic blood pressure during dynamic exercise. Cardiac index had a significant negative correlation to age (r = -0.58) at all levels of blood pressure. This observation, in children, lends some support to the concept of evolution from a hyperkinetic circulation in early childhood to a circulation with lower cardiac output and more elevated systemic vascular resistance at an older age.
mesh_terms: D000367:Age Factors; D002302:Cardiac Output; D002648:Child; D004452:Echocardiography; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008137:Longitudinal Studies; D005082:Physical Exertion; D014655:Vascular Resistance