Forearm hemodynamics at rest and stress in borderline hypertensive adolescents.

Cardiovascular adaptations to mild elevations of blood pressure (BP) may occur early in the development of essential hypertension (EH). We used strain gauge plethysmography to study forearm hemodynamics in adolescents. Ten normotensive males (N) were compared to ten males with borderline hypertension (H). Measurements of forearm blood flow (FBF) were obtained after supine rest, during ten minutes of mental stress (mental arithmetic) and five minutes post stress. Mean arterial pressure (MAP) and forearm vascular resistance (FVR) were calculated. The H maintained higher MAP and FVR (P less than or equal to .05) throughout the study. The vascular response patterns were assessed by comparing the slopes of the linear regression equation FBF = a ln FVR + b (where a = slope and b = intercept). From baseline to stress, the N exhibit a significant change in slope (P less than .05), shifting to a decrease in FVR per unit FBF change. However, the H maintain a constant slope and FVR per unit FBF change remains constant. The study suggests that a primary peripheral vascular abnormality may be present even in the young with marginally elevated BP.