Hemodynamic Characterization of Primary Hypertension in Children and Adolescents

Background Primary hypertension in children is often characterized by high pulse pressure that could be attributable to increased ventricular ejection velocities and volumes and/or increased arterial stiffness. The objective of this study was to examine the contributions of cardiac (ventricular ejection) and vascular (systemic vascular resistance, arterial stiffness, and pressure wave reflection) properties to primary hypertension in children and adolescents. Methods and Results Children aged 8 to 18 years referred to a tertiary center for evaluation of hypertension and found to have primary hypertension (n=31) were compared with normotensive controls of similar age (n=50). Peripheral (brachial) and central (carotid) blood pressure waveforms and carotid-femoral pulse wave velocity were measured by tonometry. Left ventricular outflow tract velocities and ejection volumes were measured by echocardiography. Wave separation and wave intensity analysis were used to assess pressure wave propagation. Increased mean arterial pressure in hypertensive children (90±15 versus 76±10 mmHg in hypertensive versus normotensive children; means±SD; P<0.001) was explained by increased heart rate and cardiac output (5.3±2.0 versus 4.5±1.2 L/min adjusted for age and sex; P<0.05) rather than increased systemic vascular resistance (18.0±4.6 versus 19.3±7.3 mmHg/min/mL; P=0.374). A more-marked increase in pulsatility (peripheral pulse pressure 66±21 versus 46±12 mmHg; P<0.001) was explained by increased proximal aortic stiffness (pulse wave velocity, 3.3±1.4 versus 2.5±0.8 m/s; P<0.005) and increased left ventricular ejection velocity (1.33±0.24 versus 1.21±0.18 m/s; P<0.05). Conclusions Cardiac overactivity characterized by increased heart rate and left ventricular ejection velocities and increased proximal pulse wave velocity may be the main cause of primary hypertension in children.