Background It is assumed that the initial phase of primary hypertension (PH) is characterized by the presence of hyperkinetic circulation. However, the relationship between blood pressure status (from normal blood pressure to severe ambulatory hypertension) and haemodynamic patterns in children with PH were not described. The objective of this study was to characterize the haemodynamic parameters such as cardiac index (CI) and a total peripheral resistance index (TPR) in children with PH depending on the stage of hypertension.

Materials and methods The study included 95 patients (15.3 ± 2.0 years; 27 girls) referred due to the elevated blood pressure, in whom secondary hypertension was excluded. Pulse wave velocity (PWV), CI and TPRI were assessed indirectly using Vicorder device. PH was diagnosed according to the European Society of Hypertension paediatric guidelines and confirmed by 24-hour ambulatory BP monitoring (ABPM).

Results Of 95 patients, 31 had normal blood pressure, 14 prehypertension, 7 ambulatory hypertension and 43 severe ambulatory hypertension. Comparison of the mean values of cardiac index (CI) for each group showed significant increase in CI linked to the category of hypertension. CI increase was accompanied by a non-significant decrease of TPR. Mean CI values correlated with 24-hour mean arterial pressure, 24-hour heart rate, PWV-SDS and systolic blood pressure load. Mean TPR values correlated with anthropometrical parameters, including negative correlation with waist circumference and positive with 24- hour mean arterial pressure and negative with pulse wave velocity. Stepwise regression analysis showed no predictors for CI, but for TPR the only predictor was waist circumference

Conclusions Children with PH are characterized by haemodynamic patterns typical of hyperkinetic circulation increasing with increasing stage of hypertension. Non-significant decrease in TPR in children with increased CI explains haemodynamic basis of elevation of blood pressure. Visceral Obesity expressed as a waist circumference seems to play role in the mechanism of the development of hyperkinetic circulation.