NONOINVASIVE DETECTION OF VESSEL STIFFNESS FROM CONTINUOUS BLOOD PRESSURE RECORDINGS IN HYPERTENSIVE PATIENTS

Hypertension belongs among the most important risk factors contributing to cardiovascular (CV) morbidity and mortality. This study presents parameters computed from a derivative continuous blood pressure (BP) signal, these parameters reflect dynamic properties of BP changes closely connected with vessel stiffness.
Methods: The protocol includes 5-minute measurement with paced breathing at 0.1 Hz in the supine position. ECG and BP (Finapres -2300, Ohmeda) were continuously recorded, the signals were digitalized and processed with software ANNAlab ScopeWin ANS.
Study groups: We measured 4 groups of patients: 12 young healthy individuals (YH, age 26±4, 4 female), 10 old healthy individuals (OH, age 54±10, 2 female), 12 patients with non-medicated hypertension (H1, age 31±9, 3 female) and 16 non-medicated hypertensive patients with additional risk factors (obesity, hyperlipidemia, diabetes mellitus).
Parameters: The mean and standard deviation values were computed, the following key parametrs were obtained and compared between the groups: RR intervals, SBP, DBP, pulse pressure, RR variability RSTD, SBP and DBP variability STD, maximum and minimum of derivative BP – dBP/dtmax and dBP/dtmin, difference ΔdBP = dBP/dtmax - dBP/dtmin, depression time T2 = dBP/dtmax - dBP/dtmin.
Results: The fundamental parameters are SBP and pulse pressure, which as expected differentiate between normotensive and hypertensive groups. Interval RR was shorter in the hypertension group, but the difference was not significant. Substantial differences were found between groups H1 and H2 in dynamic parameters: dBP/dtmax, dBP/dtmin, ΔdBP, T2. The results showed steeper rise of BP in the group H2. Groups H1 and H2 were equivalent in traditional markers of CV risk such as BP and HR, however the higher stiffness and lower compliance of vessels reflect in dynamic parameters.