BLOOD PRESSURE LEVEL AND DURATION OF HYPERTENSION AS PARAMETERS ASSOCIATED WITH CEREBRAL HEMODYNAMICS IN HYPERTENSION: PP.8.323

Abstract

Objective: To check, in a group of hypertensive patients the association between blood flow-related parameters of hemodynamics in middle cerebral artery (MCA) and systolic (SBP), diastolic (DBP) blood pressure and duration of hypertension (HT-time) and age. Design and Methods: The study was cross-sectional. Transcranial Doppler (TCD) examination was performed bilaterally. The MCAs were insonated through transtemporal window, and pulsatility (PI), resistance (RI) indexes and mean cerebral blood flow velocity (CBFV) were calculated. Blood pressures were measured conventionally in accordance with current guidelines. Results: Mean ± SD age of 96 patients was 58.7 ± 11.9 years. The group comprised 52.1% men, 18.9% smokers, 8.3% took nitrates (which in exploratory analyses were the only class of medications influencing PI and RI). Mean ± SD SBP/DBP was 142.6 ± 19.5/91.9 ± 12.6 mm Hg, mean PI was 0.97 ± 0.21, RI 0.59 ± 0.06 and CBFV 0.58 ± 0.17 m/s. The duration of hypertension averaged 9.5 ± 8.6 years. In multiple regression models adjusted for sex, age, smoking and use of nitrates, with SBP, DBP and HT-time forced into one model, neither duration of hypertension (p = 0.58) nor level of SBP(p = 0.60) or DBP (p = 0.58) were associated with CBFV. However, SBP (â = 0.003, p = 0.02), DBP (â = -0.007, p = 0.002), and HT-time (â = 0.006, p = 0.004) were significantly associated with PI. In similar analyses SBP (â = 0.0009, p = 0.03), DBP (â = -0.002, p = 0.004), and HT-time (â = 0.002, p = 0.006) were significantly associated with RI. After adjustment for the confounders listed above, HT-time independently explained 8.6% of variation in RI and 9.2% of variation in PI. When SBP or DBP were introduced separately, the percentage of variance in PI or RI explained by HT-time increased to over 11%. Conclusion: SBP and DBP influence PI and RI of middle cerebral artery, however, after adjustment for confounders, duration of hypertension plays a major role explaining about 10% (1/4 of the models' R-square) of variation in PI and RI. This underlines the importance of early adequate treatment of hypertension to protect against such cerebro-vascular complications as stroke or dementia.