Pressure Dependency Of Stiffness Research Articles

AMBULATORY PULSE PRESSURE COMPONENTS AT AGE 18–40 YEARS CAN PREDICT OUTCOMES

Objective: Risk factors for young adults are of special interest. It has been previously shown that average 24-hour ambulatory pulse pressure (PP) can be expressed as a sum of two components: ‘elastic’ PP (elPP) and ‘stiffening’ PP (stPP) associated, respectively, with arterial stiffness at the diastolic blood pressure (BP) and the pressure dependence of stiffness during the systole. The study objective was to determine elPP and stPP (‘PP components’) from 24-hour ambulatory BP (24-hABP) monitoring and assess their prognostic value for selected types of events for the young age using the International Database of Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO). Design and method: Longitudinal population-based study of young adults age 18–40 years from 9 cohorts; Europeans (6 cohorts), Asians (2 cohorts), and South Americans (1 cohort), with baseline observations that included 24-hABP records of adequate quality at baseline. Participants were followed up for events including the incidence of fatal and non-fatal coronary events and fatal and non-fatal heart failure (‘hard cardiac events’) and that of cerebrovascular death and non-fatal stroke (‘hard cerebrovascular events’). The PP components were determined from the individual 24-hABP record using a previously described procedure. For each PP component the hazard ratio (HR) per 1SD increase was determined using Cox regression model adjusted for cohorts (dummy variables) and the baseline characteristics given in Results. Results: Baseline characteristics of the 2635 participants were age 30 ± 5y, males 46%, average 24-hour ambulatory diastolic BP 70 ± 7 mmHg, and heart rate 75 ± 9 beats/min, body mass index 24 ± 4 Kg/m2, smoking 29%, drinking alcohol 43%, serum cholesterol 5.0 ± 1.1 mg/dL, history of cardiovascular disease 2.8%, diabetes mellitus 1.6%, and on antihypertensive drugs 2.1%. Hard cardiac and hard cerebrovascular events occurred during the 13.6 ± 6.2 years of follow up. The elPP and stPP were weakly correlated (r = 0.39). The table shows the calculated HR. Conclusions: For young adults 24-hour ambulatory elPP (but not stPP) shows protective power for hard cardiac events, while stPP (but not elPP) is a risk factor for hard cerebrovascular events.

Ambulatory pulse pressure components: concept, determination and clinical relevance.

Ambulatory pulse pressure (PP) a well known predictor of mortality, is widely believed to be a marker for arterial stiffness. However stiffness itself is pressure-dependent. Developing a model-based method for splitting PP into two components expressing the contribution of a pressure-independent stiffness ('elastic', elPP) and the pressure-dependence of stiffness ('stiffening', stPP), and investigating their predictive power for all-cause mortality. Deriving quantitative expressions for elPP and stPP assuming an exponential pressure-volume relationship in arteries, calculated from ambulatory blood pressure (BP) data and estimate standardized hazard ratios with Cox proportional hazards regression in selected patient groups. Ambulatory BP records of 1999 consecutive hypertensive patients, of whom 103 died from all causes within 5 years, were analyzed. PP, elPP, stPP and stPP/elPP (PP variables) (mean ± SD) were 60 ± 14, 50 ± 10, 10 ± 8 and 0.20 ± 0.14 mmHg, respectively. elPP and stPP were weakly correlated (r = 0.21). Predictive power was found for patients with heart rate less than 70: mean [95% confidence interval] (P value) hazard ratio of PP, stPP and stPP/elPP (adjusted) were 1.48 [1.13-1.95] (P = 0.005), 1.58 [1.20-2.09] (P = 0.001) and 1.78 [1.25-2.52] (P = 0.001), respectively. The elPP (83% of PP) did not show predictive power. None of the PP variables displayed predictive power for the higher-heart-rate subgroup. Ambulatory PP components provide a novel and clinically valuable tool bridging between PP and arterial properties. Replacing PP by its components, taken as independent variables, may improve predictive power. The prognostic significance of the PP for all-cause mortality in elderly hypertensive patients with lower heart rates is dominated by its smaller component that quantifies arterial stiffening with pressure.

A17970 Ambulatory pulse pressure components

Objectives: Ambulatory pulse pressure (PP) a known predictor of mortality, believed to be an arterial stiffness marker. However stiffness is pressure-dependent. We developed a method for splitting PP into two components expressing the contribution of a pressure-independent stiffness (‘elastic’, elPP) and the pressure-dependence of stiffness (‘stiffening’, stPP), and investigating their predictive power for all-cause mortality. Methods: Deriving quantitative expressions for elPP and stPP assuming an exponential pressure–volume relationship in arteries, calculated from ambulatory BP (ABP) data and estimate standardized hazard ratios with Cox proportional hazards regression in selected patient groups. Results: ABP records of 1,999 consecutive hypertensive patients, of whom 103 died from all causes within 5 years, were analyzed. PP, elPP, stPP and stPP/elPP (‘PP variables’) (mean ± SD) were 60 ± 14, 50 ± 10, 10 ± 8 mmHg, and 0.20 ± 0.14, respectively. elPP and stPP were weak correlated (r = 0.21). Predictive power was found for patients with heart rate < 70: Mean[95%CI](P-value) hazard-ratio of PP, stPP and stPP/elPP (adjusted) were 1.48[1.13–1.95](P = 0.005), 1.58[1.20–2.09](P = 0.001), and 1.78 (1.25–2.52](P = 0.001), respectively The elPP (83%of PP) did not show predictive power. None of the PP variables displayed predictive power for the higher-heart-rate subgroup. Conclusion: Ambulatory PP components provide a novel and clinically valuable tool bridging between PP and arterial properties. Replacing PP by its components, taken as independent variables, may improve predictive power. The prognostic significance of the PP for all-cause mortality in elderly hypertensive patients with lower heart rates is dominated by its smaller component that quantifies arterial stiffening with pressure.