Organ-Specific, Age-Dependent Associations of Steady-State Pressures and Pulsatile Pressure Wave Components With End-Organ Measures

Abstract

BACKGROUND The contribution of steady-state pressures and the forward (Pf) and backward (reflected) (Pb) wave pressure components of pulse pressure to risk prediction have produced contrasting results. We hypothesized that the independent contribution of steady-state pressures (mean arterial pressure [MAP]), Pf and Pb, to cardiovascular damage is organ specific and age dependent. METHODS In 1,384 black South Africans from a community sample, we identified independent relations between MAP, Pf, or Pb (applanation tonometry and SphygmoCor software) and left ventricular mass index (LVMI) (n = 997) (echocardiography), carotid intima-media thickness (IMT) (n = 804) (B-mode ultrasound), or aortic pulse wave velocity (PWV) (n = 1,217). RESULTS Independent of risk factors, relations between Pf and IMT were noted in those over 50 years (P < 0.02), whereas in those less than 50 years, MAP (P < 0.005) was independently associated with IMT. Pb failed to show independent relations with IMT at any age (P > 0.37) In contrast, independent relations between Pb and LVMI were noted in those less than (P < 0.0001), and greater than (P < 0.02) 50 years, whereas MAP was not independently associated with LVMI at any age (P > 0.07) and Pf tended to show significant relations only in the elderly (P = 0.05). Moreover, although MAP (P < 0.005) and Pb (P < 0.01) showed independent relations with PWV at any age, Pf failed to show independent relations (P > 0.10). CONCLUSION Independent of confounders, steady-state and aortic Pf and Pb show associations with end-organ measures that are organ specific and age dependent.

Backward in Coming Forward

“…This association remained significant after adjusting for confounding factors, such as treatment for hypertension, smoking, and lipid profiles. 9 These results confirm the findings by Chirinos et al 10 who showed that arterial wave reflections generally arrive at the central aorta in mid to late systole, thus increasing myocardial stress by increasing left ventricular (LV) afterload and pressure in late systole, and subsequently leading to an increase in left ventricular mass (LVM). In contrast, the data from Kolkenbeck-Ruh et al 9 demonstrate that the Pf was independently associated with cIMT, but only in older subjects.…”

“…These findings suggest local pulsatile mechanical load contributes toward arterial remodeling. 11 Finally, Kolkenbeck-Ruh et al 9 show that both MAP and Pb are associated with aortic PWV in both age categories. This seems logical, as PWV is mainly determined by the MAP at the time of measurement, whereas, wave reflections are determined by the properties of the peripheral arteries, such as stiffness.…”

“…Kolkenbeck-Ruh et al 9 report that ventricular mass index is associated with Pb in both young and old subjects. This association remained significant after adjusting for confounding factors, such as treatment for hypertension, smoking, and lipid profiles.…”

“…The backward wave, also known as the reflected wave, is generated by the reflection of the forward wave from the peripheral arteries and hence, the amplitude of the reflected wave is influenced by the characteristics of the peripheral vasculature, such as diameter and compliance, at the major sites of reflection. 8 Data published in this issue of American Journal of Hypertension by Kolkenbeck-Ruh et al 9 explore the differential contributions of steady-state pressure and pulsatile pressure components to various measures of vascular end-organ damage (ventricular mass index, carotid intima media thickness [cIMT], and aortic PWV) across the adult life span. 9 Their present data are taken from a relatively large population-based, cross-sectional cohort of subjects recruited from families of black African descent in Johannesburg, South Africa.…”

“…8 Data published in this issue of American Journal of Hypertension by Kolkenbeck-Ruh et al 9 explore the differential contributions of steady-state pressure and pulsatile pressure components to various measures of vascular end-organ damage (ventricular mass index, carotid intima media thickness [cIMT], and aortic PWV) across the adult life span. 9 Their present data are taken from a relatively large population-based, cross-sectional cohort of subjects recruited from families of black African descent in Johannesburg, South Africa. Detailed hemodynamic profiling was performed, including assessment of the steady-state pressure; mean arterial pressure (MAP) and pulsatile pressure components: Pf and Pb waves.…”