Hemodynamic Correlates of Blood Pressure Across the Adult Age Spectrum

Abstract

Background-Systolic blood pressure and pulse pressure are substantially higher in older adults. The relative contributions of increased forward versus reflected pressure wave amplitude or earlier arrival of the reflected wave to elevated pulse pressure remain controversial. Methods and Results-We measured proximal aortic pressure and flow, forward pressure wave amplitude, global wave reflection, reflected wave timing, and pulse wave velocity noninvasively in 6417 (age range, 19 to 90 years; 53% women) Framingham Heart Study Third Generation and Offspring participants. Variation in forward wave amplitude paralleled pulse pressure throughout adulthood. In contrast, wave reflection and pulse pressure were divergent across adulthood: In younger participants, pulse pressure was lower and wave reflection was higher with advancing age, whereas in older participants, pulse pressure was higher and wave reflection was lower with age. Reflected wave timing differed modestly across age groups despite considerable differences in pulse wave velocity. Forward wave amplitude explained 80% (central) and 66% (peripheral) of the variance in pulse pressure in younger participants (Ͻ50 years) and 90% and 84% in the older participants (Ն50 years; all PϽ0.0001). In a stepwise model that evaluated age-pulse pressure relations in the full sample, the late accelerated increases in central and peripheral pulse pressure were markedly attenuated when variation in forward wave amplitude was considered. Conclusions-Higher pulse pressure at any age and higher pulse pressure with advancing age is associated predominantly with a larger forward pressure wave. The influence of wave reflection on age-related differences in pulse pressure was minor. (Circulation. 2010;122:1379-1386.)Key Words: aorta Ⅲ blood pressure Ⅲ epidemiology Ⅲ hemodynamics B lood pressure increases substantially with advancing age across the full human lifespan; however, patterns of change in various blood pressure components (systolic, diastolic, mean, and pulse pressures) are complex and nonlinear. 1 The pathogenesis of nonlinear age trajectories of blood pressure components has been debated vigorously in recent years. There is general agreement that mean arterial pressure increases in young adulthood and then remains relatively stable in middle-aged and older adults. 2 The early increase in mean arterial pressure is a manifestation of greater cardiac output or peripheral resistance, possibly a result of activation of the sympathetic nervous system, hypervolemia, or smallvessel disease or dysfunction. 3 From midlife on, when hypertension is prevalent, systolic and pulse pressures increase substantially, mean arterial pressure plateaus, and diastolic pressure falls. 1,2 Thus, a considerable majority of the population burden of hypertension is associated with increasing pulse pressure with advancing age. Clinical Perspective on p 1386The hemodynamic mechanisms underlying the increase in pulse pressure from midlife on remain unclear. A contemporary view asserts that increasi...

Racial Differences in Arterial Stiffness are Mainly Determined by Blood Pressure Levels: Results From the ELSA‐Brasil Study

“…In this study, the prevalence of altered cf‐PWV was 69%, much higher than the 12% that was found in those who were younger than 50 31. We found that cf‐PWV increased with age in both men and women, even after controlling for the main confounders.…”

“…The Framingham Heart Study31 provided evidence of the effect of age on arterial stiffening in a group of participants aged over 50 years. In this study, the prevalence of altered cf‐PWV was 69%, much higher than the 12% that was found in those who were younger than 50 31.…”

Relations Between Aortic Stiffness and Left Ventricular Mechanical Function in the Community

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“…In a random sample of 50 cases that were blindly re‐analyzed by a second observer, the correlation coefficient was r =0.972 for CFPWV and r =0.997 for augmentation index (AI). Characteristic impedance (Zc) was calculated from the ratio of change in carotid pressure and the change in flow in the proximal aorta during early systole 26. Early systole was defined as the time interval between the onset of flow and the time that flow reaches 95% of its maximum value.…”

Misinterpretation of the Determinants of Elevated Forward Wave Amplitude Inflates the Role of the Proximal Aorta

“…The prevalent view regarding changes in PP with age considers that increased pulse wave velocity (PWV), associated with vascular stiffening,4 and the consequent earlier return of reflected waves, prominently contribute to elevated PP 2, 5, 6, 7, 8, 9, 10. Recent reports from Framingham investigators have promoted a controversial viewpoint that increased forward wave amplitude (FWA), which is proposed to result from a mismatch between aortic root properties and peak aortic flow, is the predominant contributor to elevated PP with aging, with only modest contributions from wave reflections 11, 12, 13. In steady‐state conditions, peak aortic flow is sensitive to wave reflections and properties of the vascular tree distal to the aortic root 14, 15.…”