Author + information
- James Cameron, MD, MB, BS, BE, MEngSc and
- Anthony M. Dart, BA, BM, BCh, DPhil⁎ ()
- ↵⁎Alfred Hospital Heart Centre, Third Floor, Commercial Road, Melbourne, Victoria 3004, Australia
Cecelja et al. (1) conclude that increased wave reflection, not arterial stiffness, determines pulse pressure, including central pulse pressure (cPP), in women. They base this conclusion on regression analysis showing that the ratio of femoral to aortic diameter (DFA [assumed an index of central-peripheral artery discontinuity and hence of wave reflection]) was a significant determinant of pressure augmentation (ΔPaug) whereas pulse wave velocity (PWV [a measure of arterial stiffness]) was not. However, from Table 3 in their article (1), it appears that DFA accounts for only ≈2% of variation in ΔPaug. In contrast, PWV accounts for 30% of variation in P1.
In analysis of the contribution of P1 and ΔPaug to variance in cPP, the relative contributions (for the whole cohort) were 22% and 76%, respectively. We therefore calculate that PWV contributes 6.6% and DFA 1.5% to cPP variance. From Figure 2 (1), P1 contributes about two-thirds of total cPP (for the whole cohort). For the whole group, the proportional contribution to cPP, therefore, is ≈0.7% for wave reflection and 20% for arterial stiffness (assuming PWV and DFA are indeed appropriate surrogates and using results from Table 3 ).
These analyses suggest an entirely opposite conclusion to the authors. We believe their data are actually consistent with the proposition that arterial stiffness, not wave reflection, is the major determinant of both cPP and its variation in this cohort of women; a lack of association between PWV and T1 is also consistent with this interpretation.
Perhaps the “simple approach” adopted by Cecelja et al. (1) to assessing reflected pressure is overly simplistic. The authors could not formally decompose central blood pressure into forward and reverse going waves (via reflection coefficient or wave-intensity analysis), and there are problems using central T1 to delineate forward and reverse going waves:
1. P1 only represents the full magnitude of ejection wave if any reflected wave arrives after the peak (i.e., T1 is a local minimum rather than an inflection point). Peak ejection pressure would otherwise be lost under the reflected component.
2. ΔPaug does not correspond to the magnitude of any reflected wave; even a small reverse going wave arriving early in ventricular ejection will produce an inflection point interpreted as a large ΔPaug; similarly, a large wave arriving late may result in a small ΔPaug. Reflection site and PWV predominantly determine ΔPaug, not the magnitude of the reflected wave.
3. It is well demonstrated that estimated central T1 obtained by transfer function techniques is unreliable in representing true central inflection point (2,3).
Among women ≥60 years of age, Cecelja et al. (1) observed a small influence of aortic diameter on P1 with no effect of DFA, supporting that aortic stiffness and diameter (4) rather than wave reflection are important in determining PP in this age group in whom it is an important predictor of cardiovascular risk.
- American College of Cardiology Foundation
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