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Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging
Published on: February 7, 2014
Estimation of Wave Condition Number From Pressure Waveform Alone and Its Changes With Advancing Age in Healthy Women
Niema M Pahlevan1,2, Sohrab P Mazandarani3
1Department of Aerospace Mechanical Engineering, University of Southern California, Los Angeles, CA, United States.
Insights
Wave condition number (WCN) can be estimated from a single pressure waveform, simplifying arterial wave reflection analysis. This new method, WCNp, accurately reflects age-related changes in wave reflections in healthy individuals.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Non-invasive Diagnostics
Background:
- Arterial wave reflections are critical for cardiovascular health.
- The wave condition number (WCN) quantifies arterial wave reflections.
- Current WCN calculation requires multiple parameters, limiting clinical use.
Purpose of the Study:
- To assess the feasibility of approximating WCN from pressure waveform alone (WCNp).
- To validate WCNp's ability to capture age-related differences in arterial wave reflection.
Main Methods:
- Retrospective analysis of seventeen patients (age 19-54).
- Calculation of WCN using heart rate (HR), effective length (L), and pulse wave velocity (PWV).
- Approximation of WCNp using HR and reflected wave arrival time from pressure waveform.
Main Results:
- Strong correlation (r=0.83, p<0.0001) between WCNp and WCN.
- WCNp accuracy was independent of PWV, pulse pressure, and HR.
- WCNp demonstrated similar age-related reductions in healthy men and women, decreasing from an optimal ~0.1 in young individuals.
Conclusions:
- WCN can be accurately approximated from a single non-invasive pressure waveform (WCNp).
- WCNp effectively captures age-related alterations in arterial wave reflection.
- WCNp holds significant clinical potential for assessing cardiovascular health.
Introduction:
The wave condition number (WCN) is a non-dimensional number that determines the state of arterial wave reflections. WCN is equal to HR × L /PWV where HR, L , and PWV are the heart rate, effective length, and pulse wave velocity, respectively. It has been shown that a value of WCN = 0.1 indicates the optimum state of arterial wave reflection in which left ventricle workload is minimized. The pressure wave, flow wave, and PWV are all required to compute WCN, which may limit the potential clinical utility of WCN. The aims of this study are as follows: (1) to assess the feasibility of approximating WCN from the pressure waveform alone (WCN ), and (2) to provide the proof-of-concept that WCN can capture age related differences in arterial wave reflection among healthy women and men.
Methods:
Previously published retrospective data composed of seventeen patients (age 19-54 years; 34.3 ± 9.6) were used to assess the accuracy of WCN . The exact value of WCN was computed from PWV (measured by foot-to-foot method), HR, and L . A quarter wavelength relationship with minimum impedance modulus were used to compute L . WCN was calculated using HR and the reflected wave arrival time. Previously published analyses from a healthy subset of the Anglo-Cardiff Collaborative Trial (ACCT) study population were used to investigate if non-invasive WCN captures age related differences in arterial wave reflection among healthy women and men.
Results:
A strong correlation (r = 0.83, p-value <0.0001) between WCN and WCN was observed. The accuracy of WCN was independent from relevant physiological parameters such as PWV, pulse pressure (PP), and HR. Similar changes in WCN with advancing age were observed in both healthy men and healthy women. In young, healthy individuals (women and men) the WCN was around 0.1 (the optimum value), and reduced with aging.
Conclusion:
WCN can be approximated from a single pressure waveform and can capture age related arterial wave reflection alteration. These results are clinically significant since WCN can be extracted from a single non-invasive pressure waveform. Future studies will focus on investigating if WCN is associated with risk for onset of cardiovascular disease events.
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