title: Validity and reliability of diastolic pulse contour analysis (windkessel model) in humans.
abstract: The present study assessed (1) the impact of the measurement site (lower versus upper extremity) on the corresponding compliance variables and (2) the overall reliability of diastolic pulse contour (Windkessel-derived) analysis in normal and hypertensive subjects. Arterial tonograms were recorded in the supine position from the radial and posterior tibial arteries in 20 normotensive (116+/-12/68+/-8 mm Hg) and 27 essential hypertensive subjects (160+/-16/94+/-14 mm Hg). Ensemble-averaged data for each subject were fitted to a first-order lumped-parameter model (basic Windkessel) to compute whole-body arterial compliance (C(A)) and to a third-order lumped-parameter model (modified Windkessel) to compute proximal compliance (C(1)) and distal compliance (C(2)). Despite high-fidelity waveforms in each subject, the first-order Windkessel model did not yield interpretable (positive) values for C(A) in 50% of normotensives and 41% of hypertensives, whereas the third-order model failed to yield interpretable C(1) or C(2) results in 15% of normotensives and 41% of hypertensives. No between-site correlations were found for the first-order time constant, 2 of the 3 third-order model curve-fitting constants, or C(A), C(1), or C(2) (P>0.50). Mean values for all 3 compliance variables were higher for the leg than the arm (P<0.05 each). We conclude that differences in Windkessel-derived compliance values in the arm and leg invalidate whole-body model assumptions and suggest a strong influence of regional circulatory properties. The validity and utility of Windkessel-derived variables is further diminished by the absence of between-site correlations and the common occurrence of uninterpretable values in hypertensive subjects.
authors.affiliation: Division of Clinical Pharmacology, Department of Medicine, State University of New York at Buffalo, NY, USA.
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Manning
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Shykoff
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Izzo
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D003971:Diastole; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011674:Pulse; D017534:Radial Artery / Q000502:physiology; D015203:Reproducibility of Results; D016909:Tibial Arteries / Q000502:physiology