[A new hemodynamic endothelial approach using non-invasive evaluation of instantaneous wall shear in human arteries. Application in arterial hypertension].
A new non-invasive methodology of measurement of pulsatile wall shear in superficial large arteries in man is presented from simple determinations of internal diameter of large artery and centerline instantaneous blood velocity (pulsed Doppler apparatus) and asymptotic blood viscosity (coaxial cylinder viscometer). Pulsatile distribution of velocity across the arterial lumen has been represented by a Womersley model enabling to define and calculate wall shear rate as the slope at the wall to the velocity profile at each cardiac time. These complex mathematical calculations have been performed on micro-computer by means of appropriate programmation according to the following steps (1) Digitization and processing of instantaneous centerline blood velocity (2) Decomposition of velocity signal into Fourier series as a sum of elementary velocity sinusoids of increasing frequency (3) computation of velocity profile and slope at the wall to the profile for each harmonic (4) Resynthetization of instantaneous wall shear rate as function in time (5) calculation of wall shear stress by multiplying wall shear rate by blood viscosity. Taking the brachial artery as model of peripheral large artery, pulsatile wall shear rate and stress curves were determined in individual subjects and analysed by means of several characteristic indices including: maximum, minimum and mean values; time of systolic increase and time of systolic relaxation; and oscillating index defined from the positive and negative surfaces of the shear curve. This original methodology open new way for studying hemodynamical conditions at the interface between blood and endothelium surface of large arteries and might be applied to the physiopharmacological approach of vascular disease such as hypertension.
Colin
J M
JM
Unité INSERM U 28, hôpital Broussais, Paris.
Del-Pino
M
M
Aouate
J P
JP
Flaud
P
P
Levenson
J
J
Simon
A
A
D000328:Adult; D001783:Blood Flow Velocity; D001809:Blood Viscosity; D001916:Brachial Artery; D004730:Endothelium, Vascular / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D011673:Pulsatile Flow; D012212:Rheology; D013314:Stress, Mechanical
Nouvelle approche hémodynamique endothéliale par évaluation non invasive du cisaillement pariétal instantané dans les artères humaines. Application à l'hypertension artérielle.