Noninvasively and invasively measured pulsatile haemodynamics with graded arterial stenosis

Pulsatile haemodynamics associated with graded degrees of experimentally produced stenosis were studied in the canine femoral artery. Invasively determined pulsatile blood flow and noninvasively determined blood velocity with Doppler ultrasound were measured an average of 1.3 and 2.3 cm proximal to the stenosis, respectively. Pulsatile blood pressure was measured 0.6 cm proximal and 3.7 cm distal to the stenosis. With increasing severity of stenosis there were progressive increases in the femoral artery hydraulic input impedance moduli and in the ratio of the impedance moduli to the zero harmonic impedance (or total resistance). This resulted in: a) a progressive reduction in the Fourier harmonic moduli and pulsewave amplitudes of flow, velocity, and distal pressure; b) a progressive increase in the fifth-seventh proximal pressure harmonic moduli; but c) little change in mean proximal pressure or its first 4 harmonic moduli. The data confirm the well known phenomena of a 'critical stenosis' in that there is little decrease in resting mean blood flow until there is a 70 to 80 stenosis (area reduction). Also the oscillatory portions of the femoral artery data were more sensitive to the changes in stenosis than were the nonoscillatory parameters, which confirms previously reported findings from the thoracic aorta. However, the femoral artery haemodynamics exhibited a greater amount of frequency dependent behaviour than the thoracic aorta which is probably the result of a more complex interaction of reflections from the stenosis and from the periphery in the femoral artery than in the thoracic aorta. The sensitive changes in oscillatory haemodynamics may provide a useful basis for noninvasive and invasive physiological assessment of human peripheral atherosclerotic stenosis and of experimental stenosis in animals.