A Newly-Developed Method of Measuring Local Pulse Wave Velocity for Assessing of Severiy of Arteriosclerosis and Characteristics of Endotherial-Dependent Vasodilation

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We propose a new method for local -measurement of the propagation velocity of a pulse wave for the quantitative evaluation of severity of atherosclerosis. This method uses a complex cross correlation of Doppler signals and, theoretically, has the potential for precise estimation of the propagation time of a pulse wave of less than 1 millisecond. Doppler signals shifted by blood flow are detected at two adjacent locations on the artery using the simultaneous two-gate pulsed Doppler method, stored in a computer, and then analyzed by cross correlation. Time delay at maximum correlation output gives propagation time of the pulse wave. The pulse wave velocity is calculated as the ratio between the distance separating the two transducers and the time delay. In an experimental study using a pulsatile. flow circuit model, regardless of sampling distance and flow velocity profile, there was little fluctuation in calculated pulse wave velocity. Practical velocity resolution. of this method was e … More stimated to be less than 2 m/sec, which is sufficient accuracy for measurement of local pulse wave velocity (LPWV) over a 2 cm distance. In a study in vivo of healthy volunteer, LPWV was faster in the femoral artery (6.4±0.8 m/sec) than in the carotid artery (4.8±0.5 m/sec) and abdominal aorta (4.0±0.5 m/sec).A new ultrasound system measuring LPWV has been developed, which can detect LPWV at 2 close points. The system is used to assess :1.LPWV foot-to-foot along abdominal aorta of normal and hypercholesterolemic rabbits. 2.Vascular responses to acetylcholine in conditions of inhibition of NO synthesis by L-NAME and augmentation of NO synthesis by L-NAME and L-arginine Results : (1)LPWV increases from proximal to distal along abdominal aorta of normal and hypercholesterolemic rabbits. In corresponding region, LPWV in hypercholesterolemic rabbits is higher than in normal ones, despite different sample distances. (2)L-NAME inhibits vascular relaxation to acetylcholine (Ach), Concurrent administration of L-arginine and L-NAME restores relaxation to Ach in normal rabbits, L-NAME attenuates relaxation to acetylcholine (Ach), L-arginine along with L-NAME slightly reverses relaxation to acetylcholine in hypercholesterolemic rabbits. (3)Plasma cyclic GMP is unchanged in situations of L-NAME alone or L-arginine plus L-NAME in normal and hypercholesterolemic rabbits. Conclusion : The new system is non-invasive and easy to be operated and can detect LPWV alterations, so it is worth being used to assess local vascular alteration Less