On Calculating the Time-Varying Elastance Curve of a Radial Artery Using a Miniature Vibration Method

Abstract

We examined the time-varying elastance of the radial arterial wall using a minute vibration approach in fifteen volunteers. A sinusoidal displacement of 1.5~2.0 mm with a frequency range from 50 to 100 Hz was used to impose on the superficial radial artery. Meanwhile, a force sensor was used to pick up the contact force exerted by the radial arterial wall. The amplitude of the complex force was found to be negatively proportional to the squared angular frequency imposed on the radial artery. A linear regression line can be obtained using the different frequencies (x-axis) and their force responses (yaxis). The intercept of the regression line with the y-axis denotes the elastance and the slope the effective contact mass. Ten elastance values corresponding to 10 different timings in a cardiac cycle were used to construct a time-varying elastance curve. It was found that the elastance curve fundamentally follows the arterial pressure waveform. In conclusion, we have successfully calculated the arterial elastance values at various cardiac timings by applying the minute vibration method, and the pattern of the elastance curve bears a resemblance to a blood pressure waveform.