Abstract

AIM: To analyze the spectral characteristics of the pre- and poststenotic arterial flow patterns in cases with simulated stenosis. MATERIAL AND METHODS: The study was conducted on 21 healthy volunteers, by using Toshiba Nemio XG color Doppler instrument and a 11 MHz linear array probe. In each case stenosis was simulated by inflating a sphygmomanometer cuff over the brachial artery up to 180 mm Hg. Four different brachial artery signals were obtained at two different arterial segments: 1. Proximal to the cuff, before and after inflation (simulation of prestenotic flow), and 2. distal to the cuff, before and after inflation (simulation of poststenotic flow). The signal was conveyed from the audio output of the Doppler instrument to a personal PC, in which Fourier transform operations using Mathlab software (Version 7.1). For statistical study, two different set of data within each segment (normal v.s. Pre- or poststenotic flow) were compared. The comparative data were Pulsatility Index, flow rate, maximum power spectral density and the frequency corresponding to maximum power spectral density in case of prestenotic flow, whereas they were maximum systolic velocity, end diastolic velocity, the difference between the former and the latter, flow rate, maximum power spectral density and the frequency corresponding to maximum power spectral density in case of poststenotic flow. FINDINGS: Increased distal arterial resistance resulted in: 1. An increased Pulsatiliy Index; and 2. Decreased flow volume and maximum power spectral density. In poststenotic flow, the frequency components in maximum power spectrum shifted to the earlier phases of systole, along with a decrease in the maximum systolic velocity, increase in the end diastolic velocity, decrease in the flow volume and maximum power spectral density. In both settings, the frequency corresponding to maximum power spectral density did not show a significant change. CONCLUSION: Confirmed by clinical studies, these finding may serve as a surrogate marker for arterial pulsatility and/or “tardus” component in the poststenotic flow.